{"collection":"scripture-revelation","full_text_available":true,"graph_url":"https://unchartedknowledge.5gfusion.net/v2/api/page/gutenberg_42968/graph","html_url":"https://unchartedknowledge.5gfusion.net/v2/page/gutenberg_42968","id":"gutenberg_42968","license":"Public Domain (US)","rights_basis":"gutenberg_metadata_copyright_false","source":"gutenberg","source_url":"https://www.gutenberg.org/ebooks/42968","summary":null,"tags":["Category: Philosophy & Ethics","Category: Science - Biology","Evolution","Monism","Religion and science","Soul"],"text":"Transcriber's Note:\n\n    Every effort has been made to replicate this text as faithfully as\n    possible, including inconsistencies in hyphenation. It seems that\n    the italic typeface used in this book did not have an ae ligature.\n    Names of genera and higher taxonomic groups are not capitalized in\n    the printed book: they have bee left unchanged. Some changes have\n    been made. They are listed at the end of the text.\n\n    Italic text has been marked with _underscores_.\n    OE ligatures have been expanded.\n\n\n\n\nTHE RIDDLE OF THE UNIVERSE\n\n\n[Illustration: ERNST HAECKEL]\n\n\n\n\n                               THE RIDDLE\n                            OF THE UNIVERSE\n\n                            _AT THE CLOSE OF\n                        THE NINETEENTH CENTURY_\n\n                                   BY\n\n                             ERNST HAECKEL\n\n            (Ph.D., M.D., LL.D., Sc.D., and Professor at the\n                          University of Jena)\n\n                  AUTHOR OF \"THE HISTORY OF CREATION\"\n                      \"THE EVOLUTION OF MAN\" ETC.\n\n                             TRANSLATED BY\n\n                             JOSEPH McCABE\n\n                             [Illustration]\n\n                      HARPER & BROTHERS PUBLISHERS\n                          NEW YORK AND LONDON\n                                  1905\n\n\n\n\n                 Copyright, 1900, by HARPER & BROTHERS.\n\n                         _All rights reserved._\n\n\n\n\nCONTENTS\n\n\n                                       PAGE\n\n    AUTHOR'S PREFACE                      v\n\n    TRANSLATOR'S PREFACE                 xi\n\n    CHAPTER I\n    THE NATURE OF THE PROBLEM             1\n\n    CHAPTER II\n    OUR BODILY FRAME                     22\n\n    CHAPTER III\n    OUR LIFE                             39\n\n    CHAPTER IV\n    OUR EMBRYONIC DEVELOPMENT            53\n\n    CHAPTER V\n    THE HISTORY OF OUR SPECIES           71\n\n    CHAPTER VI\n    THE NATURE OF THE SOUL               88\n\n    CHAPTER VII\n    PSYCHIC GRADATIONS                  108\n\n    CHAPTER VIII\n    THE EMBRYOLOGY OF THE SOUL          132\n\n    CHAPTER IX\n    THE PHYLOGENY OF THE SOUL           148\n\n    CHAPTER X\n    CONSCIOUSNESS                       170\n\n    CHAPTER XI\n    THE IMMORTALITY OF THE SOUL         188\n\n    CHAPTER XII\n    THE LAW OF SUBSTANCE                211\n\n    CHAPTER XIII\n    THE EVOLUTION OF THE WORLD          233\n\n    CHAPTER XIV\n    THE UNITY OF NATURE                 254\n\n    CHAPTER XV\n    GOD AND THE WORLD                   275\n\n    CHAPTER XVI\n    KNOWLEDGE AND BELIEF                292\n\n    CHAPTER XVII\n    SCIENCE AND CHRISTIANITY            308\n\n    CHAPTER XVIII\n    OUR MONISTIC RELIGION               331\n\n    CHAPTER XIX\n    OUR MONISTIC ETHICS                 347\n\n    CHAPTER XX\n    SOLUTION OF THE WORLD-PROBLEMS      365\n\n    CONCLUSION                          380\n\n    INDEX                               385\n\n\n\n\nAUTHOR'S PREFACE\n\n\nThe present study of the monistic philosophy is intended for thoughtful\nreaders of every condition who are united in an honest search for the\ntruth. An intensification of this effort of man to attain a knowledge\nof the truth is one of the most salient features of the nineteenth\ncentury. That is easily explained, in the first place, by the immense\nprogress of science, especially in its most important branch, the\nhistory of humanity; it is due, in the second place, to the open\ncontradiction that has developed during the century between science\nand the traditional \"Revelation\"; and, finally, it arises from the\ninevitable extension and deepening of the rational demand for an\nelucidation of the innumerable facts that have been recently brought to\nlight, and for a fuller knowledge of their causes.\n\nUnfortunately, this vast progress of empirical knowledge in our\n\"Century of Science\" has not been accompanied by a corresponding\nadvancement of its theoretical interpretation--that higher knowledge of\nthe causal nexus of individual phenomena which we call philosophy. We\nfind, on the contrary, that the abstract and almost wholly metaphysical\nscience which has been taught in our universities for the last hundred\nyears under the name of \"philosophy\" is far from assimilating our\nhard-earned treasures of experimental research. On the other hand, we\nhave to admit, with equal regret, that most of the representatives\nof what is called \"exact science\" are content with the special care\nof their own narrow branches of observation and experiment, and\ndeem superfluous the deeper study of the universal connection of\nthe phenomena they observe--that is, philosophy. While these pure\nempiricists \"do not see the wood for the trees,\" the metaphysicians, on\nthe other hand, are satisfied with the mere picture of the wood, and\ntrouble not about its individual trees. The idea of a \"philosophy of\nnature,\" to which both those methods of research, the empirical and the\nspeculative, naturally converge, is even yet contemptuously rejected by\nlarge numbers of representatives of both tendencies.\n\nThis unnatural and fatal opposition between science and philosophy,\nbetween the results of experience and of thought, is undoubtedly\nbecoming more and more onerous and painful to thoughtful people. That\nis easily proved by the increasing spread of the immense popular\nliterature of \"natural philosophy\" which has sprung up in the course\nof the last half-century. It is seen, too, in the welcome fact that,\nin spite of the mutual aversion of the scientific observer and the\nspeculative philosopher, nevertheless eminent thinkers from both\ncamps league themselves in a united effort to attain the solution\nof that highest object of inquiry which we briefly denominate the\n\"world-riddles.\" The studies of these \"world-riddles\" which I offer in\nthe present work cannot reasonably claim to give a perfect solution of\nthem; they merely offer to a wide circle of readers a critical inquiry\ninto the problem, and seek to answer the question as to how nearly we\nhave approached that solution at the present day. What stage in the\nattainment of truth have we actually arrived at in this closing year of\nthe nineteenth century? What progress have we really made during its\ncourse towards that immeasurably distant goal?\n\nThe answer which I give to these great questions must, naturally, be\nmerely subjective and only partly correct; for my knowledge of nature\nand my ability to interpret its objective reality are limited, as are\nthose of every man. The one point that I can claim for it, and which,\nindeed, I must ask of my strongest opponents, is that my Monistic\nPhilosophy is sincere from beginning to end--it is the complete\nexpression of the conviction that has come to me, after many years of\nardent research into Nature and unceasing reflection, as to the true\nbasis of its phenomena. For fully half a century has my mind's work\nproceeded, and I now, in my sixty-sixth year, may venture to claim\nthat it is mature; I am fully convinced that this \"ripe fruit\" of the\ntree of knowledge will receive no important addition and suffer no\nsubstantial modification during the brief spell of life that remains to\nme.\n\nI presented all the essential and distinctive elements of my monistic\nand genetic philosophy thirty-three years ago, in my _General\nMorphology of Organisms_, a large and laborious work, which has had but\na limited circulation. It was the first attempt to apply in detail the\nnewly established theory of evolution to the whole science of organic\nforms. In order to secure the acceptance of at least one part of the\nnew thought which it contained, and to kindle a wider interest in the\ngreatest advancement of knowledge that our century has witnessed, I\npublished my _Natural History of Creation_ two years afterwards.\nAs this less complicated work, in spite of its great defects, ran\ninto nine large editions and twelve different translations, it has\ncontributed not a little to the spread of monistic views. The same\nmay be said of the less known _Anthropogeny_[1] (1874), in which I\nset myself the difficult task of rendering the most important facts\nof the theory of man's descent accessible and intelligible to the\ngeneral reader; the fourth, enlarged, edition of that work appeared in\n1891. In the paper which I read at the fourth International Congress\nof Zoology at Cambridge, in 1898, on \"Our Present Knowledge of the\nDescent of Man\"[2] (a seventh edition of which appeared in 1899), I\ntreated certain significant and particularly valuable advances which\nthis important branch of anthropology has recently made. Other isolated\nquestions of our modern natural philosophy, which are peculiarly\ninteresting, have been dealt with in my _Collected Popular Lectures on\nthe Subject of Evolution_ (1878). Finally, I have briefly presented\nthe broad principles of my monistic philosophy and its relation to the\ndominant faith in my _Confession of Faith of a Man of Science: Monism\nas a Connecting Link between Religion and Science_[3] (1892, eighth\nedition, 1899).\n\nThe present work on _The Riddle of the Universe_ is the continuation,\nconfirmation, and integration of the views which I have urged for a\ngeneration in the aforesaid volumes. It marks the close of my studies\non the monistic conception of the universe. The earlier plan, which\nI projected many years ago, of constructing a complete \"System of\nMonistic Philosophy\" on the basis of evolution will never be carried\ninto effect now. My strength is no longer equal to the task, and many\nwarnings of approaching age urge me to desist. Indeed, I am wholly a\nchild of the nineteenth century, and with its close I draw the line\nunder my life's work.\n\nThe vast extension of human knowledge which has taken place during\nthe present century, owing to a happy division of labor, makes\nit impossible to-day to range over all its branches with equal\nthoroughness, and to show their essential unity and connection.\nEven a genius of the highest type, having an equal command of every\nbranch of science, and largely endowed with the artistic faculty of\ncomprehensive presentation, would be incapable of setting forth a\ncomplete view of the cosmos in the space of a moderate volume. My own\ncommand of the various branches of science is uneven and defective,\nso that I can attempt no more than to sketch the general plan of such\na world-picture, and point out the pervading unity of its parts,\nhowever imperfect be the execution. Thus it is that this work on the\nworld-enigma has something of the character of a sketch-book, in which\nstudies of unequal value are associated. As the material of the book\nwas partly written many years ago, and partly produced for the first\ntime during the last few years, the composition is, unfortunately,\nuneven at times; repetitions, too, have proved unavoidable. I trust\nthose defects will be overlooked.\n\nIn taking leave of my readers, I venture the hope that, through my\nsincere and conscientious work--in spite of its faults, of which I am\nnot unconscious--I have contributed a little towards the solution\nof the great enigma. Amid the clash of theories, I trust that I have\nindicated to many a reader who is absorbed in the zealous pursuit of\npurely rational knowledge that path which, it is my firm conviction,\nalone leads to the truth--the path of empirical investigation and of\nthe Monistic Philosophy which is based upon it.\n\n                                                          ERNST HAECKEL.\n\nJENA, GERMANY.\n\n\n\n\nPREFACE\n\n\nThe hour is close upon us when we shall commence our retrospect of one\nof the most wonderful sections of time that was ever measured by the\nsweep of the earth. Already the expert is at work, dissecting out and\nstudying his particular phase of that vast world of thought and action\nwe call the nineteenth century. Art, literature, commerce, industry,\npolitics, ethics--all have their high interpreters among us; but in\nthe chance of life it has fallen out that there is none to read aright\nfor us, in historic retrospect, what after ages will probably regard\nas the most salient feature of the nineteenth century--the conflict\nof theology with philosophy and science. The pens of our Huxleys,\nand Tyndalls, and Darwins lie where they fell; there is none left in\nstrength among us to sum up the issues of that struggle with knowledge\nand sympathy.\n\nIn these circumstances it has been thought fitting that we should\nintroduce to English readers the latest work of Professor Haeckel.\nGermany, as the reader will quickly perceive, is witnessing the same\nstrange reaction of thought that we see about us here in England,\nyet _Die Weltr\u00e4thsel_ found an immediate and very extensive circle\nof readers. One of the most prominent zoologists of the century,\nProfessor Haeckel, has a unique claim to pronounce with authority, from\nthe scientific side, on what is known as \"the conflict of science and\nreligion.\" In the contradictory estimates that are urged on us--for\nthe modern ecclesiastic is as emphatic in his assurance that the\nconflict has ended favorably to theology as the rationalist is with his\ncounter-assertion--the last words of one of the leading combatants of\nthe second half of the century, still, happily, in full vigor of mind,\nwill be heard with respect and close attention.\n\nA glance at the index of the work suffices to indicate its comprehensive\ncharacter. The judgment of the distinguished scientist cannot fail\nto have weight on all the topics included; yet the reader will soon\ndiscover a vein of exceptionally interesting thought in the chapters\non evolution. The evolution of the human body is no longer a matter\nof serious dispute. It has passed the first two tribunals--those of\ntheology and of an _\u00e0 priori_ philosophy--and is only challenged at the\nthird and last--that of empirical proof--by the decorative heads of\nscientific bodies and a few isolated thinkers.\n\n    \"_Apparent rari nantes in gurgite vasto._\"\n\nBut the question of the evolution of the human mind, or soul, has been\nsuccessfully divorced from that of the body. Roman Catholic advanced\ntheologians, whose precise terminology demanded a clear position, admit\nthe latter and deny the former categorically. Other theologians, and\nmany philosophers, have still a vague notion that the evidence for\nthe one does not impair their sentimental objection to the other. Dr.\nHaeckel's work summarizes the evidence for the evolution of mind in\na masterly and profoundly interesting fashion. It seems impossible to\nfollow his broad survey of the psychic world, from protist to man,\nwithout bearing away a conviction of the natural origin of every power\nand content of the human soul.\n\n                                                             TRANSLATOR.\n\n_October, 1900._\n\n\n\n\nTHE RIDDLE OF THE UNIVERSE\n\n\n\n\nCHAPTER I\n\nTHE NATURE OF THE PROBLEM\n\n    The Condition of Civilization and of Thought at the Close of\n    the Nineteenth Century--Progress of Our Knowledge of Nature,\n    of the Organic and Inorganic Sciences--The Law of Substance\n    and the Law of Evolution--Progress of Technical Science and\n    of Applied Chemistry--Stagnancy in other Departments of\n    Life: Legal and Political Administration, Education, and the\n    Church--Conflict of Reason and Dogma--Anthropism--Cosmological\n    Perspective--Cosmological Theorems--Refutation of the Delusion\n    of Man's Importance--Number of \"World-Riddles\"--Criticism of\n    the \"Seven\" Enigmas--The Way to Solve Them--Function of the\n    Senses and of the Brain--Induction and Deduction--Reason,\n    Sentiment, and Revelation--Philosophy and Science--Experience and\n    Speculation--Dualism and Monism\n\n\nThe close of the nineteenth century offers one of the most remarkable\nspectacles to the thoughtful observer. All educated people are\nagreed that it has in many respects immeasurably outstripped its\npredecessors, and has achieved tasks that were deemed impracticable at\nits commencement. An entirely new character has been given to the whole\nof our modern civilization, not only by our astounding theoretical\nprogress in sound knowledge of nature, but also by the remarkably\nfertile practical application of that knowledge in technical science,\nindustry, commerce, and so forth. On the other hand, however, we have\nmade little or no progress in moral and social life, in comparison with\nearlier centuries; at times there has been serious reaction. And from\nthis obvious conflict there have arisen, not only an uneasy sense of\ndismemberment and falseness, but even the danger of grave catastrophes\nin the political and social world. It is, then, not merely the right,\nbut the sacred duty, of every honorable and humanitarian thinker to\ndevote himself conscientiously to the settlement of that conflict,\nand to warding off the dangers that it brings in its train. In our\nconviction this can only be done by a courageous effort to attain the\ntruth, and by the formation of a clear view of the world--a view that\nshall be based on truth and conformity to reality.\n\nIf we recall to mind the imperfect condition of science at the\nbeginning of the century, and compare this with the magnificent\nstructure of its closing years, we are compelled to admit that\nmarvellous progress has been made during its course. Every single\nbranch of science can boast that it has, especially during the latter\nhalf of the century, made numerous acquisitions of the utmost value.\nBoth in our microscopic knowledge of the little and in our telescopic\ninvestigation of the great we have attained an invaluable insight\nthat seemed inconceivable a hundred years ago. Improved methods of\nmicroscopic and biological research have not only revealed to us an\ninvisible world of living things in the kingdom of the protists, full\nof an infinite wealth of forms, but they have taught us to recognize in\nthe tiny cell the all-pervading \"elementary organism\" of whose social\ncommunities--the tissues--the body of every multicellular plant and\nanimal, even that of man, is composed. This anatomical knowledge is\nof extreme importance; and it is supplemented by the embryological\ndiscovery that each of the higher multicellular organisms is developed\nout of one simple cell, the impregnated ovum. The \"cellular theory,\"\nwhich has been founded on that discovery, has given us the first true\ninterpretation of the physical, chemical, and even the psychological\nprocesses of life--those mysterious phenomena for whose explanation\nit had been customary to postulate a supernatural \"vital force\" or\n\"immortal soul.\" Moreover, the true character of disease has been made\nclear and intelligible to the physician for the first time by the\ncognate science of Cellular Pathology.\n\nThe discoveries of the nineteenth century in the inorganic world are no\nless important. Physics has made astounding progress in every section\nof its province--in optics and acoustics, in magnetism and electricity,\nin mechanics and thermo-dynamics; and, what is still more important,\nit has proved the unity of the forces of the entire universe. The\nmechanical theory of heat has shown how intimately they are connected,\nand how each can, in certain conditions, transform itself directly\ninto another. Spectral analysis has taught us that the same matter\nwhich enters into the composition of all bodies on earth, including\nits living inhabitants, builds up the rest of the planets, the sun,\nand the most distant stars. Astro-physics has considerably enlarged\nour cosmic perspective in revealing to us, in the immeasurable depths\nof space, millions of circling spheres larger than our earth, and,\nlike it, in endless transformation, in an eternal rhythm of life and\ndeath. Chemistry has introduced us to a multitude of new substances,\nall of which arise from the combination of a few (about seventy)\nelements that are incapable of further analysis; some of them play a\nmost important part in every branch of life. It has been shown that one\nof these elements--carbon--is the remarkable substance that effects\nthe endless variety of organic syntheses, and thus may be considered\n\"the chemical basis of life.\" All the particular advances, however, of\nphysics and chemistry yield in theoretical importance to the discovery\nof the great law which brings them all to one common focus, the \"Law\nof Substance.\" As this fundamental cosmic law establishes the eternal\npersistence of matter and force, their unvarying constancy throughout\nthe entire universe, it has become the pole-star that guides our\nMonistic Philosophy through the mighty labyrinth to a solution of the\nworld-problem.\n\nSince we intend to make a general survey of the actual condition of\nour knowledge of nature and its progress during the present century in\nthe following chapters, we shall delay no longer with the review of\nits particular branches. We would only mention one important advance,\nwhich was contemporary with the discovery of the law of substance, and\nwhich supplements it--the establishment of the theory of evolution.\nIt is true that there were philosophers who spoke of the evolution\nof things a thousand years ago; but the recognition that such a law\ndominates the entire universe, and that the world is nothing else than\nan eternal \"evolution of substance,\" is a fruit of the nineteenth\ncentury. It was not until the second half of this century that it\nattained to perfect clearness and a universal application. The immortal\nmerit of establishing the doctrine on an empirical basis, and pointing\nout its world-wide application, belongs to the great scientist Charles\nDarwin; he it was who, in 1859, supplied a solid foundation for the\ntheory of descent, which the able French naturalist Jean Lamarck had\nalready sketched in its broad outlines in 1809, and the fundamental\nidea of which had been almost prophetically enunciated in 1799 by\nGermany's greatest poet and thinker, Wolfgang Goethe. In that theory we\nhave the key to \"the question of all questions,\" to the great enigma\nof \"the place of man in nature,\" and of his natural development. If we\nare in a position to-day to recognize the sovereignty of the law of\nevolution--and, indeed, of a monistic evolution--in every province of\nnature, and to use it, in conjunction with the law of substance, for a\nsimple interpretation of all natural phenomena, we owe it chiefly to\nthose three distinguished naturalists; they shine as three stars of the\nfirst magnitude amid all the great men of the century.\n\nThis marvellous progress in a theoretical knowledge of nature has\nbeen followed by a manifold practical application in every branch\nof civilized life. If we are to-day in the \"age of commerce,\" if\ninternational trade and communication have attained dimensions beyond\nthe conception of any previous age, if we have transcended the limits\nof space and time by our telegraph and telephone, we owe it, in the\nfirst place, to the technical advancement of physics, especially in\nthe application of steam and electricity. If, in photography, we can,\nwith the utmost ease, compel the sunbeam to create for us in a moment's\ntime a correct picture of any object we like; if we have made enormous\nprogress in agriculture, and in a variety of other pursuits; if, in\nsurgery, we have brought an infinite relief to human pain by our\nchloroform and morphia, our antiseptics and serous therapeutics, we\nowe it all to applied chemistry. But it is so well known how much we\nhave surpassed all earlier centuries through these and other scientific\ndiscoveries that we need linger over the question no longer.\n\nWhile we look back with a just pride on the immense progress of the\nnineteenth century in a knowledge of nature and in its practical\napplication, we find, unfortunately, a very different and far from\nagreeable picture when we turn to another and not less important\nprovince of modern life. To our great regret we must endorse the words\nof Alfred Wallace: \"Compared with our astounding progress in physical\nscience and its practical application, our system of government, of\nadministrative justice, and of national education, and our entire\nsocial and moral organization, remain in a state of barbarism.\" To\nconvince ourselves of the truth of this grave indictment we need only\ncast an unprejudiced glance at our public life, or look into the mirror\nthat is daily offered to us by the press, the organ of public sentiment.\n\nWe begin our review with justice, the _fundamentum regnorum_. No one\ncan maintain that its condition to-day is in harmony with our advanced\nknowledge of man and the world. Not a week passes in which we do not\nread of judicial decisions over which every thoughtful man shakes his\nhead in despair; many of the decisions of our higher and lower courts\nare simply unintelligible. We are not referring in the treatment of\nthis particular \"world-problem\" to the fact that many modern states, in\nspite of their paper constitutions, are really governed with absolute\ndespotism, and that many who occupy the bench give judgment less in\naccordance with their sincere conviction than with wishes expressed\nin higher quarters. We readily admit that the majority of judges and\ncounsel decide conscientiously, and err simply from human frailty.\nMost of their errors, indeed, are due to defective preparation. It is\npopularly supposed that these are just the men of highest education,\nand that on that very account they have the preference in nominations\nto different offices. However, this famed \"legal education\" is for the\nmost part rather of a formal and technical character. They have but a\nsuperficial acquaintance with that chief and peculiar object of their\nactivity, the human organism, and its most important function, the\nmind. That is evident from the curious views as to the liberty of the\nwill, responsibility, etc., which we encounter daily. I once told an\neminent jurist that the tiny spherical ovum from which every man is\ndeveloped is as truly endowed with life as the embryo of two, or seven,\nor even nine months; he laughed incredulously. Most of the students\nof jurisprudence have no acquaintance with anthropology, psychology,\nand the doctrine of evolution--the very first requisites for a correct\nestimate of human nature. They have \"no time\" for it; their time is\nalready too largely bespoken for an exhaustive study of beer and wine\nand for the noble art of fencing. The rest of their valuable study-time\nis required for the purpose of learning some hundreds of paragraphs of\nlaw books, a knowledge of which is supposed to qualify the jurist for\nany position whatever in our modern civilized community.\n\nWe shall touch but lightly on the unfortunate province of politics, for\nthe unsatisfactory condition of the modern political world is only too\nfamiliar. In a great measure its evils are due to the fact that most of\nour officials are jurists--that is, men of high technical education,\nbut utterly devoid of that thorough knowledge of human nature which is\nonly obtained by the study of comparative anthropology and the monistic\npsychology--men without an acquaintance with those social relations of\nwhich we find the earlier types in comparative zoology and the theory\nof evolution, in the cellular theory, and the study of the protists. We\ncan only arrive at a correct knowledge of the structure and life of the\nsocial body, the state, through a scientific knowledge of the structure\nand life of the individuals who compose it, and the cells of which they\nare in turn composed. If our political rulers and our \"representatives\nof the people\" possessed this invaluable biological and anthropological\nknowledge, we should not find our journals so full of the sociological\nblunders and political nonsense which at present are far from adorning\nour parliamentary reports, and even many of our official documents.\nWorst of all is it when the modern state flings itself into the arms\nof the reactionary Church, and when the narrow-minded self-interest\nof parties and the infatuation of short-sighted party-leaders lend\ntheir support to the hierarchy. Then are witnessed such sad scenes\nas the German Reichstag puts before our eyes even at the close of\nthe nineteenth century. We have the spectacle of the educated German\npeople in the power of the ultramontane Centre, under the rule of the\nRoman papacy, which is its bitterest and most dangerous enemy. Then\nsuperstition and stupidity reign instead of right and reason. Never\nwill our government improve until it casts off the fetters of the\nChurch and raises the views of the citizens on man and the world to a\nhigher level by a general scientific education. That does not raise\nthe question of any special form of constitution. Whether a monarchy\nor a republic be preferable, whether the constitution should be\naristocratic or democratic, are subordinate questions in comparison\nwith the supreme question: Shall the modern civilized state be\nspiritual or secular? Shall it be _theocratic_--ruled by the irrational\nformul\u00e6 of faith and by clerical despotism--or _nomocratic_--under the\nsovereignty of rational laws and civic right? The first task is to\nkindle a rational interest in our youth, and to uplift our citizens\nand free them from superstition. That can only be achieved by a timely\nreform of our schools.\n\nOur education of the young is no more in harmony with modern scientific\nprogress than our legal and political world. Physical science, which\nis so much more important than all other sciences, and which, properly\nunderstood, really embraces all the so-called moral sciences, is still\nregarded as a mere accessory in our schools, if not treated as the\nCinderella of the curriculum. Most of our teachers still give the\nmost prominent place to that dead learning which has come down from\nthe cloistral schools of the Middle Ages. In the front rank we have\ngrammatical gymnastics and an immense waste of time over a \"thorough\nknowledge\" of classics and of the history of foreign nations. Ethics,\nthe most important object of practical philosophy, is entirely\nneglected, and its place is usurped by the ecclesiastical creed. Faith\nmust take precedence over knowledge--not that scientific faith which\nleads to a monistic religion, but the irrational superstition that\nlays the foundation of a perverted Christianity. The valuable teaching\nof modern cosmology and anthropology, of biology and evolution, is\nmost inadequately imparted, if not entirely unknown, in our higher\nschools; while the memory is burdened with a mass of philological and\nhistorical facts which are utterly useless, either from the point of\nview of theoretical education or for the practical purposes of life.\nMoreover, the antiquated arrangements and the distribution of faculties\nin the universities are just as little in harmony with the point we\nhave reached in monistic science as the curriculum of the primary and\nsecondary schools.\n\nThe climax of the opposition to modern education and its foundation,\nadvanced natural philosophy, is reached, of course, in the Church. We\nare not speaking here of ultramontane papistry, nor of the orthodox\nevangelical tendencies, which do not fall far short of it in ignorance\nand in the crass superstition of their dogmas. We are imagining\nourselves for the moment to be in the church of a liberal Protestant\nminister, who has a good average education, and who finds room for\n\"the rights of reason\" by the side of his faith. There, besides\nexcellent moral teaching, which is in perfect harmony with our own\nmonistic ethics, and humanitarian discussion of which we cordially\napprove, we hear ideas on the nature of God, of the world, of man, and\nof life which are directly opposed to all scientific experience. It\nis no wonder that physicists and chemists, doctors and philosophers,\nwho have made a thorough study of nature, refuse a hearing to such\npreachers. Our theologians and our politicians are just as ignorant\nas our philosophers and our jurists of that elementary knowledge of\nnature which is based on the monistic theory of evolution, and which is\nalready far exceeded in the triumph of our modern learning.\n\nFrom this opposition, which we can only briefly point out at present,\nthere arise grave conflicts in our modern life which urgently demand\na settlement. Our modern education, the outcome of our great advance\nin knowledge, has a claim upon every department of public and private\nlife; it would see humanity raised, by the instrumentality of\nreason, to that higher grade of culture, and, consequently, to that\nbetter path towards happiness which has been opened out to us by the\nprogress of modern science. That aim, however, is vigorously opposed\nby the influential parties who would detain the mind in the exploded\nviews of the Middle Ages with regard to the most important problems\nof life; they linger in the fold of traditional dogma, and would\nhave reason prostrate itself before their \"higher revelation.\" That\nis the condition of things, to a very large extent, in theology and\nphilosophy, in sociology and jurisprudence. It is not that the motives\nof the latter are to be attributed, as a rule, to pure self-interest;\nthey spring partly from ignorance of the facts, and partly from an\nindolent acquiescence in tradition. The most dangerous of the three\ngreat enemies of reason and knowledge is not malice; but ignorance, or,\nperhaps, indolence. The gods themselves still strive in vain against\nthese two latter influences when they have happily vanquished the first.\n\nOne of the main supports of that reactionary system is still what\nwe may call \"anthropism.\" I designate by this term \"that powerful\nand world-wide group of erroneous opinions which opposes the human\norganism to the whole of the rest of nature, and represents it to be\nthe preordained end of the organic creation, an entity essentially\ndistinct from it, a godlike being.\" Closer examination of this group of\nideas shows it to be made up of three different dogmas, which we may\ndistinguish as the _anthropocentric_, the _anthropomorphic_, and the\n_anthropolatrous_.[4]\n\nI. The _anthropocentric_ dogma culminates in the idea that man\nis the preordained centre and aim of all terrestrial life--or, in\na wider sense, of the whole universe. As this error is extremely\nconducive to man's interest, and as it is intimately connected with the\ncreation-myth of the three great Mediterranean religions, and with the\ndogmas of the Mosaic, Christian, and Mohammedan theologies, it still\ndominates the greater part of the civilized world.\n\nII. The _anthropomorphic_ dogma is likewise connected with the\ncreation-myth of the three aforesaid religions, and of many others. It\nlikens the creation and control of the world by God to the artificial\ncreation of a talented engineer or mechanic, and to the administration\nof a wise ruler. God, as creator, sustainer, and ruler of the world,\nis thus represented after a purely human fashion in his thought and\nwork. Hence it follows, in turn, that man is godlike. \"God made man\nto His own image and likeness.\" The older, na\u00efve mythology is pure\n\"homotheism,\" attributing human shape, flesh, and blood to the gods.\nIt is more intelligible than the modern mystic theosophy that adores\na personal God as an invisible--properly speaking, gaseous--being,\nyet makes him think, speak, and act in human fashion; it gives us the\nparadoxical picture of a \"gaseous vertebrate.\"\n\nIII. The _anthropolatric_ dogma naturally results from this comparison\nof the activity of God and man; it ends in the apotheosis of the human\norganism. A further result is the belief in the personal immortality of\nthe soul, and the dualistic dogma of the twofold nature of man, whose\n\"immortal soul\" is conceived as but the temporary inhabitant of the\nmortal frame. Thus these three anthropistic dogmas, variously adapted\nto the respective professions of the different religions, came at\nlength to be vested with an extraordinary importance, and proved the\nsource of the most dangerous errors. The anthropistic view of the world\nwhich springs from them is in irreconcilable opposition to our monistic\nsystem; indeed, it is at once disproved by our new cosmological\nperspective.\n\nNot only the three anthropistic dogmas, but many other notions of the\ndualistic philosophy and orthodox religion, are found to be untenable\nas soon as we regard them critically from the cosmological perspective\nof our monistic system. We understand by that the comprehensive view\nof the universe which we have from the highest point of our monistic\ninterpretation of nature. From that stand-point we see the truth of the\nfollowing \"cosmological theorems,\" most of which, in our opinion, have\nalready been amply demonstrated:\n\n(1) The universe, or the cosmos, is eternal, infinite, and illimitable.\n(2) Its substance, with its two attributes (matter and energy), fills\ninfinite space, and is in eternal motion. (3) This motion runs on\nthrough infinite time as an unbroken development, with a periodic\nchange from life to death, from evolution to devolution. (4) The\ninnumerable bodies which are scattered about the space-filling ether\nall obey the same \"law of substance;\" while the rotating masses slowly\nmove towards their destruction and dissolution in one part of space\nothers are springing into new life and development in other quarters\nof the universe. (5) Our sun is one of these unnumbered perishable\nbodies, and our earth is one of the countless transitory planets that\nencircle them. (6) Our earth has gone through a long process of cooling\nbefore water, in liquid form (the first condition of organic life),\ncould settle thereon. (7) The ensuing biogenetic process, the slow\ndevelopment and transformation of countless organic forms, must have\ntaken many millions of years--considerably over a hundred.[5] (8) Among\nthe different kinds of animals which arose in the later stages of the\nbiogenetic process on earth the vertebrates have far outstripped all\nother competitors in the evolutionary race. (9) The most important\nbranch of the vertebrates, the mammals, were developed later (during\nthe triassic period) from the lower amphibia and the reptilia. (10) The\nmost perfect and most highly developed branch of the class mammalia is\nthe order of primates, which first put in an appearance, by development\nfrom the lowest prochoriata, at the beginning of the Tertiary\nperiod--at least three million years ago. (11) The youngest and most\nperfect twig of the branch primates is man, who sprang from a series of\nmanlike apes towards the end of the Tertiary period. (12) Consequently,\nthe so-called \"history of the world\"--that is, the brief period of a\nfew thousand years which measures the duration of civilization--is an\nevanescently short episode in the long course of organic evolution,\njust as this, in turn, is merely a small portion of the history of\nour planetary system; and as our mother-earth is a mere speck in the\nsunbeam in the illimitable universe, so man himself is but a tiny grain\nof protoplasm in the perishable framework of organic nature.\n\nNothing seems to me better adapted than this magnificent cosmological\nperspective to give us the proper standard and the broad outlook\nwhich we need in the solution of the vast enigmas that surround us.\nIt not only clearly indicates the true place of man in nature, but it\ndissipates the prevalent illusion of man's supreme importance, and\nthe arrogance with which he sets himself apart from the illimitable\nuniverse, and exalts himself to the position of its most valuable\nelement. This boundless presumption of conceited man has misled him\ninto making himself \"the image of God,\" claiming an \"eternal life\" for\nhis ephemeral personality, and imagining that he possesses unlimited\n\"freedom of will.\" The ridiculous imperial folly of Caligula is but\na special form of man's arrogant assumption of divinity. Only when\nwe have abandoned this untenable illusion, and taken up the correct\ncosmological perspective, can we hope to reach the solution of the\n\"riddles of the universe.\"\n\nThe uneducated member of a civilized community is surrounded with\ncountless enigmas at every step, just as truly as the savage. Their\nnumber, however, decreases with every stride of civilization and of\nscience; and the monistic philosophy is ultimately confronted with but\none simple and comprehensive enigma--the \"problem of substance.\" Still,\nwe may find it useful to include a certain number of problems under\nthat title. In the famous speech which Emil du Bois-Reymond delivered\nin 1880, in the Leibnitz session of the Berlin Academy of Sciences,\nhe distinguished seven world-enigmas, which he enumerated as follows:\n(1) The nature of matter and force. (2) The origin of motion. (3) The\norigin of life. (4) The (apparently preordained) orderly arrangement\nof nature. (5) The origin of simple sensation and consciousness. (6)\nRational thought, and the origin of the cognate faculty, speech. (7)\nThe question of the freedom of the will. Three of these seven enigmas\nare considered by the orator of the Berlin Academy to be entirely\ntranscendental and insoluble--they are the first, second, and fifth;\nthree others (the third, fourth, and sixth) he considers to be capable\nof solution, though extremely difficult; as to the seventh and last\n\"world-enigma,\" the freedom of the will, which is the one of the\ngreatest practical importance, he remains undecided.\n\nAs my monism differs materially from that of the Berlin orator, and as\nhis idea of the \"seven great enigmas\" has been very widely accepted,\nit may be useful to indicate their true position at once. In my\nopinion, the three transcendental problems (1, 2, and 5) are settled\nby our conception of substance (_vide_ chap. xii.); the three which\nhe considers difficult, though soluble, (3, 4, and 6), are decisively\nanswered by our modern theory of evolution; the seventh and last, the\nfreedom of the will, is not an object for critical, scientific inquiry\nat all, for it is a pure dogma, based on an illusion, and has no real\nexistence.\n\nThe means and methods we have chosen for attaining the solution of the\ngreat enigma do not differ, on the whole, from those of all purely\nscientific investigation--firstly, experience; secondly, inference.\nScientific experience comes to us by observation and experiment, which\ninvolve the activity of our sense-organs in the first place, and,\nsecondly, of the inner sense-centres in the cortex of the brain. The\nmicroscopic elementary organs of the former are the sense-cells; of the\nlatter, groups of ganglionic cells. The experiences which we derive\nfrom the outer world by these invaluable instruments of our mental life\nare then moulded into ideas by other parts of the brain, and these,\nin their turn, are united in a chain of reasoning by association. The\nconstruction of this chain may take place in two different ways, which\nare, in my opinion, equally valuable and indispensable: _induction_\nand _deduction_. The higher cerebral operations, the construction\nof complicated chains of reasoning, abstraction, the formation of\nconcepts, the completion of the perceptive faculty by the plastic\nfaculty of the imagination--in a word, consciousness, thought, and\nspeculation--are functions of the ganglionic cells of the cortex of the\nbrain, just like the preceding simpler mental functions. We unite them\nall in the supreme concept of _reason_.[6]\n\nBy reason only can we attain to a correct knowledge of the world and a\nsolution of its great problems. Reason is man's highest gift, the only\nprerogative that essentially distinguishes him from the lower animals.\nNevertheless, it has only reached this high position by the progress of\nculture and education, by the development of knowledge. The uneducated\nman and the savage are just as little (or just as much) \"rational\"\nas our nearest relatives among the mammals (apes, dogs, elephants,\netc.). Yet the opinion still obtains in many quarters that, besides\nour godlike reason, we have two further (and even surer!) methods of\nreceiving knowledge--emotion and revelation. We must at once dispose\nof this dangerous error. Emotion has nothing whatever to do with the\nattainment of truth. That which we prize under the name of \"emotion\"\nis an elaborate activity of the brain, which consists of feelings of\nlike and dislike, motions of assent and dissent, impulses of desire and\naversion. It may be influenced by the most diverse activities of the\norganism, by the cravings of the senses and the muscles, the stomach,\nthe sexual organs, etc. The interests of truth are far from promoted\nby these conditions and vacillations of emotion; on the contrary, such\ncircumstances often disturb that reason which alone is adapted to the\npursuit of truth, and frequently mar its perceptive power. No cosmic\nproblem is solved, or even advanced, by the cerebral function we call\nemotion. And the same must be said of the so-called \"revelation,\" and\nof the \"truths of faith\" which it is supposed to communicate; they are\nbased entirely on a deception, consciously or unconsciously, as we\nshall see in the sixteenth chapter.\n\nWe must welcome as one of the most fortunate steps in the direction\nof a solution of the great cosmic problems the fact that of recent\nyears there is a growing tendency to recognize the two paths which\nalone lead thereto--_experience_ and _thought_, or _speculation_--to\nbe of equal value, and mutually complementary. Philosophers have come\nto see that pure speculation--such, for instance, as Plato and Hegel\nemployed for the construction of their _idealist_ systems--does not\nlead to knowledge of reality. On the other hand, scientists have been\nconvinced that mere experience--such as Bacon and Mill, for example,\nmade the basis of their _realist_ systems--is insufficient of itself\nfor a complete philosophy. For these two great paths of knowledge,\nsense-experience and rational thought, are two distinct cerebral\nfunctions; the one is elaborated by the sense-organs and the inner\nsense-centres, the other by the thought-centres, the great \"centres\nof association in the cortex of the brain,\" which lie between the\nsense-centres. (Cf. cc. vii. and x.) True knowledge is only acquired\nby combining the activity of the two. Nevertheless, there are still\nmany philosophers who would construct the world out of their own\ninner consciousness, and who reject our empirical science precisely\nbecause they have no knowledge of the real world. On the other hand,\nthere are many scientists who still contend that the sole object of\nscience is \"the knowledge of facts, the objective investigation of\nisolated phenomena\"; that \"the age of philosophy\" is past, and science\nhas taken its place.[7] This one-sided over-estimation of experience\nis as dangerous an error as the converse exaggeration of the value of\nspeculation. Both channels of knowledge are mutually indispensable.\nThe greatest triumphs of modern science--the cellular theory, the\ndynamic theory of heat, the theory of evolution, and the law of\nsubstance--are _philosophic achievements_; not, however, the fruit of\npure speculation, but of an antecedent experience of the widest and\nmost searching character.\n\nAt the commencement of the nineteenth century the great idealistic\npoet, Schiller, gave his counsel to both groups of combatants, the\nphilosophers and the scientists:\n\n    \"Does strife divide your efforts--no union bless your toil?\n    Will truth e'er be delivered if ye your forces rend?\"\n\nSince then the situation has, happily, been profoundly modified; while\nboth schools, in their different paths, have pressed onward towards the\nsame high goal, they have recognized their common aspiration, and they\ndraw nearer to a knowledge of the truth in mutual covenant. At the end\nof the nineteenth century we have returned to that monistic attitude\nwhich our greatest realistic poet, Goethe, had recognized from its very\ncommencement to be alone correct and fruitful.[8]\n\nAll the different philosophical tendencies may, from the point of\nview of modern science, be ranged in two antagonistic groups; they\nrepresent either a _dualistic_ or a _monistic_ interpretation of\nthe cosmos. The former is usually bound up with teleological and\nidealistic dogmas, the latter with mechanical and realistic theories.\nDualism, in the widest sense, breaks up the universe into two entirely\ndistinct substances--the material world and an immaterial God, who\nis represented to be its creator, sustainer, and ruler. Monism, on\nthe contrary (likewise taken in its widest sense), recognizes one\nsole substance in the universe, which is at once \"God and nature\";\nbody and spirit (or matter and energy) it holds to be inseparable.\nThe extramundane God of dualism leads necessarily to theism; and the\nintra-mundane God of the monist leads to pantheism.\n\nThe different ideas of _monism_ and _materialism_, and likewise\nthe essentially distinct tendencies of theoretical and practical\nmaterialism, are still very frequently confused. As this and other\nsimilar cases of confusion of ideas are very prejudicial, and give rise\nto innumerable errors, we shall make the following brief observations,\nin order to prevent misunderstanding:\n\nI. Pure monism is identical neither with the theoretical materialism\nthat denies the existence of spirit, and dissolves the world into a\nheap of dead atoms, nor with the theoretical spiritualism (lately\nentitled \"energetic\" spiritualism by Ostwald) which rejects the notion\nof matter, and considers the world to be a specially arranged group of\n\"energies\" or immaterial natural forces.\n\nII. On the contrary, we hold, with Goethe, that \"matter cannot exist\nand be operative without spirit, nor spirit without matter.\" We\nadhere firmly to the pure, unequivocal monism of Spinoza: Matter, or\ninfinitely extended substance, and spirit (or energy), or sensitive and\nthinking substance, are the two fundamental attributes or principal\nproperties of the all-embracing divine essence of the world, the\nuniversal substance. (Cf. chap. xii.)\n\n\n\n\nCHAPTER II\n\nOUR BODILY FRAME\n\n    Fundamental Importance of Anatomy--Human Anatomy--Hippocrates,\n    Aristotle, Galen, Vesalius--Comparative Anatomy--Georges\n    Cuvier--Johannes M\u00fcller--Karl Gegenbaur--Histology--The Cellular\n    Theory--Schleiden and Schwann--K\u00f6lliker--Virchow--Man a\n    Vertebrate, a Tetrapod, a Mammal, a Placental, a Primate--Prosimi\u00e6\n    and Simi\u00e6--The Catarrhin\u00e6--Papiomorphic and Anthropomorphic\n    Apes--Essential Likeness of Man and the Ape in Corporal Structure\n\n\nAll biological research, all investigation into the forms and vital\nactivities of organisms, must first deal with the visible body, in\nwhich the morphological and physiological phenomena are observed. This\nfundamental rule holds good for man just as much as for all other\nliving things. Moreover, the inquiry must not confine itself to mere\nobservation of the outer form; it must penetrate to the interior, and\nstudy both the general plan and the minute details of the structure.\nThe science which pursues this fundamental investigation in the\nbroadest sense is anatomy.\n\nThe first stimulus to an inquiry into the human frame arose, naturally,\nin medicine. As it was usually practised by the priests in the older\ncivilizations, we may assume that these highest representatives of\nthe education of the time had already acquired a certain amount\nof anatomical knowledge two thousand years before Christ, or even\nearlier. We do not, however, find more exact observations, founded\non the dissection of mammals, and applied, by analogy, to the human\nframe, until we come to the Greek scientists of the sixth and fifth\ncenturies before Christ--Empedocles (of Agrigentum) and Democritus\n(of Abdera), and especially the most famous physician of classic\nantiquity, Hippocrates (of Cos). It was from these and other sources\nthat the great Aristotle, the renowned \"father of natural history,\"\nequally comprehensive as investigator and philosopher, derived his\nfirst knowledge. After him only one anatomist of any consequence is\nfound in antiquity, the Greek physician Claudius Galenus (of Pergamus),\nwho developed a wealthy practice in Rome in the second century after\nChrist, under the Emperor Marcus Aurelius. All these ancient anatomists\nacquired their knowledge, as a rule, not by the dissection of the human\nbody itself--which was then sternly forbidden--but by a study of the\nbodies of the animals which most closely resembled man, especially the\napes; they were all, indeed, comparative anatomists.\n\nThe triumph of Christianity and its mystic theories meant retrogression\nto anatomy, as it did to all the other sciences. The popes were\nresolved above all things to detain humanity in ignorance; they rightly\ndeemed a knowledge of the human organism to be a dangerous source\nof enlightenment as to our true nature. During the long period of\nthirteen centuries the writings of Galen were almost the only source\nof human anatomy, just as the works of Aristotle were for the whole\nof natural history. It was not until the sixteenth century, when the\nspiritual tyranny of the papacy was broken by the Reformation, and the\ngeocentric theory, so intimately connected with papal doctrine, was\ndestroyed by the new cosmic system of Copernicus, that the knowledge\nof the human frame entered upon a new period of progress. The great\nanatomists, Vesalius (of Brussels), and Eustachius and Fallopius\n(of Modena), advanced the knowledge of our bodily structure so much\nby their own thorough investigations that little remained for their\nnumerous followers to do, with regard to the more obvious phenomena,\nexcept the substantiation of details. Andreas Vesalius, as courageous\nas he was talented and indefatigable, was the pioneer of the movement;\nhe completed in his twenty-eighth year (1543) that great and systematic\nwork _De humani corporis fabrica_; he gave to the whole of human\nanatomy a new and independent scope and a more solid foundation. On\nthat account he was, at a later date, at Madrid--where he was physician\nto Charles V. and Philip II.--condemned to death by the Inquisition as\na magician. He only escaped by undertaking a pilgrimage to Jerusalem;\nin returning he suffered shipwreck on the Isle of Zante, and died there\nin misery and destitution.\n\nThe great merit of the nineteenth century, as far as our knowledge of\nthe human frame is concerned, lies in the founding of two new lines\nof research of immense importance--comparative anatomy and histology,\nor microscopic anatomy. The former was intimately associated with\nhuman anatomy from the very beginning; indeed, it had to supply the\nplace of the latter so long because the dissection of human corpses\nwas a crime visited with capital punishment--that was the case even\nin the fifteenth century! But the many anatomists of the next three\ncenturies devoted themselves mainly to a more accurate study of the\nhuman organism. The elaborate science which we now call comparative\nanatomy was born in the year 1803, when the great French zoologist\nGeorges Cuvier (a native of M\u00f6mpelgard, in Alsace) published his\nprofound _Le\u00e7ons sur l'anatomie compar\u00e9e_, and endeavored to formulate,\nfor the first time, definite laws as to the organism of man and the\nbeasts. While his predecessors--among whom was Goethe in 1790--had\nmainly contented themselves with comparing the skeleton of man with\nthose of other animals, Cuvier's broader vision took in the whole\nof the animal organization. He distinguished therein four great and\nmutually independent types: Vertebrata, Articulata, Mollusca, and\nRadiata. This advance was of extreme consequence for our \"question\nof all questions,\" since it clearly brought out the fact that man\nbelonged to the vertebral type, and differed fundamentally from all\nthe other types. It is true that the keen-sighted Linn\u00e9 had already,\nin his _Systema Natuae_, made a great step in advance by assigning\nman a definite place in the class of mammals; he had even drawn up\nthe three groups of half-apes, apes, and men (_Lemur_, _simia_, and\n_homo_) in the order of primates. But his keen, systematic mind was\nnot furnished with that profound empirical foundation, supplied by\ncomparative anatomy, which Cuvier was the first to attain. Further\ndevelopments were added by the great comparative anatomists of our own\ncentury--Friedrich Meckel (Halle), Johannes M\u00fcller (Berlin), Richard\nOwen, T. Huxley, and Karl Gegenbaur (Jena, subsequently Heidelberg).\nThe last-named, in applying the evolutionary theory, which Darwin had\njust established, to comparative anatomy, raised his science to the\nfront rank of biological studies. The numerous comparative anatomical\nworks of Gegenbaur are, like his well-known _Manual of Human Anatomy_,\nequally distinguished by a thorough empirical acquaintance with their\nimmense multitudes of facts, and by a comprehensive control of his\nmaterial, and its philosophic appreciation in the evolutionary sense.\nHis recent _Comparative Anatomy of the Vertebrata_ establishes the\nsolid foundation on which our conviction of the vertebral character of\nman in every aspect is chiefly based.\n\nMicroscopic anatomy has been developed, in the course of the present\ncentury, in a very different fashion from comparative anatomy. At\nthe beginning of the century (1802) a French physician, Bichat, made\nan attempt to dissect the organs of the human body into their finer\nconstituents by the aid of the microscope, and to show the connection\nof these various _tissues_ (_hista_, or _tela_). This first attempt\nled to little result, because the scientist was ignorant of the one\ncommon element of all the different tissues. This was first discovered\n(1838) in the shape of the _cell_, in the plant world, by Matthias\nSchleiden, and immediately afterwards proved to be the same in the\nanimal world by Theodor Schwann, the pupil and assistant of Johannes\nM\u00fcller at Berlin. Two other distinguished pupils of this great master,\nwho are still living, Albert K\u00f6lliker and Rudolph Virchow, took up\nthe cellular theory, and the theory of tissues which is founded on\nit, in the sixties, and applied them to the human organism in all its\ndetails, both in health and disease; they proved that, in man and\nall other animals, every tissue is made up of the same microscopic\nparticles, the _cells_, and these \"elementary organisms\" are the real,\nself-active citizens which, in combinations of millions, constitute\nthe \"cellular state,\" our body. All these cells spring from one simple\ncell, the _cytula_, or impregnated ovum, by continuous subdivision.\nThe general structure and combination of the tissues are the same in\nman as in the other vertebrates. Among these the mammals, the youngest\nand most highly developed class take precedence, in virtue of certain\nspecial features which were acquired late. Such are, for instance, the\nmicroscopic texture of the hair, of the glands of the skin, and of the\nbreasts, and the corpuscles of the blood, which are quite peculiar to\nmammals, and different from those of the other vertebrates; man, even\nin these finest histological relations, is a _true mammal_.\n\nThe microscopic researches of Albert K\u00f6lliker and Franz Leydig (at\nW\u00fcrzburg) not only enlarged our knowledge of the finer structure of man\nand the beasts in every direction, but they were especially important\nin the light of their connection with the evolution of the cell and\nthe tissue; they confirmed the great theory of Carl Theodor Siebold\n(1845) that the lowest animals, the Infusoria and the Rhizopods, are\nunicellular organisms.\n\nOur whole frame, both in its general plan and its detailed structure,\npresents the characteristic type of the vertebrates. This most\nimportant and most highly developed group in the animal world was\nfirst recognized in its natural unity in 1801 by the great Lamarck;\nhe embraced under that title the four higher animal groups of\nLinn\u00e9--mammals, birds, amphibia, and fishes. To these he opposed the\ntwo lower classes, insects and worms, as invertebrates. Cuvier (1812)\nestablished the unity of the vertebrate type on a firmer basis by\nhis comparative anatomy. It is quite true that all the vertebrates,\nfrom the fish up to man, agree in every essential feature; they all\nhave a firm internal skeleton, a framework of cartilage and bone,\nconsisting principally of a vertebral column and a skull; the advanced\nconstruction of the latter presents many variations, but, on the whole,\nall may be reduced to the same fundamental type. Further, in all\nvertebrates the \"organ of the mind,\" the central nervous system, in\nthe shape of a spinal cord and a brain, lies at the back of this axial\nskeleton. Moreover, what we said of its bony environment, the skull,\nis also true of the brain--the instrument of consciousness and all the\nhigher functions of the mind; its construction and size present very\nmany variations in detail, but its general characteristic structure\nremains always the same.\n\nWe meet the same phenomenon when we compare the rest of our organs with\nthose of the other vertebrates; everywhere, in virtue of heredity,\nthe original plan and the relative distribution of the organs remain\nthe same, although, through adaptation to different environments,\nthe size and the structure of particular sections offer considerable\nvariation. Thus we find that in all cases the blood circulates in\ntwo main blood-vessels, of which one--the aorta--passes over the\nintestine, and the other--the principal vein--passes underneath, and\nthat by the broadening out of the latter in a very definite spot a\nheart has arisen; this \"ventral heart\" is just as characteristic of all\nvertebrates as the \"dorsal heart\" is of the articulata and mollusca.\nEqually characteristic of all vertebrates is the early division of\nthe intestinal tube into a \"head-gut\" (or gill-gut), which serves in\nrespiration, and a \"body-gut\" (or liver-gut), which co-operates with\nthe liver in digestion; so are, likewise, the ramification of the\nmuscular system, the peculiar structure of the urinary and sexual\norgans, and so forth. In all these anatomical relations _man is a true\nvertebrate_.\n\nAristotle gave the name of four-footed, or tetrapoda, to all the higher\nwarm-blooded animals which are distinguished by the possession of two\npairs of legs. The category was enlarged subsequently, and its title\nchanged into the Latin \"quadrupeda,\" when Cuvier proved that even\n\"two-legged\" birds and men are really \"four-footed\"; he showed that the\ninternal skeleton of the four legs in all the higher land-vertebrates,\nfrom the amphibia up to man, was originally constructed after the same\npattern out of a definite number of members. The \"arm\" of man and the\n\"wing\" of bats and birds have the same typical skeleton as the foreleg\nof the animals which are conspicuously \"four-footed.\"\n\nThe anatomical unity of the fully developed skeleton in the four limbs\nof all tetrapods is very important. In order to appreciate it fully\none has only to compare carefully the skeleton of a salamander or a\nfrog with that of a monkey or a man. One perceives at once that the\nhumeral zone in front and the pelvic zone behind are made up of the\nsame principal parts as in the rest of the quadrupeds. We find in all\ncases that the first section of the leg proper consists of one strong\nmarrow-bone (the _humerus_, in the forearm; the _femur_, behind);\nthe second part, on the contrary, originally always consists of two\nbones (the _ulna_ and _radius_, in front; the _fibula_ and _tibia_,\nbehind). When we further compare the developed structure of the foot\nproper we are surprised to find that the small bones of which it is\nmade up are also similarly arranged and distributed in every case: in\nthe front limb the three groups of bones of the forefoot (or \"hand\")\ncorrespond in all classes of the tetrapoda: (1) the _carpus_, (2)\nthe _metacarpus_, (3) the five fingers (_digiti anteriores_); in the\nrear limb, similarly, we have always the same three osseous groups of\nthe hind foot: (1) the _tarsus_, (2) the _metatarsus_, and (3) the\nfive toes (_digiti posteriores_). It was a very difficult task to\nreduce all these little bones to one primitive type, and to establish\nthe equivalence (or homology) of the separate parts in all cases;\nthey present extreme variations of form and construction in detail,\nsometimes being partly fused together and losing their individuality.\nThis great task was first successfully achieved by the most eminent\ncomparative anatomist of our day, Karl Gegenbaur. He pointed out,\nin his _Researches into the Comparative Anatomy of the Vertebrata_\n(1864), how this characteristic \"five-toed leg\" of the land tetrapods\noriginally (not before the Carboniferous period) arose out of the\nradiating fin (the breast-fin, or the belly-fin) of the ancient\nfishes. He had also, in his famous _Researches into the Skull of the\nVertebrata_ (1872), deduced the younger skull of the tetrapods from the\noldest cranial form among the fishes, that of the shark.\n\nIt is especially remarkable that the original number of the toes (five)\non each of the four feet, which first appeared in the old amphibia\nof the Carboniferous period, has, in virtue of a strict heredity,\nbeen preserved even to the present day in man. Also, naturally and\nharmoniously, the typical construction of the joints, ligaments,\nmuscles, and nerves of the two pairs of legs has, in the main, remained\nthe same as in the rest of the \"four-footed.\" In all these important\nrelations _man is a true tetrapod_.\n\nThe mammals are the youngest and most advanced class of the vertebrates.\nIt is true they are derived from the older class of amphibia, like\nbirds and reptiles: yet they are distinguished from all the other\ntetrapods by a number of very striking anatomical features. Externally,\nthere is the clothing of the skin with hair, and the possession of\ntwo kinds of skin glands--the sweat glands and the sebaceous glands.\nA local development of these glands on the abdominal skin gave\nrise (probably during the Triassic period) to the organ which is\nespecially characteristic of the class, and from which it derives its\nname--the _mammarium_. This important instrument of lactation is made\nup of milk glands (_mammae_) and the \"mammar-pouches\" (folds of the\nabdominal skin); in its development the teats appear, through which\nthe young mammal sucks its mother's milk. In internal structure the\nmost remarkable feature is the possession of a complete diaphragm, a\nmuscular wall which, in all mammals--and _only_ in mammals--separates\nthe thoracic from the abdominal cavity; in all other vertebrates\nthere is no such separation. The skull of mammals is distinguished\nby a number of remarkable formations, especially in the maxillary\napparatus (the upper and lower jaws, and the temporal bones). Moreover,\nthe brain, the olfactory organ, the heart, the lungs, the internal\nand external sexual organs, the kidneys, and other parts of the body\npresent special peculiarities, both in general and detailed structure,\nin the mammals; all these, taken collectively, point unequivocally\nto an early derivation of the mammals from the older groups of the\nreptiles and amphibia, which must have taken place, at the latest, in\nthe Triassic period--at least twelve million years ago! In all these\nimportant characteristics _man is a true mammal_.\n\nThe numerous orders (12-33) which modern systematic zoology\ndistinguishes in the class of mammals had been arranged in 1816\n(by Blainville) in three natural groups, which still hold good as\nsub-classes: (1) the monotrema, (2) the marsupialia, and (3) the\nplacentalia. These three sub-classes not only differ in the important\nrespect of bodily structure and development, but they correspond, also,\nto three different historical stages in the formation of the class,\nas we shall see later on. The monotremes of the Triassic period were\nfollowed by the marsupials of the Jurassic, and these by the placentals\nof the Cretaceous. Man belongs to this, the youngest, sub-class; for\nhe presents in his organization all the features which distinguish\nthe placentals from the marsupials and the still older monotremes.\nFirst of all, there is the peculiar organ which gives a name to the\nplacentals--the _placenta_. It serves the purpose of nourishing the\nyoung mammal embryo for a long time during its enclosure in the\nmother's womb; it consists of blood-bearing tufts which grow out of the\nchorion surrounding the embryo, and penetrate corresponding cavities in\nthe mucous membrane of the maternal uterus; the delicate skin between\nthe two structures is so attenuated in this spot that the nutriment in\nthe mother's blood can pass directly into the blood of the child. This\nexcellent contrivance for nourishing the embryo, which makes its first\nappearance at a somewhat late date, gives the foetus the opportunity\nof a longer maintenance and a higher development in the protecting\nwomb; it is wanting in the _implacentalia_, the two older sub-classes\nof the marsupials and the monotremes. There are, likewise, other\nanatomical features, particularly the higher development of the brain\nand the absence of the marsupial bone, which raise the placentals above\nall their implacental ancestors. In all these important particulars\n_man is a true placental_.\n\nThe very varied sub-class of the placentals has been recently\nsubdivided into a great number of orders; they are usually put at from\nten to sixteen, but when we include the important extinct forms which\nhave been recently discovered the number runs up to from twenty to\ntwenty-six. In order to facilitate the study of these numerous orders,\nand to obtain a deeper insight into their kindred construction, it\nis very useful to form them into great natural groups, which I have\ncalled \"legions.\" In my latest attempt[9] to arrange the advanced\nsystem of placentals in phylogenetic order I have substituted eight\nof these legions for the twenty-six orders, and shown that these may\nbe reduced to four main groups. These, in turn, are traceable to one\ncommon ancestral group of all the placentals, their fossil ancestors,\nthe _prochoriata_ of the Cretaceous period. These are directly\nconnected with the marsupial ancestors of the Jurassic period. We\nwill only specify here, as the most important living representatives\nof these four main groups, the rodentia, the ungulata, the carnivora,\nand the primates. To the legion of the primates belong the prosimi\u00e6\n(half-apes), the simi\u00e6 (real apes), and man. All the members of these\nthree orders agree in many important features, and are at the same\ntime distinguished by these features from the other twenty-three\norders of placentals. They are especially conspicuous for the length\nof their bones, which were originally adapted to their arboreal manner\nof life. Their hands and feet are five-fingered, and the long fingers\nare excellently suited for grasping and embracing the branches of\ntrees; they are provided, either partially or completely, with nails,\nbut have no claws. The dentition is complete, containing all four\nclasses--incisors, canine, premolars, and molars. Primates are also\ndistinguished from all the other placentals by important features in\nthe special construction of the skull and the brain; and these are the\nmore striking in proportion to their development and the lateness of\ntheir appearance in the history of the earth. In all these important\nanatomical features our human organism agrees with that of all the\nother primates: _man is a true primate_.\n\nAn impartial and thorough comparison of the bodily structure of the\nprimates forces us to distinguish two orders in this most advanced\nlegion of the mammalia--half-apes (_prosimiae_ or _hemipitheci_) and\napes (_simiae_ or _pitheci_). The former seem in every respect to be\nthe lower and older, the latter to be the higher and younger order. The\nwomb of the half-ape is still double, or two-horned, as it is in all\nthe other mammals. In the true ape, on the contrary, the right and left\nwombs have completely amalgamated; they blend into a pear-shaped womb,\nwhich the human mother possesses besides the ape. In the skull of the\napes, just as in that of man, the orbits of the eyes are completely\nseparated from the temporal cavities by an osseous partition; in\nthe _prosimiae_ this is either entirely wanting or very imperfect.\nFinally, the cerebrum of the _prosimia_ is either quite smooth or very\nslightly furrowed, and proportionately small; that of the true ape is\nmuch larger, and the gray bed especially, the organ of higher psychic\nactivity, is much more developed; the characteristic convolutions\nand furrows appear on its surface exactly in proportion as the ape\napproaches to man. In these and other important respects, particularly\nin the construction of the face and the hands, _man presents all the\nanatomical marks of a true ape_.\n\nThe extensive order of apes was divided by Geoffroi, in 1812, into\ntwo sub-orders, which are still universally accepted in systematic\nzoology--New World and Old World monkeys, according to the hemisphere\nthey respectively inhabit. The American \"New World\" monkeys are called\n_Platyrrhinae_ (flat-nosed); their nose is flat, and the nostrils\ndivergent, with a broad partition. The \"Old World\" monkeys, on the\ncontrary, are called collectively _Catarrhinae_ (narrow-nosed); their\nnostrils point downward, like man's, and the dividing cartilage is\nnarrow. A further difference between the two groups is that the\ntympanum is superficial in the _platyrrhinae_, but lies deeper,\ninside the petrous bone, in the _catarrhinae_; in the latter a long\nand narrow bony passage has been formed, while in the former it is\nstill short and wide, or even altogether wanting. Finally, we have a\nmuch more important and decisive difference between the two groups in\nthe circumstance that all the Old World monkeys have the same teeth\nas man--_i. e._, twenty deciduous and thirty-two permanent teeth\n(two incisors, one canine, two premolars, and three molars in each\nhalf of the jaw). The New World monkeys, on the other hand, have an\nadditional premolar in each half-jaw, or thirty-six teeth altogether.\nThe fact that these anatomical differences of the two simian groups\nare universal and conspicuous, and that they harmonize with their\ngeographical distribution in the two hemispheres, fully authorizes\na sharp systematic division of the two, as well as the phylogenetic\nconclusion that for a very long period (for more than a million years)\nthe two sub-orders have been developing quite independently of each\nother in the western and eastern hemispheres. That is a most important\npoint in view of the genealogy of our race; for man bears all the marks\nof a _true catarrhina_; he has descended from some extinct member of\nthis sub-order in the Old World.\n\nThe numerous types of _catarrhinae_ which still survive in Asia and\nAfrica have been formed into two sections for some time--the tailed,\ndoglike apes (the _cynopitheci_) and the tailless, manlike apes (the\n_anthropomorpha_). The latter are much nearer to man than the former,\nnot only in the absence of a tail and in the general build of the body\n(especially of the head), but also on account of certain features\nwhich are unimportant in themselves but very significant in their\nconstancy. The sacrum of the anthropoid ape, like that of man, is made\nup of the fusion of five vertebr\u00e6; that of the _cynopithecus_ consists\nof three (more rarely four) sacral vertebr\u00e6. The premolar teeth of\nthe _cynopitheci_ are greater in length than breadth; those of the\n_anthropomorpha_ are broader than they are long; and the first molar\nhas four protuberances in the former, five in the latter. Furthermore,\nthe outer incisor of the lower jaw is broader than the inner one\nin the manlike apes and man; in the doglike ape it is the smaller.\nFinally, there is a special significance in the fact, established by\nSelenka in 1890, that the anthropoid apes share with man the peculiar\nstructure of the discoid _placenta_, the _decidua reflexa_, and the\npedicle of the allantois. In fact, even a superficial comparison of\nthe bodily structure of the _anthropomorpha_ which still survive makes\nit clear that both the Asiatic (the orang-outang and the gibbous ape)\nand the African (the gorilla and chimpanzee) representatives of this\ngroup are nearer to man in build than any of the _cynopitheci_. Under\nthe latter group we include the dog-faced papiomorpha, the baboon,\nand the long-tailed monkey, at a very low stage. The anatomical\ndifference between these low papiomorpha and the most highly developed\nanthropoid apes is greater in every respect, whatever organ we take\nfor comparison, than the difference between the latter and man.\nThis instructive fact was established with great penetration by the\nanatomist Robert Hartmann, in his work on _The Anthropoid Apes_;[10]\nhe proposed to divide the order of _Simiae_ in a new way--namely, into\nthe two great groups of _primaria_ (man and the anthropoid ape) and the\n_simiae_ proper, or _pitheci_ (the rest of the catarrhin\u00e6 and all the\nplatyrrhin\u00e6). In any case, we have a clear proof of _the close affinity\nof man and the anthropoid ape_.\n\nThus comparative anatomy proves to the satisfaction of every\nunprejudiced and critical student the significant fact that the body of\nman and that of the anthropoid ape are not only peculiarly similar, but\nthey are practically one and the same in every important respect. The\nsame two hundred bones, in the same order and structure, make up our\ninner skeleton; the same three hundred muscles effect our movements;\nthe same hair clothes our skin; the same groups of ganglionic cells\nbuild up the marvellous structure of our brain; the same four chambered\nheart is the central pulsometer in our circulation; the same thirty-two\nteeth are set in the same order in our jaws; the same salivary,\nhepatic, and gastric glands compass our digestive process; the same\nreproductive organs insure the maintenance of our race.\n\nIt is true that we find, on close examination, certain minor\ndifferences in point of size and shape in most of the organs of man\nand the ape; but we discover the same, or similar, differences\nbetween the higher and lower races of men, when we make a careful\ncomparison--even, in fact, in a minute comparison of the various\nindividuals of our own race. We find no two persons who have exactly\nthe same size and form of nose, ears, eyes, and so forth. One has\nonly to compare attentively these special features in many different\npersons in any large company to convince one's self of the astonishing\ndiversity of their construction and the infinite variability of\nspecific forms. Not infrequently even two sisters are so much unlike\nas to make their origin from the same parents almost incredible. Yet\nall these individual variations do not weaken the significance of the\nfundamental similarity of structure; they are traceable to certain\nminute differences in the growth of the individual features.\n\n\n\n\nCHAPTER III\n\nOUR LIFE\n\n    Development of Physiology in Antiquity and the Middle Ages:\n    Galen--Experiment and Vivisection--Discovery of the Circulation\n    of the Blood by Harvey--Vitalism: Haller--Teleological and\n    Vitalistic Conception of Life--Mechanical and Monistic View\n    of the Physiological Processes--Comparative Physiology in the\n    Nineteenth Century: Johannes M\u00fcller--Cellular Physiology: Max\n    Verworn--Cellular Pathology: Virchow--Mammal Physiology--Similarity\n    of all Vital Activity in Man and the Ape\n\n\nIt is only in the nineteenth century that our knowledge of human life\nhas attained the dignity of a genuine, independent science; during the\ncourse of the century it has developed into one of the highest, most\ninteresting, and most important branches of knowledge. This \"science\nof the vital functions,\" physiology, had, it is true, been regarded\nat a much earlier date as a desirable, if not a necessary, condition\nof success in medical treatment, and had been constantly associated\nwith anatomy, the science of the structure of the body. But it was\nonly much later, and much more slowly, than the latter that it could\nbe thoroughly studied, as it had to contend with much more serious\ndifficulties.\n\nThe idea of life, as the opposite of death, naturally became the\nsubject of speculation at a very early age. In the living man, just\nas in other living animals, there were certain peculiar changes,\nespecially movements, which were wanting in lifeless nature:\nspontaneous locomotion, the beat of the heart, the drawing of the\nbreath, speech, and so forth. But the discrimination of such \"organic\nmovements\" from similar phenomena in inorganic bodies was by no means\neasy, and was frequently impossible; the flowing stream, the flickering\nflame, the rushing wind, the falling rock, seemed to man to exhibit\nthe same movements. It was quite natural that primitive man should\nattribute an independent life to these \"dead\" bodies. He knew no more\nof the real sources of movement in the one case than in the other.\n\nWe find the earliest scientific observations on the nature of man's\nvital functions (as well as on his structure) in the Greek natural\nphilosophers and physicians of the sixth and fifth centuries before\nChrist. The best collection of the physiological facts which were known\nat that time is to be found in the _Natural History_ of Aristotle; a\ngreat number of his assertions were probably taken from Democritus\nand Hippocrates. The school of the latter had already made attempts\nto explain the mystery; it postulated as the ultimate source of life\nin man and the beasts a volatile \"spirit of life\" (Pneuma); and\nErasistratus (280 B.C.) already drew a distinction between the lower\nand the higher \"spirit of life,\" the _pneuma zoticon_ in the heart and\nthe _pneuma psychicon_ in the brain.\n\nThe credit of gathering these scattered truths into unity, and of\nmaking the first attempt at a systematic physiology, belongs to the\ngreat Greek physician Galen; we have already recognized in him the\nfirst great anatomist of antiquity (cf. p. 23). In his researches\ninto the organs of the body he never lost sight of the question of\ntheir vital activity, their functions; and even in this direction he\nproceeded by the same comparative method, taking for his principal\nstudy the animals which approach nearest to man. Whatever he learned\nfrom these he applied directly to man. He recognized the value of\nphysiological experiment; in his vivisection of apes, dogs, and\nswine he made a number of interesting experiments. Vivisection has\nbeen made the object of a violent attack in recent years, not only\nby the ignorant and narrow-minded, but by theological enemies of\nknowledge and by perfervid sentimentalists; it is, however, one of the\n_indispensable_ methods of research into the nature of life, and has\ngiven us invaluable information on the most important questions. This\nwas recognized by Galen seventeen hundred years ago.\n\nGalen reduces all the different functions of the body to three\ngroups, which correspond to the three forms of the _pneuma_, or vital\nspirit. The _pneuma psychicon_--the soul--which resides in the brain\nand nerves, is the cause of thought, sensation, and will (voluntary\nmovement); the _pneuma zoticon_--the heart--is responsible for the beat\nof the heart, the pulse, and the temperature; the _pneuma physicon_,\nseated in the liver, is the source of the so-called vegetative\nfunctions, digestion and assimilation, growth and reproduction.\nHe especially emphasized the renewal of the blood in the lungs,\nand expressed a hope that we should some day succeed in isolating\nthe permanent element in the atmosphere--the _pneuma_, as he calls\nit--which is taken into the blood in respiration. More than fifteen\ncenturies elapsed before this _pneuma_--oxygen--was discovered by\nLavoisier.\n\nIn human physiology, as well as in anatomy, the great system of Galen\nwas for thirteen centuries the _Codex aureus_, the inviolable source of\nall knowledge. The influence of Christianity, so fatal to scientific\nculture, raised the same insuperable obstacles in this as in every\nother branch of secular knowledge. Not a single scientist appeared\nfrom the third to the sixteenth century who dared to make independent\nresearch into man's vital activity, and transcend the limits of the\nGalenic system. It was not until the sixteenth century that experiments\nwere made in that direction by a number of distinguished physicians\nand anatomists (Paracelsus, Servetus, Vesalius, and others). In 1628\nHarvey published his great discovery of the circulation of the blood,\nand showed that the heart is a pump, which drives the red stream\nunceasingly through the connected system of arteries and veins by a\nrhythmic, unconscious contraction of its muscles. Not less important\nwere Harvey's researches into the procreation of animals, as a result\nof which he formulated the well-known law: \"Every living thing comes\nfrom an egg\" (_omne vivum ex ovo_).\n\nThe powerful impetus which Harvey gave to physiological observation and\nexperiment led to a great number of discoveries in the sixteenth and\nseventeenth centuries. These were co-ordinated for the first time by\nthe learned Albrecht Haller about the middle of the last century; in\nhis great work, _Elementa Physiologiae_, he established the inherent\nimportance of the science, independently of its relation to practical\nmedicine. In postulating, however, a special \"sensitive force or\nsensibility\" for neural action, and a special \"irritability\" for\nmuscular movement, Haller gave strong support to the erroneous idea of\na specific \"vital force\" (_vis vitalis_).\n\nFor more than a century afterwards, from the middle of the eighteenth\nuntil the middle of the nineteenth century, medicine and (especially)\nphysiology were dominated by the old idea that a certain number of the\nvital processes may be traced to physical and chemical causes, but that\nothers are the outcome of a special vital force which is independent\nof physical agencies. However much scientists differed in their\nconceptions of its nature and its relation to the \"soul,\" they were all\nagreed as to its independence of, and essential distinction from, the\nchemico-physical forces of ordinary \"matter\"; it was a self-contained\nforce (_archaeus_), unknown in inorganic nature, which compelled\nordinary forces into its service. Not only the distinctly psychical\nactivity, the sensibility of the nerves and the irritability of the\nmuscles, but even the phenomena of sense activity, of reproduction,\nand of development seemed so wonderful and so mysterious in their\nsources that it was impossible to attribute them to simple physical\nand chemical processes. As the free activity of the vital force\nwas purposive and conscious, it led, in philosophy, to a complete\n_teleology_; especially did this seem indisputable when even the\n\"critical\" philosopher Kant had acknowledged, in his famous critique\nof the teleological position, that, though the mind's authority to\ngive a mechanical interpretation of all phenomena is theoretically\nunlimited, yet its actual capacity for such interpretation does not\nextend to the phenomena of organic life; here we are compelled to have\nrecourse to a _purposive_--therefore _supernatural_--principle. This\ndivergence of the _vital_ phenomena from the _mechanical_ processes of\nlife became, naturally, more conspicuous as science advanced in the\nchemical and physical explanation of the latter. The circulation of the\nblood and a number of other phenomena could be traced to mechanical\nagencies; respiration and digestion were attributable to chemical\nprocesses like those we find in inorganic nature. On the other hand,\nit seemed impossible to do this with the wonderful performances of the\nnerves and muscles, and with the characteristic life of the mind; the\nco-ordination of all the different forces in the life of the individual\nseemed also beyond such a mechanical interpretation. Hence there arose\na complete physiological dualism--an essential distinction was drawn\nbetween inorganic and organic nature, between mechanical and vital\nprocesses, between material force and life force, between the body and\nthe soul. At the beginning of the nineteenth century this vitalism was\nfirmly established in France by Louis Dumas, and in Germany by Reil.\nAlexander Humboldt had already published a poetical presentation of it\nin 1795, in his narrative of the _Legend of Rhodes_; it is repeated,\nwith critical notes, in his _Views of Nature_.\n\nIn the first half of the seventeenth century the famous philosopher\nDescartes, starting from Harvey's discovery of the circulation of the\nblood, put forward the idea that the body of man, like that of other\nanimals, is merely an intricate machine, and that its movements take\nplace under the same mechanical laws as the movements of an automaton\nof human construction. It is true that Descartes, at the same time,\nclaimed for man the exclusive possession of a perfectly independent,\nimmaterial soul, and held that its subjective experience, thought,\nwas the only thing in the world of which we have direct and certain\ncognizance (\"_Cogito, ergo sum_\"). Yet this dualism did not prevent\nhim from doing much to advance our knowledge of the mechanical life\nprocesses in detail. Borelli followed (1660) with a reduction of the\nmovements of the animal body to purely physical laws, and Sylvius\nendeavored, about the same time, to give a purely chemical explanation\nof the phenomena of digestion and respiration; the former founded the\n_iatromechanical_, the latter the _iatrochemical_, school of medicine.\nHowever, these rational tendencies towards a natural, mechanical\nexplanation of the phenomena of life did not attain to a universal\nacceptance and application; in the course of the eighteenth century\nthey fell entirely away before the advance of teleological vitalism.\nThe final disproof of the latter and a return to mechanism only became\npossible with the happy growth of the new science of comparative\nphysiology in the forties of the present century.\n\nOur knowledge of the vital functions, like our knowledge of the\nstructure of the human body, was originally obtained, for the most\npart, not by direct observation of the human organism itself, but by\na study of the more closely related animals among the vertebrates,\nespecially the mammals. In this sense the very earliest beginning\nof human anatomy and physiology was \"comparative.\" But the distinct\nscience of \"comparative physiology,\" which embraces the whole sphere\nof life phenomena, from the lowest animal up to man, is a triumph of\nthe nineteenth century. Its famous creator was Johannes M\u00fcller, of\nBerlin (born, the son of a shoemaker, at Coblentz, in 1801). For fully\ntwenty-five years--from 1833 to 1858--this most versatile and most\ncomprehensive biologist of our age evinced an activity at the Berlin\nUniversity, as professor and investigator, which is only comparable\nwith the associated work of Haller and Cuvier. Nearly every one of the\ngreat biologists who have taught and worked in Germany for the last\nsixty years was, directly or indirectly, a pupil of Johannes M\u00fcller.\nStarting from the anatomy and physiology of man, he soon gathered all\nthe chief groups of the higher and lower animals within his sphere\nof comparison. As, moreover, he compared the structure of extinct\nanimals with the living, and the healthy organism with the diseased,\nendeavoring to bring together all the phenomena of life in a truly\nphilosophic fashion, he attained a biological knowledge far in advance\nof his predecessors.\n\nThe most valuable fruit of these comprehensive studies of Johannes\nM\u00fcller was his _Manual of Human Physiology_. This classical work\ncontains much more than the title indicates; it is the sketch of\na comprehensive \"comparative biology.\" It is still unsurpassed in\nrespect of its contents and range of investigation. In particular,\nwe find the methods of observation and experiment applied in it as\nmasterfully as the philosophic processes of induction and deduction.\nM\u00fcller was originally a vitalist, like all the physiologists of his\ntime. Nevertheless, the current idea of a vital force took a novel\nform in his speculations, and gradually transformed itself into the\nvery opposite. For he attempted to explain the phenomena of life\nmechanically in every department of physiology. His \"transfigured\"\nvital force was not _above_ the physical and chemical laws of the rest\nof nature but entirely bound up with them. It was, in a word, nothing\nmore than life itself--that is, the sum of all the movements which we\nperceive in the living organism. He sought especially to give them\nthe same mechanical interpretation in the life of the senses and of\nthe mind as in the working of the muscles; the same in the phenomena\nof circulation, respiration, and digestion as in generation and\ndevelopment. M\u00fcller's success was chiefly due to the fact that he\nalways began with the simplest life phenomena of the lowest animals,\nand followed them step by step in their gradual development up to the\nvery highest, to man. In this his method of _critical comparison_\nproved its value both from the physiological and from the anatomical\npoint of view. Johannes M\u00fcller is, moreover, the only great scientist\nwho has equally cultivated these two branches of research, and combined\nthem with equal brilliancy. Immediately after his death his vast\nscientific kingdom fell into four distinct provinces, which are now\nnearly always represented by four or more chairs--human and comparative\nanatomy, pathological anatomy, physiology, and the history of\nevolution. This sudden division of M\u00fcller's immense realm of learning\nin 1858 has been compared to the dissolution of the empire which\nAlexander the Great had consolidated and ruled.\n\nAmong the many pupils of Johannes M\u00fcller who, either during his\nlifetime or after his death, labored hard for the advancement of the\nvarious branches of biology, one of the most fortunate--if not the\nmost important--was Theodor Schwann. When the able botanist Schleiden,\nin 1838, indicated the cell as the common elementary organ of all\nplants, and proved that all the different tissues of the plant are\nmerely combinations of cells, Johannes M\u00fcller recognized at once the\nextraordinary possibilities of this important discovery. He himself\nsought to point out the same composition in various tissues of the\nanimal body--for instance, in the spinal cord of vertebrates--and\nthus led his pupil, Schwann, to extend the discovery to all the\nanimal tissues. This difficult task was accomplished by Schwann in\nhis _Microscopic Researches into the Accordance in the Structure and\nGrowth of Plants and Animals_ (1839). Thus was the foundation laid\nof the \"cellular theory,\" the profound importance of which, both in\nphysiology and anatomy, has become clearer and more widely recognized\nin each subsequent year. Moreover, it was shown by two other pupils\nof Johannes M\u00fcller that the activity of all organisms is, in the\nultimate analysis, the activity of the components of their tissues, the\nmicroscopic cells--these were the able physiologist Ernst Br\u00fccke, of\nVienna, and the distinguished histologist Albert K\u00f6lliker, of W\u00fcrzburg.\nBr\u00fccke correctly denominated the cells the \"elementary organisms,\" and\nshowed that, in the body of man and of all other animals, they are the\nonly actual, independent factors of the life process. K\u00f6lliker earned\nspecial distinction, not only in the construction of the whole science\nof histology, but particularly by showing that the animal ovum and its\nproducts are simple cells.\n\nStill, however widely the immense importance of the cellular theory for\nall biological research was acknowledged, the \"cellular physiology\"\nwhich is based on it only began an independent development very\nrecently. In this Max Verworn (of Jena) earned a twofold distinction.\nIn his _Psycho-physiological Studies of the Protistae_ (1889) he\nshowed, as a result of an ingenious series of experimental researches,\nthat the \"theory of a cell-soul\" which I put forward in 1866[11]\nis completely established by an accurate study of the unicellular\nprotozoa, and that \"the psychic phenomena of the protist\u00e6 form the\nbridge which unites the chemical processes of inorganic nature with\nthe mental life of the highest animals.\" Verworn has further developed\nthese views, and based them on the modern theory of evolution, in\nhis _General Physiology_. This distinguished work returns to the\ncomprehensive point of view of Johannes M\u00fcller, in opposition to the\none-sided and narrow methods of those modern physiologists who think\nto discover the nature of the vital phenomena by the exclusive aid of\nchemical and physical experiments. Verworn showed that it is only by\nM\u00fcller's comparative method and by a profound study of the physiology\nof the cell that we can reach the higher stand-point which will give us\na comprehensive survey of the wonderful realm of the phenomena of life.\nOnly thus do we become convinced that the vital processes in man are\nsubject to the same physical and chemical laws as those of all other\nanimals.\n\nThe fundamental importance of the cellular theory for all branches of\nbiology was made clear in the second half of the nineteenth century,\nnot only by the rapid progress of morphology and physiology, but also\nby the entire reform of that biological science which has always\nbeen deemed most important on account of its relation to practical\nmedicine--pathology, or the science of disease. Many even of the\nolder physicians were convinced that human diseases were natural\nphenomena, like all other manifestations of life, and should be studied\nscientifically, like other vital functions. Particular schools of\nmedicine--the Iatrophysical and the Iatrochemical--had already, in\nthe seventeenth century, attempted to trace the sources of disease to\ncertain physical and chemical changes. However, the imperfect condition\nof science at that period precluded any lasting results of these\nefforts. Many of the older theories, which sought the nature of disease\nin supernatural and mystical causes, were almost universally accepted\ndown to the middle of the nineteenth century.\n\nIt was then that Rudolf Virchow, another pupil of M\u00fcller, conceived\nthe happy idea of transferring the cellular theory from the healthy to\nthe diseased organism; he sought in the more minute metamorphoses of\nthe diseased cells and the tissues they composed the true source of\nthose larger changes which, in the form of disease, threaten the living\norganism with peril and death. Especially during the seven years of\nhis professorship at W\u00fcrzburg (1849-56) Virchow pursued his great task\nwith such brilliant results that his _Cellular Pathology_ (published in\n1858) turned, at one stroke, the whole of pathology and the dependent\nscience of practical medicine into new and eminently fruitful paths.\nThis reform of medicine is significant for our present purpose in that\nit led us to a monistic and purely scientific conception of disease. In\nsickness, no less than in health, man is subject to the same eternal\n\"iron laws\" of physics and chemistry as all the rest of the organic\nworld.\n\nAmong the numerous classes of animals which modern zoology\ndistinguishes the mammals occupy a pre-eminent position, not only on\nmorphological grounds, but also for physiological reasons. As man\nbelongs to the class of mammals (see p. 27) by every portion of his\nframe, we must expect him to share his characteristic functions with\nthe rest of the mammals. Such we find to be the case. The circulation\nof the blood and respiration are accomplished in man under precisely\nthe same laws and in the same manner as in all the other mammals--_and\nin these alone_; they are determined by the peculiar structure of\ntheir heart and lungs. In mammals only is all the arterial blood\nconducted from the left ventricle of the heart to the body by one,\nthe _left_, branch of the aorta, while in birds it passes along the\n_right_ branch, and in reptiles along both branches. The blood of\nmammals is distinguished from that of any other vertebrate by the\ncircumstance that its red cells have lost their nucleus (by reversion).\nThe respiratory movements are effected largely by the diaphragm in\nthis class of animals alone, because only in them does it form a\ncomplete partition between the pectoral and abdominal cavities. Special\nimportance, however, in this highest class of animals, attaches to\nthe production of milk in the breasts (_mammae_), and to the peculiar\nmethod of the rearing of the young, which entails the supplying of the\noffspring with the mother's milk. As this nutritive process reacts most\npowerfully on the other vital functions, and the maternal affection of\nmammals must have arisen from this intimate form of rearing, the name\nof the class justly reminds us of its great importance. In millions of\npictures, most of them produced by painters of the highest rank, the\n\"madonna with the child\" is revered as the purest and noblest type of\nmaternal love--the instinct which is found in its extreme form in the\nexaggerated tenderness of the mother-ape.\n\nAs the apes approach nearest to man of all the mammals in point of\nstructure, we shall expect to hear the same of their vital functions;\nand that we find to be the case. Everybody knows how closely the\nhabits, the movements, the sense activity, the mental life, and the\nparental customs of apes resemble those of man. Scientific physiology\nproves the same significant resemblance in other less familiar\nprocesses, particularly in the working of the heart, the division\nof the breasts, and the sexual life. In the latter connection it is\nespecially noteworthy that the mature females of many kinds of apes\nsuffer a periodical discharge of blood from the womb, which corresponds\nto the menstruation of the human female. The secretion of the milk in\nthe glands and the suctorial process also take place in the female ape\nin precisely the same fashion as in women.\n\nFinally, it is of especial interest that the speech of apes seems on\nphysiological comparison to be a stage in the formation of articulate\nhuman speech. Among living apes there is an Indian species which is\nmusical; the _hylobates syndactylus_ sings a full octave in perfectly\npure, harmonious half-tones. No impartial philologist can hesitate any\nlonger to admit that our elaborate rational language has been slowly\nand gradually developed out of the imperfect speech of our Pliocene\nsimian ancestors.\n\n\n\n\nCHAPTER IV\n\nOUR EMBRYONIC DEVELOPMENT\n\n    The Older Embryology--The Theory of Preformation--The Theory of\n    Scatulation: Haller and Leibnitz--The Theory of Epigenesis: C. F.\n    Wolff--The Theory of Germinal Layers: Carl Ernst Baer--Discovery\n    of the Human Ovum: Remak, K\u00f6lliker--The Egg-Cell and the\n    Sperm-Cell--The Theory of the Gastr\u00e6a--Protozoa and Metazoa--The\n    Ova and the Spermatozoa: Oscar Hertwig--Conception--Embryonic\n    Development in Man--Uniformity of the Vertebrate Embryo--The\n    Germinal Membranes in Man--The Amnion, the Serolemma, and the\n    Allantois--The Formation of the Placenta and the \"After-Birth\"--The\n    _Decidua_ and the _Funiculus Umbilicalis_--The Discoid Placenta of\n    Man and the Ape\n\n\nComparative ontogeny, or the science of the development of the\nindividual animal, is a child of the nineteenth century in even a truer\nsense than comparative anatomy and physiology. How is the child formed\nin the mother's womb? How do animals evolve from ova? How does the\nplant come forth from the seed? These pregnant questions have occupied\nthe thoughtful mind for thousands of years. Yet it is only seventy\nyears since the embryologist Baer pointed out the correct means and\nmethods for penetrating into the mysteries of embryonic life; it is\nonly forty years since Darwin, by his reform of the theory of descent,\ngave us the key which should open the long-closed door, and lead to\na knowledge of embryonic agencies. As I have endeavored to give a\ncomplete, popular presentation of this very interesting but difficult\nstudy in the first section of my _Anthropogeny_, I will confine myself\nhere to a brief survey and discussion of the most important phenomena.\nLet us first cast a historical glance at the older ontogeny, and the\ntheory of preformation which is connected with it.\n\nThe classical works of Aristotle, the many-sided \"father of science,\"\nare the oldest known scientific sources of embryology, as we found them\nto be for comparative anatomy. Not only in his great natural history,\nbut also in a special small work, _Five Books on the Generation and\nDevelopment of Animals_, the great philosopher gives us a host of\ninteresting facts, adding many observations on their significance; it\nwas not until our own days that many of them were fully appreciated,\nand, indeed, we may say, discovered afresh. Naturally, many fables and\nerrors are mixed up with them; it was all that was known at that time\nof the hidden growth of the human germ. Yet during the long space of\nthe next two thousand years the slumbering science made no further\nprogress. It was not until the commencement of the seventeenth century\nthat there was a renewal of activity. In 1600 the Italian anatomist\nFabricius ab Aquapendente published at Padua the first pictures and\ndescriptions of the embryos of man and some of the higher animals; in\n1687 the famous Marcello Malpighi, of Bologna, a distinguished pioneer\nalike in zoology and botany, published the first consistent exposition\nof the growth of the chick in the hatched egg.\n\nAll these older scientists were possessed with the idea that the\ncomplete body, with all its parts, was already contained in the ovum\nof animals, only it was so minute and transparent that it could not\nbe detected; that, therefore, the whole development was nothing more\nthan a _growth_, or an \"unfolding,\" of the parts that were already\n\"infolded\" (_involutae_). This erroneous notion, almost universally\naccepted until the beginning of the present century, is called the\n\"preformation theory\"; sometimes it is called the \"evolution theory\"\n(in the literal sense of \"unfolding\"); but the latter title is accepted\nby modern scientists for the very different theory of \"transformation.\"\n\nClosely connected with the preformation theory, and as a logical\nconsequence of it, there arose in the last century a further theory\nwhich keenly interested all thoughtful biologists--the curious\n\"theory of scatulation.\" As it was thought that the outline of the\nentire organism, with all its parts, was present in the egg, the\novary of the embryo had to be supposed to contain the ova of the\nfollowing generation; these, again, the ova of the next, and so on\n_in infinitum_! On that basis the distinguished physiologist Haller\ncalculated that God had created together, 6000 years ago--on the sixth\nday of his creatorial labors--the germs of 200,000,000,000 men, and\ningeniously packed them all in the ovary of our venerable mother Eve.\nEven the gifted philosopher Leibnitz fully accepted this conclusion,\nand embodied it in his monadist theory; and as, on his theory, soul and\nbody are in eternal, inseparable companionship, the consequence had to\nbe accepted for the soul; \"the souls of men have existed in organized\nbodies in their ancestors from Adam downward--that is, from the very\nbeginning of things.\"\n\nIn the month of November, 1759, a young doctor of twenty-six years,\nCaspar Friedrich Wolff (son of a Berlin tailor), published his\ndissertation for the degree at Halle, under the title, _Theoria\nGenerationis_. Supported by a series of most laborious and painstaking\nobservations, he proved the entire falsity of the dominant theories of\npreformation and scatulation. In the hatched egg there is at first no\ntrace of the coming chick and its organs; instead of it we find on top\nof the yolk a small, circular, white disk. This thin \"germinal disk\"\nbecomes gradually round, and then breaks up into four folds, lying\nupon each other, which are the rudiments of the four chief systems of\norgans--the nervous system above, the muscular system underneath, the\nvascular system (with the heart), and, finally, the alimentary canal.\nThus, as Wolff justly remarked, the embryonic development does not\nconsist in an unfolding of the preformed organs, but in a series of\nnew constructions; it is a true _epigenesis_. One part arises after\nanother, and all make their appearance in a simple form, which is very\ndifferent from the later structure. This only appears after a series of\nmost remarkable formations. Although this great discovery--one of the\nmost important of the eighteenth century--could be directly proved by a\nverification of the facts Wolff had observed, and although the \"theory\nof generation\" which was founded on it was in reality not a theory at\nall, but a simple fact, it met with no sympathy whatever for half a\ncentury. It was particularly retarded by the high authority of Haller,\nwho fought it strenuously with the dogmatic assertion that \"there is\nno such thing as development: no part of the animal body is formed\nbefore another; all were created together.\" Wolff, who had to go to St.\nPetersburg, was long in his grave before the forgotten facts he had\nobserved were discovered afresh by Oken at Jena, in 1806.\n\nAfter Wolff's \"epigenesis theory\" had been established by Oken and\nNeckel (whose important work on the development of the alimentary\ncanal was translated from Latin into German), a number of young German\nscientists devoted themselves eagerly to more accurate embryological\nresearch. The most important and successful of these was Carl Ernst\nBaer. His principal work appeared in 1828, with the title, _History of\nthe Development of Animals: Observations and Reflections_. Not only\nthe phenomena of the formation of the germ are clearly illustrated\nand fully described in it, but it adds a number of very pregnant\nspeculations. In particular, the form of the embryo of man and the\nmammals is correctly presented, and the vastly different development\nof the lower invertebrate animals is also considered. The two leaflike\nlayers which appear in the round germ disk of the higher vertebrates\nfirst divide, according to Baer, into two further layers, and these\nfour germinal layers are transformed into four tubes, which represent\nthe fundamental organs--the skin layer, the muscular layer, the\nvascular layer, and the mucous layer. Then, by very complicated\nevolutionary processes, the later organs arise, in substantially the\nsame manner, in man and all the other vertebrates. The three chief\ngroups of invertebrates, which in their turn differ widely from each\nother, have a very different development.\n\nOne of the most important of Baer's many discoveries was the finding of\nthe human ovum. Up to that time the little vesicles which are found in\ngreat numbers in the human ovary and in that of all other mammals had\nbeen taken for the ova. Baer was the first to prove, in 1827, that the\nreal ova are enclosed in these vesicles--the \"Graafian follicles\"--and\nmuch smaller, being tiny spheres 1-120th inch in diameter, visible\nto the naked eye as minute specks under favorable conditions. He\ndiscovered likewise that from this tiny ovum of the mammal there\ndevelops first a characteristic germ globule, a hollow sphere with\nliquid contents, the wall of which forms the slender germinal membrane,\nor blastoderm.\n\nTen years after Baer had given a firm foundation to embryological\nscience by his theory of germ layers a new task confronted it on the\nestablishment of the cellular theory in 1838. What is the relation of\nthe ovum and the layers which arise from it to the tissues and cells\nwhich compose the fully developed organism? The correct answer to this\ndifficult question was given about the middle of this century by two\ndistinguished pupils of Johannes M\u00fcller--Robert Remak, of Berlin, and\nAlbert K\u00f6lliker, of W\u00fcrzburg. They showed that the ovum is at first one\nsimple cell, and that the many germinal globules, or granules, which\narise from it by repeated segmentation, are also simple cells. From\nthis mulberry-like group of cells are constructed first the germinal\nlayers, and subsequently by differentiation, or division of labor,\nall the different organs. K\u00f6lliker has the further merit of showing\nthat the seminal fluid of male animals is also a mass of microscopic\ncells. The active pin-shaped \"seed-animalcules,\" or _spermatozoa_, in\nit are merely ciliated cells, as I first proved in the case of the\nseed-filaments of the sponge in 1866. Thus it was proved that both\nthe materials of generation, the male sperm and the female ova, fell\nin with the cellular theory. That was a discovery of which the great\nphilosophic significance was not appreciated until a much later date,\non a close study of the phenomena of conception in 1875.\n\nAll the older studies in embryonic development concern man and the\nhigher vertebrates, especially the embryonic bird, since hens' eggs\nare the largest and most convenient objects for investigation, and\nare plentiful enough to facilitate experiment; we can hatch them in\nthe incubator, as well as by the natural function of the hen, and\nso observe from hour to hour, during the space of three weeks, the\nwhole series of formations, from the simple germ cell to the complete\norganism. Even Baer had only been able to gather from such observations\nthe fact that the different classes of vertebrates agreed in the\ncharacteristic form of the germ layers and the growth of particular\norgans. In the innumerable classes of invertebrates, on the other\nhand--that is, in the great majority of animals--the embryonic\ndevelopment seemed to run quite a different course, and most of them\nseemed to be altogether without true germinal layers. It was not until\nabout the middle of the century that such layers were found in some of\nthe invertebrates. Huxley, for instance, found them in the medus\u00e6 in\n1849, and K\u00f6lliker in the cephalopods in 1844. Particularly important\nwas the discovery of Kowalewsky (1886) that the lowest vertebrate--the\nlancelot, or amphioxus--is developed in just the same manner (and a\nvery original fashion it is) as an invertebrate, apparently quite\nremote, tunicate, the sea-squirt, or ascidian. Even in some of the\nworms, the radiata and the articulata, a similar formation of the\ngerminal layers was pointed out by the same observer. I myself was\nthen (since 1886) occupied with the embryology of the sponges, corals,\nmedus\u00e6, and siphonophor\u00e6, and, as I found the same formation of two\nprimary germ layers everywhere in these lowest classes of multicellular\nanimals, I came to the conclusion that this important embryonic\nfeature is common to the entire animal world. The circumstance that\nin the sponges and the cnidaria (polyps, medus\u00e6, etc.) the body\nconsists for a long time, sometimes throughout life, merely of two\nsimple layers of cells, seemed to me especially significant. Huxley\nhad already (1849) compared these, in the case of the medus\u00e6, with the\ntwo primary germinal layers of the vertebrates. On the ground of these\nobservations and comparisons I then, in 1872, in my _Philosophy of the\nCalcispongiae_, published the \"theory of the gastr\u00e6a,\" of which the\nfollowing are the essential points:\n\nI. The whole animal world falls into two essentially different groups,\nthe unicellular primitive animals (Protozoa) and the multicellular\nanimals with complex tissues (Metazoa). The entire organism of the\nprotozoon (the rhizopods of the infusoria) remains throughout life a\nsingle simple cell (or occasionally a loose colony of cells without\nthe formation of tissue, a _coenobium_). The organism of the metazoon,\non the contrary, is only unicellular at the commencement, and is\nsubsequently built up of a number of cells which form tissues.\n\nII. Hence the method of reproduction and development is very different\nin each of these great categories of animals. The protozoa usually\nmultiply by _non-sexual_ means, by fission, gemmation, or spores;\nthey have no real ova and no sperm. The metazoa, on the contrary, are\ndivided into male and female sexes, and generally propagate sexually,\nby means of true ova, which are fertilized by the male sperm.\n\nIII. Hence, further, true germinal layers, and the tissues which are\nformed from them, are found only in the metazoa; they are entirely\nwanting in the protozoa.\n\nIV. In all the metazoa only two primary layers appear at first, and\nthese have always the same essential significance; from the _outer_\nlayer the external skin and the nervous system are developed; from the\n_inner_ layer are formed the alimentary canal and all the other organs.\n\nV. I called the germ, which always arises first from the impregnated\novum, and which consists of these two primary layers, the \"gut-larva,\"\nor the _gastrula_; its cup-shaped body with the two layers encloses\noriginally a simple digestive cavity, the primitive gut (the\n_progaster_ or _archenteron_), and its simple opening is the primitive\nmouth (the _prostoma_ or _blastoporus_). These are the earliest organs\nof the multicellular body, and the two cell layers of its enclosing\nwall, simple epithelia, are its earliest tissues; all the other organs\nand tissues are a later and secondary growth from these.\n\nVI. From this similarity, or _homology_, of the gastrula in all classes\nof compound animals I drew the conclusion, in virtue of the biogenetic\nlaw (p. 81), that all the metazoa come originally from one simple\nancestral form, the _gastraea_, and that this ancient (Laurentian),\nlong-extinct form had the structure and composition of the actual\ngastrula, in which it is preserved by heredity.\n\nVII. This phylogenetic conclusion, based on the comparison of\nontogenetic facts, is confirmed by the circumstance that there are\nseveral of these gastr\u00e6ades still in existence (_gastraemaria_,\n_cyemaria_, _physemaria_, etc.), and also some ancient forms of\nother animal groups whose organization is very little higher (the\n_olynthus_ of the sponges, the _hydra_, or common fresh-water polyp,\nof the cnidaria, the _convoluta_ and other cryptoc\u00e6la, or worms of the\nsimplest type, of the _platodes_).\n\nVIII. In the further development of the various tissue-forming animals\nfrom the gastrula we have to distinguish two principal groups. The\nearlier and _lower_ types (the _coelenteria_ or _acoelomia_) have\nno body cavity, no vent, and no blood; such is the case with the\ngastr\u00e6ades, sponges, cnidaria, and platodes. The later and _higher_\ntypes (the _caelomaria_ or _bilateria_), on the other hand, have a\ntrue body cavity, and generally blood and a vent; to these we must\nrefer the worms and the higher types of animals which were evolved from\nthese later on, the echinodermata, mollusca, articulata, tunicata, and\nvertebrata.\n\nThose are the main points of my \"gastr\u00e6a theory\"; I have since\nenlarged the first sketch of it (given in 1872), and have endeavored\nto substantiate it in a series of \"Studies on the gastr\u00e6a theory\"\n(1873-84). Although it was almost universally rejected at first, and\nfiercely combated for ten years by many authorities, it is now (and has\nbeen for the last fifteen years) accepted by nearly all my colleagues.\nLet us now see what far-reaching consequences follow from it, and\nfrom the evolution of the germ, especially with regard to our great\nquestion, \"the place of man in nature.\"\n\nThe human ovum, like that of all other animals, is a single cell, and\nthis tiny globular egg cell (about the 120th of an inch in diameter)\nhas just the same characteristic appearance as that of all other\nviviparous organisms. The little ball of protoplasm is surrounded\nby a thick, transparent, finely reticulated membrane, called the\n_zona pellucida_; even the little, globular, germinal vesicle (the\ncell-nucleus), which is enclosed in the protoplasm (the cell-body),\nis of the same size and the same qualities as in the rest of the\nmammals. The same applies to the active spermatozoa of the male,\nthe minute, threadlike, ciliated cells of which millions are found\nin every drop of the seminal fluid; on account of their lifelike\nmovements they were previously taken to be forms of life, as the name\nindicates (spermatozoa--sperm animals). Moreover, the origin of both\nthese important sexual cells in their respective organs is the same in\nman as in the other mammals; both the ova in the ovary of the female\nand the spermatozoa in the spermarium of the male arise in the same\nfashion--they always come from cells, which are originally derived from\nthe coelous epithelium, the layer of cells which clothes the cavity\nof the body.\n\nThe most important moment in the life of every man, as in that of all\nother complex animals, is the moment in which he begins his individual\nexistence; it is the moment when the sexual cells of both parents meet\nand coalesce for the formation of a single simple cell. This new cell,\nthe impregnated egg cell, is the individual stem cell (the _cytula_),\nthe continued segmentation of which produces the cells of the germinal\nlayers and the gastrula. With the formation of this cytula, hence in\nthe process of conception itself, the existence of the personality, the\nindependent individual, commences. This ontogenic fact is supremely\nimportant, for the most far-reaching conclusions may be drawn from\nit. In the first place, we have a clear perception that man, like all\nthe other complex animals, inherits all his personal characteristics,\nbodily and mental, from his parents; and, further, we come to the\nmomentous conclusion that the new personality which arises thus can lay\nno claim to \"immortality.\"\n\nHence the minute processes of conception and sexual generation are\nof the first importance. We are, however, only familiar with their\ndetails since 1875, when Oscar Hertwig, my pupil and fellow-traveller\nat that time, began his researches into the impregnation of the egg\nof the sea-urchin at Ajaccio, in Corsica. The beautiful capital of\nthe island in which Napoleon the Great was born, in 1769, was also\nthe spot in which the mysteries of animal conception were carefully\nstudied for the first time in their most important aspects. Hertwig\nfound that the one essential element in conception is the coalescence\nof the two sexual cells and their nuclei. Only one out of the millions\nof male ciliated cells which press round the ovum penetrates to its\nnucleus. The nuclei of both cells, of the spermatozoon and of the ovum,\ndrawn together by a mysterious force, which we take to be a chemical\nsense-activity, related to smell, approach each other and melt into\none. Thus, by the sensitive perception of the sexual nuclei, following\nupon a kind of \"erotic chemicotropism,\" a new cell is formed, which\nunites in itself the inherited qualities of both parents; the nucleus\nof the spermatozoon conveys the paternal features, the nucleus of the\novum those of the mother, to the stem cell, from which the child is\nto be developed. That applies both to the bodily and to the mental\ncharacteristics.\n\nThe formation of the germinal layers by the repeated division of\nthe stem cell, the growth of the gastrula and of the later germ\nstructures which succeed it, take place in man in just the same manner\nas in the other higher mammals, under the peculiar conditions which\ndifferentiate this group from the lower vertebrates. In the earlier\nstages of development these special characters of the placentalia are\nnot to be detected. The significant embryonic or larval form of the\nchordula, which succeeds the gastrula, has substantially the same\nstructure in all vertebrates; a simple straight rod, the dorsal cord,\nlies lengthways along the main axis of the shield-shaped body--the\n\"embryonic shield\"; above the cord the spinal marrow develops out\nof the outer germinal layer, while the gut makes its appearance\nunderneath. Then, on both sides, to the right and left of the axial\nrod, appear the segments of the \"pro-vertebr\u00e6\" and the outlines of\nthe muscular plates, with which the formation of the members of the\nvertebrate body begins. The gill-clefts appear on either side of the\nfore-gut; they are the openings of the gullet, through which, in our\nprimitive fish-ancestors, the water which had entered at the mouth\nfor breathing purposes made its exit at the sides of the head. By a\ntenacious heredity these gill-clefts, which have no meaning except for\nour fish-like aquatic ancestors, are still preserved in the embryo of\nman and all the other vertebrates. They disappear after a time. Even\nafter the five vesicles of the embryonic brain appear in the head,\nand the rudiments of the eyes and ears at the sides, and after the\nlegs sprout out at the base of the fish-like embryo, in the form of\ntwo roundish, flat buds, the foetus is still so like that of other\nvertebrates that it is indistinguishable from them.\n\nThe substantial similarity in outer form and inner structure which\ncharacterizes the embryo of man and other vertebrates in this early\nstage of development is an embryological fact of the first importance;\nfrom it, by the fundamental law of biogeny, we may draw the most\nmomentous conclusions. There is but one explanation of it--heredity\nfrom a common parent form. When we see that, at a certain stage,\nthe embryos of man and the ape, the dog and the rabbit, the pig and\nthe sheep, although recognizable as higher vertebrates, cannot be\ndistinguished from each other, the fact can only be elucidated by\nassuming a common parentage. And this explanation is strengthened when\nwe follow the subsequent divergence of these embryonic forms. The\nnearer two animals are in their bodily structure, and, therefore, in\nthe scheme of nature, so much the longer do we find their embryos to\nretain this resemblance, and so much the closer do they approach each\nother in the ancestral tree of their respective group, so much the\ncloser is their genetic relationship. Hence it is that the embryos of\nman and the anthropoid ape retain the resemblance much later, at an\nadvanced stage of development, when their distinction from the embryos\nof other mammals can be seen at a glance. I have illustrated this\nsignificant fact by a juxtaposition of corresponding stages in the\ndevelopment of a number of different vertebrates in my _Natural History\nof Creation_ and in my _Anthropogeny_.\n\nThe great phylogenetic significance of the resemblance we have\ndescribed is seen, not only in the comparison of the embryos of\nvertebrates, but also in the comparison of their protective membranes.\nAll vertebrates of the three higher classes--reptiles, birds, and\nmammals--are distinguished from the lower classes by the possession\nof certain special foetal membranes, the amnion and the serolemma.\nThe embryo is enclosed in these membranes, or bags, which are full of\nwater, and is thus protected from pressure or shock. This provident\narrangement probably arose during the Permian period, when the oldest\nreptiles, the _proreptilia_, the common ancestors of all the amniotes\n(animals with an _amnion_), completely adapted themselves to a life on\nland. Their direct ancestors, the amphibia, and the fishes are devoid\nof these foetal membranes; they would have been superfluous to these\ninhabitants of the water. With the inheritance of these protective\ncoverings are closely connected two other changes in the amniotes:\nfirstly, the entire disappearance of the gills (while the gill arches\nand clefts continue to be inherited as \"rudimentary organs\"); secondly,\nthe construction of the _allantois_. This vesicular bag, filled with\nwater, grows out of the hind-gut in the embryo of all the amniotes,\nand is nothing else than an enlargement of the bladder of their\namphibious ancestors. From its innermost and inferior section is formed\nsubsequently the permanent bladder of the amniotes, while the larger\nouter part shrivels up. Usually this has an important part to play for\na long time as the respiratory organ of the embryo, a number of large\nblood-vessels spreading out over its inner surface. The formation of\nthe membranes, the amnion and the serolemma, and of the allantois,\nis just the same, and is effected by the same complicated process of\ngrowth, in man as in all the other amniotes; _man is a true amniote_.\n\nThe nourishment of the foetus in the maternal womb is effected, as\nis well known, by a peculiar organ, richly supplied with blood at its\nsurface, called the _placenta_. This important nutritive organ is a\nspongy, round disk, from six to eight inches in diameter, about an\ninch thick, and one or two pounds in weight; it is separated after\nthe birth of the child, and issues as the \"after-birth.\" The placenta\nconsists of two very different parts, the foetal and the maternal\npart. The latter contains highly developed sinuses, which retain the\nblood conveyed to them by the arteries of the mother. On the other\nhand, the foetal placenta is formed by innumerable branching tufts or\nvilli, which grow out of the outer surface of the allantois, and derive\ntheir blood from the umbilical vessels. The hollow, blood-filled villi\nof the foetal placenta protrude into the sinuses of the maternal\nplacenta, and the slender membrane between the two is so attenuated\nthat it offers no impediment to the direct interchange of material\nthrough the nutritive blood-stream (by osmosis).\n\nIn the older and lower groups of the placentals the entire surface\nof the chorion is covered with a number of short villi; these\n\"chorion-villi\" take the form of pit-like depressions of the mucous\nmembrane of the mother, and are easily detached at birth. That\nhappens in most of the ungulata (the sow, camel, mare, etc.), the\ncetacea, and the prosimi\u00e6; these \"mallo-placentalia\" (with a _diffuse_\nplacenta) have been denominated the _indeciduata_. The same formation\nis present in man and the other placentals in the beginning. It is\nsoon modified, however, as the villi on one part of the chorion are\nwithdrawn; while on the other part they grow proportionately stronger,\nand unite intimately with the mucous membrane of the womb. It is in\nconsequence of this intimate blending that a portion of the uterus is\ndetached at birth, and carried away with loss of blood. This detachable\nmembrane--the _decidua_--is a characteristic of the higher placentalia,\nwhich have, consequently, been grouped under the title of _deciduata_;\nto that category belong the carnassia, rodentia, simi\u00e6, and man. In\nthe carnassia and some of the ungulata (the elephant, for instance)\nthe placenta takes the form of a girdle, hence they are known as the\n_zonoplacentalia_; in the rodentia, the insectivora (the mole and the\nhedge-hog), the apes, and man, it takes the form of a disk.\n\nEven ten years ago the majority of embryologists thought that man\nwas distinguished by certain peculiarities in the form of the\nplacenta--namely, by the possession of what is called the _decidua\nreflexa_, and by a special formation of the umbilical chord which\nunites the _decidua_ to the foetus. It was supposed that the rest\nof the placentals, including the apes, were without these special\nembryonic structures. The _funiculus umbilicalis_ is a smooth,\ncylindrical cord, from sixteen to twenty-three inches long, and as\nthick as the little finger. It forms the connecting link between the\nfoetus and the maternal placenta, since it conducts the nutritive\nvessels from the body of the foetus to the placenta; it comprises,\nbesides, the pedicle of the allantois and the yelk-sac. The yelk-sac in\nthe human case forms the greater portion of the germinal vesicle during\nthe third week of gestation; but it shrivels up afterwards so that it\nwas formerly entirely missed in the mature foetus. Yet it remains all\nthe time in a rudimentary condition, and may be detected even after\nbirth as the little umbilical vesicle. Moreover, even the vesicular\nstructure of the allantois disappears at an early stage in the human\ncase; with a deflection of the amnion, it gives rise to the pedicle.\nWe cannot enter here into a discussion of the complicated anatomical\nand embryological relations of these structures. I have described and\nillustrated them in my _Anthropogeny_ (twenty-third chapter).\n\nThe opponents of evolution still appealed to these \"special features\"\nof human embryology, which were supposed to distinguish man from all\nthe other mammals, even so late as ten years ago. But in 1890 Emil\nSelenka proved that the same features are found in the anthropoid apes,\nespecially in the orang (_satyrus_), while the lower apes are without\nthem. Thus Huxley's pithecometra thesis was substantiated once more:\n\"The differences between man and the great apes are not so great as\nare those between the manlike apes and the lower monkeys.\" The supposed\n\"evidences _against_ the near blood-relationship of man and the apes\"\nproved, on a closer examination of the real circumstances, to be strong\nreasons in favor of it.\n\nEvery scientist who penetrates with open eyes into this dark but\nprofoundly interesting labyrinth of our embryonic development, and who\nis competent to compare it critically with that of the rest of the\nmammals, will find in it a most important aid towards the elucidation\nof the descent of our species. For the various stages of our embryonic\ndevelopment, in the character of _palingenetic_ phenomena of heredity,\ncast a brilliant light on the corresponding stages of our ancestral\ntree, in accordance with the great law of biogeny. But even the\n_cenogenetic_ phenomena of adaptation, the formation of the temporary\nfoetal organs--the characteristic foetal membranes, and especially\nthe placenta--gives us sufficiently definite indications of our _close\ngenetic relationship with the primates_.\n\n\n\n\nCHAPTER V\n\nTHE HISTORY OF OUR SPECIES\n\n    Origin of Man--Mythical History of Creation--Moses and Linn\u00e9--The\n    Creation of Permanent Species--The Catastrophic Theory:\n    Cuvier--Transformism: Goethe--Theory of Descent: Lamarck--Theory\n    of Selection: Darwin--Evolution (Phylogeny)--Ancestral\n    Trees--General Morphology--Natural History of Creation--Systematic\n    Phylogeny--Fundamental Law of Biogeny--Anthropogeny--Descent of Man\n    from the Ape--Pithecoid Theory--The Fossil Pithecanthropus of Dubois\n\n\nThe youngest of the great branches of the living tree of biology is\nthe science we call biological evolution, or _phylogeny_. It came into\nexistence much later, and under much more difficult circumstances, than\nits natural sister, embryonic evolution or _ontogeny_. The object of\nthe latter was to attain a knowledge of the mysterious processes by\nwhich the individual organism, plant or animal, developed from the egg.\nPhylogeny has to answer the much more obscure and difficult question:\n\"What is the origin of the different organic species of plants and\nanimals?\"\n\nOntogeny (embryology and metamorphism) could follow the empirical\nmethod of direct observation in the solution of its not remote problem;\nit needed but to follow, day by day and hour by hour, the visible\nchanges which the foetus experiences during a brief period in the\ncourse of its development from the ovum. Much more difficult was\nthe remote problem of phylogeny; for the slow processes of gradual\nconstruction, which effect the rise of new species of animals and\nplants, go on imperceptibly during thousands and even millions of\nyears. Their direct observation is possible only within very narrow\nlimits; the vast majority of these historical processes can only be\nknown by direct inference--by critical reflection, and by a comparative\nuse of empirical sciences which belong to very different fields of\nthought, pal\u00e6ontology, ontogeny, and morphology. To this we must\nadd the immense opposition which was everywhere made to biological\nevolution on account of the close connection between questions of\norganic creation and supernatural myths and religious dogmas. For these\nreasons it can easily be understood how it is that the scientific\nexistence of a true theory of origins was only secured, amid fierce\ncontroversy, in the course of the last forty years.\n\nEvery serious attempt that was made before the beginning of the\nnineteenth century to solve the problem of the origin of species\nlost its way in the mythological labyrinth of the supernatural\nstories of creation. The efforts of a few distinguished thinkers to\nemancipate themselves from this tyranny and attain to a naturalistic\ninterpretation proved unavailing. A great variety of creation myths\narose in connection with their religion in all the ancient civilized\nnations. During the Middle Ages triumphant Christendom naturally\narrogated to itself the sole right of pronouncing on the question; and,\nthe Bible being the basis of the structure of the Christian religion,\nthe whole story of creation was taken from the book of Genesis. Even\nCarl Linn\u00e9, the famous Swedish scientist, started from that basis\nwhen, in 1735, in his classical _Systema Naturae_, he made the first\nattempt at a systematic arrangement, nomenclature, and classification\nof the innumerable objects in nature. As the best practical aid in that\nattempt he introduced the well-known double or binary nomenclature; to\neach kind of animals and plants he gave a particular specific name,\nand added to it the wider-reaching name of the genus. A _genus_ served\nto unite the nearest related _species_; thus, for instance, Linn\u00e9\ngrouped under the genus \"dog\" (_canis_), as different species, the\nhouse-dog (_canis familiaris_), the jackal (_canis aureus_), the wolf\n(_canis lupus_) the fox (_canis vulpes_), etc. This binary nomenclature\nimmediately proved of such great practical assistance that it was\nuniversally accepted, and is still always followed in zoological and\nbotanical classification.\n\nBut the theoretical dogma which Linn\u00e9 himself connected with his\npractical idea of species was fraught with the gravest peril to\nscience. The first question which forced itself on the mind of the\nthoughtful scientist was the question as to the nature of the concept\nof species, its contents, and its range. And the creator of the idea\nanswered this fundamental question by a na\u00efve appeal to the dominant\nMosaic legend of creation: \"_Species tot sunt diversae, quot diversas\nformas ab initio creavit infinitum ens_\"--(There are just so many\ndistinct species as there were distinct types created in the beginning\nby the Infinite). This theosophic dogma cut short all attempt at a\nnatural explanation of the origin of species. Linn\u00e9 was acquainted only\nwith the plant and animal worlds that exist to-day; he had no suspicion\nof the much more numerous extinct species which had peopled the earth\nwith their varying forms in the earlier period of its development.\n\nIt was not until the beginning of the nineteenth century that we were\nintroduced to these fossil animals by Cuvier. In his famous work on\nthe fossil bones of the four-footed vertebrates he gave (1812) the\nfirst correct description and true interpretation of many of these\nfossil remains. He showed, too, that a series of very different animal\npopulations have succeeded each other in the various stages of the\nearth's history. Since Cuvier held firmly to Linn\u00e9's idea of the\nabsolute permanency of species, he thought their origin could only be\nexplained by the supposition that a series of great cataclysms and new\ncreations had marked the history of the globe; he imagined that all\nliving creatures were destroyed at the commencement of each of these\nterrestrial revolutions, and an entirely new population was created\nat its close. Although this \"catastrophic theory\" of Cuvier's led to\nthe most absurd consequences, and was nothing more than a bald faith\nin miracles, it obtained almost universal recognition, and reigned\ntriumphant until the coming of Darwin.\n\nIt is easy to understand that these prevalent ideas of the absolute\nunchangeability and supernatural creation of organic species could not\nsatisfy the more penetrating thinkers. We find several eminent minds\nalready, in the second half of the last century, busy with the attempt\nto find a natural explanation of the \"problem of creation.\" Pre-eminent\namong them was the great German poet and philosopher, Wolfgang Goethe,\nwho, by his long and assiduous study of morphology, obtained, more than\na hundred years ago, a clear insight into the intimate connection of\nall organic forms, and a firm conviction of a common natural origin.\nIn his famed _Metamorphosis of Plants_ (1790) he derived all the\ndifferent species of plants from one primitive type, and all their\ndifferent organs from one primitive organ--the leaf. In his vertebral\ntheory of the skull he endeavored to prove that the skulls of the\nvertebrates--including man--were all alike made up of certain groups\nof bones, arranged in a definite structure, and that these bones are\nnothing else than transformed vertebr\u00e6. It was his penetrating study\nof comparative osteology that led Goethe to a firm conviction of the\nunity of the animal organization; he had recognized that the human\nskeleton is framed on the same fundamental type as that of all other\nvertebrates--\"built on a primitive plan that only deviates more or less\nto one side or other in its very constant features, and still develops\nand refashions itself daily.\" This remodelling, or transformation,\nis brought about, according to Goethe, by the constant interaction\nof two powerful constructive forces--a centripetal force within the\norganism, the \"tendency to specification,\" and a centrifugal force\nwithout, the tendency to variation, or the \"idea of metamorphosis\";\nthe former corresponds to what we now call heredity, the latter to\nthe modern idea of adaptation. How deeply Goethe had penetrated into\ntheir character by these philosophic studies of the \"construction and\nreconstruction of organic natures,\" and how far, therefore, he must be\nconsidered the most important precursor of Darwin and Lamarck,[12] may\nbe gathered from the interesting passages from his works which I have\ncollected in the fourth chapter of my _Natural History of Creation_.\nThese evolutionary ideas of Goethe, however, like analogous ideas of\nKant, Owen, Treviranus, and other philosophers of the commencement of\nthe century (which we have quoted in the above work), did not amount to\nmore than certain general conclusions. They had not that great lever\nwhich the \"natural history of creation\" needed for its firm foundation\non a criticism of the dogma of fixed species; this lever was first\nsupplied by Lamarck.\n\nThe first thorough attempt at a scientific establishment of transformism\nwas made at the beginning of the nineteenth century by the great\nFrench scientist Jean Lamarck, the chief opponent of his colleague,\nCuvier, at Paris. He had already, in 1802, in his _Observations on\nLiving Organisms_, expressed the new ideas as to the mutability and\nformation of species, which he thoroughly established in 1809 in the\ntwo volumes of his profound work, _Philosophie Zoologique_. In this\nwork he first gave expression to the correct idea, in opposition to\nthe prevalent dogma of fixed species, that the organic \"species\" is\nan _artificial abstraction_, a concept of only relative value, like\nthe wider-ranging concepts of genus, family, order, and class. He\nwent on to affirm that all species are changeable, and have arisen\nfrom older species in the course of very long periods of time. The\ncommon parent forms from which they have descended were originally\nvery simple and lowly organisms. The first and oldest of them arose\nby abiogenesis. While the type is preserved by _heredity_ in the\nsuccession of generations, _adaptation_, on the other hand, effects\na constant modification of the species by change of habits and the\nexercise of the various organs. Even our human organism has arisen in\nthe same natural manner, by gradual transformation, from a group of\npithecoid mammals. For all these phenomena--indeed, for all phenomena\nboth in nature and in the mind--Lamarck takes exclusively mechanical,\nphysical, and chemical activities to be the true efficient causes. His\nmagnificent _Philosophie Zoologique_ contains all the elements of a\npurely monistic system of nature on the basis of evolution. I have\nfully treated these achievements of Lamarck in the fourth chapter of my\n_Anthropogeny_, and in the fourth chapter of the _Natural History of\nCreation_.\n\nScience had now to wait until this great effort to give a scientific\nfoundation to the theory of evolution should shatter the dominant myth\nof a \"specific creation, and open out the path of natural\" development.\nIn this respect Lamarck was not more successful in resisting the\nconservative authority of his great opponent, Cuvier, than was his\ncolleague and sympathizer, Geoffrey St. Hilaire, twenty years later.\nThe famous controversies which he had with Cuvier in the Parisian\nAcademy in 1830 ended with the complete triumph of the latter. I have\nelsewhere fully described these conflicts, in which Goethe took so\nlively an interest. The great expansion which the study of biology\nexperienced at that time, the abundance of interesting discoveries\nin comparative anatomy and physiology, the establishment of the\ncellular theory, and the progress of ontogeny, gave zoologists and\nbotanists so overwhelming a flood of welcome material to deal with\nthat the difficult and obscure question of the origin of species was\neasily forgotten for a time. People rested content with the old dogma\nof creation. Even when Charles Lyell refuted Cuvier's extraordinary\n\"catastrophic theory\" in his _Principles of Geology_, in 1830, and\nvindicated a natural, continuous evolution for the inorganic structure\nof our planet, his simple principle of continuity found no one to\napply it to the inorganic world. The rudiments of a natural phylogeny\nwhich were buried in Lamarck's works were as completely forgotten as\nthe germ of a natural ontogeny which Caspar Friedrich Wolff had given\nfifty years earlier in his _Theory of Generation_. In both cases a full\nhalf-century elapsed before the great idea of a natural development\nwon a fitting recognition. Only when Darwin (in 1859) approached the\nsolution of the problem from a different side altogether, and made\na happy use of the rich treasures of empirical knowledge which had\naccumulated in the mean time, did men begin to think once more of\nLamarck as his great precursor.\n\nThe unparalleled success of Charles Darwin is well known. It shows him\nto-day, at the close of the century, to have been, if not the greatest,\nat least the most effective of its distinguished scientists. No other\nof the many great thinkers of our time has achieved so magnificent, so\nthorough, and so far-reaching a success with a single classical work as\nDarwin did in 1859 with his famous _Origin of Species_. It is true that\nthe reform of comparative anatomy and physiology by Johannes M\u00fcller\nhad inaugurated a new and fertile epoch for the whole of biology, that\nthe establishment of the cellular theory by Schleiden and Schwann, the\nreform of ontogeny by Baer, and the formulation of the law of substance\nby Robert Mayer and Helmholtz were scientific facts of the first\nimportance; but no one of them has had so profound an influence on the\nwhole structure of human knowledge as Darwin's theory of the natural\norigin of species. For it at once gave us the solution of the mystic\n\"problem of creation,\" the great \"question of all questions\"--the\nproblem of the true character and origin of man himself.\n\nIf we compare the two great founders of transformism, we find in\nLamarck a preponderant inclination to _deduction_, and to forming a\ncompletely monistic scheme of nature; in Darwin we have a predominant\napplication of _induction_, and a prudent concern to establish the\ndifferent parts of the theory of selection as firmly as possible on a\nbasis of observation and experiment. While the French scientist far\noutran the then limits of empirical knowledge, and rather sketched the\nprogramme of future investigation, the English empiricist was mainly\npreoccupied about securing a unifying principle of interpretation for\na mass of empirical knowledge which had hitherto accumulated without\nbeing understood. We can thus understand how it was that the success\nof Darwin was just as overwhelming as that of Lamarck was evanescent.\nDarwin, however, had not only the signal merit of bringing all the\nresults of the various biological sciences to a common focus in the\nprinciple of descent, and thus giving them a harmonious interpretation,\nbut he also discovered, in the principle of selection, that direct\ncause of transformation which Lamarck had missed. In applying, as a\npractical breeder, the experience of artificial selection to organisms\nin a state of nature, and in recognizing in the \"struggle for life\" the\nselective principle of natural selection, Darwin created his momentous\n\"theory of selection,\" which is what we properly call Darwinism.\n\nOne of the most pressing of the many important tasks which Darwin\nproposed to modern biology was the reform of the zoological and\nbotanical system. Since the innumerable species of animals and plants\nwere not created by a supernatural miracle, but evolved by natural\nprocesses, their ancestral tree is their \"natural system.\" The first\nattempt to frame a system in this sense was made by myself in 1866,\nin my _General Morphology of Organisms_. The first volume of this\nwork (\"General Anatomy\") dealt with the \"mechanical science of the\ndeveloped forms\"; the second volume (\"General Evolution\") was occupied\nwith the science of the \"developing forms.\" The systematic introduction\nto the latter formed a \"genealogical survey of the natural system\nof organisms.\" Until that time the term \"evolution\" had been taken\nto mean exclusively, both in zoology and botany, the development of\nindividual organisms--embryology, or metamorphic science. I established\nthe opposite view, that this history of the embryo (ontogeny) must be\ncompleted by a second, equally valuable, and closely connected branch\nof thought--the history of the race (phylogeny). Both these branches\nof evolutionary science are, in my opinion, in the closest causal\nconnection; this arises from the reciprocal action of the laws of\nheredity and adaptation; it has a precise and comprehensive expression\nin my \"fundamental law of biogeny.\"\n\nAs the new views I had put forward in my _General Morphology_ met with\nvery little notice, and still less acceptance, from my scientific\ncolleagues, in spite of their severely scientific setting, I thought\nI would make the most important of them accessible to a wider circle\nof informed readers by a smaller work, written in a more popular\nstyle. This was done in 1868, in _The Natural History of Creation_ (a\nseries of popular scientific lectures on evolution in general, and the\nsystems of Darwin, Goethe, and Lamarck in particular). If the success\nof my _General Morphology_ was far below my reasonable anticipation,\nthat of _The Natural History of Creation_ went far beyond it. In a\nperiod of thirty years nine editions and twelve different translations\nof it have appeared. In spite of its great defects, the book has\ncontributed much to the popularization of the main ideas of modern\nevolution. Still, I could only give the barest outlines in it of my\nchief object, the phylogenetic construction of a natural system. I\nhave, therefore, given the complete proof, which is wanting in the\nearlier work, of the phylogenetic system in a subsequent larger work,\nmy _Systematic Phylogeny_ (outlines of a natural system of organisms\non the basis of their specific development). The first volume of\nit deals with the protists and plants (1894), the second with the\ninvertebrate animals (1896), the third with the vertebrates (1895). The\nancestral tree of both the smaller and the larger groups is carried\non in this work as far as my knowledge of the three great \"ancestral\ndocuments\"--pal\u00e6ontology, ontogeny, and morphology--qualified me to\nextend it.\n\nI had already, in my _General Morphology_ (at the end of the fifth\nbook), described the close causative connection which exists, in\nmy opinion, between the two branches of organic evolution as one\nof the most important ideas of transformism, and I had framed a\nprecise formula for it in a number of \"theses on the causal nexus of\nbiontic and phyletic development\": \"_Ontogenesis is a brief and rapid\nrecapitulation of phylogenesis_, determined by the physiological\nfunctions of heredity (generation) and adaptation (maintenance).\"\nDarwin himself had emphasized the great significance of his theory\nfor the elucidation of embryology in 1859, and Fritz M\u00fcller had\nendeavored to prove it as regards the Crustacea in the able little\nwork, _Facts and Arguments for Darwin_ (1864). My own task has been\nto prove the universal application and the fundamental importance of\nthe biogenetic law in a series of works, especially in the _Biology\nof the Calcispongiae_ (1872), and in _Studies on the Gastraea Theory_\n(1873-1884). The theory of the homology of the germinal layers and of\nthe relations of _palingenesis_ to _cenogenesis_ which I have exposed\nin them has been confirmed subsequently by a number of works of other\nzoologists. That theory makes it possible to follow nature's law of\nunity in the innumerable variations of animal embryology; it gives us\nfor their ancestral history a common derivation from a simple primitive\nstem form.\n\nThe far-seeing founder of the theory of descent, Lamarck, clearly\nrecognized in 1809 that it was of universal application; that even man\nhimself, the most highly developed of the mammals, is derived from the\nsame stem as all the other mammals; and that this in its turn belongs\nto the same older branch of the ancestral tree as the rest of the\nvertebrates. He had even indicated the agencies by which it might be\npossible to explain man's descent from the apes as the nearest related\nmammals. Darwin, who was, naturally, of the same conviction, purposely\navoided this least acceptable consequence of his theory in his chief\nwork in 1859, and put it forward for the first time in his _Descent of\nMan_ in 1871. In the mean time (1863) Huxley had very ably discussed\nthis most important consequence of evolution in his famous _Place of\nMan in Nature_. With the aid of comparative anatomy and ontogeny,\nand the support of the facts of pal\u00e6ontology, Huxley proved that the\n\"descent of man from the ape\" is a necessary consequence of Darwinism,\nand that no other scientific explanation of the origin of the human\nrace is possible. Of the same opinion was Karl Gegenbaur, the most\ndistinguished representative of comparative anatomy, who lifted his\nscience to a higher level by a consistent and ingenious application of\nthe theory of descent.\n\nAs a further consequence of the \"pithecoid theory\" (the theory of the\ndescent of man from the ape) there now arose the difficult task of\ninvestigating, not only the nearest related mammal ancestors of man\nin the Tertiary epoch, but also the long series of the older animal\nancestors which had lived in earlier periods of the earth's history and\nbeen developed in the course of countless millions of years. I had made\na start with the hypothetical solution of this great historic problem\nin my _General Morphology_; a further development of it appeared in\n1874 in my _Anthropogeny_ (first section, Origin of the Individual;\nsecond section, Origin of the Race). The fourth, enlarged, edition of\nthis work (1891) contains that theory of the development of man which\napproaches nearest, in my own opinion, to the still remote truth, in\nthe light of our present knowledge of the documentary evidence. I was\nespecially preoccupied in its composition to use the three empirical\n\"documents\"--pal\u00e6ontology, ontogeny, and morphology (or comparative\nanatomy)--as evenly and harmoniously as possible. It is true that my\nhypotheses were in many cases supplemented and corrected in detail by\nlater phylogenetic research; yet I am convinced that the ancestral tree\nof human origin which I have sketched therein is substantially correct.\nFor the historical succession of vertebrate fossils corresponds\ncompletely with the morphological evolutionary scale which is revealed\nto us by comparative anatomy and ontogeny. After the Silurian fishes\ncome the _dipnoi_ of the Devonian period--the Carboniferous amphibia,\nthe Permian reptilia, and the Mesozoic mammals. Of these, again, the\nlowest forms, the monotremes, appear first in the Triassic period,\nthe marsupials in the Jurassic, and then the oldest placentals in\nthe Cretaceous. Of the placentals, in turn, the first to appear in\nthe oldest Tertiary period (the Eocene) are the lowest primates,\nthe prosimi\u00e6, which are followed by the simi\u00e6 in the Miocene. Of the\ncatarrhin\u00e6, the cynopitheci precede the anthropomorpha; from one branch\nof the latter, during the Pliocene period, arises the ape-man without\nspeech (the _pithecanthropus alalus_); and from him descends, finally,\nspeaking man.\n\nThe chain of our earlier invertebrate ancestors is much more difficult\nto investigate and much less safe than this tree of our vertebrate\npredecessors; we have no fossilized relics of their soft, boneless\nstructures, so pal\u00e6ontology can give us no assistance in this case.\nThe evidence of comparative anatomy and ontogeny, therefore, becomes\nall the more important. Since the human embryo passes through the\nsame _chordula_-stage as the germs of all other vertebrates, since\nit evolves, similarly, out of two germinal layers of a _gastrula_,\nwe infer, in virtue of the biogenetic law, the early existence of\ncorresponding ancestral forms--vermalia, gastr\u00e6ada, etc. Most important\nof all is the fact that the human embryo, like that of all other\nanimals, arises originally from a single cell; for this \"stem-cell\"\n(_cytula_)--the impregnated egg cell--points indubitably to a\ncorresponding unicellular ancestor, a primitive, Laurentian protozoon.\n\nFor the purpose of our monistic philosophy, however, it is a matter of\ncomparative indifference how the succession of our animal predecessors\nmay be confirmed in detail. Sufficient for us, as an incontestable\nhistorical fact, is the important thesis that man descends immediately\nfrom the ape, and secondarily from a long series of lower vertebrates.\nI have laid stress on the logical proof of this \"pithecometra-thesis\"\nin the seventh book of the _General Morphology_: \"The thesis that\nman has been evolved from lower vertebrates, and immediately from the\n_simiae_, is a special inference which results with absolute necessity\nfrom the general inductive law of the theory of descent.\"\n\nFor the definitive proof and establishment of this fundamental\npithecometra-thesis the pal\u00e6ontological discoveries of the last\nthirty years are of the greatest importance; in particular, the\nastonishing discoveries of a number of extinct mammals of the Tertiary\nperiod have enabled us to draw up clearly in its main outlines the\nevolutionary history of this most important class of animals, from\nthe lowest oviparous monotremes up to man. The four chief groups\nof the placentals, the heterogeneous legions of the carnassia, the\nrodentia, the ungulata, and the primates, seem to be separated by\nprofound gulfs, when we confine our attention to their representatives\nof to-day. But these gulfs are completely bridged, and the sharp\ndistinctions of the four legions are entirely lost, when we compare\ntheir extinct predecessors of the Tertiary period, and when we go\nback into the Eocene twilight of history, in the oldest part of the\nTertiary period--at least three million years ago. There we find the\ngreat sub-class of the placentals, which to-day comprises more than\ntwo thousand five hundred species, represented by only a small number\nof little, insignificant \"proplacentals\"; and in these _prochoriata_\nthe characters of the four divergent legions are so intermingled and\ntoned down that we cannot in reason do other than consider them as the\nprecursors of those features. The oldest carnassia (the _ictopsales_),\nthe oldest rodentia (the _esthonychales_), the oldest ungulata (the\n_condylarthrales_) and the oldest primates (the _lemuravales_), all\nhave the same fundamental skeletal structure, and the same typical\ndentition of the primitive placentals, consisting of forty-four teeth\n(three incisors, one canine, four premolars, and three molars in each\nhalf of the jaw); all are characterized by the small size and the\nimperfect structure of the brain (especially of its chief part, the\ncortex, which does not become a true \"organ of thought\" until later on\nin the Miocene and Pliocene representatives); they have all short legs\nand five-toed, flat-soled feet (_plantigrada_). In many cases among\nthese oldest placentals of the Eocene period it was very difficult\nto say at first whether they should be classed with the carnassia,\nrodentia, ungulata, or primates; so very closely, even to confusion,\ndo these four groups of the placentals, which diverge so widely\nafterwards, approach each other at that time. Their common origin from\na single ancestral group follows incontestably. These _prochoriata_\nlived in the preceding Cretaceous period (more than three million years\nago), and were probably developed in the Jurassic period from a group\nof insectivorous marsupials (_amphitheria_) by the formation of a\nprimitive _placenta diffusa_, a placenta of the simplest type.\n\nBut the most important of all the recent palaeontological discoveries\nwhich have served to elucidate the origin of the placentals relate\nto our own stem, the legion of primates. Formerly fossil remains of\nthe primates were very scarce. Even Cuvier, the great founder of\npalaeontology, maintained until his last day (1832) that there were no\nfossilized primates; he had himself, it is true, described the skull\nof an Eocene prosimi\u00e6 (_adapis_), but he had wrongly classed it with\nthe ungulata. However, during the last twenty years a fair number of\nwell-preserved fossilized skeletons of prosimi\u00e6 and simi\u00e6 have been\ndiscovered; in them we find all the chief intermediate members which\ncomplete the connecting chain of ancestors from the oldest prosimi\u00e6 to\nman.\n\nThe most famous and most interesting of these discoveries is the\nfossil ape-man of Java, the much-talked-of _pithecanthropus erectus_,\nfound by a Dutch military doctor, Eugen Dubois, in 1894. It is in\ntruth the much-sought \"missing link,\" supposed to be wanting in\nthe chain of primates, which stretches unbroken from the lowest\ncatarrhin\u00e6 to the highest-developed man. I have dealt exhaustively\nwith the significance of this discovery in the paper which I read on\nAugust 26, 1898, at the Fourth International Zoological Congress at\nCambridge.[13] The pal\u00e6ontologist, who knows the conditions of the\nformation and preservation of fossils, will think the discovery of the\npithecanthropus an unusually lucky accident. The apes, being arboreal,\nseldom came into the circumstances (unless they happened to fall into\nthe water) which would secure the preservation and petrifaction of\ntheir skeleton. Thus, by the discovery of this fossil man-monkey of\nJava the descent of man from the ape has become just as clear and\ncertain from the pal\u00e6ontological side as it was previously from the\nevidence of comparative anatomy and ontogeny. We now have all the\nprincipal documents which tell the history of our race.\n\n\n\n\nCHAPTER VI\n\nTHE NATURE OF THE SOUL\n\n    Fundamental Importance of Psychology--Its Definition and\n    Methods--Divergence of Views Thereon--Dualistic and Monistic\n    Psychology--Relation to the Law of Substance--Confusion\n    of Ideas--Psychological Metamorphoses: Kant, Virchow,\n    Du Bois-Reymond--Methods of Research of Psychic\n    Science--Introspective Method (Self-Observation)--Exact\n    Method (Psycho-Physics)--Comparative Method (Animal\n    Psychology)--Psychological Change of Principles:\n    Wundt--Folk-Psychology and Ethnography: Bastian--Ontogenetic\n    Psychology: Preyer--Phylogenetic Psychology: Darwin, Romanes\n\n\nThe phenomena which are comprised under the title of the \"life of\nthe soul,\" or the psychic activity, are, on the one hand, the most\nimportant and interesting, on the other the most intricate and\nproblematical, of all the phenomena we are acquainted with. As the\nknowledge of nature, the object of the present philosophic study,\nis itself a part of the life of the soul, and as anthropology, and\neven cosmology, presuppose a correct knowledge of the \"psyche,\" we\nmay regard psychology, the scientific study of the soul, both as the\nfoundation and the postulate of all other sciences. From another\npoint of view it is itself a part of philosophy, or physiology, or\nanthropology.\n\nThe great difficulty of establishing it on a naturalistic basis\narises from the fact that psychology, in turn, presupposes a correct\nacquaintance with the human organism, especially the brain, the chief\norgan of psychic activity. The great majority of \"psychologists\" have\nlittle or no acquaintance with these anatomical foundations of the\nsoul, and thus it happens that in no other science do we find such\ncontradictions and untenable notions as to its proper meaning and\nits essential object as are current in psychology. This confusion\nhas become more and more palpable during the last thirty years, in\nproportion as the immense progress of anatomy and physiology has\nincreased our knowledge of the structure and the functions of the chief\npsychic organ.\n\nWhat we call the soul is, in my opinion, a natural phenomenon; I\ntherefore consider psychology to be a branch of natural science--a\nsection of physiology. Consequently, I must emphatically assert\nfrom the commencement that we have no different methods of research\nfor that science than for any of the others; we have in the first\nplace observation and experiment, in the second place the theory of\nevolution, and in the third place metaphysical speculation, which\nseek to penetrate as far as possible into the cryptic nature of the\nphenomena by inductive and deductive reasoning. However, with a view\nto a thorough appreciation of the question, we must first of all put\nclearly before the reader the antithesis of the dualistic and the\nmonistic theories.\n\nThe prevailing conception of the psychic activity, which we contest,\nconsiders soul and body to be two distinct entities. These two\nentities can exist independently of each other; there is no intrinsic\nnecessity for their union. The organized body is a mortal, material\nnature, chemically composed of living protoplasm and its compounds\n(plasma-products). The soul, on the other hand, is an immortal,\nimmaterial being, a spiritual agent, whose mysterious activity\nis entirely incomprehensible to us. This trivial conception is,\nas such, spiritualistic, and its contradictory is, in a certain\nsense, materialistic. It is, at the same time, supernatural and\ntranscendental, since it affirms the existence of forces which can\nexist and operate without a material basis; it rests on the assumption\nthat outside of and beyond nature there is a \"spiritual,\" immaterial\nworld, of which we have no experience, and of which we can learn\nnothing by natural means.\n\nThis hypothetical \"spirit world,\" which is supposed to be entirely\nindependent of the material universe, and on the assumption of which\nthe whole artificial structure of the dualistic system is based, is\npurely a product of poetic imagination; the same must be said of the\nparallel belief in the \"immortality of the soul,\" the scientific\nimpossibility of which we must prove more fully later on (chap. xi.).\nIf the beliefs which prevail in these credulous circles had a sound\nfoundation, the phenomena they relate to could not be subject to the\n\"law of substance\"; moreover, this single exception to the highest\nlaw of the cosmos must have appeared very late in the history of the\norganic world, since it only concerns the \"soul\" of man and of the\nhigher animals. The dogma of \"free will,\" another essential element\nof the dualistic psychology, is similarly irreconcilable with the\nuniversal law of substance.\n\nOur own naturalistic conception of the psychic activity sees in it a\ngroup of vital phenomena, which are dependent on a definite material\nsubstratum, like all other phenomena. We shall give to this material\nbasis of all psychic activity, without which it is inconceivable,\nthe provisional name of \"psychoplasm\"; and for this good reason--that\nchemical analysis proves it to be a body of the group we call\nprotoplasmic bodies the albuminoid carbon-combinations which are at\nthe root of all vital processes. In the higher animals, which have a\nnervous system and sense-organs, \"neuroplasm,\" the nerve-material,\nhas been differentiated out of psychoplasm. Our conception is, in\nthis sense, materialistic. It is at the same time empirical and\nnaturalistic, for our scientific experience has never yet taught us the\nexistence of forces that can dispense with a material substratum, or of\na spiritual world over and above the realm of nature.\n\nLike all other natural phenomena, the psychic processes are subject to\nthe supreme, all-ruling law of substance; not even in this province\nis there a single exception to this highest cosmological law (compare\nchap. xii.). The phenomena of the lowly psychic life of the unicellular\nprotist and the plant, and of the lowest animal forms--their\nirritability, their reflex movements, their sensitiveness and instinct\nof self-preservation--are directly determined by physiological action\nin the protoplasm of their cells--that is, by physical and chemical\nchanges which are partly due to heredity and partly to adaptation.\nAnd we must say just the same of the higher psychic activity of the\nhigher animals and man, of the formation of ideas and concepts, of\nthe marvellous phenomena of reason and consciousness; for the latter\nhave been phylogenetically evolved from the former, and it is merely\na higher degree of integration or centralization, of association\nor combination of functions which were formerly isolated, that has\nelevated them in this manner.\n\nThe first task of every science is the clear definition of the object\nit has to investigate. In no science, however, is this preliminary\ntask so difficult as in psychology; and this circumstance is the\nmore remarkable since logic, the science of defining, is itself a\npart of psychology. When we compare all that has been said by the\nmost distinguished philosophers and scientists of all ages on the\nfundamental idea of psychology, we find ourselves in a perfect chaos\nof contradictory notions. What, really, is the \"soul\"? What is its\nrelation to the \"mind\"? What is the inner meaning of \"consciousness\"?\nWhat is the difference between \"sensation\" and \"sentiment\"? What is\n\"instinct\"? What is the meaning of \"free will\"? What is \"presentation\"?\nWhat is the difference between \"intellect\" and \"reason\"? What is the\ntrue nature of \"emotion\"? What is the relation between all these\n\"psychic phenomena\" and the \"body\"? The answers to these and many other\ncognate questions are infinitely varied; not only are the views of the\nmost eminent thinkers on these questions widely divergent, but even the\nsame scientific authority has often completely changed his views in the\ncourse of his psychological development. Indeed, this \"psychological\nmetamorphosis\" of so many thinkers has contributed not a little to the\n_colossal confusion of ideas_ which prevails in psychology more than in\nany other branch of knowledge.\n\nThe most interesting example of such an entire change of objective\nand subjective psychological opinions is found in the case of the\nmost influential leader of German philosophy, Immanuel Kant. The\nyoung, severely _critical_ Kant came to the conclusion that the three\ngreat buttresses of mysticism--\"God, freedom, and immortality\"--were\nuntenable in the light of \"pure reason\"; the older, _dogmatic_ Kant\nfound that these three great hallucinations were postulates of\n\"practical reason,\" and were, as such, indispensable. The more the\ndistinguished modern school of \"Neokantians\" urges a \"return to Kant\"\nas the only possible salvation from the frightful jumble of modern\nmetaphysics, the more clearly do we perceive the undeniable and fatal\ncontradiction between the fundamental opinions of the young and the\nolder Kant. We shall return to this point later on.\n\nOther interesting examples of this change of views are found in two of\nthe most famous living scientists, R. Virchow and E. du Bois-Reymond;\nthe metamorphoses of their fundamental views on psychology cannot\nbe overlooked, as both these Berlin biologists have played a most\nimportant part at Germany's greatest university for more than forty\nyears, and have, therefore, directly and indirectly, had a most\nprofound influence on the modern mind. Rudolph Virchow, the eminent\nfounder of cellular pathology, was a _pure monist_ in the best days of\nhis scientific activity, about the middle of the century; he passed at\nthat time as one of the most distinguished representatives of the newly\nawakened _materialism_, which appeared in 1855, especially through two\nfamous works, almost contemporaneous in appearance--Ludwig B\u00fcchner's\n_Matter and Force_ and Carl Vogt's _Superstition and Science_. Virchow\npublished his general biological views on the vital processes in\nman--which he takes to be purely mechanical natural phenomena--in a\nseries of distinguished papers in the first volumes of the _Archiv\nf\u00fcr pathologische Anatomie_, which he founded. The most important of\nthese articles, and the one in which he most clearly expresses his\nmonistic views of that period, is that on \"The Tendencies Towards\nUnity in Scientific Medicine\" (1849). It was certainly not without\ncareful thought, and a conviction of its philosophic value, that\nVirchow put this \"medical confession of faith\" at the head of his\n_Collected Essays on Scientific Medicine_ in 1856. He defended in it,\nclearly and definitely, the fundamental principles of monism, which I\nam presenting here with a view to the solution of the world-problem;\nhe vindicated the exclusive title of empirical science, of which the\nonly reliable sources are sense and brain activity; he vigorously\nattacked anthropological dualism, the alleged \"revelation,\" and\nthe transcendental philosophy, with their two methods--\"faith and\nanthropomorphism.\" Above all, he emphasized the monistic character of\nanthropology, the inseparable connection of spirit and body, of force\nand matter. \"I am convinced,\" he exclaims, at the end of his preface,\n\"that I shall never find myself compelled to deny the thesis of _the\nunity_ of human nature.\" Unhappily, this \"conviction\" proved to be a\ngrave error. Twenty-eight years afterwards Virchow represented the\ndiametrically opposite view; it is to be found in the famous speech on\n\"The Liberty of Science in Modern States,\" which he delivered at the\nScientific Congress at Munich in 1877, and which contains attacks that\nI have repelled in my _Free Science and Free Teaching_ (1878).\n\nIn Emil du Bois-Reymond we find similar contradictions with regard\nto the most important and fundamental theses of philosophy. The\nmore completely the distinguished orator of the Berlin Academy had\ndefended the main principles of the monistic philosophy, the more he\nhad contributed to the refutation of vitalism and the transcendental\nview of life, so much the louder was the triumphant cry of our\nopponents when in 1872, in his famous _Ignorabimus-Speech_, he spoke\nof consciousness as an insoluble problem, and opposed it to the other\nfunctions of the brain as a supernatural phenomenon. I return to the\npoint in the tenth chapter.\n\nThe peculiar character of many of the psychic phenomena, especially\nof consciousness, necessitates certain modifications of our ordinary\nscientific methods. We have, for instance, to associate with the\ncustomary _objective_, external observation, the _introspective_\nmethod, the _subjective_, internal observation which scrutinizes\nour own personality in the mirror of consciousness. The majority of\npsychologists have started from this \"certainty of the ego\": \"_Cogito\nergo sum_,\" as Descartes said--I think, therefore I am. Let us first\ncast a glance at this way of inquiry, and then deal with the second,\ncomplementary, method.\n\nBy far the greater part of the theories of the soul which have been\nput forward during the last two thousand years or more are based on\nintrospective inquiry--that is, on \"self-observation,\" and on the\nconclusions which we draw from the association and criticism of these\nsubjective experiences. Introspection is the only possible method of\ninquiry for an important section of psychology, especially for the\nstudy of consciousness. Hence this cerebral function occupies a special\nposition, and has been a more prolific source of philosophic error than\nany of the others (cf. chap. x.). It is, however, most unsatisfactory,\nand it leads to entirely false or incomplete notions, to take this\nself-observation of the mind to be the chief, or, especially, to be\nthe only source of mental science, as has happened in the case of\nmany and distinguished philosophers. A great number of the principal\npsychic phenomena, particularly the activity of the senses and speech,\ncan only be studied in the same way as every other vital function of\nthe organism--that is, firstly, by a thorough anatomical study of\ntheir organs, and, secondly, by an exact physiological analysis of\nthe functions which depend on them. In order, however, to complete\nthis external study of the mental life, and to supplement the results\nof _internal_ observation, one needs a thorough knowledge of human\nanatomy, histology, ontogeny, and physiology. Most of our so-called\n\"psychologists\" have little or no knowledge of these indispensable\nfoundations of anthropology; they are, therefore, incompetent to\npronounce on the character even of their own \"soul.\" It must be\nremembered, too, that the distinguished personality of one of these\npsychologists usually offers a specimen of an educated mind of the\nhighest civilized races; it is the last link of a long ancestral chain,\nand the innumerable older and inferior links are indispensable for\nits proper understanding. Hence it is that most of the psychological\nliterature of the day is so much waste paper. The introspective method\nis certainly extremely valuable and indispensable; still it needs the\nconstant co-operation and assistance of the other methods.\n\nIn proportion as the various branches of the human tree of knowledge\nhave developed during the century, and the methods of the different\nsciences have been perfected, the desire has grown to make them\n_exact_; that is, to make the study of phenomena as purely empirical\nas possible, and to formulate the laws that result as clearly as\nthe circumstances permit--if possible, _mathematically_. The latter\nis, however, only feasible in a small province of human knowledge,\nespecially in those sciences in which there is question of measurable\nquantities; in mathematics, in the first place, and to a greater or\nless extent in astronomy, mechanics, and a great part of physics and\nchemistry. Hence these studies are called \"exact sciences\" in the\nnarrower sense. It is, however, productive only of error to call all\nthe physical sciences _exact_, and oppose them to the historical,\nmental, and moral sciences. The greater part of physical science can\nno more be treated as an _exact_ science than history can; this is\nespecially true of biology and of its subsidiary branch, psychology.\nAs psychology is a part of physiology, it must, as a general rule,\nfollow the chief methods of that science. It must establish the facts\nof psychic activity by empirical methods as much as possible, by\nobservation and experiment, and it must then gather the laws of the\nmind by inductive and deductive inferences from its observations,\nand formulate them with the utmost distinctness. But, for obvious\nreasons, it is rarely possible to formulate them mathematically. Such\na procedure is only profitable in one section of the physiology of\nthe senses; it is not practicable in the greater part of cerebral\nphysiology.\n\nOne small section of physiology, which seems amenable to the \"exact\"\nmethod of investigation, has been carefully studied for the last\ntwenty years and raised to the position of a separate science under\nthe title of _psycho-physics_. Its founders, the physiologists Theodor\nFechner and Ernst Heinrich Weber, first of all closely investigated\nthe dependence of sensations on the external stimuli that act on the\norgans of sense, and particularly the quantitative relation between\nthe strength of the stimulus and the intensity of the sensation. They\nfound that a certain minimum strength of stimulus is requisite for\nthe excitement of a sensation, and that a given stimulus must be\nvaried to a definite amount before there is any perceptible change\nin the sensation. For the highest sensations (of sight, hearing, and\npressure) the law holds good that their variations are proportionate\nto the changes in the strength of the stimulus. From this empirical\n\"law of Weber\" Fechner inferred, by mathematical operations, his\n\"fundamental law of psycho-physics,\" according to which the intensity\nof a sensation increases in arithmetical progression, the strength\nof the stimulus in geometrical progression. However, Fechner's law\nand other psycho-physical laws are frequently contested, and their\n\"exactness\" is called into question. In any case modern psycho-physics\nhas fallen far short of the great hopes with which it was greeted\ntwenty years ago; the field of its applicability is extremely limited.\nOne important result of its work is that it has proved the application\nof physical laws in one, if only a small, branch of the life of the\n\"soul\"--an application which was long ago postulated on principle by\nthe materialist psychology for the whole province of mental life. In\nthis, as in many other branches of physiology, the \"exact\" method has\nproved inadequate and of little service. It is the ideal to aim at\neverywhere, but it is unattainable in most cases. Much more profitable\nare the comparative and genetic methods.\n\nThe striking resemblance of man's psychic activity to that of\nthe higher animals--especially our nearest relatives among the\nmammals--is a familiar fact. Most uncivilized races still make no\nmaterial distinction between the two sets of mental processes, as\nthe well-known animal fables, the old legends, and the idea of the\ntransmigration of souls prove. Even most of the philosophers of\nclassical antiquity shared the same conviction, and discovered no\nessential qualitative difference, but merely a quantitative one,\nbetween the soul of man and that of the brute. Plato himself, who was\nthe first to draw a fundamental distinction between soul and body,\nmade one and the same soul (or \"idea\") pass through a number of animal\nand human bodies in his theory of metempsychosis. It was Christianity,\nintimately connecting faith in immortality with faith in God, that\nemphasized the essential difference of the immortal soul of man from\nthe mortal soul of the brute. In the dualistic philosophy the idea\nprevailed principally through the influence of Descartes (1643);\nhe contended that man alone had a true \"soul,\" and, consequently,\nsensation and free will, and that the animals were mere automata, or\nmachines, without will or sensibility. Ever since the majority of\npsychologists--including even Kant--have entirely neglected the mental\nlife of the brute, and restricted psychological research to man:\nhuman psychology, mainly introspective, dispensed with the fruitful\ncomparative method, and so remained at that lower point of view which\nhuman morphology took before Cuvier raised it to the position of a\n\"philosophic science\" by the foundation of comparative anatomy.\n\nScientific interest in the psychic activity of the brute was revived\nin the second half of the last century, in connection with the\nadvance of systematic zoology and physiology. A strong impulse was\ngiven to it by the work of Reimarus: \"General observations on the\ninstincts of animals\" (Hamburg, 1760). At the same time a deeper\nscientific investigation had been facilitated by the thorough reform\nof physiology by Johannes M\u00fcller. This distinguished biologist, having\na comprehensive knowledge of the whole field of organic nature, of\nmorphology, and of physiology, introduced the \"exact methods\" of\nobservation and experiment into the whole province of physiology, and,\nwith consummate skill, combined them with the comparative methods. He\napplied them, not only to mental life in the broader sense (to speech,\nsenses, and brain-action), but to all the other phenomena of life. The\nsixth book of his _Manual of Human Physiology_ treats specially of the\nlife of the soul, and contains eighty pages of important psychological\nobservations.\n\nDuring the last forty years a great number of works on comparative\nanimal psychology have appeared, principally occasioned by the great\nimpulse which Darwin gave in 1859 by his work on _The Origin of\nSpecies_, and by the application of the idea of evolution to the\nprovince of psychology. The more important of these works we owe to\nRomanes and Sir J. Lubbock, in England; to W. Wundt, L. B\u00fcchner, G.\nSchneider, Fritz Schultze, and Karl Groos, in Germany; to Alfred\nEspinas and E. Jourdan, in France; and to Tito Vignoli, in Italy.\n\nIn Germany, Wilhelm Wundt, of Leipzig, is considered to be the ablest\nliving psychologist; he has the inestimable advantage over most other\nphilosophers of a thorough zoological, anatomical, and physiological\neducation. Formerly assistant and pupil of Helmholtz, Wundt had early\naccustomed himself to follow the application of the laws of physics and\nchemistry through the whole field of physiology, and, consequently,\nin the sense of Johannes M\u00fcller, in _psychology_, as a subsection\nof the latter. Starting from this point of view, Wundt published\nhis valuable \"Lectures on human and animal psychology\" in 1863. He\nproved, as he himself tells us in the preface, that the theatre of\nthe most important psychic processes is in the \"unconscious soul,\"\nand he affords us \"a view of the mechanism which, in the unconscious\nbackground of the soul, manipulates the impressions which arise\nfrom the external stimuli.\" What seems to me, however, of special\nimportance and value in Wundt's work is that he \"extends the law of the\npersistence of force for the first time to the psychic world, and makes\nuse of a series of facts of electro-physiology by way of demonstration.\"\n\nThirty years afterwards (1892) Wundt published a second, much\nabridged and entirely modified, edition of his work. The important\nprinciples of the first edition are entirely abandoned in the second,\nand the monistic is exchanged for a purely dualistic stand-point.\nWundt himself says in the preface to the second edition that he has\nemancipated himself from the fundamental errors of the first, and\nthat he \"learned many years ago to consider the work a sin of his\nyouth\"; it \"weighed on him as a kind of crime, from which he longed\nto free himself as soon as possible.\" In fact, the most important\nsystems of psychology are completely opposed to each other in the two\neditions of Wundt's famous _Observations_. In the first edition he\nis purely monistic and materialistic, in the second edition purely\ndualistic and spiritualistic. In the one psychology is treated as a\n_physical_ science, on the same laws as the whole of physiology, of\nwhich it is only a part; thirty years afterwards he finds psychology\nto be a _spiritual_ science, with principles and objects entirely\ndifferent from those of physical science. This conversion is most\nclearly expressed in his principle of psycho-physical parallelism,\naccording to which \"every psychic event has a corresponding physical\nchange\"; but the two are completely independent, and are not in any\nnatural causal connection. This complete dualism of body and soul,\nof nature and mind, naturally gave the liveliest satisfaction to the\nprevailing school-philosophy, and was acclaimed by it as an important\nadvance, especially seeing that it came from a distinguished scientist\nwho had previously adhered to the opposite system of monism. As I\nmyself continue, after more than forty years' study, in this \"narrow\"\nposition, and have not been able to free myself from it in spite of\nall my efforts, I must naturally consider the \"youthful sin\" of the\nyoung physiologist Wundt to be a correct knowledge of nature, and\nenergetically defend it against the antagonistic view of the old\nphilosopher Wundt.\n\nThis entire change of philosophical principles, which we find in Wundt,\nas we found it in Kant, Virchow, Du Bois-Reymond, Karl Ernst Baer, and\nothers, is very interesting. In their youth these able and talented\nscientists embrace the whole field of biological research in a broad\nsurvey, and make strenuous efforts to find a unifying, natural basis\nfor their knowledge; in their later years they have found that this is\nnot completely attainable, and so they entirely abandon the idea. In\nextenuation of these psychological metamorphoses they can, naturally,\nplead that in their youth they overlooked the difficulties of the great\ntask, and misconceived the true goal; with the maturer judgment of age\nand the accumulation of experience they were convinced of their errors,\nand discovered the true path to the source of truth. On the other hand,\nit is possible to think that great scientists approach their task with\nless prejudice and more energy in their earlier years--that their\nvision is clearer and their judgment purer; the experiences of later\nyears sometimes have the effect, not of enriching, but of disturbing,\nthe mind, and with old age there comes a gradual decay of the brain,\njust as happens in all other organs. In any case, this change of views\nis in itself an instructive psychological fact; because, like many\nother forms of change of opinion, it shows that the highest psychic\nfunctions are subject to profound individual changes in the course of\nlife, like all the other vital processes.\n\nFor the profitable construction of comparative psychology it is\nextremely important not to confine the critical comparison to man\nand the brute in general, but to put side by side the innumerable\ngradations of their mental activity. Only thus can we attain a clear\nknowledge of the long scale of psychic development which runs unbroken\nfrom the lowest, unicellular forms of life up to the mammals, and to\nman at their head. But even within the limits of our own race such\ngradations are very noticeable, and the ramifications of the \"psychic\nancestral tree\" are very numerous. The psychic difference between the\ncrudest savage of the lowest grade and the most perfect specimen of\nthe highest civilization is colossal--much greater than is commonly\nsupposed. By the due appreciation of this fact, especially in the\nlatter half of the century, the \"Anthropology of the uncivilized races\"\n(Waitz) has received a strong support, and comparative ethnography has\ncome to be considered extremely important for psychological purposes.\nUnfortunately, the enormous quantity of raw material of this science\nhas not yet been treated in a satisfactory critical manner. What\nconfused and mystic ideas still prevail in this department may be seen,\nfor instance, in the _V\u00f6lkergedanke_ of the famous traveller, Adolf\nBastian, who, though a prolific writer, merely turns out a hopeless\nmass of uncritical compilation and confused speculation.\n\nThe most neglected of all psychological methods, even up to the present\nday, is the evolution of the soul; yet this little-frequented path\nis precisely the one that leads us most quickly and securely through\nthe gloomy primeval forest of psychological prejudices, dogmas, and\nerrors, to a clear insight into many of the chief psychic problems. As\nI did in the other branch of organic evolution, I again put before the\nreader the two great branches of the science which I differentiated in\n1866--ontogeny and phylogeny. The ontogeny, or embryonic development,\nof the soul, individual or biontic psychogeny, investigates the gradual\nand hierarchic development of the soul in the individual, and seeks to\nlearn the laws by which it is controlled. For a great part of the life\nof the mind a good deal has been done in this direction for centuries;\nrational pedagogy must have set itself the task at an early date of the\ntheoretical study of the gradual development and formative capacity of\nthe young mind that was committed to it for education and formation.\nMost pedagogues, however, were idealistic or dualistic philosophers,\nand so they went to work with all the prejudices of the spiritualistic\npsychology. It is only in the last few decades that this dogmatic\ntendency has been largely superseded even in the school by scientific\nmethods; we now find a greater concern to apply the chief laws of\nevolution even in the discussion of the soul of the child. The raw\nmaterial of the child's soul is already qualitatively determined by\n_heredity_ from parents and ancestors; education has the noble task of\nbringing it to a perfect maturity by intellectual instruction and moral\ntraining--that is, by _adaptation_. Wilhelm Preyer was the first to\nlay the foundation of our knowledge of the early psychic development\nin his interesting work on _The Mind of the Child_. Much is still to\nbe done in the study of the later stages and metamorphoses of the\nindividual soul, and once more the correct, critical application of the\nbiogenetic law is proving a guiding star to the scientific mind.\n\nA new and fertile epoch of higher development dawned for psychology\nand all other biological sciences when Charles Darwin applied the\nprinciples of evolution to them forty years ago. The seventh chapter\nof his epoch-making work on _The Origin of Species_ is devoted to\ninstinct. It contains the valuable proof that the instincts of animals\nare subject, like all other vital processes, to the general laws of\nhistoric development. The special instincts of particular species were\nformed by _adaptation_, and the modifications thus acquired were handed\non to posterity by _heredity_; in their formation and preservation\nnatural selection plays the same part as in the transformation of\nevery other physiological function. Darwin afterwards developed this\nfundamental thought in a number of works, showing that the same laws of\n\"mental evolution\" hold good throughout the entire organic world, not\nless in man than in the brute, and even in the plant. Hence the unity\nof the organic world, which is revealed by the common origin of its\nmembers, applies also to the entire province of psychic life, from the\nsimplest unicellular organism up to man.\n\nTo George Romanes we owe the further development of Darwin's\npsychology and its special application to the different sections of\npsychic activity. Unfortunately, his premature decease prevented the\ncompletion of the great work which was to reconstruct every section\nof comparative psychology on the lines of monistic evolution. The\ntwo volumes of this work which were completed are among the most\nvaluable productions of psychological literature. For, conformably\nto the principles of our modern monistic research, his first care\nwas to collect and arrange all the important facts which have been\nempirically established in the field of comparative psychology in the\ncourse of centuries; in the second place, these facts are tested with\nan _objective criticism_, and systematically distributed; finally, such\nrational conclusions are drawn from them on the chief general questions\nof psychology as are in harmony with the fundamental principles of\nmodern monism. The first volume of Romanes's work bears the title\nof _Mental Evolution in the Animal World_; it presents, in natural\nconnection, the entire length of the chain of psychic evolution in the\nanimal world, from the simplest sensations and instincts of the lowest\nanimals to the elaborate phenomena of consciousness and reason in the\nhighest. It contains also a number of extracts from a manuscript which\nDarwin left \"on instinct,\" and a complete collection of all that he\nwrote in the province of psychology.\n\nThe second and more important volume of Romanes's work treats of\n\"Mental evolution in man and the origin of human faculties.\" The\ndistinguished psychologist gives a convincing proof in it \"that the\npsychological barrier between man and the brute has been overcome.\"\nMan's power of conceptual thought and of abstraction has been gradually\nevolved from the non-conceptual stages of thought and ideation in the\nnearest related mammals. Man's highest mental powers--reason, speech,\nand conscience--have arisen from the lower stages of the same faculties\nin our primate ancestors (the simi\u00e6 and prosimi\u00e6). Man has no single\nmental faculty which is his exclusive prerogative. His whole psychic\nlife differs from that of the nearest related mammals only in degree,\nand not in kind; quantitatively, not qualitatively.\n\nI recommend those of my readers who are interested in these momentous\nquestions of psychology to study the profound work of Romanes. I am\ncompletely at one with him and Darwin in almost all their views and\nconvictions. Wherever an apparent discrepancy is found between these\nauthors and my earlier productions, it is either a case of imperfect\nexpression on my part or an unimportant difference in application of\nprinciple. For the rest, it is characteristic of this \"science of\nideas\" that the most eminent philosophers hold entirely antagonistic\nviews on its fundamental notions.\n\n\n\n\nCHAPTER VII\n\nPSYCHIC GRADATIONS\n\n    Psychological Unity of Organic Nature--Material Basis of the\n    Soul: Psychoplasm--Scale of Sensation--Scale of Movement--Scale\n    of Reflex Action--Simple and Compound Reflex Action--Reflex\n    Action and Consciousness--Scale of Perception--Unconscious and\n    Conscious Perception--Scale of Memory--Unconscious and Conscious\n    Memory--Association of Perceptions--Instinct--Primary and Secondary\n    Instincts--Scale of Reason--Language--Emotion and Passion--The\n    Will--Freedom of the Will\n\n\nThe great progress which psychology has made, with the assistance\nof evolution, in the latter half of the century culminates in the\nrecognition of _the psychological unity of the organic world_.\nComparative psychology, in co-operation with the ontogeny and phylogeny\nof the _psyche_, has enforced the conviction that organic life in all\nits stages, from the simplest unicellular protozoon up to man, springs\nfrom the same elementary forces of nature, from the physiological\nfunctions of sensation and movement. The future task of scientific\npsychology, therefore, is not, as it once was, the exclusively\nsubjective and introspective analysis of the highly developed mind\nof a philosopher, but the objective, comparative study of the long\ngradation by which man has slowly arisen through a vast series of lower\nanimal conditions. This great task of separating the different steps\nin the psychological ladder, and proving their unbroken phylogenetic\nconnection, has only been seriously attempted during the last ten\nyears, especially in the splendid work of Romanes. We must confine\nourselves here to a brief discussion of a few of the general questions\nwhich that gradation has suggested.\n\nAll the phenomena of the psychic life are, without exception, bound\nup with certain material changes in the living substance of the body,\nthe _protoplasm_. We have given to that part of the protoplasm which\nseems to be the indispensable substratum of psychic life the name\nof _psychoplasm_ (the \"soul-substance,\" in the monistic sense); in\nother words, we do not attribute any peculiar \"essence\" to it, but\nwe consider the _psyche_ to be merely _a collective idea of all the\npsychic functions of protoplasm_. In this sense the \"soul\" is merely\na physiological abstraction like \"assimilation\" or \"generation.\" In\nman and the higher animals, in accordance with the division of labor\nof the organs and tissues, the psychoplasm is a differentiated part of\nthe nervous system, the _neuroplasm_ of the ganglionic cells and their\nfibres. In the lower animals, however, which have no special nerves\nand organs of sense, and in the plants, the psychoplasm has not yet\nreached an independent differentiation. Finally, in the unicellular\nprotists, the psychoplasm is identified either with the whole of the\nliving protoplasm of the simple cell or with a portion of it. In all\ncases, in the lowest as well as the highest stages of the psychological\nhierarchy, a certain chemical composition and a certain physical\nactivity of the psychoplasm are indispensable before the \"soul\" can\nfunction or act. That is equally true of the elementary psychic\nfunction of the plasmatic sensation and movement of the protozoa,\nand of the complex functions of the sense-organs and the brain in the\nhigher animals and man. The activity of the psychoplasm, which we call\nthe \"soul,\" is always connected with metabolism.\n\nAll living organisms, without exception, are sensitive; they are\ninfluenced by the condition of their environment, and react thereon by\ncertain modifications in their own structure. Light and heat, gravity\nand electricity, mechanical processes and chemical action in the\nenvironment, act as _stimuli_ on the sensitive psychoplasm, and effect\nchanges in its molecular composition. We may distinguish the following\nfive chief stages of this sensibility:\n\nI. At the lowest stage of organization the _whole psychoplasm_, as\nsuch, is sensitive, and reacts on the stimuli from without; that is the\ncase with the lowest protists, with many plants, and with some of the\nmost rudimentary animals.\n\nII. At the second stage very simple and undiscriminating _sense-organs_\nbegin to appear on the surface of the organism, in the form of\nprotoplasmic filaments and pigment spots, the forerunners of the nerves\nof touch and the eyes; these are found in some of the higher protists\nand in many of the lower animals and plants.\n\nIII. At the third stage _specific organs_ of sense, each with a\npeculiar adaptation, have arisen by differentiation out of these\nrudimentary processes: there are the chemical instruments of smell\nand taste, and the physical organs of touch, temperature, hearing,\nand sight. The \"specific energy\" of these sense-organs is not an\noriginal inherent property of theirs, but has been gained by functional\nadaptation and progressive heredity.\n\nIV. The fourth stage is characterized by the _centralization_ or\nintegration of the _nervous system_, and, consequently, of sensation;\nby the association of the previously isolated or localized sensations\npresentations arise, though they still remain unconscious. That is the\ncondition of many both of the lower and the higher animals.\n\nV. Finally, at the fifth stage, the highest psychic function,\n_conscious perception_, is developed by the mirroring of the sensations\nin a central part of the nervous system, as we find in man and the\nhigher vertebrates, and probably in some of the higher invertebrates,\nnotably the articulata.\n\nAll living organisms without exception have the faculty of _spontaneous\nmovement_, in contradistinction to the rigidity and inertia of\nunorganized substances (_e.g._, crystals); in other words, certain\nchanges of place of the particles occur in the living psychoplasm\nfrom internal causes, which have their source in its own chemical\ncomposition. These active vital movements are partly discovered by\ndirect observation and partly only known indirectly, by inference from\ntheir effects. We may distinguish five stages of them.\n\nI. At the lowest stage of organic life, in the chromacea, and many\nprotophyta and lower metaphyta, we perceive only those _movements of\ngrowth_ which are common to all organisms. They are usually so slow\nthat they cannot be directly observed; they have to be inferred from\ntheir results--from the change in size and form of the growing organism.\n\nII. Many protists, particularly unicellular alg\u00e6 of the groups of\ndiatomacea and desmidiacea, accomplish a kind of creeping or swimming\nmotion by _secretion_, by ejecting a slimy substance at one side.\n\nIII. Other organisms which float in water--for instance, many of the\nradiolaria, siphonophora, ktenophora, and others--ascend and descend by\naltering their _specific gravity_, sometimes by osmosis, sometimes by\nthe separation or squeezing-out of air.\n\nIV. Many plants, especially the sensitive plants (mimosa) and other\npapilionacea, effect movements of their leaves or other organs by\n_change of pressure_--that is, they alter the strain of the protoplasm,\nand, consequently, its pressure on the enclosing elastic walls of the\ncells.\n\nV. The most important of all organic movements are the _phenomena\nof contraction_--_i.e._, changes of form at the surface of the\norganism, which are dependent on a twofold displacement of their\nelements; they always involve two different conditions or phases\nof motion--contraction and expansion. Four different forms of this\nplasmatic contraction may be enumerated:\n\n    (_a_) Amoeboid movement (in rhizopods, blood-cells,\n    pigment-cells, etc.).\n\n    (_b_) A similar flow of protoplasm within enclosed cells.\n\n    (_c_) Vibratory motion (ciliary movements) in infusoria,\n    spermatozoa, ciliated epithelial cells.\n\n    (_d_) Muscular movement (in most animals).\n\nThe elementary psychic activity that arises from the combination of\nsensation and movement is called _reflex_ (in the widest sense),\nreflective function, or _reflex action_. The movement--no matter what\nkind it is--seems in this case to be the immediate result of the\n_stimulus_ which evoked the sensation; it has, on that account, been\ncalled stimulated motion in its simplest form (in the protists). All\nliving protoplasm has this feature of irritability. Any physical or\nchemical change in the environment may, in certain circumstances,\nact as a stimulus on the psychoplasm, and elicit or \"release\" a\nmovement. We shall see later on how this important physical concept of\n\"releasing\" directly connects the simplest organic reflex actions with\nsimilar mechanical phenomena of movement in the inorganic world (for\ninstance, in the explosion of powder by a spark, or of dynamite by a\nblow). We may distinguish the following seven stages in the scale of\nreflex action:\n\nI. At the lowest stage of organization, in the lowest protists, the\nstimuli of the outer world (heat, light, electricity, etc.) cause in\nthe indifferent protoplasm only those indispensable movements of growth\nand nutrition which are common to all organisms, and are absolutely\nnecessary for their preservation. That is also the case in most of the\nplants.\n\nII. In the case of many freely moving protists (especially the\namoeba, the heliozoon, and the rhizopod) the stimuli from without\nproduce on every spot of the unprotected surface of the unicellular\norganism external movements which take the form of changes of shape,\nand sometimes changes of place (amoeboid movement, pseudopod\nformation, the extension and withdrawal of what look like feet); these\nindefinite, variable processes of the protoplasm are not yet permanent\norgans. In the same way, general organic irritability takes the form\nof indeterminate reflex action in the sensitive plants and the lowest\nmetazoa; in many multicellular organisms the stimuli may be conducted\nfrom one cell to another, as all the cells are connected by fine fibres.\n\nIII. Many protists, especially the more highly developed protozoa,\nproduce on their unicellular body two little organs of the simplest\ncharacter--an organ of touch and an organ of movement. Both these\ninstruments are direct external projections of protoplasm; the\nstimulus, which alights on the first, is immediately conducted to\nthe other by the psychoplasm of the unicellular body, and causes it\nto contract. This phenomenon is particularly easy to observe, and\neven produce experimentally, in many of the stationary infusoria\n(for instance, the _poteriodendron_ among the flagellata, and the\n_vorticella_ among the ciliata). The faintest stimulus that touches the\nextremely sensitive hairs, or _cilia_, at the free end of the cells,\nimmediately causes a contraction of a thread-like stalk at the other,\nfixed end. This phenomenon is known as a \"simple reflex arch.\"\n\nIV. These phenomena of the unicellular organism of the infusoria lead\non to the interesting mechanism of the neuro-muscular cells, which we\nfind in the multicellular body of many of the lower metazoa, especially\nin the cnidaria (polyps and corals). Each single neuro-muscular cell\nis a \"unicellular reflex organ\"; it has on its surface a sensitive\nspot, and a motor muscular fibre inside at the opposite end; the latter\ncontracts as soon as the former is stimulated.\n\nV. In other cnidaria, notably in the free swimming medus\u00e6--which are\nclosely related to the stationary polyps--the simple neuro-muscular\ncell becomes two different cells, connected by a filament; an external\n_sense-cell_ (in the outer skin) and an internal _muscular cell_ (under\nthe skin). In this _bicellular reflex organ_ the one cell is the\nrudimentary organ of sensation, the other of movement; the connecting\nbridge of the psychoplasmic filament conducts the stimulus from one to\nthe other.\n\nVI. The most important step in the gradual construction of the reflex\nmechanism is the division into three cells; in the place of the simple\nconnecting bridge we spoke of there appears a third independent cell,\nthe _soul-cell_, or ganglionic cell; with it appears also a new psychic\nfunction, _unconscious presentation_, which has its seat in this\ncell. The stimulus is first conducted from the sensitive cell to this\nintermediate presentative or psychic cell, and then issued from this to\nthe motor muscular cell as a mandate of movement. These _tricellular\nreflex organs_ are preponderantly developed in the great majority of\nthe invertebrates.\n\nVII. Instead of this arrangement we find in most of the vertebrates\na _quadricellular reflex organ_, two distinct \"soul-cells,\" instead\nof one, being inserted between the sensitive cell and the motor cell.\nThe external stimulus, in this case, is first conducted centripetally\nto the sensitive cell (the sensible psychic cell), from this to the\n_will-cell_ (the motor psychic cell), and from this, finally, to the\ncontractile muscular cell. When many such reflex organs combine and new\npsychic cells are interposed we have the intricate reflex mechanism of\nman and the higher vertebrates.\n\nThe important distinction which we make, in morphology and physiology,\nbetween unicellular and multicellular organisms holds good for their\nelementary psychic activity, reflex action. In the unicellular\nprotists (both the plasmodomous primitive plants, or _protophyta_,\nand the plasmophagous primitive animals, or _protozoa_) the whole\nphysical process of reflex action takes place in the protoplasm of\none single cell; their \"cell-soul\" seems to be a unifying function\nof the psychoplasm of which the various phases only begin to be seen\nseparately when the differentiation of special organs sets in.\n\nThe second stage of psychic activity, compound reflex action, begins\nwith the cenobitic protists (_v.g._, the volvox and the carchesium).\nThe innumerable social cells, which make up this cell-community\nor coenobium, are always more or less connected, often directly\nconnected by filamentous bridges of protoplasm. A stimulus that alights\non one or more cells of the community is communicated to the rest by\nmeans of the connecting fibres, and may produce a general contraction.\nThis connection is found, also, in the tissues of the multicellular\nanimals and plants. It was erroneously believed at one time that the\ncells of vegetal tissue were completely isolated from each other, but\nwe have now discovered fine filaments of protoplasm throughout, which\npenetrate the thick membranes of the cells, and maintain a material\nand psychological communication between their living plasmic contents.\nThat is the explanation of the mimosa: when the tread of the passer-by\nshakes the root of the plant, the stimulus is immediately conveyed to\nall the cells, and causes a general contraction of its tender leaves\nand a drooping of the stems.\n\nAn important and universal feature of all reflex phenomena is the\nabsence of consciousness. For reasons which we shall give in the tenth\nchapter we only admit the presence of consciousness in man and the\nhigher animals, not in plants, the lower animals, and the protists;\nconsequently all stimulated movements in the latter must be regarded\nas reflex--that is, all movements which are not _spontaneous_, not the\noutcome of internal causes (impulsive and automatic movements).[14]\nIt is different with the higher animals which have developed a\ncentralized nervous system and elaborate sense-organs. In these cases\nconsciousness has been gradually evolved from the psychic reflex\nactivity, and now conscious, voluntary action appears, in opposition to\nthe still continuing reflex action below. However, we must distinguish\ntwo different processes, as we did in the question of instinct--primary\nand secondary reflex action. Primary reflex actions are those which\nhave never reached the stage of consciousness in phyletic development,\nand thus preserve the primitive character (by heredity from lower\nanimal forms). Secondary reflex actions are those which were conscious,\nvoluntary actions in our ancestors, but which afterwards became\nunconscious from habit or the lapse of consciousness. It is impossible\nto draw a hard and fast line in such cases between conscious and\nunconscious psychic function.\n\nOlder psychologists (Herbart, for instance) considered \"presentation\"\nto be the fundamental psychic phenomenon, from which all the others are\nderived. Modern comparative psychology endorses this view in so far as\nit relates to the idea of _unconscious_ presentation; but it considers\n_conscious_ presentation to be a secondary phenomenon of mental life,\nwhich is entirely wanting in plants and the lower animals, and is\nonly developed in the higher animals. Among the many contradictory\ndefinitions which psychologists have given of \"presentation,\" we think\nthe best is that which makes it consist in an internal picture of the\nexternal object which is given us in sensation--an \"idea,\" in the\nbroader sense. We may distinguish the following four stages in the\nrising scale of presentative function:\n\nI. _Cellular presentation._--At the lowest stages we find presentation\nto be a general physiological property of psychoplasm; even in the\nsimplest unicellular protist sensations may leave a permanent trace in\nthe psychoplasm, and these may be reproduced by memory. In more than\nfour thousand kinds of radiolaria, which I have described, every single\nspecies is distinguished by special, hereditary skeletal structure. The\nconstruction of this specific, and often highly elaborate, skeleton\nby a cell of the simplest description (generally globular) is only\nintelligible when we attribute the faculty of presentation, and,\nindeed, of a special reproduction of the plastic \"feeling of distance,\"\nto the constructive protoplasm--as I have pointed out in my _Psychology\nof the Radiolaria_.[15]\n\nII. _Histionic presentation._--In the coenobia or cell-colonies of\nthe social protists, and still better in the tissues of plants and\nlower, nerveless animals (sponges, polyps, etc.), we find the second\nstage of unconscious presentation, which consists of the common psychic\nactivity of a number of closely connected cells. If a single stimulus\nmay, instead of simply spending itself in the reflex movement of an\norgan (the leaf of a plant, for instance, or the arm of a polyp),\nleave a permanent impression, which can be spontaneously reproduced\nlater on, we are bound to assume, in explaining the phenomenon, a\nhistionic presentation, dependent on the psychoplasm of the associated\ntissue-cells.\n\nIII. _Unconscious presentation in the ganglionic cells._--This\nthird and higher stage of presentation is the commonest form the\nfunction takes in the animal world; it seems to be a localization of\npresentation in definite \"soul-cells.\" In its simplest form it appears\nat the sixth stage of reflex action, when the tricellular reflex organ\narises: the seat of presentation is then the intermediate psychic\ncell, which is interposed between the sensitive cell and the muscular\ncell. With the increasing development of the animal nervous system\nand its progressive differentiation and integration, this unconscious\npresentation also rises to higher stages.\n\nIV. _Conscious presentation in the cerebral cells._--With the highest\nstage of development of the animal organization consciousness arises,\nas a special function of a certain central organ of the nervous\nsystem. As the presentations are conscious, and as special parts of\nthe brain arise for the association of these conscious presentations,\nthe organism is qualified for those highest psychic functions which\nwe call thought and reflection, intellect and reason. Although the\ntracing of the phyletic barrier between the older, unconscious, and the\nyounger, conscious, presentation is extremely difficult, we can affirm,\nwith some degree of probability, that the evolution of the latter from\nthe former was _polyphyletic_; because we find conscious and rational\nthought, not only in the highest forms of the vertebrate stem (man,\nmammals, birds, and a part of the lower vertebrates), but also in the\nmost highly developed representatives of other animal groups (ants\nand other insects, spiders and the higher crabs among the articulata,\ncephalopods among the mollusca).\n\nThe evolutionary scale of memory is closely connected with that of\npresentation; this extremely important function of the psychoplasm--the\ncondition of all further psychic development--consists essentially\nin the _reproduction of presentations_. The impressions in the\nbioplasm, which the stimulus produced as sensations, and which\nbecame presentations in remaining, are revived by memory; they pass\nfrom potentiality to actuality. The latent potential energy of the\npsychoplasm is transformed into kinetic energy. We may distinguish\nfour stages in the upward development of memory, corresponding to the\nfour stages of presentation.\n\nI. _Cellular memory._--Thirty years ago Ewald Hering showed \"memory to\nbe a general property of organized matter\" in a thoughtful work, and\nindicated the great significance of this function, \"to which we owe\nalmost all that we are and have.\" Six years later, in my work on _The\nPerigenesis of the Plastidule, or the Undulatory Origin of the Parts\nof Life: an Experiment in the Mechanical Explanation of Elementary\nEvolutionary Processes_, I developed these ideas, and endeavored\nto base them on the principles of evolution. I have attempted to\nshow in that work that unconscious memory is a universal and very\nimportant function of all _plastidules_; that is, of those hypothetical\nmolecules, or groups of molecules, which Naegeli has called _micellae_,\nothers _bioplasts_, and so forth. Only _living_ plastidules, as\nindividual molecules of the active protoplasm, are reproductive,\nand so gifted with memory; that is the chief difference between the\norganic and inorganic worlds. It might be stated thus: \"Heredity is\nthe memory of the plastidule, while variability is its comprehension.\"\nThe elementary memory of the unicellular protist is made up of the\nmolecular memory of the plastidules or _micellae_, of which its living\ncell-body is constructed. As regards the extraordinary performances\nof unconscious memory in these unicellular protists, nothing could be\nmore instructive than the infinitely varied and regular formation of\ntheir defensive apparatus, their shells and skeletons; in particular,\nthe diatomes and cosmaria among the protophytes, and the radiolaria\nand thalamophora among the protozoa, afford an abundance of most\ninteresting illustrations. In many thousand species of these protists\nthe specific form which is inherited is _relatively constant_, and\nproves the fidelity of their unconscious cellular memory.\n\nII. _Histionic memory._--Equally interesting examples of the second\nstage of memory, the unconscious memory of tissues, are found in the\nheredity of the individual organs of plants and the lower, nerveless\nanimals (sponges, etc.). This second stage seems to be _a reproduction\nof the histionic presentations_, that association of cellular\npresentations which sets in with the formation of coenobia in the\nsocial protists.\n\nIII. In the same way we must regard the third stage, the unconscious\nmemory of those animals which have a nervous system, as a reproduction\nof the corresponding \"unconscious presentations\" which are stored up\nin certain ganglionic cells. In most of the lower animals all memory\nis unconscious. Moreover, even in man and the higher animals, to whom\nwe must ascribe consciousness, the daily acts of unconscious memory\nare much more numerous and varied than those of the conscious faculty;\nwe shall easily convince ourselves of that if we make an impartial\nstudy of a thousand unconscious acts we perform daily out of habit, and\nwithout thinking of them, in walking, speaking, writing, eating, and so\nforth.\n\nIV. Conscious memory, which is the work of certain brain-cells in\nman and the higher animals, is an \"internal mirroring\" of very late\ndevelopment, the highest outcome of the same psychic reproduction of\npresentations which were mere unconscious processes in the ganglionic\ncells of our lower animal ancestors.\n\nThe concatenation of presentations--usually called the association of\nideas--also runs through a long scale, from the lowest to the highest\nstages. This, too, is originally and predominantly unconscious\n(\"instinct\"); only in the higher classes of animals does it gradually\nbecome conscious (\"reason\"). The psychic results of this \"association\nof ideas\" are extremely varied; still, a very long, unbroken line of\ngradual development connects the simplest unconscious association of\nthe lowest protist with the elaborate conscious chain of ideas of the\ncivilized man. The _unity of consciousness_ in man is given as its\nhighest consequence (Hume, Condillac). All higher mental activity\nbecomes more perfect in proportion as the normal association extends\nto more numerous presentations, and in proportion to the order which\nis imposed on them by the \"criticism of pure reason.\" In dreams,\nwhere this criticism is absent, the association of the reproduced\nimpressions often takes the wildest forms. Even in the work of the\npoetic imagination, which constructs new groups of images by varying\nthe association of the impressions received, and in hallucinations,\netc., they are often most unnaturally arranged, and seem to the\nprosaic observer to be perfectly irrational. This is especially true\nof supernatural \"forms of belief,\" the apparitions of spiritism,\nand the fantastic notions of the transcendental dualist philosophy;\nthough it is precisely these _abnormal associations_ of \"faith\" and of\n\"revelation\" that have often been deemed the greatest treasures of the\nhuman mind (cf. chap. xvi.).\n\nThe antiquated psychology of the Middle Ages (which, however, still\nnumbers many adherents) considered the mental life of man and that\nof the brute to be two entirely different phenomena; the one it\nattributed to \"reason,\" the other to \"instinct.\" In harmony with the\ntraditional story of creation, it was assumed that each animal species\nhad received a definite, unconscious psychic force from the Creator\nat its formation, and that this instinct of each species was just as\nunchangeable as its bodily structure. Lamarck proved the untenableness\nof this error in 1809 by establishing the theory of Descent, and Darwin\ncompletely demolished it in 1859. He proved the following important\ntheses with the aid of his theory of selection:\n\n1. The instincts of species show individual differences, and are\njust as subject to modification under the law of _adaptation_ as the\nmorphological features of their bodily structure.\n\n2. These modifications (generally arising from a change of habits) are\npartly transmitted to offspring by _heredity_, and thus accumulate and\nare accentuated in the course of generations.\n\n3. _Selection_, both artificial and natural, singles out certain of\nthese inherited modifications of the psychic activity; it preserves the\nmost useful and rejects the least adaptive.\n\n4. The _divergence_ of psychic character which thus arises leads, in\nthe course of generations, to the formation of new instincts, just as\nthe divergence of morphological character gives rise to new species.\n\nDarwin's theory of instinct is now accepted by most biologists; Romanes\nhas treated it so ably, and so greatly expanded it in his distinguished\nwork on _Mental Evolution in the Animal World_, that I need merely\nrefer to it here. I will only venture the brief statement that, in my\nopinion, there are instincts in _all_ organisms--in all the protists\nand plants as well as in all the animals and in man; though in the\nlatter they tend to disappear in proportion as reason makes progress at\ntheir expense.\n\nThe two chief classes of instincts to be differentiated are the\nprimary and secondary. Primary instincts are the common lower\nimpulses which are unconscious and inherent in the psychoplasm\nfrom the commencement of organic life; especially the impulses to\nself-preservation (by defence and maintenance) and to the preservation\nof the species (by generation and the care of the young). Both these\nfundamental instincts of organic life, _hunger_ and _love_, sprang\nup originally in perfect unconsciousness, without any co-operation\nof the intellect or reason. It is otherwise with the _secondary_\ninstincts. These were due originally to an intelligent adaptation, to\nrational thought and resolution, and to purposive conscious action.\nGradually, however, they became so automatic that this \"other nature\"\nacted unconsciously, and, even through the action of heredity, seemed\nto be \"innate\" in subsequent generations. The consciousness and\ndeliberation which originally accompanied these particular instincts\nof the higher animals and man have died away in the course of the\nlife of the plastidules (as in \"abridged heredity\"). The unconscious\npurposive actions of the higher animals (for instance, their mechanical\ninstincts) thus come to appear in the light of innate impulses. We have\nto explain in the same way the origin of the \"_\u00e0 priori_ ideas\" of man;\nthey were originally formed empirically by his predecessors.[16]\n\nIn the superficial psychological treatises which ignore the mental\nactivity of animals and attribute to man only a \"true soul,\" we\nfind him credited also with the exclusive possession of reason and\nconsciousness. This is another trivial error (still to be found in many\na manual, nevertheless) which the comparative psychology of the last\nforty years has entirely dissipated. The higher vertebrates (especially\nthose mammals which are most nearly related to man) have just as good a\ntitle to \"reason\" as man himself, and within the limits of the animal\nworld there is the same long chain of the gradual development of\nreason as in the case of humanity. The difference between the reason\nof a Goethe, a Kant, a Lamarck, or a Darwin, and that of the lowest\nsavage, a Veddah, an Akka, a native Australian, or a Patagonian, is\nmuch greater than the graduated difference between the reason of the\nlatter and that of the most \"rational\" mammals, the anthropoid apes, or\neven the papiomorpha, the dog, or the elephant. This important thesis\nhas been convincingly proved by the thoroughly critical comparative\nwork of Romanes and others. We shall not, therefore, attempt to cover\nthat ground here, nor to enlarge on the distinction between the reason\nand the intellect; as to the meaning and limits of these concepts\nphilosophic experts give the most contradictory definitions, as they do\non so many other fundamental questions of psychology. In general it may\nbe said that the process of the formation of concepts, which is common\nto both these cerebral functions, is confined to the narrower circle of\nconcrete, proximate associations in the intellect, but reaches out to\nthe wider circle of abstract, more comprehensive groups of associations\nin the work of reason. In the long gradation which connects the reflex\nactions and the instincts of the lower animals with the reason of the\nhighest, intellect precedes the latter. And there is the fact, of\ngreat importance to our whole psychological treatise, that even these\nhighest of our mental faculties are just as much subject to the laws\nof heredity and adaptation as are their respective organs; Flechsig\npointed out in 1894 that the \"organs of thought,\" in man and the higher\nmammals, are those parts of the cortex of the brain which lie between\nthe four inner sense-centres (cf. chapters x. and xi.).\n\nThe higher grade of development of ideas, of intellect and reason,\nwhich raises man so much above the brute, is intimately connected with\nthe rise of language. Still here also we have to recognize a long chain\nof evolution which stretches unbroken from the lowest to the highest\nstages. Speech is no more an exclusive prerogative of man than reason.\nIn the wider sense, it is a common feature of all the higher gregarious\nanimals, at least of all the articulata and the vertebrates, which live\nin communities or herds; they need it for the purpose of understanding\neach other and communicating their impressions. This is effected either\nby touch or by signs, or by sounds having a definite meaning. The\nsong of the bird or of the anthropoid ape (_hylobates_), the bark of\nthe dog, the neigh of the horse, the chirp of the cricket, the cry of\nthe cicada, are all specimens of animal speech. Only in man, however,\nhas that articulate conceptual speech developed which has enabled his\nreason to attain such high achievements. Comparative philology, one\nof the most interesting sciences that has arisen during the century,\nhas shown that the numerous elaborate languages of the different\nnations have been slowly and gradually evolved from a few simple\nprimitive tongues (Wilhelm Humboldt, Bopp, Schleicher, Steinthal, and\nothers). August Schleicher, of Jena, in particular, has proved that\nthe historical development of language takes place under the same\nphylogenetic laws as the evolution of other physiological faculties\nand their organs. Romanes (1893) has expanded this proof, and amply\ndemonstrated that human speech, also, differs from that of the brute\nonly in _degree_ of development, not in essence and kind.\n\nThe important group of psychic activities which we embrace under the\nname of \"emotion\" plays a conspicuous part both in theoretical and\npractical psychology. From our point of view they have a peculiar\nimportance from the fact that we clearly see in them the direct\nconnection of cerebral functions with other physiological functions\n(the beat of the heart, sense-action, muscular movement, etc.);\nthey, therefore, prove the unnatural and untenable character of\nthe philosophy which would essentially dissociate psychology from\nphysiology. All the external expressions of emotional life which we\nfind in man are also present in the higher animals (especially in the\nanthropoid ape and the dog); however varied their development may be,\nthey are all derived from the two elementary functions of the _psyche_,\nsensation and motion, and from their combination in reflex action and\npresentation. To the province of sensation, in a wide sense, we must\nattribute the feeling of _like_ and _dislike_ which determines the\nemotion; while the corresponding _desire_ and _aversion_ (love and\nhatred), the effort to attain what is liked and avoid what is disliked,\nbelong to the category of movement. \"Attraction\" and \"repulsion\"\nseem to be the sources of _will_, that momentous element of the soul\nwhich determines the character of the individual. The _passions_,\nwhich play so important a part in the psychic life of man, are but\nintensifications of emotion. Romanes has recently shown that these also\nare common to man and the brute. Even at the lowest stage of organic\nlife we find in all the protists those elementary feelings of like\nand dislike, revealing themselves in what are called their _tropisms_,\nin the striving after light and darkness, heat or cold, and in their\ndifferent relations to positive and negative electricity. On the other\nhand, we find at the highest stage of psychic life, in civilized man,\nthose finer shades of emotion, of delight and disgust, of love and\nhatred, which are the mainsprings of civilization and the inexhaustible\nsources of poetry. Yet a connecting chain of all conceivable gradations\nunites the most primitive elements of feeling in the psychoplasm of the\nunicellular protist with the highest forms of passion that rule in the\nganglionic cells of the cortex of the human brain. That the latter are\nabsolutely amenable to physical laws was proved long ago by the great\nSpinoza in his famous _Statics of Emotion_.\n\nThe notion of _will_ has as many different meanings and definitions\nas most other psychological notions--presentation, soul, mind, and\nso forth. Sometimes will is taken in the widest sense as a _cosmic\nattribute_, as in the \"World as will and presentation\" of Schopenhauer;\nsometimes it is taken in its narrowest sense as an _anthropological\nattribute_, the exclusive prerogative of man--as Descartes taught, for\ninstance, who considered the brute to be a mere machine, without will\nor sensation. In the ordinary use of the term, _will_ is derived from\nthe phenomenon of voluntary movement, and is thus regarded as a psychic\nattribute of most animals. But when we examine the will in the light of\ncomparative physiology and evolution, we find--as we do in the case of\nsensation--that it is a universal property of living psychoplasm. The\nautomatic and the reflex movements which we observe everywhere, even\nin the unicellular protists, seem to be the outcome of inclinations\nwhich are inseparably connected with the very idea of life. Even in the\nplants and lowest animals these inclinations, or tropisms, seem to be\nthe joint outcome of the inclinations of all the combined individual\ncells.\n\nBut when the \"tricellular reflex organ\" arises (page 115), and a third\nindependent cell--the \"psychic,\" or \"ganglionic,\" cell--is interposed\nbetween the sense-cell and the motor cell, we have an independent\nelementary organ of will. In the lower animals, however, this will\nremains _unconscious_. It is only when consciousness arises in the\nhigher animals, as the subjective mirror of the objective, though\ninternal, processes in the neuroplasm of the psychic cells, that the\nwill reaches that highest stage which likens it in character to the\nhuman will, and which, in the case of man, assumes in common parlance\nthe predicate of \"liberty.\" Its free dominion and action become more\nand more deceptive as the muscular system and the sense-organs develop\nwith a free and rapid locomotion, entailing a correlative evolution of\nthe brain and the organs of thought.\n\nThe question of the liberty of the will is the one which has more than\nany other cosmic problem occupied the time of thoughtful humanity,\nthe more so that in this case the great philosophic interest of the\nquestion was enhanced by the association of most momentous consequences\nfor practical philosophy--for ethics, education, law, and so forth.\nEmil du Bois-Reymond, who treats it as the seventh and last of his\n\"seven cosmic problems,\" rightly says of the question: \"Affecting\neverybody, apparently accessible to everybody, intimately involved in\nthe fundamental conditions of human society, vitally connected with\nreligious belief, this question has been of immeasurable importance\nin the history of civilization. There is probably no other object\nof thought on which the modern library contains so many dusty folios\nthat will never again be opened.\" The importance of the question is\nalso seen in the fact that Kant put it in the same category with the\nquestions of the immortality of the soul and belief in God. He called\nthese three great questions the indispensable \"postulates of practical\nreason,\" though he had already clearly shown them to have no reality\nwhatever in the light of _pure_ reason.\n\nThe most remarkable fact in connection with this fierce and confused\nstruggle over the freedom of the will is, perhaps, that it has been\ntheoretically rejected, not only by the greatest critical philosophers,\nbut even by their extreme opponents, and yet it is still affirmed to\nbe self-evident by the majority of people. Some of the first teachers\nof the Christian Churches--such as St. Augustine and Calvin--rejected\nthe freedom of the will as decisively as the famous leaders of pure\nmaterialism, Holbach in the eighteenth and B\u00fcchner in the nineteenth\ncentury. Christian theologians deny it, because it is irreconcilable\nwith their belief in the omnipotence of God and in predestination. God,\nomnipotent and omniscient, saw and willed all things from eternity--he\nmust, consequently, have predetermined the conduct of man. If man, with\nhis free will, were to act otherwise than God had ordained, God would\nnot be all-mighty and all-knowing. In the same sense Leibnitz, too,\nwas an unconditional determinist. The monistic scientists of the last\ncentury, especially Laplace, defended determinism as a consequence of\ntheir mechanical view of life.\n\nThe great struggle between the determinist and the indeterminist,\nbetween the opponent and the sustainer of the freedom of the will,\nhas ended to-day, after more than two thousand years, completely in\nfavor of the determinist. The human will has no more freedom than that\nof the higher animals, from which it differs only in degree, not in\nkind. In the last century the dogma of liberty was fought with general\nphilosophic and cosmological arguments. The nineteenth century has\ngiven us very different weapons for its definitive destruction--the\npowerful weapons which we find in the arsenal of comparative physiology\nand evolution. We now know that each act of the will is as fatally\ndetermined by the organization of the individual and as dependent on\nthe momentary condition of his environment as every other psychic\nactivity. The character of the inclination was determined long ago\nby _heredity_ from parents and ancestors; the determination to each\nparticular act is an instance of _adaptation_ to the circumstances of\nthe moment wherein the strongest motive prevails, according to the laws\nwhich govern the statics of emotion. Ontogeny teaches us to understand\nthe evolution of the will in the individual child. Phylogeny reveals\nto us the historical development of the will within the ranks of our\nvertebrate ancestors.\n\n\n\n\nCHAPTER VIII\n\nTHE EMBRYOLOGY OF THE SOUL\n\n    Importance of Ontogeny to Psychology--Development of the\n    Child-Soul--Commencement of Existence of the Individual\n    Soul--The Storing of the Soul--Mythology of the Origin of\n    the Soul--Physiology of the Origin of the Soul--Elementary\n    Processes in Conception--Coalescence of the Ovum and\n    the Spermatozoon--Cell-Love--Heredity of the Soul from\n    Parents and Ancestors--Its Physiological Nature as the\n    Mechanics of the Protoplasm--Blending of Souls (Psychic\n    Amphigony)--Reversion, Psychological Atavism--The Biogenetic\n    Law in Psychology--Palingenetic Repetition and Cenogenetic\n    Modification--Embryonic and Post-Embryonic Psychogeny\n\n\nThe human soul--whatever we may hold as to its nature--undergoes\na continual development throughout the life of the individual.\nThis ontogenetic fact is of fundamental importance in our monistic\npsychology, though the \"professional\" psychologists pay little or no\nattention to it. Since the embryology of the individual is, on Baer's\nprinciple--and in accordance with the universal belief of modern\nbiologists--the \"true torch-bearer for all research into the organic\nbody,\" it will afford us a reliable light on the momentous problems of\nits psychic activity.\n\nAlthough, however, this \"embryology of the soul\" is so important and\ninteresting, it has hitherto met with the consideration it deserves\nonly within a very narrow circle. Until recently teachers were almost\nthe only ones to occupy themselves with a part of the problem;\nsince their avocation compelled them to assist and supervise the\nformation of the psychic activity in the child, they were bound to\ntake a theoretical interest, also, in the psychogenetic facts that\ncame under their notice. However, these teachers, for the most part,\nboth in recent and in earlier times, were dominated by the current\ndualistic psychology--in so far as they reflected at all; and they were\ntotally ignorant of the important facts of comparative psychology, and\nunacquainted with the structure and function of the brain. Moreover,\ntheir observations only extended to children in their school-days, or\nin the years immediately preceding. The remarkable phenomena which\nthe individual psychogeny of the child offers in its earliest years,\nand which are the joy and admiration of all thoughtful parents, were\nscarcely ever made the subject of serious scientific research. Wilhelm\nPreyer was the pioneer of this study in his interesting work on _The\nMind of the Child_ (1881). To obtain a perfectly clear knowledge of the\nmatter, however, we must go further back still; we must commence at the\nfirst appearance of the soul in the impregnated ovum.\n\nThe origin of the human individual--body and soul--was still wrapped\nin complete mystery at the beginning of the nineteenth century. Caspar\nFriedrich Wolff had, it is true, discovered the true character of\nembryonic development in 1759, in his _theoria generationis_, and\nproved with the confidence of a critical observer that there is a\ntrue _epigenesis_--_i.e._, a series of very remarkable formative\nprocesses--in the evolution of the foetus from the simple ovum. But\nthe physiologists of the time, with the famous Albert Haller at their\nhead, flatly refused to entertain these empirical truths, which may be\ndirectly proved by microscopic observation, and clung to the old dogma\nof \"preformation.\" This theory assumed that in the human ovum--and in\nthe egg of all other animals--the organism was already present, or\n\"preformed,\" in all its parts; the \"evolution\" of the embryo consisted\nliterally in an \"unfolding\" (_evolutio_) of the folded organs. One\ncurious consequence of this error was the theory of _scatulation_,\nwhich we have mentioned on p. 55; since the ovary had to be admitted to\nbe present in the embryo of the woman, it was also necessary to suppose\nthat the germs of the next generation were already formed in it, and\nso on _in infinitum_. Opposed to this dogma of the \"Ovulists\" was\nthe equally erroneous notion of the \"Animalculists\"; the latter held\nthat the germ was not really in the female ovum, but in the paternal\nelement, and that the store of succeeding generations was to be sought\nin the spermatozoa.\n\nLeibnitz consistently applied this theory of scatulation to the human\nsoul; he denied that either soul or body had a real development\n(_epigenesis_), and said in his _Theodicy_: \"Thus I consider that the\nsouls which are destined one day to become human exist in the seed,\nlike those of other species; that they have existed in our ancestors\nas far back as Adam--that is, since the beginning of the world--in\nthe forms of organized bodies.\" Similar notions prevailed in biology\nand philosophy until the third decade of the present century, when\nthe reform of embryology by Baer gave them their death blow. In the\nprovince of psychology, however, they still find many adherents; they\nform one group of the many curious mystical ideas which give us a\nliving illustration of the ontogeny of the soul.\n\nThe more accurate knowledge which we have recently obtained, through\ncomparative ethnology, of the various forms of myths of ancient and\nmodern uncivilized races, is also of great interest in psychogeny.\nStill, it would take us too far from our purpose if we were to enter\ninto it with any fulness here; we must refer the reader to Adalbert\nSvoboda's excellent work on _Forms of Faith_ (1897). In respect of\ntheir scientific and poetical contents, we may arrange all pertinent\n_psychogenetic myths_ in the following five groups:\n\nI. The myth of transmigration.--The soul lived formerly in the body of\nanother animal, and passed from this into a human body. The Egyptian\npriests, for instance, taught that the human soul wandered through all\nthe species of animals after the death of the body, returning to a\nhuman frame after three thousand years of transmigration.\n\nII. The myth of the in-planting of the soul.--The soul existed\nindependently in another place--a psychogenetic store, as it were (in a\nkind of embryonic slumber or latent life); it was taken out by a bird\n(sometimes represented as an eagle, generally as a white stork), and\nimplanted in the human body.\n\nIII. The myth of the creation of the soul.--God creates the souls,\nand keeps them stored--sometimes in a pond (living in the form of\n_plankton_), according to other myths in a tree (where they are\nconceived as the fruit of a phanerogam); the Creator takes them from\nthe pond or tree, and inserts them in the human germ during the act of\nconception.\n\nIV. The myth of the scatulation of the soul (the theory of Leibnitz\nwhich we have given above).\n\nV. The myth of the division of the soul (the theory of Rudolph Wagner\n[1855] and of other physiologists).--In the act of procreation a\nportion is detached from both the (immaterial) souls of the parents;\nthe maternal contribution passes in the ovum, the paternal in the\nspermatozoa; when these two germinal cells coalesce, the two psychic\nfragments that accompany them also combine to form a new (immaterial)\nsoul.\n\nAlthough the poetic fancies we have mentioned as to the origin of\nthe individual human soul are still widely accepted, their purely\nmythological character is now firmly established. The deeply\ninteresting and remarkable research which has been made in the course\nof the last twenty-five years into the more minute processes of the\nimpregnation and germination of the ovum has made it clear that these\nmysterious phenomena belong entirely to the province of cellular\nphysiology (cf. p. 48). Both the female element, the ovum, and the male\nfertilizing body, the sperma or spermatozoa, are _simple cells_. These\nliving cells possess a certain sum of physiological properties to which\nwe give the title of the \"cell-soul,\" just as we do in the permanently\nunicellular protist (see p. 48). Both germinal cells have the faculty\nof movement and sensation. The young ovum, or egg-cell, moves after\nthe manner of an amoeba; the minute spermatozoa, of which there are\nmillions in every drop of the seminal fluid, are ciliated cells, and\nswim about as freely in the sperm, by means of their lashes or _cilia_,\nas the ordinary ciliated infusoria (the flagellata).\n\nWhen the two cells meet as a result of copulation, or when they are\nbrought into contact through artificial fertilization (in the fishes,\nfor instance), they attract each other and become firmly attached. The\nmain cause of this cellular attraction is a chemical sensitive action\nof the protoplasm, allied to smell or taste, which we call \"erotic\nchemicotropism\"; it may also be correctly (both in the chemical and\nthe romantic sense) termed \"cellular affinity\" or \"sexual cell-love.\"\nA number of the ciliated cells in the sperm swim rapidly towards the\nstationary egg-cell and seek to penetrate into it. As Hertwig showed in\n1875, as a rule only one of the suitors is fortunate enough to reach\nthe desired goal. As soon as this favored spermatozoon has pierced\ninto the body of the ovum with its head (the nucleus of the cell), a\nthin mucous layer is detached from the ovum which prevents the further\nentrance of spermatozoa. The formation of this protective membrane\nwas only prevented when Hertwig kept the ovum stiff with cold by\nlowering the temperature, or benumbed it with narcotics (chloroform,\nmorphia, nicotine, etc.); then there was \"super-impregnation\" or\n\"poly-spermy\"--a number of sperm-threads pierced into the body of\nthe unconscious ovum. This remarkable fact proved that there is a\nlow degree of \"cellular instinct\" (or, at least, of specific, lively\nsensation) in the sexual cells just as effectively as do the important\nphenomena that immediately follow in their interior. Both nuclei--that\nof the ovum and of the spermatozoon--attract each other, approach, and,\non contact, completely fuse together. Thus from the impregnated ovum\narises the important new cell which we call the \"stem-cell\" (_cytula_),\nfrom the repeated segmentation of which the whole polycellular organism\nis evolved.\n\nThe psychological information which is afforded by these remarkable\nfacts of impregnation, which have only been properly observed\nduring the last twenty-five years, is supremely important; its vast\nsignificance has hitherto been very far from appreciated. We shall\ncondense the main conclusions of research in the following five theses:\n\nI. Each human individual, like every other higher animal, is a single\nsimple cell at the commencement of his existence.\n\nII. This \"stem-cell\" (cytula) is formed in the same manner in all\ncases--that is, by the blending or copulation of two separate cells of\ndiverse origin, the female ovum and the male spermatozoon.\n\nIII. Each of these sexual cells has its own \"cell-soul\"--that is, each\nis distinguished by a peculiar form of sensation and movement.\n\nIV. At the moment of conception or impregnation, not only the\nprotoplasm and the nuclei of the two sexual cells coalesce, but also\ntheir \"cell-souls\"; in other words, the potential energies which are\nlatent in both, and inseparable from the matter of the protoplasm,\nunite for the formation of a new potential energy, the \"germ-soul\" of\nthe newly constructed stem-cell.\n\nV. Consequently each personality owes his bodily and spiritual\nqualities to both parents; by heredity the nucleus of the ovum\ncontributes a portion of the maternal features, while the nucleus of\nthe spermatozoon brings a part of the father's characteristics.\n\nBy these empirical facts of conception, moreover, the further fact of\nextreme importance is established, that every man, like every other\nanimal, _has a beginning of existence_; the complete copulation of\nthe two sexual cell-nuclei marks the precise moment when not only the\nbody, but also the \"soul,\" of the new stem-cell makes its appearance.\nThis fact suffices of itself to destroy the myth of the immortality\nof the soul, to which we shall return later on. It suffices, too, for\nthe destruction of the still prevalent superstition that man owes\nhis personal existence to the favor of God. Its origin is rather to\nbe attributed solely to the \"eros\" of his parents, to that powerful\nimpulse that is common to all polycellular animals and plants,\nand leads to their nuptial union. But the essential point in this\nphysiological process is not the \"embrace,\" as was formerly supposed,\nor the amorousness connected therewith; it is simply the introduction\nof the spermatozoa into the vagina. This is the sole means, in the\nland-dwelling animals, by which the fertilizing element can reach the\nreleased ova (which usually takes place in the uterus in man). In the\ncase of the lower aquatic animals (fishes, mussels, medus\u00e6, etc.) the\nmature sexual elements on both sides are simply discharged into the\nwater, and their union is let to chance; they have no real copulation,\nand so they show none of those higher psychic \"erotic\" functions which\nplay so conspicuous a part in the life of the higher animals. Hence\nit is, also, that all the lower, non-copulating animals are wanting\nin those interesting organs which Darwin has called \"secondary sexual\ncharacters,\" and which are the outcome of sexual selection: such are\nthe beard of man, the antlers of the stag, the beautiful plumage of\nthe bird of paradise and of so many other birds, together with other\ndistinctions of the male which are absent in the female.\n\nAmong the above theses as to the physiology of conception the\ninheritance of the psychic qualities of the two parents is of\nparticular importance for psychological purposes. It is well known that\nevery child inherits from both his parents peculiarities of character,\ntemperament, talent, acuteness of sense, and strength of will. It\nis equally well known that even psychic qualities are often (if not\nalways) transmitted from grandparents by heredity--often, in fact,\na man resembles his grandparents more than his parents in certain\nrespects; and that is true both of bodily and mental features. All\nthe chief laws of heredity which I first formulated in my _General\nMorphology_, and popularized in my _Natural History of Creation_, are\njust as valid and universal in their application to psychic phenomena\nas to bodily structure--in fact, they are frequently more striking and\nconspicuous in the former than in the latter.\n\nHowever, the great province of heredity, to the inestimable importance\nof which Darwin first opened our eyes in 1859, is thickly beset with\nobscure problems and physiological difficulties. We dare not claim,\neven after forty years of research, that all its aspects are clear\nto us. Yet we have done so much that we can confidently speak of\nheredity as a _physiological function_ of the organism, which is\ndirectly connected with the faculty of generation; and we must reduce\nit, like all other vital phenomena, to exclusively physical and\nchemical processes, to the _mechanics of the protoplasm_. We now know\naccurately enough the process of impregnation itself; we know that in\nit the nucleus of the spermatozoon contributes the qualities of the\nmale parent, and the nucleus of the ovum gives the qualities of the\nmother, to the newly born stem-cell. The blending of the two nuclei is\nthe \"physiological moment\" of heredity; by it the personal features of\nboth body and soul are transmitted to the new individual. These facts\nof ontogeny are beyond the explanation of the dualistic and mystic\npsychology which still prevails in the schools; whereas they find a\nperfectly simple interpretation in our monistic philosophy.\n\nThe physiological fact which is most material for a correct appreciation\nof individual psychogeny is the _continuity_ of the _psyche_ through\nthe rise and fall of generations. A new individual comes into\nexistence at the moment of conception; yet it is not an independent\nentity, either in respect of its mental or its bodily features, but\nmerely the product of the blending of the two parental factors, the\nmaternal egg-cell and paternal sperm-cell. The cell-souls of these\ntwo sexual cells combine in the act of conception for the formation\nof a new cell-soul, just as truly as the two cell-nuclei, which are\nthe material vehicles of this psychic potential energy, unite to form\na new nucleus. As we now see that the individuals of one and the same\nspecies--even sisters born of the same parents--always show certain\ndifferences, however slight, we must assume that these variations\nwere already present in the chemical plasmatic constitution of the\ngenerative cells themselves.[17]\n\nThese facts alone would suffice to explain the infinite variety of\nindividual features, of soul and of bodily form, that we find in the\norganic world. As an extreme, but one-sided, consequence of them, there\nis the theory of Weismann, which considers the _amphimixis_, or the\nblending of the germ-plasm in sexual generation, to be the universal\nand the sole cause of individual variability. This exclusive theory,\nwhich is connected with his theory of the continuity of the germ-plasm,\nis, in my opinion, an exaggeration. I am convinced, on the contrary,\nthat the great laws of _progressive heredity_ and of the correlative\n_functional adaptation_ apply to the soul as well as to the body. The\nnew characteristics which the individual has acquired during life may\nreact to some extent on the molecular texture of the germ-plasm in\nthe egg-cell and sperm-cell, and may thus be transferred to the next\ngeneration by heredity in certain conditions (naturally, only in the\nform of latent energy).\n\nAlthough in the soul-blending at the moment of conception only\nthe latent forces of the two parent souls are transmitted by the\ncoalescence of the erotic cell-nuclei, still it is possible that the\nhereditary psychic influence of earlier, and sometimes very much\nolder, generations may be communicated at the same time. For the laws\nof _latent heredity_ or atavism apply to the soul just as validly as\nto the anatomical organization. We find these remarkable phenomena of\nreversion in a very simple and instructive form in the alternation of\ngenerations of the polyps and medus\u00e6. Here we see two very different\ngenerations alternate so regularly that the first resembles the third,\nfifth, and so on; while the second (very different from the preceding)\nis like the fourth, sixth, etc. (_Natural History of Creation_). We do\nnot find such alternation of generations in man and the higher animals\nand plants, in which, owing to continuous heredity, each generation\nresembles the next; nevertheless, even in these cases we often meet\nwith phenomena of reversion, which must be reduced to the same law of\nlatent heredity.\n\nEminent men often take more after their grandparents than their parents\neven in the finer shades of psychic activity--in the possession of\ncertain artistic talents or inclinations, in force of character, and\nin warmth of temperament; not infrequently there is a striking feature\nwhich neither parents nor grandparents possessed, but which may be\ntraced a long way back to an older branch of the family. Even in\nthese remarkable cases of atavism the same laws of heredity apply to\nthe _psyche_ and to the physiognomy, to the personal quality of the\nsense-organs, muscles, skeleton, and other parts of the body. We can\ntrace them most clearly in the reigning dynasties and in old families\nof the nobility, whose conspicuous share in the life of the State has\ngiven occasion to a more careful historical picture of the individuals\nin the chain of generations--for instance, in the Hohenzollerns, the\nprinces of Orange, the Bourbons, etc., and in the Roman C\u00e6sars.\n\nThe causal-nexus of _biontic_ (individual) and _phyletic_ (historical)\nevolution, which I gave in my _General Morphology_ as the supreme law\nat the root of all biogenetic research, has a universal application to\npsychology no less than to morphology. I have fully treated the special\nimportance which it has with regard to man, in both respects, in the\nfirst chapter of my _Anthropogeny_. In man, as in all other organisms,\n\"the embryonic development is an epitome of the historical development\nof the species. This condensed and abbreviated recapitulation is the\nmore complete in proportion as the original _epitomized development_\n(_palingenesis_) is preserved by a constant heredity; on the other\nhand, it falls off from completeness in proportion as the later\n_disturbing development_ (_cenogenesis_) is accentuated by varying\nadaptation.\"\n\nWhile we apply this law to the evolution of the soul, we must lay\nspecial stress on the injunction to keep _both_ sides of it critically\nbefore us. For, in the case of man, just as in all the higher animals\nand plants, such appreciable perturbations of type (or _cenogeneses_)\nhave taken place during the millions of years of development that\nthe original simple idea of _palingenesis_, or \"epitome of history,\"\nhas been greatly disturbed and altered. While, on the one side, the\n_palingenetic_ recapitulation is preserved by the laws of like-time\nand like-place heredity, it is subject to an essential _cenogenetic_\nchange, on the other hand, by the laws of abbreviated and simplified\nheredity. That is clearly seen in the embryonic evolution of the\npsychic organs, the nervous system, the muscles, and the sense-organs.\nBut it applies in just the same manner to the psychic functions, which\nare absolutely dependent on the normal construction of these organs.\nTheir evolution is subject to great cenogenetic modification in man\nand all other viviparous animals, precisely because the complete\ndevelopment of the embryo occupies a longer time within the body of\nthe mother. But we have to distinguish two periods of individual\npsychogeny: (1) the embryonic, and (2) the post-embryonic development\nof the soul.\n\nI. _Embryonic Psychogeny._--The human foetus, or embryo, normally\ntakes nine months (or two hundred and seventy days) to develop in\nthe uterus. During this time it is entirely cut off from the outer\nworld, and protected, not only by the thick muscular wall of the womb,\nbut also by the special foetal membranes (_embryolemmata_) which\nare common to all the three higher classes of vertebrates--reptiles,\nbirds, and mammals. In all the classes of amniotes these membranes\n(the _amnion_ and the _serolemma_) develop in just the same fashion.\nThey represent the protective arrangements which were acquired by\nthe earliest reptiles (_proreptilia_), the common parents of all the\namniotes, in the Permian period (towards the end of the pal\u00e6ozoic\nage), when these higher vertebrates accustomed themselves to live on\nland and breathe the atmosphere. Their ancestors, the amphibia of the\nCarboniferous period, still lived and breathed in the water, like their\nearlier predecessors, the fishes.\n\nIn the case of these older and lower vertebrates that lived in the\nwater, the embryonic development had the palingenetic character in\na still higher degree, as is the case in most of the fishes and\namphibia of the present day. The familiar tadpole and the larva of\nthe salamander or the frog still preserve the structure of their\nfish-ancestors in the first part of their life in the water; they\nresemble them, likewise, in their habits of life, in breathing by\ngills, in the action of their sense-organs, and in other psychic\norgans. Then, when the interesting metamorphosis of the swimming\ntadpole takes place, and when it adapts itself to a land-life, the\nfish-like body changes into that of a four-footed, crawling amphibium;\ninstead of the gill-breathing in the water comes an exclusive\nbreathing of the atmosphere by means of lungs, and, with the changed\nhabits of life, even the psychic apparatus, the nervous system, and\nthe sense-organs reach a higher degree of construction. If we could\ncompletely follow the psychogeny of the tadpole from beginning to end,\nwe should be able to apply the biogenetic law in many ways to its\npsychic evolution. For it develops in direct communication with the\nchanging conditions of the outer world, and so must quickly adapt its\nsensation and movement to these. The swimming tadpole has not only the\nstructure but the habits of life of a fish, and only acquires those of\na frog in its metamorphosis.\n\nIt is different with man and all the other amniotes; their embryo is\nentirely withdrawn from the direct influence of the outer world, and\ncut off from any reciprocal action therewith, by enclosure in its\nprotective membranes. Besides, the special care of the young on the\npart of the amniotes gives their embryo much more favorable conditions\nfor the cenogenetic abbreviation of the palingenetic evolution. There\nis, in the first place, the excellent arrangement for the nourishment\nof the embryo; in the reptiles, birds, and monotremes (the oviparous\nmammals) it is effected by the great yellow nutritive yelk, which is\nassociated with the egg; in the rest of the mammals (the marsupials and\nplacentals) it is effected by the mother's blood, which is conducted to\nthe foetus by the blood-vessels of the yelk-sac and the allantois.\nIn the case of the most highly developed placentals this elaborate\nnutritive arrangement has reached the highest degree of perfection by\nthe construction of a placenta; hence in these classes the embryo is\nfully developed before birth. But its soul remains during all this time\nin a state of embryonic slumber, a state of repose which Preyer has\njustly compared to the hibernation of animals. We have a similar long\nsleep in the chrysalis stage of those insects which undergo a complete\nmetamorphosis--butterflies, bees, flies, beetles, and so forth. This\nsleep of the pupa, during which the most important formations of\norgans and tissues take place, is the more interesting from the fact\nthat the preceding condition of the free larva (caterpillar, grub, or\nmaggot) included a highly developed psychic activity, and that this is,\nsignificantly, lower than the stage which is seen afterwards (when the\nchrysalis sleep is over) in the perfect, winged, sexually mature insect.\n\nMan's psychic activity, like that of most of the higher animals, runs\nthrough a long series of stages of development during the individual\nlife. We may single out the five following as the most important of\nthem:\n\nI. The soul of the new-born infant up to the birth of self-consciousness\nand the learning of speech.\n\nII. The soul of the boy or girl up to puberty (_i.e._, until the\nawakening of the sexual instinct).\n\nIII. The soul of the youth or maiden up to the time of sexual\nintercourse (the \"idealist\" period).\n\nIV. The soul of the grown man and the mature woman (the period of\nfull maturity and of the founding of families, lasting until about\nthe sixtieth year for the man and the fiftieth for the woman--until\n_involution_ sets in).\n\nV. The soul of the old man or woman (the period of degeneration).\n\nMan's psychic life runs the same evolution--upward progress, full\nmaturity, and downward degeneration--as every other vital activity in\nhis organization.\n\n\n\n\nCHAPTER IX\n\nTHE PHYLOGENY OF THE SOUL\n\n    Gradual Historical Evolution of the Human Soul from the Animal\n    Soul--Methods of Phylogenetic Psychology--Four Chief Stages in\n    the Phylogeny of the Soul: I. The Cell-Soul (Cytopsyche) of the\n    Protist (Infusoria, Ova, etc.): Cellular Psychology; II. The Soul\n    of a Colony of Cells, or the Cenobitic Soul (Coenopsyche):\n    Psychology of the Morula and Blastula; III. The Soul of the Tissue\n    (Histopsyche): Its Twofold Nature: The Soul of the Plant: The Soul\n    of the Lower, Nerveless Animal: Double Soul of the Siphonophora\n    (Personal and Kormal Soul); IV. The Nerve-Soul (Neuropsyche)\n    of the Higher Animal--Three Sections of its Psychic Apparatus:\n    Sense-Organs, Muscles, and Nerves--Typical Formation of the\n    Nerve-Centre in the Various Groups of Animals--Psychic Organ of the\n    Vertebrate: the Brain and the Spinal Cord--Phylogeny of the Mammal\n    Soul\n\n\nThe theory of descent, combined with anthropological research, has\nconvinced us of the descent of our human organism from a long series\nof animal ancestors by a slow and gradual transformation occupying\nmany millions of years. Since, then, we cannot dissever man's psychic\nlife from the rest of his vital functions--we are rather forced to a\nconviction of the natural evolution of our whole body and mind--it\nbecomes one of the main tasks of the modern monistic psychology to\ntrace the stages of the historical development of the soul of man from\nthe soul of the brute. Our \"phylogeny of the soul\" seeks to attain this\nobject; it may also, as a branch of general psychology, be called\n_phylogenetic_ psychology, or, in contradistinction to _biontic_\n(individual), _phyletic psychogeny_. And, although this new science has\nscarcely been taken up in earnest yet, and most of the \"professional\"\npsychologists deny its very right to existence, we must claim for it\nthe utmost importance and the deepest interest. For, in our opinion, it\nis its special province to solve for us the great enigma of the nature\nand origin of the human soul.\n\nThe methods and paths which will lead us to the remote goal of a\ncomplete phylogenetic psychology--a goal that is still buried in the\nmists of the future, and almost imperceptible to many--do not differ\nfrom those of other branches of evolutionary research. Comparative\nanatomy, physiology, and ontogeny are of the first importance. Much\nsupport is given also by pal\u00e6ontology, for the order in which the\nfossil remains of the various classes of vertebrates succeed each other\nin the course of organic evolution reveals to us, to some extent,\nthe gradual growth of their psychic power as well as their phyletic\nconnection. We must admit that we are here, as we are in every branch\nof phylogenetic research, driven to the construction of a number of\nhypotheses in order to fill up the considerable lacun\u00e6 of empirical\nphylogeny. Yet these hypotheses cast so clear and significant a light\non the chief stages of historical development that we are afforded a\nmost gratifying insight into their entire course.\n\nThe comparative psychology of man and the higher animals enables us\nto learn from the highest group of the placentals, the primates, the\nlong strides by which the human soul has advanced beyond the _psyche_\nof the anthropoid ape. The phylogeny of the mammals and of the lower\nvertebrates acquaints us with the long series of the earlier ancestors\nof the primates which have arisen within this stem since the Silurian\nage. All these vertebrates agree in the structure and development of\ntheir characteristic psychic organ--the spinal cord. We learn from\nthe comparative anatomy of the vermalia that this spinal cord has\nbeen evolved from a dorsal _acroganglion_, or vertical brain, of an\ninvertebrate ancestor. We learn, further, from comparative ontogeny\nthat this simple psychic organ has been evolved from the stratum of\ncells in the outer germinal layer, the ectoderm, of the platodes. In\nthese earliest flat-worms, which have no specialized nervous system,\nthe outer skin-covering serves as a general sensitive and psychic\norgan. Finally, comparative embryology teaches us that these simple\nmetazoa have arisen by gastrulation from blast\u00e6ades, from hollow\nspheres, the wall of which is merely one simple layer of cells, the\n_blastoderm_; and the same science, with the aid of the biogenetic law,\nexplains how these protozoic coenobia originally sprang from the\nsimplest unicellular organisms.\n\nOn a critical study of these different embryonic formations, the\nevolution of which from each other we can directly observe under the\nmicroscope, we arrive, by means of the great law of biogeny, at a\nseries of most important conclusions as to the chief stages in the\ndevelopment of our psychic life. We may distinguish eight of these to\nbegin with:\n\nI. Unicellular protozoa with a simple cell-soul: the infusoria.\n\nII. Multicellular protozoa with a communal soul: the catallacta.\n\nIII. The earliest metazoa with an epithelial soul: the platodes.\n\nIV. Invertebrate ancestors with a simple vertical brain: the vermalia.\n\nV. Vertebrates without skull or brain, with a simple spinal cord: the\nacrania.\n\nVI. Animals with skull and brain (of five vesicles): the craniota.\n\nVII. Mammals with predominant development of the cortex of the brain:\nthe placentals.\n\nVIII. The higher anthropoid apes and man, with organs of thought (in\nthe cerebrum): the anthropomorpha.\n\nAmong these eight stages in the development of the human soul we may\nfurther distinguish more or less clearly a number of subordinate\nstages. Naturally, however, in reconstructing them we have to fall\nback on the same defective evidence of empirical psychology which the\ncomparative anatomy and physiology of the actual fauna affords us. As\nthe craniote animals of the sixth stage--and these are true fishes--are\nalready found fossilized in the Silurian system, we are forced to\nassume that the five preceding series of ancestors (which were\nincapable of fossilization) were evolved in an earlier, pre-Silurian\nage.\n\nI. _The cell-soul_ (_or cytopsyche_): first stage of phyletic\npsychogenesis.--The earliest ancestors of man and all other animals\nwere unicellular protozoa. This fundamental hypothesis of rational\nphylogeny is based, in virtue of the phylogenetic law, on the\nfamiliar embryological fact that every man, like every other metazoon\n(_i.e._, every multicellular organism with tissues), begins his\npersonal existence as a simple cell, the stem-cell (_cytula_), or the\nimpregnated egg-cell (see p. 63). As this cell has a \"soul\" from the\ncommencement, so had also the corresponding unicellular _ancestral\nforms_, which were represented in the oldest series of man's ancestors\nby a number of different protozoa.\n\nWe learn the character of the psychic activity of these unicellular\norganisms from the comparative physiology of the protists of to-day.\nClose observation and careful experiment have opened out to us in this\nrespect, in the second half of the nineteenth century, a new world of\nthe most interesting phenomena. The best description of them was given\nby Max Verworn in his thoughtful work, based on original research,\n_Psycho-physiological Studies of the Protists_. The work includes also\nthe few earlier observations of the \"psychic life of the protist.\"\nVerworn came to the firm conclusion that the psychic processes are\nunconscious in all the protists, that the phenomena of sensation\nand movement coincide with the molecular vital processes in their\nprotoplasm, and that their ultimate causes are to be sought in the\nproperties of the protoplasmic molecules (the _plastidules_). \"Hence\nthe psychic phenomena of the protists form a bridge that connects the\nchemical processes of the inorganic world with the psychic life of\nthe highest animals; they represent the germ of the highest psychic\nphenomena of the metazoa and of man.\"\n\nThe careful observations and many experiments of Verworn, together\nwith those of Wilhelm Engelmann, Wilhelm Preyer, Richard Hertwig, and\nother more recent students of the protists, afford conclusive evidence\nfor my \"theory of the cell-soul\" (1866). On the strength of several\nyears of study of different kinds of protists, especially rhizopods and\ninfusoria, I published a theory thirty-three years ago to the effect\nthat every living cell has psychic properties, and that the psychic\nlife of the multicellular animals and plants is merely the sum total of\nthe psychic functions of the cells which build up their structure. In\nthe lower groups (in alg\u00e6 and sponges, for instance) _all_ the cells of\nthe body have an equal share in it (or with very slight differences);\nin the higher groups, in harmony with the law of the \"division of\nlabor,\" only a select portion of them are involved--the \"soul-cells.\"\nThe important consequences of this \"cellular psychology\" were partly\ntreated in my work on _The Perigenesis of the Plastidule_ (1876),\nand partly in my speech at Munich, in 1877, on \"Modern Evolution in\nRelation to the Whole of Science.\" A more popular presentation of\nthem is to be found in my two Vienna papers (1878) on \"The Origin and\nDevelopment of the Sense-Organs\" and on \"Cell-Souls and Soul-Cells.\"\n\nMoreover, the cell-soul, even within the limits of the protist world,\npresents a long series of stages of development, from the most simple\nand primitive to a comparatively elaborate activity. In the earliest\nand simplest protists the faculty of sensation and movement is equally\ndistributed over the entire protoplasm of the homogeneous morsel; in\nthe higher forms certain \"cell-instruments,\" or _organella_, appear,\nas their physiological organs. Motor cell-parts of that character are\nfound in the pseudopodia of the rhizopods, and the vibrating hairs,\nlashes, or cilia of the infusoria. The cell-nucleus, which is wanting\nin the earlier and lower protists, is considered to be an internal\ncentral organ of the cell-life. It is especially noteworthy, from a\nphysiologico-chemical point of view, that the very earliest protists\nwere plasmodomous, with plant-like nutrition--hence _protophyta_, or\nprimitive plants; from these came as a secondary stage, by metasitism,\nthe first plasmophagi, with animal nutrition--the _protozoa_, or\nprimitive animals.[18] This metasitism, or circulation of nutritive\nmatter, implies an important psychological advance; with it began the\ndevelopment of those characteristic properties of the animal soul which\nare wanting in the plant.\n\nWe find the highest development of the animal cell-soul in the class\nof ciliata, or ciliated infusoria. When we compare their activity\nwith the corresponding psychic life of the higher, multicellular\nanimals, we find scarcely any psychological difference; the sensitive\nand motor _organella_ of these protozoa seem to accomplish the same\nas the sense-organs, nerves, and muscles of the metazoa. Indeed, we\nhave found in the great cell-nucleus (_meganucleus_) of the infusoria\na central organ of psychic activity, which plays much the same part\nin their unicellular organism as the brain does in the psychic life\nof higher animals. However, it is very difficult to determine how far\nthis comparison is justified; the views of experts diverge considerably\nover the matter. Some take all spontaneous bodily movement in them to\nbe automatic, or impulsive, and all stimulated movement to be reflex;\nothers are convinced that such movements are partly voluntary and\nintentional. The latter would attribute to the infusoria a certain\ndegree of consciousness, and even self-consciousness; but this is\nrejected by the others. However that very difficult question may be\nsettled, it does not alter the fact that these unicellular protozoa\ngive proof of the possession of a highly developed \"cell-soul,\" which\nis of great interest for a correct decision as to the _psyche_ of our\nearliest unicellular ancestors.\n\nII. _The communal or cenobitic soul_ (_coenopsyche_): second stage of\nphyletic psychogenesis.--Individual development begins, in man and in\nall other multicellular animals, with the repeated segmentation of one\nsimple cell. This _stem-cell_, the impregnated ovum, divides first into\ntwo daughter cells, by a process of ordinary indirect segmentation;\nas the process is repeated there arise (by equal division of the egg)\nsuccessively four, eight, sixteen, thirty-two, sixty-four such new\ncells, or \"blastomeres.\" Usually (that is, in the case of the majority\nof animals) an irregular enlargement sooner or later takes the place\nof this original regular division of cells. But the result is the same\nin all cases--the formation of a (generally spherical) cluster of\nheterogeneous (originally homogeneous) cells. This stage is called the\n_morula_ (\"mulberry,\" which it somewhat resembles in shape). Then, as\na rule, a fluid gathers in the interior of this aggregate of cells; it\nchanges into a spherical vesicle; all the cells go to its surface, and\narrange themselves in one simple layer--the _blastoderm_. The hollow\nsphere which is thus formed is the important stage of the \"germinal\nvesicle,\" the _blastula_, or blastosphere.\n\nThe psychological phenomena which we directly observe in the formation\nof the blastula are partly sensations, partly movements, of this\ncommunity of cells. The movements may be divided into two groups: (1)\nthe inner movements, which are always repeated in substantially the\nsame manner in the process of ordinary (indirect) segmentation of\ncells (formation of the axis of the nucleus, mitosis, karyokinesis,\netc.); (2) the outer movements, which are seen in the regular change of\nposition of the social cells and their grouping for the construction\nof the blastoderm. We assume that these movements are hereditary and\nunconscious, because they are always determined in the same fashion by\nheredity from the earlier protist ancestors. The sensations also fall\ninto two groups: (1) the sensations of the individual cells, which\nreveal themselves in the assertion of their individual independence and\ntheir relation to neighboring cells (with which they are in contact,\nand partly in direct combination, by means of protoplasmic fibres); (2)\nthe common sensation of the entire community of cells, which is seen in\nthe individual formation of the _blastula_ as a hollow vesicle.\n\nThe causal interpretation of the formation of the blastula is given us\nby the biogenetic law, which explains the phenomena we directly observe\nto be the outcome of heredity, and relates them to corresponding\nhistorical processes which took place long ago in the origin of the\nearliest protist-coenobia, the blast\u00e6ads. But we get a physiological\nand psychological insight into these important phenomena of the\nearliest cell-communities by observation and experiment on their modern\nrepresentatives. Such permanent cell-communities or colonies are still\nfound in great numbers both among the plasmodomous primitive plants\n(for instance, the paulotomacea, diatomacea, volvocin\u00e6, etc.) and the\nplasmophagous primitive animals (the infusoria and rhizopods). In\nall these coenobia we can easily distinguish two different grades\nof psychic activity: (1) the cell-soul of the individual cells (the\n\"elementary organisms\") and (2) the communal soul of the entire colony.\n\nIII. _The tissue-soul_ (_histopsyche_): third stage of phyletic\npsychogenesis.--In all multicellular, tissue-forming plants\n(_metaphyta_) and in the lowest, nerveless classes of tissue-forming\nanimals (_metazoa_) we have to distinguish two different forms of\npsychic activity--namely: (1) the _psyche_ of the individual cells\nwhich compose the tissue, and (2) the _psyche_ of the tissue itself, or\nof the \"cell-state\" which is made up of the tissues. This \"tissue-soul\"\nis the higher psychological function which gives physiological\nindividuality to the compound multicellular organism as a true\n\"cell-commonwealth.\" It controls all the separate \"cell-souls\" of the\nsocial cells--the mutually dependent \"citizens\" which constitute the\ncommunity. This fundamental twofold character of the _psyche_ in the\nmetaphyta and the lower, nerveless metazoa is very important. It may\nbe verified by unprejudiced observation and suitable experiment. In\nthe first place, each single cell has its own sensation and movement,\nand, in addition, each tissue and each organ, composed of a number\nof homogeneous cells, has its special irritability and psychic unity\n(_e.g._, the pollen and stamens).\n\nA. _The plant-soul_ (_phytopsyche_) is, in our view, the summary of\nthe entire psychic activity of the tissue-forming, multicellular plant\n(the _metaphyton_, as distinct from the unicellular _protophyton_);\nit is, however, the subject of the most diverse opinions even at the\npresent day. It was once customary to draw an essential distinction\nbetween the plant and the animal, on the ground that the latter had\na \"soul\" and the plant had none. However, an unprejudiced comparison\nof the irritability and movements of various higher plants and lower\nanimals convinced many observers, even at the beginning of the century,\nthat there must be a \"soul\" on both sides. At a later date Fechner,\nLeitgeb, and others strongly contended for the plant-soul. But a\nprofounder knowledge of the subject was obtained when the similarity\nof the elementary structure of the plant and of the animal was proved\nby the cellular theory, and especially when the similarity of conduct\nof the active, living protoplasm in both was shown in the plasma\ntheory of Max Schultze (1859). Modern comparative physiology has\nshown that the physiological attitude towards various stimuli (light,\nheat, electricity, gravity, friction, chemical action, etc.) of the\n\"sensitive\" portions of many plants and animals is exactly the same,\nand that the reflex movements which the stimuli elicit take place in\nprecisely the same manner on both sides. Hence, if it was necessary to\nattribute this activity to a \"soul\" in the lower, nerveless metazoa\n(sponges, polyps, etc.), it was also necessary in the case of many\n(if not all) metaphyta, at least in the very sensitive _mimosa_, the\n\"fly-traps\" (_dionaea_ and _drosera_), and the numerous kinds of\nclimbing plants.\n\nIt is true that modern vegetal physiology has given a purely physical\nexplanation of many of these stimulated movements, or tropisms, by\nspecial features of growth, variations of pressure, etc. Yet these\nmechanical causes are neither more nor less _psychophysical_ than\nthe similar \"reflex movements\" of the sponges, polyps, and other\nnerveless metazoa, even though their mechanism is entirely different.\nThe character of the tissue-soul reveals itself in the same way in\nboth cases--the cells of the tissue (the regular, orderly structure\nof cells) transmit the stimuli they have received in one part, and\nthus provoke movements of other parts, or of the whole organ. This\ntransmission of stimuli has as much title to be called \"psychic\nactivity\" as its more complete form in the higher animals with nerves;\nthe anatomic explanation of it is that the social cells of the tissue,\nor cell-community, are not isolated from each other (as was formerly\nsupposed), but are connected throughout by fine threads or bridges of\nprotoplasm. When the sensitive mimosa closes its graceful leaves and\ndroops its stalk at contact, or on being shaken; when the irritable\nfly-trap (the dion\u00e6a) swiftly clasps its leaves together at a touch,\nand captures a fly; the sensation seems to be keener, the transmission\nof the stimulus more rapid, and the movement more energetic than in the\nreflex action of the stimulated bath-sponge and many other sponges.\n\nB. _The soul of the nerveless metazoa._--Of very special interest for\ncomparative psychology in general, and for the phylogeny of the animal\nsoul in particular, is the psychic activity of those lower metazoa\nwhich have tissues, and sometimes differentiated organs, but no nerves\nor specific organs of sense. To this category belong four different\ngroups of the earliest coelenterates: (_a_) the gastr\u00e6ads, (_b_) the\nplatodaria, (_c_) the sponges, and (_d_) the hydropolyps, the lowest\nform of cnidaria.\n\nThe _gastraeads_ (or animals with a primitive gut) form a small group\nof the lowest coelenterates, which is of great importance as the\ncommon ancestral group of all the metazoa. The body of these little\nswimming animals looks like a tiny (generally oval) vesicle, which has\na simple cavity with one opening--the primitive gut and the primitive\nmouth. The wall of the digestive cavity is formed of two simple\nlayers of cells, or epithelium, the inner of which--the gut-layer--is\nresponsible for the vegetal activity of nourishment, while the outer,\nor skin-layer, discharges the animal functions of movement and\nsensation. The homogeneous sensitive cells of the skin-layer bear long,\nslender hairs or lashes (_cilia_), by the vibration of which the\nswimming motion is effected. The few surviving forms of gastr\u00e6ads,\nthe gastr\u00e6maria (_trichoplacidae_) and cyemaria (_orthonectidae_),\nare extremely interesting, from the fact that they remain throughout\nlife at a stage of structure which is passed by all the other metazoa\n(from the sponge to man) at the commencement of their embryonic\ndevelopment. As I have shown in my _Theory of the Gastraea_ (1872),\na very characteristic embryonic form, the _gastrula_, is immediately\ndeveloped from the _blastula_ in all the tissue animals. The germinal\nmembrane (blastoderm), which represents the wall of the hollow vesicle,\nforms a depression at one side, and this soon sinks in so deep that the\ninner cavity of the vesicle disappears. The half of the membrane which\nbends in is thus laid on, and inside, the other half; the latter forms\nthe _skin-layer_, or outer germinal layer (ectoderm or epiblast), and\nthe former becomes the _gut-layer_, or inner germinal layer (endoderm\nor hypoblast). The new cavity of the cup-shaped body is the digestive\nstomach cavity (the _progaste_), and its opening is the primitive mouth\n(or _prostoma_).[19] The skin-layer, or ectoderm, is the primitive\npsychic organ in the metazoa; from it, in all the nerve animals, not\nonly the external skin and the organs of sense, but also the nervous\nsystem, are developed. In the gastr\u00e6ads, which have no nerves, all the\ncells which compose the simple epithelium of the ectoderm are equally\norgans of sensation and of movement; we have here the tissue-soul in\nits simplest form.\n\nThe platodaria, the earliest and simplest form of the platodes, seem to\nbe of the same primitive construction. Some of these cryptocoela--the\n_convoluta_, etc.--have no specific nervous system, while their\nnearest relatives, the turbellaria, have already differentiated one,\nand even developed a vertical brain.\n\nThe _sponges_ form a peculiar group in the animal world, which differs\nwidely in organization from all the other metazoa. The innumerable\nkinds of sponges grow, as a rule, at the bottom of the sea. The\nsimplest form of sponge, the _olynthus_, is in reality nothing more\nthan a _gastraea_, the body-wall of which is perforated like a sieve,\nwith fine pores, in order to permit the entrance of the nourishing\nstream of water. In the majority of sponges--even in the most familiar\none, the bath-sponge--the bulbous organism constructs a kind of stem or\ntree, which is made up of thousands of these gastr\u00e6ads, and permeated\nby a nutritive system of canals. Sensation and movement are only\ndeveloped in the faintest degree in the sponges; they have no nerves,\nmuscles, or organs of sense. It was therefore quite natural that such\nstationary, shapeless, insensitive animals should have been commonly\ntaken to be plants in earlier years. Their psychic life--for which no\nspecial organs have been differentiated--is far inferior to that of the\nmimosa and other sensitive plants.\n\n_The soul of the cnidaria_ is of the utmost importance in comparative\nand phylogenetic psychology; for in this numerous group of the\ncoelenterates the historical evolution of the _nerve-soul_ out of the\n_tissue-soul_ is repeated before our eyes. To this group belong the\ninnumerable classes of stationary polyps and corals, and of swimming\nmedus\u00e6 and siphonophora. As the common ancestor of all the cnidaria\nwe can safely assign a very simple polyp, which is substantially\nthe same in structure as the common, still surviving, fresh-water\npolyp--the hydra. Yet the hydr\u00e6, and the stationary, closely related\n_hydropolyps_, have no nerves or higher sense-organs, although they\nare extremely sensitive. On the other hand, the free-swimming medus\u00e6,\nwhich are developed from them--and are still connected with them\nby alternation of generations--have an independent nervous system\nand specific sense-organs. Here, also, we may directly observe the\nontogenetic evolution of the nerve-soul (_neuropsyche_) out of the\ntissue-soul (_histopsyche_), and thus learn its phylogenetic origin.\nThis is the more interesting as such phenomena are _polyphyletic_--that\nis, they have occurred several times--more than once, at least--quite\nindependently. As I have shown elsewhere, the hydromedus\u00e6 have arisen\nfrom the hydropolyps in a different manner from that of the evolution\nof the scyphomedus\u00e6 from the scyphopolyps; the gemmation is terminal in\nthe case of the latter, and lateral with the former. In addition, both\ngroups have characteristic hereditary differences in the more minute\nstructure of their psychic organs. The class of siphonophora is also\nvery interesting to the psychologist. In these pretty, free-swimming\norganisms, which come from the hydromedus\u00e6 we can observe a double\nsoul: the _personal soul_ of the numerous individualities which compose\nthem, and the common, harmoniously acting psyche of the entire colony.\n\nIV. _The nerve-soul_ (_neuropsyche_): fourth stage of phyletic\npsychogeny.--The psychic life of all the higher animals is conducted,\nas in man, by means of a more or less complicated \"psychic apparatus.\"\nThis apparatus is always composed of three chief sections: the _organs\nof sense_ are responsible for the various sensations; the _muscles_\neffect the movements; the _nerves_ form the connection between the\ntwo by means of a special central organ, the brain or ganglion. The\narrangement and action of this psychic mechanism have been frequently\ncompared with those of a telegraphic system: the nerves are the wires,\nthe brain the central, and the sense-organs subordinate stations. The\nmotor nerves conduct the commands of the will centrifugally from the\nnerve-centre to the muscles, by the contraction of which they produce\nthe movements: the sensitive nerves transmit the various sensations\ncentripetally--that is, from the peripheral sense-organs to the\nbrain, and thus render an account of the impressions they receive\nfrom the outer world. The ganglionic cells, or \"psychic cells,\" which\ncompose the central nervous organ, are the most perfect of all organic\nelements; they not only conduct the commerce between the muscles and\nthe organs of sense, but they also effect the highest performances of\nthe animal soul, the formation of ideas and thoughts, and especially\nconsciousness.\n\nThe great progress of anatomy, physiology, histology, and ontogeny has\nrecently added a wealth of interesting discoveries to our knowledge of\nthe mechanism of the soul. If speculative philosophy assimilated only\nthe most important of these significant results of empirical biology,\nit would have a very different character from that it unfortunately\npresents. As I have not space for an exhaustive treatment of them here,\nI will confine myself to a relation of the chief facts.\n\nEach of the higher animal species has a characteristic psychic organ;\nthe central nervous system of each has certain peculiarities of shape,\nposition, and composition. The medus\u00e6, among the radiating cnidaria,\nhave a ring of nervous matter at the border of the fringe, generally\nprovided with four or eight ganglia. The mouth of the five-rayed\ncnidarion is girt with a nerve-ring, from which proceed five branches.\nThe bi-symmetrical _platodes_ and the _vermalia_ have a vertical\nbrain, or acroganglion, composed of two dorsal ganglia, lying above\nthe mouth; from these \"upper ganglia\" two branch nerves proceed to the\nskin and the muscles. In some of the vermalia and in the mollusca a\npair of ventral \"lower ganglia\" are added, which are connected with\nthe former by a ring round the gullet. This ring is found also in the\n_articulata_; but in these it is continued on the belly side of the\nlong body as a ventral medulla, a double fibre like a rope-ladder,\nwhich expands into a double ganglion in each member. The vertebrates\nhave an entirely different formation of the psychic organ; they have\nalways a spinal medulla developed at the back of the body; and from an\nexpansion of its fore part there arises subsequently the characteristic\nvesicular brain.[20]\n\nAlthough the psychic organs of the higher species of animals differ\nvery materially in position, form, and composition, nevertheless\ncomparative anatomy is in a position to prove a common origin for most\nof them--namely, from the vertical brain of the platodes and vermalia;\nthey have all, moreover, had their origin in the outermost layer of the\nembryo, the _ectoderm_, or outer skin-layer. Hence we find the same\ntypical structure in all varieties of the central nervous organ--a\ncombination of ganglionic cells, or \"psychic cells\" (the real active\nelementary organs of the soul), and of nerve-fibres, which effect the\nconnection and transmission of the action.\n\nThe first fact we meet in the comparative psychology of the vertebrates,\nand which should be the empirical starting-point of all scientific\nhuman psychology, is the characteristic structure of the central\nnervous system. This central psychic organ has a particular position,\nshape, and texture in the vertebrate as it has in all the higher\nspecies. In every case we find a spinal medulla, a strong cylindrical\nnervous cord, which runs down the middle of the back, in the upper\npart of the vertebral column (or the cord which represents it). In\nevery case a number of nerves branch off from this medulla in regular\ndivision, one pair to each segment or vertebra. In every case this\nmedullary cord arises in the same way in the foetus; a fine groove\nappears in the middle axis of the skin at the back; then the parallel\nborders of this medullary groove are lifted up a little, bend over\ntowards each other, and form into a kind of tube.\n\nThe long dorsal cylindrical medullary tube which is thus formed is\nthoroughly characteristic of the vertebrates; it is always the same in\nthe early embryonic sketch of the organism, and it is always the chief\nfeature of the different kinds of psychic organ which evolve from it in\ntime. Only one single group of invertebrates has a similar structure:\nthe rare, marine _tunicata_, copelata, ascidia, and thalidi\u00e6. These\nanimals have other important peculiarities of structure (especially\nin the chorda and the gut) which show a striking divergence from\nthe other invertebrates and resemblance to the vertebrates. The\ninference we draw is that both these groups, the vertebrates and the\ntunicates, have arisen from a common ancestral group of the vermalia,\nthe _prochordonia_.[21] Still, there is a great difference between\nthe two classes in the fact that the body of the tunicate does not\narticulate, or form members, and has a very simple organization (most\nof them subsequently attach themselves to the bottom of the sea and\ndegenerate). The vertebrate, on the other hand, is characterized\nby an early development of internal members, and the formation of\npro-vertebr\u00e6 (_vertebratio_). This prepares the way for the much higher\ndevelopment of their organism, which finally attains perfection in man.\nThis is easily seen in the finer structure of his spinal cord, and in\nthe development of a number of segmental pairs of nerves, the spinal\nnerves, which proceed to the various parts of the body.\n\nThe long ancestral history of our \"vertebrate soul\" commences with the\nformation of the most rudimentary spinal cord in the earliest acrania;\nslowly and gradually, through a period of many millions of years, it\nconducts to that marvellous structure of the human brain which seems\nto entitle the highest primate form to quite an exceptional position\nin nature. Since a clear conception of this slow and steady progress\nof our phyletic psychogeny is indispensable for a true psychology, we\nmust divide that vast period into a number of stages or sections: in\neach of them the perfecting of the structure of the nervous centre has\nbeen accompanied by a corresponding evolution of its function, the\n_psyche_. I distinguish eight of these periods in the phylogeny of\nthe spinal cord, which are characterized by eight different groups of\nvertebrates: (1) the acrania; (2) the cyclostomata; (3) the fishes; (4)\nthe amphibia; (5) the implacental mammals (monotremes and marsupials);\n(6) the earlier placental mammals, especially the prosimi\u00e6; (7) the\nyounger primates, the simi\u00e6; and (8) the anthropoid apes and man.\n\nI. First stage--the _acrania_: their only modern representative is the\nlancelot or amphioxus; the psychic organ remains a simple medullary\ntube, and contains a regularly segmented spinal cord, without brain.\n\nII. Second stage--the _cyclostomata_: the oldest group of the craniota,\nnow only represented by the _petromyzontes_ and _myxinoides_:\nthe fore-termination of the cord expands into a vesicle, which\nthen subdivides into five successive parts--the great-brain,\nintermediate-brain, middle-brain, little-brain, and hind-brain: these\nfive cerebral vesicles form the common type from which the brain of all\ncraniota has evolved, from the lamprey to man.\n\nIII. Third stage--the _primitive fishes_ (_selachii_): similar to the\nmodern shark: in these oldest fishes, from which all the gnathostomata\ndescend, the more pronounced division of the five cerebral vesicles\nsets in.\n\nIV. Fourth stage--the _amphibia_. These earliest land animals, making\ntheir first appearance in the Carboniferous period, represent the\ncommencement of the characteristic structure of the _tetrapod_ and\na corresponding development of the fish-brain: it advances still\nfurther in their Permian successors, the _reptiles_, the earliest\nrepresentatives of which, the _tocosauria_, are the common ancestors of\nall the amniota (reptiles and birds on one side, mammals on the other).\n\nV.-VIII. Fifth to the eighth stages--the _mammals_. I have exhaustively\ntreated, and illustrated with a number of plates, in my _Anthropogeny_,\nthe evolution of our nervous system and the correlative question of the\ndevelopment of the soul. I have now, therefore, merely to refer the\nreader to that work. It only remains for me to add a few remarks on the\nlast and most interesting class of facts pertaining to this--to the\nevolution of the soul and its organs within the limits of the class\nmammalia. In doing so, I must remind the reader that the _monophyletic\norigin_ of this class--that is, the descent of all the mammals from\none common ancestral form (of the Triassic period)--is now fully\nestablished.\n\nThe most important consequence of the monophyletic origin of the\nmammals is the necessity of deriving the human soul from a long\nevolutionary series of other mammal souls. A deep anatomical and\nphysiological gulf separated the brain structure and the dependent\npsychic activity of the higher mammals from those of the lower:\nthis gulf, however, is completely bridged over by a long series of\nintermediate stages. The period of at least fourteen (more than a\nhundred, on other estimates) million years, which has elapsed since the\ncommencement of the Triassic period, is amply sufficient to allow even\nthe greatest psychological advance. The following is a summary of the\nresults of investigation in this quarter, which has recently been very\npenetrating:\n\nI. The brain of the mammal is differentiated from that of the other\nvertebrates by certain features, which are found in all branches of the\nclass; especially by a preponderant development of the first and fourth\nvesicles, the cerebrum and cerebellum, while the third vesicle, the\nmiddle brain, disappears altogether.\n\nII. The brain development of the lowest and earliest mammals (the\nmonotremes, marsupials, and prochoriates) is closely allied to\nthat of their pal\u00e6ozoic ancestors, the Carboniferous amphibia (the\n_stegocephala_) and the Permian reptiles (the _tocosauria_).\n\nIII. During the Tertiary period commences the typical development of\nthe cerebrum, which distinguishes the younger mammals so strikingly\nfrom the older.\n\nIV. The special development (quantitatively and qualitatively) of\nthe cerebrum which is so prominent a feature in man, and which is the\nroot of his pre-eminent psychic achievements, is only found, outside\nhumanity, in a small section of the most highly developed mammals of\nthe earlier Tertiary epoch, especially in the anthropoid apes.\n\nV. The differences of brain structure and psychic faculty which\nseparate man from the anthropoid ape are slighter than the corresponding\ninterval between the anthropoid apes and the lower primates (the\nearliest simi\u00e6 and prosimi\u00e6).\n\nVI. Consequently, the historical, gradual evolution of the human soul\nfrom a long chain of higher and lower mammal souls must, by application\nof the universally valid phyletic laws of the theory of descent, be\nregarded as a _fact_ which has been scientifically proved.\n\n\n\n\nCHAPTER X\n\nCONSCIOUSNESS\n\n    Consciousness as a Natural Phenomenon--Its Definition--Difficulties\n    of the Problem--Its Relation to the Life of the Soul--Our\n    Human Consciousness--Various Theories: I. Anthropistic\n    Theory (Descartes); II. Neurological Theory (Darwin);\n    III. Animal Theory (Schopenhauer); IV. Biological Theory\n    (Fechner); V. Cellular Theory (Fritz Schultze); VI. Atomistic\n    Theory--Monistic and Dualistic Theories--Transcendental\n    Character of Consciousness--The Ignorabimus Verdict of Du\n    Bois-Reymond--Physiology of Consciousness--Discovery of the\n    Organs of Thought by Flechsig--Pathology--Double and Intermittent\n    Consciousness--Ontogeny of Consciousness: Modifications at\n    Different Ages--Phylogeny of Consciousness--Formation of Concepts\n\n\nNo phenomenon of the life of the soul is so wonderful and so variously\ninterpreted as consciousness. The most contradictory views are current\nto-day, as they were two thousand years ago, not only with regard to\nthe nature of this psychic function and its relation to the body,\nbut even as to its diffusion in the organic world and its origin and\ndevelopment. It is more responsible than any other psychic faculty for\nthe erroneous idea of an \"immaterial soul\" and the belief in \"personal\nimmortality\"; many of the gravest errors that still dominate even\nour modern civilization may be traced to it. Hence it is that I have\nentitled consciousness \"the central mystery of psychology\"; it is\nthe strong citadel of all mystic and dualistic errors, before whose\nramparts the best-equipped efforts of reason threaten to miscarry. This\nfact would suffice of itself to induce us to make a special critical\nstudy of consciousness from our monistic point of view. We shall see\nthat consciousness is simply a natural phenomenon like any other\npsychic quality, and that it is subject to the law of substance like\nall other natural phenomena.\n\nEven as to the elementary idea of consciousness, its contents and\nextension, the views of the most distinguished philosophers and\nscientists are widely divergent. Perhaps the meaning of consciousness\nis best conceived as an _internal perception_, and compared with the\naction of _a mirror_. As its two chief departments we distinguish\nobjective and subjective consciousness--consciousness of the world,\nthe non-ego, and of the ego. By far the greater part of our conscious\nactivity, as Schopenhauer justly remarked, belongs to the consciousness\nof the outer world, or the non-ego: this _world-consciousness_\nembraces all possible phenomena of the outer world which are in any\nsense accessible to our minds. Much more contracted is the sphere\nof _self-consciousness_, the internal mirror of all our own psychic\nactivity, all our presentations, sensations, and volitions.\n\nMany distinguished thinkers, especially on the physiological side\n(Wundt and Ziehen, for instance) take the ideas of consciousness and\npsychic function to be identical--\"all psychic action is conscious\";\nthe province of psychic life, they say, is coextensive with that\nof consciousness. In our opinion, such a definition gives an undue\nextension to the meaning of consciousness, and occasions many\nerrors and misunderstandings. We share, rather, the view of other\nphilosophers (Romanes, Fritz Schultze, and Paulsen), that even our\nunconscious presentations, sensations, and volitions pertain to our\npsychic life; indeed, the province of these unconscious psychic actions\n(reflex action, and so forth) is far more extensive than that of\nconsciousness. Moreover, the two provinces are intimately connected,\nand are separated by no sharp line of demarcation. An unconscious\npresentation may become conscious at any moment; let our attention be\nwithdrawn from it by some other object, and forthwith it disappears\nfrom consciousness once more.\n\nThe only source of our knowledge of consciousness is that faculty\nitself; that is the chief cause of the extraordinary difficulty of\nsubjecting it to scientific research. Subject and object are one and\nthe same in it: the perceptive subject mirrors itself in its own\ninner nature, which is to be the object of our inquiry. Thus we can\nnever have a complete objective certainty of the consciousness of\nothers; we can only proceed by a comparison of their psychic condition\nwith our own. As long as this comparison is restricted to _normal_\npeople we are justified in drawing certain conclusions as to their\nconsciousness, the validity of which is unchallenged. But when we pass\non to consider _abnormal_ individuals (the genius, the eccentric, the\nstupid, or the insane) our conclusions from analogy are either unsafe\nor entirely erroneous. The same must be said with even greater truth\nwhen we attempt to compare human consciousness with that of the animals\n(even the higher, but especially the lower). In that case such grave\ndifficulties arise that the views of physiologists and philosophers\ndiverge as widely as the poles on the subject. We shall briefly\nenumerate the most important of these views.\n\nI. _The anthropistic theory of consciousness._--It is peculiar to man.\nTo Descartes we must trace the widespread notion that consciousness\nand thought are man's exclusive prerogative, and that he alone is\nblessed with an \"immortal soul.\" This famous French philosopher and\nmathematician (educated in a Jesuit College) established a rigid\npartition between the psychic activity of man and that of the brute.\nIn his opinion the human soul, a thinking, immaterial being, is\ncompletely separated from the body, which is extended and material.\nYet it is united to the body at a certain point in the brain (the\n_glandula pinealis_) for the purpose of receiving impressions from the\nouter world and effecting muscular movements. The animals, not being\nendowed with thought, have no soul: they are mere automata, or cleverly\nconstructed machines, whose sensations, presentations, and volitions\nare purely mechanical, and take place according to the ordinary laws\nof physics. Hence Descartes was a _dualist_ in human psychology, and\na _monist_ in the psychology of the brute. This open contradiction in\nso clear and acute a thinker is very striking; in explaining it, it\nis not unnatural to suppose that he concealed his real opinion, and\nleft the discovery of it to independent scholars. As a pupil of the\nJesuits, Descartes had been taught to deny the truth in the face of his\nbetter insight; and perhaps he dreaded the power and the fires of the\nChurch. Besides, his sceptical principle, that every sincere effort to\nattain the truth must start with a doubt of the traditional dogma had\nalready drawn upon him fanatical accusations of scepticism and atheism.\nThe great influence which Descartes had on subsequent philosophy was\nvery remarkable, and entirely in harmony with his \"book-keeping by\ndouble entry.\" The _materialists_ of the seventeenth and eighteenth\ncenturies appealed to the Cartesian theory of the animal soul and its\npurely mechanical activity in support of their monistic psychology. The\n_spiritualists_, on the other hand, asserted that their dogma of the\nimmortality of the soul and its independence of the body was firmly\nestablished by Descartes' theory of the human soul. This view is still\nprevalent in the camp of the theologians and dualistic metaphysicians.\nThe scientific conception of nature, however, which has been built up\nin the nineteenth century, has, with the aid of empirical progress, in\nphysiological and comparative psychology, completely falsified it.\n\nII. _Neurological theory of consciousness._--It is present only\nin man and those higher animals which have a centralized nervous\nsystem and organs of sense. The conviction that a large number of\nanimals--at least the higher mammals--are not less endowed than man\nwith a thinking soul and consciousness prevails in modern zoology,\nexact physiology, and the monistic psychology. The immense progress we\nhave made in the various branches of biology has contributed to bring\nabout a recognition of this important truth. We confine ourselves for\nthe present to the higher vertebrates, and especially the mammals.\nThat these most intelligent specimens of these highly developed\nvertebrates--apes and dogs, in particular--have a strong resemblance to\nman in their whole psychic life has been recognized and speculated on\nfor thousands of years. Their faculty of presentation and sensation,\nof feeling and desire, is so like that of man that we need adduce no\nproof of our thesis. But even the higher associational activity of\nthe brain, the formation of judgments and their connection into chains\nof reasoning, thought, and consciousness in the narrower sense, are\ndeveloped in them after the same fashion as in man: they differ only in\ndegree, not in kind. Moreover, we learn from comparative anatomy and\nhistology that the intricate structure of the brain (both in general\nand in detail) is substantially the same in the mammals as it is in\nman. The same lesson is enforced by comparative ontogeny with regard\nto the origin of these psychic organs. Comparative physiology teaches\nus that the various states of consciousness are just the same in these\nhighest placentals as in man; and we learn by experiment that there\nis the same reaction to external stimuli. The higher animals can be\nnarcotized by alcohol, chloroform, ether, etc., and may be hypnotized\nby the usual methods, just as in the case of man.\n\nIt is, however, impossible to determine mathematically at what stage\nof animal life consciousness is to be first recognized as such. Some\nzoologists draw the line very high in the scale, others very low.\nDarwin, who most accurately distinguishes the various stages of\nconsciousness, intelligence, and emotion in the higher animals, and\nexplains them by progressive evolution, points out how difficult,\nor even impossible, it is to determine the first beginning of this\nsupreme psychic faculty in the lower animals. Personally, out of the\nmany contradictory theories, I take that to be most probable which\nholds _the centralization of the nervous system_ to be a condition of\nconsciousness; and that is wanting in the lower classes of animals. The\npresence of a central nervous organ, of highly developed sense-organs,\nand an elaborate association of groups of presentations, seem to me to\nbe required before the unity of consciousness is possible.\n\nIII. _Animal theory of consciousness._--All animals, and they alone,\nhave consciousness. This theory would draw a sharp distinction between\nthe psychic life of the animal and of the plant. Such a distinction\nwas urged by many of the older writers, and was clearly formulated\nby Linn\u00e9 in his celebrated _Systema Naturae_; the two great kingdoms\nof the organic world are, in his opinion, divided by the fact that\nanimals have sensation and consciousness, and the plants are devoid\nof them. Later on Schopenhauer laid stress on the same distinction:\n\"Consciousness is only known to us as a feature of animal nature.\nEven though it extend upwards through the whole animal kingdom, even\nto man and his reason, the unconsciousness of the plant, from which\nit started, remains as the basic feature. In the lowest animals we\nhave but the dawn of it.\" The inaccuracy of this view was obvious by\nabout the middle of the present century, when a deeper study was made\nof the psychic activity of the lower animal forms, especially the\ncoelenterates (sponges and cnidaria): they are undoubtedly animals,\nyet there is no more trace of a definite consciousness in them than in\nmost of the plants. The distinction between the two kingdoms was still\nfurther obliterated when more careful research was made into their\nunicellular forms. There is no psychological difference between the\nplasmophagous protozoa and the plasmodomous protophyta, even in respect\nof their consciousness.\n\nIV. _Biological theory of consciousness._--It is found in all\norganisms, animal or vegetal, but not in lifeless bodies (such as\ncrystals). This opinion is usually associated with the idea that all\norganisms (as distinguished from inorganic substances) have souls:\nthe three ideas--life, soul, and consciousness--are then taken to be\ncoextensive. Another modification of this view holds that, though\nthese fundamental phenomena of organic life are inseparably connected,\nyet consciousness is only a part of the activity of the soul, and of\nthe vital activity. Fechner, in particular, has endeavored to prove\nthat the plant has a \"soul,\" in the same sense as an animal is said\nto have one; and many credit the vegetal soul with a consciousness\nsimilar to that of the animal soul. In truth, the remarkable stimulated\nmovements of the leaves of the sensitive plants (the mimosa, drosera,\nand dion\u00e6a), the automatic movements of other plants (the clover\nand wood-sorrel, and especially the hedysarum), the movements of\nthe \"sleeping plants\" (particularly the _papilionacea_), etc., are\nstrikingly similar to the movements of the lower animal forms: whoever\nascribes consciousness to the latter cannot refuse it to such vegetal\nforms.\n\nV. _Cellular theory of consciousness._--It is a vital property of every\ncell. The application of the cellular theory to every branch of biology\ninvolved its extension to psychology. Just as we take the living cell\nto be the \"elementary organism\" in anatomy and physiology, and derive\nthe whole system of the multicellular animal or plant from it, so, with\nequal right, we may consider the \"cell-soul\" to be the psychological\nunit, and the complex psychic activity of the higher organism to be\nthe result of the combination of the psychic activity of the cells\nwhich compose it. I gave the outlines of this _cellular psychology_\nin my _General Morphology_ in 1866, and entered more fully into the\nsubject in my paper on \"Cell-Souls and Soul-Cells.\" I was led to a\ndeeper study of this \"elementary psychology\" by my protracted research\ninto the unicellular forms of life. Many of these tiny (generally\nmicroscopic) protists show similar expressions of sensation and will,\nand similar instincts and movements, to those of higher animals; that\nis especially true of the very sensitive and lively infusoria. In the\nrelation of these sensitive cell-organisms to their environment, and in\nmany other of their vital expressions (for instance, in the wonderful\narchitecture of the rhizopods, the thalamophor\u00e6, and the infusoria),\nwe seemed to have clear indications of conscious psychic action. If,\nthen, we accept the biological theory of consciousness (No. IV.), and\ncredit every psychic function with a share of that faculty, we shall be\ncompelled to ascribe it to each independent protist cell. In that case\nits material basis would be either the entire protoplasm of the cell,\nor its nucleus, or a portion of it. In the \"psychade theory\" of Fritz\nSchultze the elementary consciousness of the _psychade_ would have\nthe same relation to the individual cells as personal consciousness\nhas to the multicellular organism of the personality in the higher\nanimals and man. It is impossible definitively to disprove this theory,\nwhich I held at one time. Still, I now feel compelled to agree with\nMax Verworn, in his belief that none of the protists have a developed\nself-consciousness, but that their sensations and movements are of an\nunconscious character.\n\nVI. _Atomistic theory of consciousness._--It is an elementary property\nof all atoms. This atomistic hypothesis goes furthest of all the\ndifferent views as to the extension of consciousness. It certainly\nescapes the difficulty which so many philosophers and biologists\nexperience in solving the problem of the first origin of consciousness.\nIt is a phenomenon of so peculiar a character that a derivation of\nit from other psychic functions seems extremely hazardous. It seemed,\ntherefore, the easiest way out of the difficulty to conceive it as an\ninherent property of all matter, like gravitation or chemical affinity.\nOn that hypothesis there would be as many forms of this original\nconsciousness as there are chemical elements; each atom of hydrogen\nwould have its hydrogenic consciousness, each atom of carbon its\ncarbonic consciousness, and so forth. There are philosophers, even, who\nascribe consciousness to the four elements of Empedocles, the union of\nwhich, by \"love and hate,\" produces the totality of things.\n\nPersonally, I have never subscribed to this hypothesis of atomic\nconsciousness. I emphasize the point because Emil du Bois-Reymond\nhas attributed it to me. In the controversy I had with him (1880) he\nviolently attacked my \"pernicious and false philosophy,\" and contended\nthat I had, in my paper on \"The Perigenesis of the Plastidule,\" \"laid\nit down as a metaphysical axiom that every atom has its individual\nconsciousness.\" On the contrary, I explicitly stated that I conceive\nthe elementary psychic qualities of sensation and will, which may\nbe attributed to atoms, to be _unconscious_--just as unconscious as\nthe elementary memory which I, in company with that distinguished\nphysiologist, Ewald Hering, consider to be \"a common function of\nall organized matter\"--or, more correctly, \"living substance.\" Du\nBois-Reymond curiously confuses \"soul\" and \"consciousness\"; whether\nfrom oversight or not I cannot say. Since he considers consciousness\nto be a transcendental phenomenon (as we shall see presently), while\ndenying that character to other psychic functions--the action of the\nsenses, for example--I must infer that he recognizes the difference\nof the two ideas. Other parts of his eloquent speeches contain quite\nthe opposite view, for the famous orator not infrequently contradicts\nhimself on important questions of principle. However, I repeat that, in\nmy opinion, consciousness is only _part_ of the psychic phenomena which\nwe find in man and the higher animals; the great majority of them are\nunconscious.\n\nHowever divergent are the different views as to the nature and\norigin of consciousness, they may, nevertheless, on a clear and\nlogical examination, all be reduced to two fundamental theories--the\ntranscendental (or dualistic) and the physiological (or monistic).\nI have myself always held the latter view, in the light of my\nevolutionary principles, and it is now shared by a great number of\ndistinguished scientists, though it is by no means generally accepted.\nThe transcendental theory is the older and much more common; it\nhas recently come once more into prominence, principally through\nDu Bois-Reymond, and it has acquired a great importance in modern\ndiscussions of cosmic problems through his famous \"Ignorabimus speech.\"\nOn account of the extreme importance of this fundamental question we\nmust touch briefly on its main features.\n\nIn the celebrated discourse on \"The Limits of Natural Science,\"\nwhich E. du Bois-Reymond gave on August 14, 1872, at the Scientific\nCongress at Leipzig, he spoke of two \"absolute limits\" to our possible\nknowledge of nature which the human mind will never transcend in its\nmost advanced science--_never_, as the oft-quoted termination of the\naddress, \"Ignorabimus,\" emphatically pronounces. The first absolutely\ninsoluble \"world-enigma\" is the \"connection of matter and force,\" and\nthe distinctive character of these fundamental natural phenomena; we\nshall go more fully into this \"problem of substance\" in the twelfth\nchapter. The second insuperable difficulty of philosophy is given as\nthe problem of consciousness--the question how our mental activity\nis to be explained by material conditions, especially movements, how\n\"substance [the substance which underlies matter and force] comes,\nunder certain conditions, to feel, to desire, and to think.\"\n\nFor brevity, and in order to give a characteristic name to the Leipzig\ndiscourse, I have called it the \"Ignorabimus speech\"; this is the\nmore permissible, as E. du Bois-Reymond himself, with a just pride,\neight years afterwards, speaking of the extraordinary consequences\nof his discourse, said: \"Criticism sounded every possible note, from\nfriendly praise to the severest censure, and the word 'Ignorabimus,'\nwhich was the culmination of my inquiry, was at once transformed into a\nkind of scientific shibboleth.\" It is quite true that loud praise and\napprobation resounded in the halls of the dualistic and spiritualistic\nphilosophy, and especially in the camp of the \"Church militant\"; even\nthe spiritists and the host of believers, who thought the immortality\nof their precious souls was saved by the \"Ignorabimus,\" joined in the\nchorus. The \"severest censure\" came at first only from a few scientists\nand philosophers--from the few who had sufficient scientific knowledge\nand moral courage to oppose the dogmatism of the all-powerful secretary\nand dictator of the Berlin Academy of Science.\n\nTowards the end, however, the author of the \"Ignorabimus speech\" briefly\nalluded to the question whether these two great \"world-enigmas,\" the\ngeneral problem of substance and the special problem of consciousness,\nare not two aspects of one and the same problem. \"This idea,\" he said,\n\"is certainly the simplest, and preferable to the one which makes the\nworld doubly incomprehensible. Such, however, is the nature of things\nthat even here we can obtain no clear knowledge, and it is useless to\nspeak further of the question.\" The latter sentiment I have always\nstoutly contested, and have endeavored to prove that the two great\nquestions are not two distinct problems. \"The neurological problem\nof consciousness is but a particular aspect of the all-pervading\ncosmological problem of substance.\"\n\nThe peculiar phenomenon of consciousness is not, as Du Bois-Reymond\nand the dualistic school would have us believe, a completely\n\"transcendental\" problem; it is, as I showed thirty-three years ago,\na _physiological_ problem, and, as such, must be reduced to the\nphenomena of physics and chemistry. I subsequently gave it the more\ndefinite title of a _neurological_ problem, as I share the view that\ntrue consciousness (thought and reason) is only present in those higher\nanimals which have a centralized nervous system and organs of sense\nof a certain degree of development. Those conditions are certainly\nfound in the higher vertebrates, especially in the placental mammals,\nthe class from which man has sprung. The consciousness of the highest\napes, dogs, elephants, etc., differs from that of man in degree only,\nnot in kind, and the graduated interval between the consciousness of\nthese \"rational\" placentals and that of the lowest races of men (the\nVeddahs, etc.) is less than the corresponding interval between these\nuncivilized races and the highest specimens of thoughtful humanity\n(Spinoza, Goethe, Lamarck, Darwin, etc.). Consciousness is but a part\nof the higher activity of the soul, and as such it is dependent on the\nnormal structure of the corresponding psychic organ, the brain.\n\nPhysiological observation and experiment determined twenty years ago\nthat the particular portion of the mammal-brain which we call the\n_seat_ (preferably the _organ_) of consciousness is a part of the\ncerebrum, an area in the late-developed gray bed, or cortex, which\nis evolved out of the convex dorsal portion of the primary cerebral\nvesicle, the \"fore-brain.\" Now, the morphological proof of this\nphysiological thesis has been successfully given by the remarkable\nprogress of the microscopic anatomy of the brain, which we owe to the\nperfect methods of research of modern science (K\u00f6lliker, Flechsig,\nGolgi, Edinger, Weigert, and others).\n\nThe most important development is the discovery of the _organs of\nthought_ by Paul Flechsig, of Leipzig; he proved that in the gray bed\nof the brain are found the four seats of the central sense-organs,\nor four \"inner spheres of sensation\"--the sphere of touch in the\nvertical lobe, the sphere of smell in the frontal lobe, the sphere\nof sight in the occipital lobe, and the sphere of hearing in the\ntemporal lobe. Between these four \"sense-centres\" lie the four great\n\"thought-centres,\" or centres of association, the _real organs of\nmental life_; they are those highest instruments of psychic activity\nthat produce thought and consciousness. In front we have the frontal\nbrain or centre of association; behind, on top there is the vertical\nbrain, or parietal centre of association, and underneath the principal\nbrain, or \"the great occipito-temporal centre of association\" (the\nmost important of all); lower down, and internally, the insular brain\nor the insula of Reil, the insular centre of association. These four\n\"thought-centres,\" distinguished from the intermediate \"sense-centres\"\nby a peculiar and elaborate nerve-structure, are the true and sole\norgans of thought and consciousness. Flechsig has recently pointed out\nthat, in the case of man, very specific structures are found in one\npart of them; these structures are wanting in the other mammals, and\nthey, therefore, afford an explanation of the superiority of man's\nmental powers.\n\nThe momentous announcement of modern physiology, that the cerebrum is\nthe organ of consciousness and mental action in man and the higher\nmammals, is illustrated and confirmed by the pathological study of\nits diseases. When parts of the cortex are destroyed by disease their\nrespective functions are affected, and thus we are enabled, to some\nextent, to localize the activities of the brain; when certain parts\nof the area are diseased, that portion of thought and consciousness\ndisappears which depends on those particular sections. Pathological\nexperiment yields the same result; the decay of some known area (for\ninstance, the centre of speech) extinguishes its function (speech).\nIn fact, there is proof enough in the most familiar phenomena of\nconsciousness of their complete dependence on chemical changes in\nthe substance of the brain. Many beverages (such as coffee and\ntea) stimulate our powers of thought; others (such as wine and\nbeer) intensify feeling; musk and camphor reanimate the fainting\nconsciousness; ether and chloroform deaden it, and so forth. How\nwould that be possible if consciousness were an immaterial entity,\nindependent of these anatomical organs? And what becomes of the\nconsciousness of the \"immortal soul\" when it no longer has the use of\nthese organs?\n\nThese and other familiar facts prove that man's consciousness--and\nthat of the nearest mammals--is _changeable_, and that its activity\nis always open to modification from inner (alimentation, circulation,\netc.) and outer causes (lesion of the brain, stimulation, etc.).\nVery instructive, too, are the facts of double and intermittent\nconsciousness, which remind us of \"alternate generations of\npresentations.\" The same individual has an entirely different\nconsciousness on different days, with a change of circumstances; he\ndoes not know to-day what he did yesterday: yesterday he could say, \"I\nam I\"; to-day he must say, \"I am another being.\" Such intermittence of\nconsciousness may last not only days, but months, and even years; the\nchange may even become permanent.\n\nAs everybody knows, the new-born infant has no consciousness. Preyer\nhas shown that it is only developed after the child has begun to\nspeak; for a long time it speaks of itself in the third person.\nIn the important moment when it first pronounces the word \"I,\"\nwhen the feeling of self becomes clear, we have the beginning of\nself-consciousness, and of the antithesis to the non-ego. The rapid\nand solid progress in knowledge which the child makes in its first\nten years, under the care of parents and teachers, and the slower\nprogress of the second decade, until it reaches complete maturity of\nmind, are intimately connected with a great advancement in the growth\nand development of consciousness and of its organ, the brain. But even\nwhen the pupil has got his \"certificate of maturity\" his consciousness\nis still far from mature; it is then that his \"world-consciousness\"\nfirst begins to develop, in his manifold relations with the outer\nworld. Then, in the third decade, we have the full maturity of rational\nthought and consciousness, which, in cases of normal development, yield\ntheir ripe fruits during the next three decades. The slow, gradual\ndegeneration of the higher mental powers, which characterizes senility,\nusually sets in at the commencement of the seventh decade--sometimes\nearlier, sometimes later. Memory, receptiveness, and interest in\nparticular objects gradually decay; though productivity, mature\nconsciousness, and philosophic interest in general truths often remain\nfor many years longer.\n\nThe individual development of consciousness in earlier youth proves the\nuniversal validity of the _biogenetic law_; and, indeed, it is still\nrecognizable in many ways during the later years. In any case, the\nontogenesis of consciousness makes it perfectly clear that it is not\nan \"immaterial entity,\" but a physiological function of the brain, and\nthat it is, consequently, no exception to the general law of substance.\n\nFrom the fact that consciousness, like all other psychic functions,\nis dependent on the normal development of certain organs, and that\nit gradually unfolds in the child in proportion to the development\nof those organs, we may already conclude that it has arisen in the\nanimal kingdom by a gradual historical development. Still, however\ncertain we are of the fact of this natural evolution of consciousness,\nwe are, unfortunately, not yet in a position to enter more deeply\ninto the question and construct special hypotheses in elucidation\nof it. Pal\u00e6ontology, it is true, gives us a few facts which are not\nwithout significance. For instance, the quantitative and qualitative\ndevelopment of the brain of the placental mammals during the Tertiary\nperiod is very remarkable. The cavity of many of the fossil skulls of\nthe period has been carefully examined, and has given us a good deal of\nreliable information as to the size, and, to some extent, as to the\nstructure, of the brain they enclosed. We find, within the limits of\none and the same group (the ungulates, the rodents, or the primates), a\nmarked advance in the later miocene and pliocene specimens as compared\nwith the earlier eocene and oligocene representatives of the same stem;\nin the former the brain (in proportion to the size of the organism) is\nsix to eight times as large as in the latter.\n\nMoreover, that highest stage of consciousness, which is reached by man\nalone, has been evolved step by step--even by the very progress of\ncivilization--from a lower condition, as we find illustrated to-day in\nthe case of uncivilized races. That is easily proved by a comparison\nof their languages, which is closely connected with the comparison of\ntheir ideas. The higher the conceptual faculty advances in thoughtful\ncivilized man, the more qualified he is to detect common features amid\na multitude of details, and embody them in general concepts, and so\nmuch the clearer and deeper does his consciousness become.\n\n\n\n\nCHAPTER XI\n\nTHE IMMORTALITY OF THE SOUL\n\n    The Citadel of Superstition--Athanatism and Thanatism--Individual\n    Character of Death--Immortality of the Unicellular Organisms\n    (Protists)--Cosmic and Personal Immortality--Primary Thanatism (of\n    Uncivilized Peoples)--Secondary Thanatism (of Ancient and Recent\n    Philosophers)--Athanatism and Religion--Origin of the Belief\n    in Immortality--Christian Athanatism--Eternal Life--The Day of\n    Judgment--Metaphysical Athanatism--Substance of the Soul--Ether\n    Souls and Air Souls; Fluid Souls and Solid Souls--Immortality of\n    the Animal Soul--Arguments for and Against Athanatism--Athanatist\n    Illusions\n\n\nWhen we turn from the genetic study of the soul to the great question\nof its immortality, we come to that highest point of superstition which\nis regarded as the impregnable citadel of all mystical and dualistic\nnotions. For in this crucial question, more than in any other problem,\nphilosophic thought is complicated by the selfish interest of the human\npersonality, who is determined to have a guarantee of his existence\nbeyond the grave at any price. This \"higher necessity of feeling\" is\nso powerful that it sweeps aside all the logical arguments of critical\nreason. Consciously or unconsciously, most men are influenced in all\ntheir general views, and, therefore, in their theory of life, by the\ndogma of personal immortality; and to this theoretical error must be\nadded practical consequences of the most far-reaching character. It is\nour task, therefore, to submit every aspect of this important dogma to\na critical examination, and to prove its untenability in the light of\nthe empirical data of modern biology.\n\nIn order to have a short and convenient expression for the two opposed\nopinions on the question, we shall call the belief in man's personal\nimmortality \"athanatism\" (from _athanes_ or _athanatos_ == immortal).\nOn the other hand, we give the name of \"thanatism\" (from _thanatos_\n== death) to the opinion which holds that at a man's death not only\nall the other physiological functions are arrested, but his \"soul\"\nalso disappears--that is, that sum of cerebral functions which psychic\ndualism regards as a peculiar entity, independent of the other vital\nprocesses in the living body.\n\nIn approaching this physiological problem of death we must point out\nthe _individual_ character of this organic phenomenon. By death we\nunderstand simply the definitive cessation of the vital activity of\nthe _individual_ organism, no matter to which category or stage of\nindividuality the organism in question belongs. Man is dead when his\nown personality ceases to exist, whether he has left offspring that\nthey may continue to propagate for many generations or not. In a\ncertain sense we often say that the minds of great men (in a dynasty\nof eminent rulers, for instance, or a family of talented artists) live\nfor many generations; and in the same way we speak of the \"soul\" of\na noble woman living in her children and children's children. But in\nthese cases we are dealing with intricate phenomena of _heredity_,\nin which a microscopic cell (the sperm-cell of the father or the\negg-cell of the mother) transmits certain features to offspring. The\nparticular personalities who produce those sexual cells in thousands\nare mortal beings, and at their death their personal psychic activity\nis extinguished like every other physiological function.\n\nA number of eminent zoologists--Weismann being particularly\nprominent--have recently defended the opinion that only the lowest\nunicellular organisms, the protists, are immortal, in contradistinction\nto the multicellular plants and animals, whose bodies are formed of\ntissues. This curious theory is especially based on the fact that\nmost of the protists multiply without sexual means, by division or\nthe formation of spores. In such processes the whole body of the\nunicellular organism breaks up into two or more equal parts (daughter\ncells), and each of these portions completes itself by further growth\nuntil it has the size and form of the mother cell. However, by the very\nprocess of division the _individuality_ of the unicellular creature\nhas been destroyed; both its physiological and its morphological unity\nhave gone. The view of Weismann is logically inconsistent with the\nvery notion of _individual_--an \"indivisible\" entity; for it implies\na unity which cannot be divided without destroying its nature. In\nthis sense the unicellular protophyta and protozoa are throughout\nlife _physiological individuals_, just as much as the multicellular\ntissue-plants and animals. A sexual propagation by simple division\nis found in many of the multicellular species (for instance, in many\ncnidaria, corals, medus\u00e6, etc.); the mother animal, the division of\nwhich gives birth to the two daughter animals, ceases to exist with\nthe segmentation. \"The protozoa,\" says Weismann, \"have no individuals\nand no generations in the metazoic sense.\" I must entirely dissent\nfrom his thesis. As I was the first to introduce the title of\n_metazoa_, and oppose these multicellular, tissue-forming animals to\nthe unicellular _protozoa_ (infusoria, rhizopods, etc.), and as I was\nthe first to point out the essential difference in the development of\nthe two (the former from germinal layers, and the latter not), I must\nprotest that I consider the _protozoa_ to be just as mortal in the\nphysiological (and psychological) sense as the _metazoa_; neither body\nnor soul is immortal in either group. The other erroneous consequences\nof Weismann's notion have been refuted by Moebius (1884), who justly\nremarks that \"every event in the world is periodic,\" and that \"there is\nno source from which immortal organic individuals might have sprung.\"\n\nWhen we take the idea of immortality in the widest sense, and extend\nit to the totality of the knowable universe, it has a scientific\nsignificance; it is then not merely acceptable, but self-evident,\nto the monistic philosopher. In that sense the thesis of the\nindestructibility and eternal duration of all that exists is equivalent\nto our supreme law of nature, the _law of substance_ (see chap. xii).\nAs we intend to discuss this immortality of the cosmos fully later on,\nin establishing the theory of the persistence of matter and force,\nwe shall not dilate on it at present. We pass on immediately to the\ncriticism of that belief in immortality which is the only sense usually\nattached to the word, the immortality of the individual soul. We\nshall first inquire into the extent and the origin of this mystic and\ndualistic notion, and point out, in particular, the wide acceptance\nof the contradictory thesis, our monistic, empirically established\n_thanatism_. I must distinguish two essentially different forms of\nthanatism--primary and secondary; primary thanatism is the original\nabsence of the dogma of immortality (in the primitive uncivilized\nraces); secondary thanatism is the later outcome of a rational\nknowledge of nature in the civilized intelligence.\n\nWe still find it asserted in philosophic, and especially in theological,\nworks that belief in the personal immortality of the human soul was\noriginally shared by all men--or, at least, by all \"rational\" men. That\nis not the case. This dogma is not an original idea of the human mind,\nnor has it ever found universal acceptance. It has been absolutely\nproved by modern comparative ethnology that many uncivilized races\nof the earliest and most primitive stage had no notion either of\nimmortality or of God. That is true, for instance, of the Veddahs of\nCeylon, those primitive pygmies whom, on the authority of the able\nstudies of the Sarasins, we consider to be a relic of the earliest\ninhabitants of India;[22] it is also the case in several of the\nearliest groups of the nearly related Dravidas, the Indian Seelongs,\nand some native Australian races. Similarly, several of the primitive\nbranches of the American race, in the interior of Brazil, on the upper\nAmazon, etc., have no knowledge either of gods or immortality. This\n_primary_ absence of belief in immortality and deity is an extremely\nimportant fact; it is, obviously, easy to distinguish from the\n_secondary_ absence of such belief, which has come about in the highest\ncivilized races as the result of laborious critico-philosophical study.\n\nDifferently from the primary thanatism which originally characterized\nprimitive man, and has always been widely spread, the _secondary_\nabsence of belief in immortality is only found at a late stage of\nhistory: it is the ripe fruit of profound reflection on life and death,\nthe outcome of bold and independent philosophical speculation. We first\nmeet it in some of the Ionic philosophers of the sixth century B.C.,\nthen in the founders of the old materialistic philosophy, Democritus\nand Empedocles, and also in Simonides and Epicurus, Seneca and Plinius,\nand in an elaborate form in Lucretius Carus. With the spread of\nChristianity at the decay of classical antiquity, athanatism, one of\nits chief articles of faith, dominated the world, and so, amid other\nforms of superstition, the myth of personal immortality came to be\ninvested with a high importance.\n\nNaturally, through the long night of the Dark Ages it was rarely that\na brave free-thinker ventured to express an opinion to the contrary:\nthe examples of Galileo, Giordano Bruno, and other independent\nphilosophers, effectually destroyed all freedom of utterance. Heresy\nonly became possible when the Reformation and the Renaissance had\nbroken the power of the papacy. The history of modern philosophy tells\nof the manifold methods by which the matured mind of man sought to\nrid itself of the superstition of immortality. Still, the intimate\nconnection of the belief with the Christian dogma invested it with\nsuch power, even in the more emancipated sphere of Protestantism,\nthat the majority of convinced free-thinkers kept their sentiments to\nthemselves. From time to time some distinguished scholar ventured to\nmake a frank declaration of his belief in the impossibility of the\ncontinued life of the soul after death. This was done in France in the\nsecond half of the eighteenth century by Voltaire, Danton, Mirabeau,\nand others, and by the leaders of the materialistic school of those\ndays, Holbach, Lamettrie, etc. The same opinion was defended by the\nable friend of the Materialists, the greatest of the Hohenzollerns, the\nmonistic \"philosopher of Sans-souci.\" What would Frederick the Great,\nthe \"crowned thanatist and atheist,\" say, could he compare his monistic\nviews with those of his successor of to-day?\n\nAmong thoughtful physicians the conviction that the existence of the\nsoul came to an end at death has been common for centuries: generally,\nhowever, they refrained from giving it expression. Moreover, the\nempirical science of the brain remained so imperfect during the last\ncentury that the soul could continue to be regarded as its mysterious\ninhabitant. It was the gigantic progress of biology in the present\ncentury, and especially in the latter half of the century, that\nfinally destroyed the myth. The establishment of the theory of descent\nand the cellular theory, the astounding discoveries of ontogeny and\nexperimental physiology--above all, the marvellous progress of the\nmicroscopic anatomy of the brain, gradually deprived athanatism of\nevery basis; now, indeed, it is rarely that an informed and honorable\nbiologist is found to defend the immortality of the soul. All the\nmonistic philosophers of the century (Strauss, Feuerbach, B\u00fcchner,\nSpencer, etc.) are thanatists.\n\nThe dogma of personal immortality owes its great popularity and its\nhigh importance to its intimate connection with the teaching of\nChristianity. This circumstance gave rise to the erroneous and still\nprevalent belief that the myth is a fundamental element of all the\nhigher religions. That is by no means the case. The higher Oriental\nreligions include no belief whatever in the immortality of the soul;\nit is not found in Buddhism, the religion that dominates thirty per\ncent. of the entire human race; it is not found in the ancient popular\nreligion of the Chinese, nor in the reformed religion of Confucius\nwhich succeeded it; and, what is still more significant, it is not\nfound in the earlier and purer religion of the Jews. Neither in the\n\"five Mosaic books,\" nor in any of the writings of the Old Testament\nwhich were written before the Babylonian Exile, is there any trace of\nthe notion of individual persistence after death.\n\nThe mystic notion that the human soul will live forever after death has\nhad a polyphyletic origin. It was unknown to the earliest speaking man\n(the hypothetical _homo primigenius_ of Asia), to his predecessors, of\ncourse, the _pithecanthropus_ and _prothylobates_, and to the least\ndeveloped of his modern successors, the Veddahs of Ceylon, the Seelongs\nof India, and other distant races. With the development of reason and\ndeeper reflection on life and death, sleep and dreams, mystic ideas of\na dualistic composition of our nature were evolved--independently of\neach other--in a number of the earlier races. Very different influences\nwere at work in these polyphyletic creations--worship of ancestors,\nlove of relatives, love of life and desire of its prolongation, hope of\nbetter conditions of life beyond the grave, hope of the reward of good\nand punishment of evil deeds, and so forth. Comparative psychology has\nrecently brought to our knowledge a great variety of myths and legends\nof that character; they are, for the most part, closely associated\nwith the oldest forms of theistic and religious belief. In most of the\nmodern religions athanatism is intimately connected with theism; the\nmajority of believers transfer their materialistic idea of a \"personal\nGod\" to their \"immortal soul.\" That is particularly true of the\ndominant religion of modern civilized states, Christianity.\n\nAs everybody knows, the dogma of the immortality of the soul has long\nsince assumed in the Christian religion that rigid form which it\nhas in the articles of faith: \"I believe in the resurrection of the\nbody and in an eternal life.\" Man will arise on \"the last day,\" as\nChrist is alleged to have done on Easter morn, and receive a reward\naccording to the tenor of his earthly life. This typically Christian\nidea is thoroughly materialistic and anthropomorphic; it is very little\nsuperior to the corresponding crude legends of uncivilized peoples. The\nimpossibility of \"the resurrection of the body\" is clear to every man\nwho has some knowledge of anatomy and physiology. The resurrection of\nChrist, which is celebrated every Easter by millions of Christians, is\nas purely mythical as \"the awakening of the dead,\" which he is alleged\nto have taught. These mystic articles of faith are just as untenable in\nthe light of pure reason as the cognate hypothesis of \"eternal life.\"\n\nThe fantastic notions which the Christian Church disseminates as to the\neternal life of the immortal soul after the dissolution of the body are\njust as materialistic as the dogma of \"the resurrection of the body.\"\nIn his interesting work on _Religion in the Light of the Darwinian\nTheory_, Savage justly remarks: \"It is one of the standing charges of\nthe Church against science that it is materialistic. I must say, in\npassing, that the whole ecclesiastical doctrine of a future life has\nalways been, and still is, materialism of the purest type. It teaches\nthat the material body shall rise, and dwell in a material heaven.\" To\nprove this one has only to read impartially some of the sermons and\nornate discourses in which the glory of the future life is extolled\nas the highest good of the Christian, and belief in it is laid down to\nbe the foundation of morality. According to them, all the joys of the\nmost advanced modern civilization await the pious believer in Paradise,\nwhile the \"All-loving Father\" reserves his eternal fires for the\ngodless materialist.\n\nIn opposition to the materialist athanatism, which is dominant in\nthe Christian and Mohammedan Churches, we have, apparently, a purer\nand higher form of faith in the _metaphysical athanatism_, as taught\nby most of our dualist and spiritualist philosophers. Plato must be\nconsidered its chief creator: in the fourth century before Christ\nhe taught that complete dualism of body and soul which afterwards\nbecame one of the most important, theoretically, and one of the most\ninfluential, practically, of the Christian articles of faith. The\nbody is mortal, material, physical; the soul is immortal, immaterial,\nmetaphysical. They are only temporarily associated, for the course of\nthe individual life. As Plato postulated an eternal life before as well\nas after this temporary association, he must be classed as an adherent\nof \"metempsychosis,\" or transmigration of souls; the soul existed as\nsuch, or as an \"eternal idea,\" before it entered into a human body.\nWhen it quits one body it seeks such other as is most suited to its\ncharacter for its habitation. The souls of bloody tyrants pass into the\nbodies of wolves and vultures, those of virtuous toilers migrate into\nthe bodies of bees and ants, and so forth. The childish na\u00efvety of this\nPlatonic morality is obvious; on closer examination his views are found\nto be absolutely incompatible with the scientific truth which we owe to\nmodern anatomy, physiology, histology, and ontogeny; we mention them\nonly because, in spite of their absurdity, they have had a profound\ninfluence on thought and culture. On the one hand, the mysticism of the\nNeo-Platonists, which penetrated into Christianity, attaches itself to\nthe psychology of Plato; on the other hand, it became subsequently one\nof the chief supports of spiritualistic and idealistic philosophy. The\nPlatonic \"idea\" gave way in time to the notion of psychic \"substance\";\nthis is just as incomprehensible and metaphysical, though it often\nassumed a physical appearance.\n\nThe conception of the soul as a \"substance\" is far from clear in many\npsychologists; sometimes it is regarded as an \"immaterial\" entity of\na peculiar character in an abstract and idealistic sense, sometimes\nin a concrete and realistic sense, and sometimes as a confused\n_tertium quid_ between the two. If we adhere to the monistic idea of\nsubstance, which we develop in chap. xii., and which takes it to be\nthe simplest element of our whole world-system, we find _energy_ and\n_matter_ inseparably associated in it. We must, therefore, distinguish\nin the \"substance of the soul\" the characteristic psychic _energy_\nwhich is all we perceive (sensation, presentation, volition, etc.),\nand the psychic _matter_, which is the inseparable basis of its\nactivity--that is, the living protoplasm. Thus, in the higher animals\nthe \"matter\" of the soul is a part of the nervous system; in the lower\nnerveless animals and plants it is a part of their multicellular\nprotoplasmic body; and in the unicellular protists it is a part of\ntheir protoplasmic cell-body. In this way we are brought once more\nto the psychic organs, and to an appreciation of the fact that these\nmaterial organs are indispensable for the action of the soul; but the\nsoul itself is _actual_--it is the sum-total of their physiological\nfunctions.\n\nHowever, the idea of a specific \"soul-substance\" found in the\ndualistic philosophers who admit such a thing is very different from\nthis. They conceive the immortal soul to be material, yet invisible,\nand essentially different from the visible body which it inhabits.\n\nThus _invisibility_ comes to be regarded as a most important attribute\nof the soul. Some, in fact, compare the soul with ether, and regard\nit, like ether, as an extremely subtle, light, and highly elastic\nmaterial, an imponderable agency, that fills the intervals between the\nponderable particles of the living organism, others compare the soul\nwith the wind, and so give it a gaseous nature; and it is this simile\nwhich first found favor with primitive peoples, and led in time to the\nfamiliar dualistic conception. When a man died, the body remained as a\nlifeless corpse, but the immortal soul \"flew out of it with the last\nbreath.\"\n\nThe comparison of the human soul with physical ether as a qualitatively\nsimilar idea has assumed a more concrete shape in recent times through\nthe great progress of optics and electricity (especially in the last\ndecade); for these sciences have taught us a good deal about the\nenergy of ether, and enabled us to formulate certain conclusions as\nto the material character of this all-pervading agency. As I intend\nto describe these important discoveries later on (in chap. xii.), I\nshall do no more at present than briefly point out that they render\nthe notion of an \"etheric soul\" absolutely untenable. Such an etheric\nsoul--that is a psychic substance--which is similar to physical ether,\nand which, like ether, passes between the ponderable elements of the\nliving protoplasm or the molecules of the brain, cannot possibly\naccount for the individual life of the soul. Neither the mystic\nnotions of that kind which were warmly discussed about the middle\nof the century, nor the attempts of modern \"Neovitalists\" to put\ntheir mystical \"vital force\" on a line with physical ether, call for\nrefutation any longer.\n\nMuch more widespread, and still much respected, is the view which\nascribes a gaseous nature to the substance of the soul. The comparison\nof human breath with the wind is a very old one; they were originally\nconsidered to be identical, and were both given the same name. The\n_anemos_ and _psyche_ of the Greeks, and the _anima_ and _spiritus_\nof the Romans, were originally all names for \"a breath of wind\"; they\nwere transferred from this to the breath of man. After a time this\n\"living breath\" was identified with the \"vital force,\" and finally it\ncame to be regarded as the soul itself, or, in a narrower sense, as its\nhighest manifestation, the \"spirit.\" From that the imagination went on\nto derive the mystic notion of individual \"spirits\"; these, also, are\nstill usually conceived as \"a\u00ebriform beings\"--though they are credited\nwith the physiological functions of an organism, and they have been\nphotographed in certain well-known spiritist circles.\n\nExperimental physics has succeeded, during the last decade of the\ncentury, in reducing all gaseous bodies to a liquid--most of them,\nalso, to a solid--condition. Nothing more is needed than special\napparatus, which exerts a violent pressure on the gases at a very low\ntemperature. By this process not only the atmospheric elements, oxygen,\nhydrogen, and nitrogen, but even compound gases (such as carbonic-acid\ngas) and gaseous aggregates (like the atmosphere) have been changed\nfrom gaseous to liquid form. In this way the \"invisible\" substances\nhave become \"visible\" to all, and in a certain sense \"tangible.\"\nWith this transformation the mystic nimbus which formerly veiled\nthe character of the gas in popular estimation--as an invisible body\nthat wrought visible effects--has entirely disappeared. If, then, the\nsubstance of the soul were really gaseous, it should be possible to\nliquefy it by the application of a high pressure at a low temperature.\nWe could then catch the soul as it is \"breathed out\" at the moment of\ndeath, condense it, and exhibit it in a bottle as \"immortal fluid\"\n(_Fluidum animae immortale_). By a further lowering of temperature and\nincrease of pressure it might be possible to solidify it--to produce\n\"soul-snow.\" The experiment has not yet succeeded.\n\nIf athanatism were true, if, indeed, the human soul were to live for\nall eternity, we should have to grant the same privilege to the souls\nof the higher animals, at least to those of the nearest related mammals\n(apes, dogs, etc.). For man is not distinguished from them by a special\n_kind_ of soul, or by any peculiar and exclusive psychic function,\nbut only by a higher _degree_ of psychic activity, a superior stage\nof development. In particular, consciousness--the function of the\nassociation of ideas, thought, and reason--has reached a higher level\nin many men (by no means in all) than in most of the animals. Yet this\ndifference is far from being so great as is popularly supposed; and it\nis much slighter in every respect than the corresponding difference\nbetween the higher and the lower animal souls, or even the difference\nbetween the highest and the lowest stages of the human soul itself. If\nwe ascribe \"personal immortality\" to man, we are bound to grant it also\nto the higher animals.\n\nIt is, therefore, quite natural that we should find this belief in\nthe immortality of the animal soul among many ancient and modern\npeoples; we even meet it sometimes to-day in many thoughtful men\nwho postulate an \"immortal life\" for themselves, and have, at the\nsame time, a thorough empirical knowledge of the psychic life of the\nanimals. I once knew an old head-forester, who, being left a widower\nand without children at an early age, had lived alone for more than\nthirty years in a noble forest of East Prussia. His only companions\nwere one or two servants, with whom he exchanged merely a few necessary\nwords, and a great pack of different kinds of dogs, with which he\nlived in perfect psychic communion. Through many years of training\nthis keen observer and friend of nature had penetrated deep into the\nindividual souls of his dogs, and he was as convinced of their personal\nimmortality as he was of his own. Some of his most intelligent dogs\nwere, in his impartial and objective estimation, at a higher stage of\npsychic development than his old, stupid maid and the rough, wrinkled\nmanservant. Any unprejudiced observer, who will study the conscious\nand intelligent psychic activity of a fine dog for a year, and follow\nattentively the physiological processes of its thought, judgment,\nand reason, will have to admit that it has just as valid a claim to\nimmortality as man himself.\n\nThe proofs of the immortality of the soul, which have been adduced for\nthe last two thousand years, and are, indeed, still credited with some\nvalidity, have their origin, for the most part, not in an effort to\ndiscover the truth, but in an alleged \"necessity of emotion\"--that is,\nin imagination and poetic conceit. As Kant puts it, the immortality of\nthe soul is not an object of pure reason, but a \"postulate of practical\nreason.\" But we must set \"practical reason\" entirely aside, together\nwith all the \"exigencies of emotion, or of moral education, etc.,\" when\nwe enter upon an honest and impartial pursuit of truth; for we shall\nonly attain it by the work of pure reason, starting from empirical\ndata and capable of logical analysis. We have to say the same of\nathanatism as of theism; both are creations of poetic mysticism and of\ntranscendental \"faith,\" not of rational science.\n\nWhen we come to analyze all the different proofs that have been urged\nfor the immortality of the soul, we find that not a single one of them\nis of a scientific character; not a single one is consistent with the\ntruths we have learned in the last few decades from physiological\npsychology and the theory of descent. The _theological_ proof--that\na personal creator has breathed an immortal soul (generally regarded\nas a portion of the divine soul) into man--is a pure myth. The\n_cosmological_ proof--that the \"moral order of the world\" demands\nthe eternal duration of the human soul--is a baseless dogma. The\n_teleological_ proof--that the \"higher destiny\" of man involves the\nperfecting of his defective, earthly soul beyond the grave--rests\non a false anthropism. The _moral_ proof--that the defects and\nthe unsatisfied desires of earthly existence must be fulfilled by\n\"compensative justice\" on the other side of eternity--is nothing\nmore than a pious wish. The _ethnological_ proof--that the belief in\nimmortality, like the belief in God, is an innate truth, common to\nall humanity--is an error in fact. The _ontological_ proof--that the\nsoul, being a \"simple, immaterial, and indivisible entity,\" cannot be\ninvolved in the corruption of death--is based on an entirely erroneous\nview of the psychic phenomena; it is a spiritualistic fallacy. All\nthese and similar \"proofs of athanatism\" are in a parlous condition;\nthey are definitely annulled by the scientific criticism of the last\nfew decades.\n\nThe extreme importance of the subject leads us to oppose to these\nuntenable \"proofs of immortality\" a brief exposition of the sound\nscientific arguments against it. The _physiological_ argument shows\nthat the human soul is not an independent, immaterial substance, but,\nlike the soul of all the higher animals, merely a collective title\nfor the sum-total of man's cerebral functions; and these are just\nas much determined by physical and chemical processes as any of the\nother vital functions, and just as amenable to the law of substance.\nThe _histological_ argument is based on the extremely complicated\nmicroscopic structure of the brain; it shows us the true \"elementary\norgans of the soul\" in the ganglionic cells. The _experimental_\nargument proves that the various functions of the soul are bound up\nwith certain special parts of the brain, and cannot be exercised unless\nthese are in a normal condition; if the areas are destroyed, their\nfunction is extinguished; and this is especially applicable to the\n\"organs of thought,\" the four central instruments of mental activity.\nThe _pathological_ argument is the complement of the physiological;\nwhen certain parts of the brain (the centres of speech, sight,\nhearing, etc.) are destroyed by sickness, their activity (speech,\nvision, hearing, etc.) disappears; in this way nature herself makes\nthe decisive physiological experiment. The _ontogenetic_ argument\nputs before us the facts of the development of the soul in the\nindividual; we see how the child-soul gradually unfolds its various\npowers; the youth presents them in full bloom, the mature man shows\ntheir ripe fruit; in old age we see the gradual decay of the psychic\npowers, corresponding to the senile degeneration of the brain. The\n_phylogenetic_ argument derives its strength from pal\u00e6ontology, and the\ncomparative anatomy and physiology of the brain; co-operating with and\ncompleting each other, these sciences prove to the hilt that the human\nbrain (and, consequently, its function--the soul) has been evolved step\nby step from that of the mammal, and, still further back, from that of\nthe lower vertebrate.\n\nThese inquiries, which might be supplemented by many other results of\nmodern science, prove the old dogma of the immortality of the soul\nto be absolutely untenable; in the twentieth century it will not be\nregarded as a subject of serious scientific research, but will be left\nwholly to transcendental \"faith.\" The \"critique of pure reason\" shows\nthis treasured faith to be a mere _superstition_, like the belief in a\npersonal God which generally accompanies it. Yet even to-day millions\nof \"believers\"--not only of the lower, uneducated masses, but even of\nthe most cultured classes--look on this superstition as their dearest\npossession and their most \"priceless treasure.\" It is, therefore,\nnecessary to enter more deeply into the subject, and--assuming it to\nbe true--to make a critical inquiry into its practical value. It soon\nbecomes apparent to the impartial critic that this value rests, for\nthe most part, on fancy, on the want of clear judgment and consecutive\nthought. It is my firm and honest conviction that a definitive\nabandonment of these \"athanatist illusions\" would involve no painful\nloss, but an inestimable positive gain for humanity.\n\nMan's \"emotional craving\" clings to the belief on immortality for two\nmain reasons: firstly, in the hope of better conditions of life beyond\nthe grave; and, secondly, in the hope of seeing once more the dear\nand loved ones whom death has torn from us. As for the first hope,\nit corresponds to a natural feeling of the justice of compensation,\nwhich is quite correct subjectively, but has no objective validity\nwhatever. We make our claim for an indemnity for the unnumbered defects\nand sorrows of our earthly existence, without the slightest real\nprospect or guarantee of receiving it. We long for an eternal life in\nwhich we shall meet no sadness and no pain, but an unbounded peace\nand joy. The pictures that most men form of this blissful existence\nare extremely curious; the immaterial soul is placed in the midst of\ngrossly material pleasures. The imagination of each believer paints\nthe enduring splendor according to his personal taste. The American\nIndian, whose athanatism Schiller has so well depicted, trusts to\nfind in his Paradise the finest hunting-grounds with innumerable\nhordes of buffaloes and bears; the Eskimo looks forward to sun-tipped\nicebergs with an inexhaustible supply of bears, seals, and other polar\nanimals; the effeminate Cingalese frames his Paradise on the wonderful\nisland-paradise of Ceylon with its noble gardens and forests--adding\nthat there will be unlimited supplies of rice and curry, of cocoanuts\nand other fruit, always at hand; the Mohammedan Arab believes it will\nbe a place of shady gardens of flowers, watered by cool springs, and\nfilled with lovely maidens; the Catholic fisherman of Sicily looks\nforward to a daily superabundance of the most valuable fishes and the\nfinest macaroni, and eternal absolution for all his sins, which he\ncan go on committing in his eternal home; the evangelical of North\nEurope longs for an immense Gothic cathedral, in which he can chant\nthe praises of the Lord of Hosts for all eternity. In a word, each\nbeliever really expects his eternal life to be a direct continuation\nof his individual life on earth, only in a \"much improved and enlarged\nedition.\"\n\nWe must lay special stress on the thoroughly materialistic character\nof _Christian_ athanatism, which is closely connected with the absurd\ndogma of the \"resurrection of the body.\" As thousands of paintings of\nfamous masters inform us, the bodies that have risen again, with the\nsouls that have been born again, walk about in heaven just as they did\nin this vale of tears; they see God with their eyes, they hear His\nvoice with their ears, they sing hymns to His praise with their larynx,\nand so forth. In fine, the modern inhabitants of the Christian Paradise\nhave the same dual character of body and soul, the same organs of an\nearthly body, as our ancient ancestors had in Odin's Hall in Walhalla,\nas the \"immortal\" Turks and Arabs have in Mohammed's lovely gardens, as\nthe old Greek demi-gods and heroes had in the enjoyment of nectar and\nambrosia at the table of Zeus.\n\nBut, however gloriously we may depict this eternal life in Paradise,\nit remains _endless_ in duration. Do we realize what \"eternity\"\nmeans?--the uninterrupted continuance of our individual life forever!\nThe profound legend of the \"wandering Jew,\" the fruitless search for\nrest of the unhappy Ahasuerus, should teach us to appreciate such\nan \"eternal life\" at its true value. The best we can desire after a\ncourageous life, spent in doing good according to our light, is the\neternal peace of the grave. \"Lord, give them an eternal rest.\"\n\nAny impartial scholar who is acquainted with geological calculations\nof time, and has reflected on the long series of millions of years the\norganic history of the earth has occupied, must admit that the crude\nnotion of an eternal life is not a _comfort_, but a fearful _menace_,\nto the best of men. Only want of clear judgment and consecutive thought\ncan dispute it.\n\nThe best and most plausible ground for athanatism is found in the\nhope that immortality will reunite us to the beloved friends who have\nbeen prematurely taken from us by some grim mischance. But even this\nsupposed good fortune proves to be an illusion on closer inquiry; and\nin any case it would be greatly marred by the prospect of meeting the\nless agreeable acquaintances and the enemies who have troubled our\nexistence here below. Even the closest family ties would involve many\na difficulty. There are plenty of men who would gladly sacrifice all\nthe glories of Paradise if it meant the eternal companionship of their\n\"better half\" and their mother-in-law. It is more than questionable\nwhether Henry VIII. would like the prospect of living eternally with\nhis six wives; or Augustus the Strong of Poland, who had a hundred\nmistresses and three hundred and fifty-two children. As he was on good\nterms with the Vicar of Christ, he must be assumed to be in Paradise,\nin spite of his sins, and in spite of the fact that his mad military\nventures cost the lives of more than a hundred thousand Saxons.\n\nAnother insoluble difficulty faces the athanatist when he asks _in what\nstage of their individual development_ the disembodied souls will spend\ntheir eternal life. Will the new-born infant develop its psychic powers\nin heaven under the same hard conditions of the \"struggle for life\"\nwhich educate man here on earth? Will the talented youth who has fallen\nin the wholesale murder of war unfold his rich, unused mental powers in\nWalhalla? Will the feeble, childish old man, who has filled the world\nwith the fame of his deeds in the ripeness of his age, live forever in\nmental decay? Or will he return to an earlier stage of development?\nIf the immortal souls in Olympus are to live in a condition of\nrejuvenescence and perfectness, then both the stimulus to the formation\nof, and the interest in, personality disappear for them.\n\nNot less impossible, in the light of pure reason, do we find the\nanthropistic myth of the \"last judgment,\" and the separation of the\nsouls of men into two great groups, of which one is destined for\nthe eternal joys of Paradise and the other for the eternal torments\nof hell--and that from a personal God who is called the \"Father of\nLove\"! And it is this \"Universal Father\" who has himself created the\nconditions of heredity and adaptation, in virtue of which the elect, on\nthe one side, were _bound_ to pursue the path towards eternal bliss,\nand the luckless poor and miserable, on the other hand, were _driven_\ninto the paths of the damned?\n\nA critical comparison of the countless and manifold fantasies which\nbelief in immortality has produced during the last few thousand years\nin the different races and religions yields a most remarkable picture.\nAn intensely interesting presentation of it, based on most extensive\noriginal research, may be found in Adalbert Svoboda's distinguished\nworks, _The Illusion of the Soul_ and _Forms of Faith_. However absurd\nand inconsistent with modern knowledge most of these myths seem to be,\nthey still play an important part, and, as \"postulates of practical\nreason,\" they exercise a powerful influence on the opinions of\nindividuals and on the destiny of races.\n\nThe idealist and spiritualist philosophy of the day will freely grant\nthat these prevalent materialistic forms of belief in immortality are\nuntenable; it will say that the refined idea of an immaterial soul,\na Platonic \"idea\" or a transcendental psychic substance, must be\nsubstituted for them. But modern realism can have nothing whatever to\ndo with these incomprehensible notions; they satisfy neither the mind's\nfeeling of causality nor the yearning of our emotions. If we take a\ncomprehensive glance at all that modern anthropology, psychology,\nand cosmology teach with regard to athanatism, we are forced to this\ndefinite conclusion: \"The belief in the immortality of the human soul\nis a dogma which is in hopeless contradiction with the most solid\nempirical truths of modern science.\"\n\n\n\n\nCHAPTER XII\n\nTHE LAW OF SUBSTANCE\n\n    The Fundamental Chemical Law of the Constancy of Matter--The\n    Fundamental Physical Law of the Conservation of Energy--Combination\n    of Both Laws in the Law of Substance--The Kinetic, Pyknotic,\n    and Dualistic Ideas of Substance--Monism of Matter--Ponderable\n    Matter--Atoms and Elements--Affinity of the Elements--The Soul of\n    the Atom (Feeling and Inclination)--Existence and Character of\n    Ether--Ether and Ponderable Matter--Force and Energy--Potential\n    and Actual Force--Unity of Natural Forces--Supremacy of the Law of\n    Substance\n\n\nThe supreme and all-pervading law of nature, the true and only\ncosmological law, is, in my opinion, _the law of substance_; its\ndiscovery and establishment is the greatest intellectual triumph of the\nnineteenth century, in the sense that all other known laws of nature\nare subordinate to it. Under the name of \"law of substance\" we embrace\ntwo supreme laws of different origin and age--the older is the chemical\nlaw of the \"conservation of matter,\" and the younger is the physical\nlaw of the \"conservation of energy.\"[23] It will be self-evident to\nmany readers, and it is acknowledged by most of the scientific men of\nthe day, that these two great laws are essentially inseparable. This\nfundamental thesis, however, is still much contested in some quarters,\nand we must proceed to furnish the proof of it. But we must first\ndevote a few words to each of the two laws.\n\nThe law of the \"_persistence_\" or \"_indestructibility of matter_,\"\nestablished by Lavoisier in 1789, may be formulated thus: The sum of\nmatter, which fills infinite space, is unchangeable. A body has merely\nchanged its form, when it seems to have disappeared. When coal burns,\nit is changed into carbonic-acid gas by combination with the oxygen of\nthe atmosphere; when a piece of sugar melts in water, it merely passes\nfrom the solid to the fluid condition. In the same way, it is merely\na question of change of form in the cases where a new body seems to\nbe produced. A shower of rain is the moisture of the atmosphere cast\ndown in the form of drops of water; when a piece of iron rusts, the\nsurface layer of the metal has combined with water and with atmospheric\noxygen, and formed a \"rust,\" or oxyhydrate of iron. Nowhere in nature\ndo we find an example of the production, or \"creation,\" of new matter;\nnowhere does a particle of existing matter pass entirely away. This\nempirical truth is now the unquestionable foundation of chemistry; it\nmay be directly verified at any moment by means of the balance. To the\ngreat French chemist Lavoisier belongs the high merit of first making\nthis experiment with the balance. At the present day the scientist, who\nis occupied from one end of the year to the other with the study of\nnatural phenomena, is so firmly convinced of the absolute \"constancy\"\nof matter that he is no longer able to imagine the contrary state of\nthings.\n\nWe may formulate the \"_law of the persistence of force_\" or\n\"_conservation of energy_\" thus: The sum of force, which is at work in\ninfinite space and produces all phenomena, is unchangeable. When the\nlocomotive rushes along the line, the potential energy of the steam\nis transformed into the kinetic or actual energy of the mechanical\nmovement; when we hear its shrill whistle, as it speeds along, the\nsound-waves of the vibrating atmosphere are conveyed through the\ntympanum and the three bones of the ear into the inner labyrinth, and\nthence transferred by the auditory nerve to the acoustic ganglionic\ncells which form the centre of hearing in the temporal lobe of the\ngray bed of the brain. The whole marvellous panorama of life that\nspreads over the surface of our globe is, in the last analysis,\ntransformed sunlight. It is well known how the remarkable progress of\ntechnical science has made it possible for us to convert the different\nphysical forces from one form to another; heat may be changed into\nmolar movement, or movement of mass; this in turn into light or sound,\nand then into electricity, and so forth. Accurate measurement of\nthe quantity of force which is used in this metamorphosis has shown\nthat it is \"constant\" or unchanged. No particle of living energy is\never extinguished; no particle is ever created anew. Friedrich Mohr,\nof Bonn, was very near to the discovery of this great fact in 1837,\nbut the discovery was actually made by the able Swabian physician,\nRobert Mayer, of Heilbronn, in 1842. Independently of Mayer, however,\nthe principle was reached almost at the same time by the famous\nphysiologist, Hermann Helmholtz; five years afterwards he pointed out\nits general application to, and fertility in, every branch of physics.\nWe ought to say to-day that it rules also in the entire province of\nphysiology--that is, of \"organic physics\"; but on that point we meet\na strenuous opposition from the vitalistic biologists and the dualist\nand spiritualist philosophers. For these the peculiar \"spiritual\nforces\" of human nature are a group of \"free\" forces, not subject to\nthe law of energy; the idea is closely connected with the dogma of the\n\"freedom of the will.\" We have, however, already seen (p. 204) that the\ndogma is untenable. Modern physics draws a distinction between \"force\"\nand \"energy,\" but our general observations so far have not needed a\nreference to it.\n\nThe conviction that these two great cosmic theorems, the chemical law\nof the persistence of matter and the physical law of the persistence\nof force, are fundamentally one, is of the utmost importance in our\nmonistic system. The two theories are just as intimately united as\ntheir objects--matter and force or energy. Indeed, this fundamental\nunity of the two laws is self-evident to many monistic scientists and\nphilosophers, since they merely relate to two different aspects of one\nand the same object, the _cosmos_. But, however natural the thought may\nbe, it is still very far from being generally accepted. It is stoutly\ncontested by the entire dualistic philosophy, vitalistic biology,\nand parallelistic psychology; even, in fact, by a few (inconsistent)\nmonists, who think they find a check to it in \"consciousness,\" in the\nhigher mental activity of man, or in other phenomena of our \"free\nmental life.\"\n\nFor my part, I am convinced of the profound importance of the unifying\n\"law of substance,\" as an expression of the inseparable connection in\nreality of two laws which are only separated in conception. That they\nwere not originally taken together and their unity recognized from\nthe beginning is merely an accident of the date of their respective\ndiscoveries. The earlier and more accessible chemical law of the\npersistence of matter was detected by Lavoisier in 1789, and, after\na general application of the balance, became the basis of exact\nchemistry. On the other hand, the more recondite law of the persistence\nof force was only discovered by Mayer in 1842, and only laid down\nas the basis of exact physics by Helmholtz. The unity of the two\nlaws--still much disputed--is expressed by many scientists who are\nconvinced of it in the formula: \"Law of the persistence of matter and\nforce.\" In order to have a briefer and more convenient expression for\nthis fundamental thought, I proposed some time ago to call it the \"law\nof substance\" or the \"fundamental cosmic law\"; it might also be called\nthe \"universal law,\" or the \"law of constancy,\" or the \"axiom of the\nconstancy of the universe.\" In the ultimate analysis it is found to be\na necessary consequence of the principle of causality.[24]\n\nThe first thinker to introduce the purely monistic conception of\nsubstance into science and appreciate its profound importance was the\ngreat philosopher Baruch Spinoza; his chief work appeared shortly after\nhis premature death in 1677, just one hundred years before Lavoisier\ngave empirical proof of the constancy of matter by means of the\nchemist's principal instrument, the balance. In his stately pantheistic\nsystem the notion of the _world_ (the universe, or the cosmos) is\nidentical with the all-pervading notion of God; it is at one and the\nsame time the purest and most rational _monism_ and the clearest and\nmost abstract _monotheism_. This universal substance, this \"divine\nnature of the world,\" shows us two different aspects of its being, or\ntwo fundamental attributes--matter (infinitely _extended_ substance)\nand spirit (the all-embracing energy of _thought_). All the changes\nwhich have since come over the idea of substance are reduced, on a\nlogical analysis, to this supreme thought of Spinoza's; with Goethe\nI take it to be the loftiest, profoundest, and truest thought of all\nages. Every single object in the world which comes within the sphere\nof our cognizance, all individual forms of existence, are but special\ntransitory forms--_accidents_ or _modes_--of substance. These modes are\nmaterial things when we regard them under the attribute of _extension_\n(or \"occupation of space\"), but forces or ideas when we consider them\nunder the attribute of _thought_ (or \"energy\"). To this profound\nthought of Spinoza our purified monism returns after a lapse of two\nhundred years; for us, too, matter (space-filling substance) and energy\n(moving force) are but two inseparable attributes of the one underlying\nsubstance.\n\nAmong the various modifications which the fundamental idea of substance\nhas undergone in modern physics, in association with the prevalent\natomism, we shall select only two of the most divergent theories for\na brief discussion, the kinetic and the pyknotic. Both theories agree\nthat we have succeeded in reducing all the different forces of nature\nto one common original force; gravity and chemical action, electricity\nand magnetism, light and heat, etc., are only different manifestations,\nforms, or _dynamodes_, of a single primitive force (_prodynamis_).\nThis fundamental force is generally conceived as a vibratory motion\nof the smallest particles of matter--a vibration of atoms. The atoms\nthemselves, according to the usual \"kinetic theory of substance,\" are\ndead, separate particles of matter, which dance to and fro in empty\nspace and act at a distance. The real founder and most distinguished\nrepresentative of the kinetic theory is Newton, the famous discoverer\nof the law of gravitation. In his great work, the _Philosophiae\nNaturalis Principia Mathematica_ (1687), he showed that throughout the\nuniverse the same law of attraction controls the unvarying constancy of\ngravitation; the attraction of two particles being in direct proportion\nto their mass and in inverse proportion to the square of their\ndistance. This universal force of gravity is at work in the fall of\nan apple and the tidal wave no less than in the course of the planets\nround the sun and the movements of all the heavenly bodies. Newton\nhad the immortal merit of establishing the law of gravitation and\nembodying it in an indisputable mathematical formula. Yet this _dead\nmathematical formula_, on which most scientists lay great stress, as so\nfrequently happens, gives us merely the _quantitative_ demonstration\nof the theory; it gives us no insight whatever into the _qualitative_\nnature of the phenomena. The action at a distance without a medium,\nwhich Newton deduced from his law of gravitation, and which became one\nof the most serious and most dangerous dogmas of later physics, does\nnot afford the slightest explanation of the real causes of attraction;\nindeed, it long obstructed our way to the real discovery of them. I\ncannot but suspect that his speculations on this mysterious action at a\ndistance contributed not a little to the leading of the great English\nmathematician into the obscure labyrinth of mystic dreams and theistic\nsuperstition in which he passed the last thirty-four years of his\nlife; we find him, at the end, giving metaphysical hypotheses on the\npredictions of Daniel and on the paradoxical fantasies of St. John.\n\nIn fundamental opposition to the theory of vibration, or the kinetic\ntheory of substance, we have the modern \"theory of condensation,\"\nor the pyknotic theory of substance. It is most ably established\nin the suggestive work of J. C. Vogt on _The Nature of Electricity\nand Magnetism on the Basis of a Simplified Conception of Substance_\n(1891). Vogt assumes the primitive force of the world, the universal\n_prodynamis_, to be, not the vibration or oscillation of particles in\nempty space, but the condensation of a simple primitive substance,\nwhich fills the infinity of space in an unbroken continuity. Its\nsole inherent mechanical form of activity consists in a tendency to\ncondensation or contraction, which produces infinitesimal centres\nof condensation; these may change their degree of thickness, and,\ntherefore, their volume, but are constant as such. These minute parts\nof the universal substance, the centres of condensation, which might\nbe called _pyknatoms_, correspond in general to the ultimate separate\natoms of the kinetic theory; they differ, however, very considerably in\nthat they are credited with sensation and inclination (or will-movement\nof the simplest form), _with souls_, in a certain sense--in harmony\nwith the old theory of Empedocles of the \"love and hatred of the\nelements.\" Moreover, these \"atoms with souls\" do not float in empty\nspace, but in the continuous, extremely attenuated intermediate\nsubstance, which represents the uncondensed portion of the primitive\nmatter. By means of certain \"constellations, centres of perturbation,\nor systems of deformation,\" great masses of centres of condensation\nquickly unite in immense proportions, and so obtain a preponderance\nover the surrounding masses. By that process the primitive substance,\nwhich in its original state of quiescence had the same mean consistency\nthroughout, divides or differentiates into two kinds. The centres\nof disturbance, which _positively_ exceed the mean consistency in\nvirtue of the _pyknosis_ or condensation, form the ponderable matter\nof bodies; the finer, intermediate substance, which occupies the space\nbetween them, and _negatively_ falls below the mean consistency, forms\nthe ether, or imponderable matter. As a consequence of this division\ninto mass and ether there ensues a ceaseless struggle between the two\nantagonistic elements, and this struggle is the source of all physical\nprocesses. The positive ponderable matter, the element with the feeling\nof like or desire, is continually striving to complete the process of\ncondensation, and thus collecting an enormous amount of _potential_\nenergy; the negative, imponderable matter, on the other hand, offers a\nperpetual and equal resistance to the further increase of its strain\nand of the feeling of dislike connected therewith, and thus gathers the\nutmost amount of _actual_ energy.\n\nWe cannot go any further here into the details of the brilliant\ntheory of J. C. Vogt. The interested reader cannot do better than\nhave recourse to the second volume of the above work for a clear,\npopular exposition of the difficult problem. I am myself too little\ninformed in physics and mathematics to enter into a critical discussion\nof its lights and shades; still, I think that this pyknotic theory\nof substance will prove more acceptable to every biologist who is\nconvinced of the unity of nature than the kinetic theory which prevails\nin physics to-day. A misunderstanding may easily arise from the fact\nthat Vogt puts his process of condensation in explicit contradiction\nwith the general phenomenon of motion; but it must be remembered that\nhe is speaking of vibratory movement in the sense of the physicist. His\nhypothetical \"condensation\" is just as much determined by a movement\nof substance as is the hypothetical \"vibration\"; only the kind of\nmovement and the relation of the moving elements are very different in\nthe two hypotheses. Moreover, it is not the whole theory of vibration,\nbut only an important section of it, that is contradicted by the theory\nof condensation.\n\nModern physics, for the most part, still firmly adheres to the older\ntheory of vibration, to the idea of an _actio in distans_ and the\neternal vibration of dead atoms in empty space; it rejects the pyknotic\ntheory. Although Vogt's theory may be still far from perfect, and his\noriginal speculations may be marred by many errors, yet I think he has\nrendered a very good service in eliminating the untenable principles\nof the kinetic theory of substance. As to my own opinion--and that of\nmany other scientists--I must lay down the following theses, which\nare involved in Vogt's pyknotic theory, as indispensable for a truly\nmonistic view of substance, and one that covers the whole field of\norganic and inorganic nature:\n\nI. The two fundamental forms of substance, ponderable matter and ether,\nare not dead and only moved by extrinsic force, but they are endowed\nwith sensation and will (though, naturally, of the lowest grade); they\nexperience an inclination for condensation, a dislike of strain; they\nstrive after the one and struggle against the other.\n\nII. There is no such thing as empty space; that part of space which is\nnot occupied with ponderable atoms is filled with ether.\n\nIII. There is no such thing as an action at a distance through\nperfectly empty space; all action of bodies upon each other is either\ndetermined by immediate contact or is effected by the mediation of\nether.\n\nBoth the theories of substance which we have just contrasted are\n_monistic_ in principle, since the opposition between the two\nconditions of substance--mass and ether--is not original; moreover,\nthey involve a continuous immediate contact and reciprocal action\nof the two elements. It is otherwise with the _dualistic_ theories\nof substance which still obtain in the idealist and spiritualist\nphilosophy, and which have the support of a powerful theology, in so\nfar as theology indulges in such metaphysical speculations. These\ntheories draw a distinction between two entirely different kinds of\nsubstance, material and immaterial. Material substance enters into\nthe composition of the bodies which are the object of physics and\nchemistry; the law of the persistence of matter and force is confined\nto this world (apart from a belief in its \"creation from nothing\"\nand other miracles). Immaterial substance is found in the \"spiritual\nworld\" to which the law does not extend; in this province the laws\nof physics and chemistry are either entirely inapplicable or they\nare subordinated to a \"vital force,\" or a \"free will,\" or a \"divine\nomnipotence,\" or some other phantom which is beyond the ken of critical\nscience. In truth, these profound errors need no further refutation\nto-day, for experience has never yet discovered for us a single\nimmaterial substance, a single force which is not dependent on matter,\nor a single form of energy which is not exerted by material movement,\nwhether it be of mass, or of ether, or of both. Even the most elaborate\nand most perfect forms of energy that we know--the psychic life of\nthe higher animals, the thought and reason of man--depend on material\nprocesses, or changes in the neuroplasm of the ganglionic cells; they\nare inconceivable apart from such modifications. I have already shown\n(chap. xi.) that the physiological hypothesis of a special, immaterial\n\"soul-substance\" is untenable.\n\nThe study of ponderable matter is primarily the concern of chemistry.\nFew are ignorant of the astonishing theoretical progress which this\nscience has made in the course of the century and the immense practical\ninfluence it has had on every aspect of modern life. We shall confine\nourselves here to a few remarks on the more important questions\nwhich concern the nature of ponderable matter. It is well known that\nanalytical chemistry has succeeded in resolving the immense variety\nof bodies in nature into a small number of simple elements--that is,\nsimple bodies which are incapable of further analysis. The number of\nthese elements is about seventy. Only fourteen of them are widely\ndistributed on the earth and of much practical importance; the majority\nare rare elements (principally metals) of little practical moment. The\naffinity of these groups of elements, and the remarkable proportions of\ntheir atomic weights, which Lothar Meyer and Mendelejeff have proved\nin their _Periodic System of the Elements_, make it extremely probable\nthat they are not _absolute species_ of ponderable matter--that is,\nnot eternally unchangeable particles. The seventy elements have in\nthat system been distributed into eight leading groups, and arranged\nin them according to their atomic weight, so that the elements which\nhave a chemical affinity are formed into families. The relations of\nthe various groups in such a natural system of the elements recall,\non the one hand, similar relations of the innumerable compounds of\ncarbon, and, again, the relations of parallel groups in the natural\narrangement of the animal and plant species. Since in the latter\ncases the \"affinity\" of the related forms is based on descent from a\ncommon parent form, it seems very probable that the same holds good of\nthe families and orders of the chemical elements. We may, therefore,\nconclude that the \"empirical elements\" we now know are not really\nsimple, ultimate, and unchangeable forms of matter, but compounds\nof homogeneous, simple, primitive atoms, variously distributed as\nto number and grouping. The recent speculations of Gustav Wendt,\nWilhelm Preyer, Sir W. Crookes, and others, have pointed out how we\nmay conceive the evolution of the elements from a simple primitive\nmaterial, the _prothyl_.\n\nThe modern atomistic theory, which is regarded as an indispensable\ninstrument in chemistry to-day, must be carefully distinguished from\nthe old philosophic atomism which was taught more than two thousand\nyears ago by a group of distinguished thinkers of antiquity--Leucippus,\nDemocritus, and Epicurus: it was considerably developed and modified\nlater on by Descartes, Hobbes, Leibnitz, and other famous philosophers.\nBut it was not until 1808 that modern atomism assumed a definite and\nacceptable form, and was furnished with an empirical basis by Dalton,\nwho formulated the \"law of simple and multiple proportions\" in the\nformation of chemical combinations. He first determined the atomic\nweight of the different elements, and thus created the solid and exact\nfoundation on which more recent chemical theories are based; these\nare all _atomistic_, in the sense that they assume the elements to be\nmade up of homogeneous, infinitesimal, distinct particles, which are\nincapable of further analysis. That does not touch the question of the\nreal nature of the atoms--their form, size, psychology, etc. These\natomic qualities are merely hypothetical; while the _chemistry_ of the\natoms, their \"chemical affinity\"--that is, the constant proportion in\nwhich they combine with the atoms of other elements--is empirical.[25]\n\nThe different relation of the various elements towards each other,\nwhich chemistry calls \"affinity,\" is one of the most important\nproperties of ponderable matter; it is manifested in the different\nrelative quantities or proportions of their combination in the\nintensity of its consummation. Every shade of inclination, from\ncomplete indifference to the fiercest passion, is exemplified in the\nchemical relation of the various elements towards each other, just\nas we find in the psychology of man, and especially in the life of\nthe sexes. Goethe, in his classical romance, _Affinities_, compared\nthe relations of pairs of lovers with the phenomenon of the same name\nin the formation of chemical combinations. The irresistible passion\nthat draws Edward to the sympathetic Ottilia, or Paris to Helen, and\nleaps over all bounds of reason and morality, is the same powerful\n\"unconscious\" attractive force which impels the living spermatozoon to\nforce an entrance into the ovum in the fertilization of the egg of the\nanimal or plant--the same impetuous movement which unites two atoms\nof hydrogen to one atom of oxygen for the formation of a molecule of\nwater. This fundamental _unity of affinity in the whole of nature_,\nfrom the simplest chemical process to the most complicated love story,\nwas recognized by the great Greek scientist, Empedocles, in the fifth\ncentury B.C., in his theory of \"the love and hatred of the elements.\"\nIt receives empirical confirmation from the interesting progress of\ncellular psychology, the great significance of which we have only\nlearned to appreciate in the last thirty years. On those phenomena we\nbase our conviction that even the _atom_ is not without a rudimentary\nform of sensation and will, or as it is better expressed, of feeling\n(_aesthesis_) and inclination (_tropesis_)--that is, a universal \"soul\"\nof the simplest character. The same must be said of the molecules which\nare composed of two or more atoms. Further combinations of different\nkinds of these molecules give rise to simple and, subsequently, complex\nchemical compounds, in the activity of which the same phenomena are\nrepeated in a more complicated form.\n\nThe study of ether, or imponderable matter, pertains principally to\nphysics. The existence of an extremely attenuated medium, filling the\nwhole of space outside of ponderable matter, was known and applied\nto the elucidation of various phenomena (especially light) a long\ntime ago; but it was not until the second half of the nineteenth\ncentury that we became more closely acquainted with this remarkable\nsubstance, in connection with our astonishing empirical discoveries in\nthe province of electricity, with their experimental detection, their\ntheoretical interpretation, and their practical application. The path\nwas opened in particular by the famous researches of Heinrich Hertz, of\nBonn, in 1888. The premature death of a brilliant young physicist of so\nmuch promise cannot be sufficiently deplored. Like the premature death\nof Spinoza, Raphael, Schubert, and many other great men, it is one of\nthose brutal facts of human history which are enough of themselves to\ndestroy the untenable myth of a \"wise Providence\" and an \"All-loving\nFather in heaven.\"\n\nThe existence of ether (or cosmic ether) as a real element is a\n_positive fact_, and has been known as such for the last twelve years.\nWe sometimes read even to-day that ether is a \"pure hypothesis\";\nthis erroneous assertion comes not only from uninformed philosophers\nand \"popular\" writers, but even from certain \"prudent and exact\nphysicists.\" But there would be just as much reason to deny the\nexistence of ponderable matter. As a matter of fact, there are\nmetaphysicians who accomplish even this feat, and whose highest wisdom\nlies in denying or calling into question the existence of an external\nuniverse; according to them only one real entity exists--their own\nprecious personality, or, to be more correct, their immortal soul.\nSeveral modern physiologists have embraced this ultra-idealist view,\nwhich is to be found in Descartes, Berkeley, Fichte, and others.\nTheir \"psycho-monism\" affirms: \"One thing only exists, and that is\nmy own mind.\" This audacious spiritualism seems to us to rest on an\nerroneous inference from Kant's correct critical theory, that we can\nknow the outer world only in the phenomenal aspect which is accessible\nto our human organs of thought--the brain and the organs of sense. If\nby those means we can attain only an imperfect and limited knowledge\nof the material world, that is no reason for denying its existence\naltogether. In my opinion, the existence of ether is as certain as that\nof ponderable matter--as certain as my own existence, as I reflect and\nwrite on it. As we assure ourselves of the existence of ponderable\nmatter by its mass and weight, by chemical and mechanical experiments,\nso we prove that of ether by the experiences and experiments of optics\nand electricity.\n\nAlthough, however, the existence of ether is now regarded as a\npositive fact by nearly all physicists, and although many effects of\nthis remarkable substance are familiar to us through an extensive\nexperience, especially in the way of optical and electrical experiments,\nyet we are still far from being clear and confident as to its real\ncharacter. The views of the most eminent physicists, who have made\na special study of it, are extremely divergent; they frequently\ncontradict each other on the most important points. One is, therefore,\nfree to choose among the contradictory hypotheses according to one's\nknowledge and judgment. I will put in the following eight theses the\nview which has approved itself to me after mature reflection on the\nsubject, though I am no expert in this department:\n\nI. Ether fills the whole of space, in so far as it is not occupied by\nponderable matter, as a _continuous substance_; it fully occupies the\nspace between the atoms of ponderable matter.\n\nII. Ether has probably no chemical quality, and is not composed of\natoms. If it be supposed that it consists of minute homogeneous atoms\n(for instance, indivisible etheric particles of a uniform size), it\nmust be further supposed that there is something else between these\natoms, either \"empty space\" or a third, completely unknown medium, a\npurely hypothetical \"interether\"; the question as to the nature of this\nbrings us back to the original difficulty, and so on _in infinitum_.\n\nIII. As the idea of an empty space and an action at a distance is\nscarcely possible in the present condition of our knowledge (at least\nit does not help to a clear monistic view), I postulate for ether a\nspecial structure which is not atomistic, like that of ponderable\nmatter, and which may provisionally be called (without further\ndetermination) _etheric_ or _dynamic_ structure.\n\nIV. The consistency of ether is also peculiar, on our hypothesis, and\ndifferent from that of ponderable matter. It is neither gaseous, as\nsome conceive, nor solid, as others suppose; the best idea of it can be\nformed by comparison with an extremely attenuated, elastic, and light\njelly.\n\nV. Ether may be called _imponderable_ matter in the sense that we\nhave no means of determining its weight experimentally. If it really\nhas weight, as is very probable, it must be so slight as to be far\nbelow the capacity of our most delicate balance. Some physicists have\nattempted to determine its weight by the energy of the light-waves, and\nhave discovered that it is some fifteen trillion times lighter than\natmospheric air; on that hypothesis a sphere of ether of the size of\nour earth would weigh at least two hundred and fifty pounds(?).\n\nVI. The etheric consistency may probably (in accordance with the\npyknotic theory) pass into the gaseous state under certain conditions\nby progressive condensation, just as a gas may be converted into a\nfluid, and ultimately into a solid, by lowering its temperature.\n\nVII. Consequently, these three conditions of matter may be arranged\n(and it is a point of great importance in our monistic cosmogony) in a\ngenetic, continuous order. We may distinguish five stages in it: (1)\nthe etheric, (2) the gaseous, (3) the fluid, (4) the viscous (in the\nliving protoplasm), and (5) the solid state.\n\nVIII. Ether is boundless and immeasurable, like the space it occupies.\nIt is in eternal motion; and this specific movement of ether (it is\nimmaterial whether we conceive it as vibration, strain, condensation,\netc.), in reciprocal action with mass-movement (or gravitation), is the\nultimate cause of all phenomena.\n\n\"The great question of the nature of ether,\" as Hertz justly calls\nit, includes the question of its relation to ponderable matter; for\nthese two forms of matter are not only always in the closest external\ncontact, but also in eternal, dynamic, reciprocal action. We may divide\nthe most general phenomena of nature, which are distinguished by\nphysics as natural forces or \"functions of matter,\" into two groups;\nthe first of them may be regarded mainly (though not exclusively) as a\nfunction of ether, and the second a function of ponderable matter--as\nin the following scheme which I take from my _Monism_:\n\n THE WORLD (NATURE, OR THE COSMOS)\n\n ---------------------------------+-------------------------------------\n  ETHER--Imponderable.            | MASS--Ponderable.\n ---------------------------------+-------------------------------------\n                                  |\n 1. _Consistency_:                | 1. _Consistency_:\n                                  |\n Etheric (_i.e._, neither         | Not etheric (but gaseous, fluid,\n gaseous nor fluid, nor solid).   | or solid).\n                                  |\n 2. _Structure_:                  | 2. _Structure_:\n                                  |\n Not atomistic, not made up of    | Atomistic, made up of infinitesimal,\n separate particles (atoms), but  | distinct particles (atoms)\n continuous.                      | discontinuous.\n                                  |\n 3. _Chief Functions_:            | 3. _Chief Functions_:\n                                  |\n Light, radiant heat, electricity,| Gravity, inertia, molecular heat,\n and magnetism.                   | and chemical affinity.\n ---------------------------------+-------------------------------------\n\nThe two groups of functions of matter, which we have opposed in this\ntable, may, to some extent, be regarded as the outcome of the first\n\"division of labor\" in the development of matter, the \"primary ergonomy\nof matter.\" But this distinction must not be supposed to involve an\nabsolute separation of the two antithetic groups; they always retain\ntheir connection, and are in constant reciprocal action. It is well\nknown that the optical and electrical phenomena of ether are closely\nconnected with mechanical and chemical changes in ponderable elements;\nthe radiant heat of ether may be directly converted into the mechanical\nheat of the mass; gravitation is impossible unless the ether effects\nthe mutual attraction of the separated atoms, because we cannot admit\nthe idea of an _actio in distans_. In like manner, the conversion\nof one form of energy into another, as indicated in the law of the\npersistence of force, illustrates the constant reciprocity of the two\nchief types of substance, ether and mass.\n\nThe great law of nature, which, under the title of the \"law of\nsubstance,\" we put at the head of all physical considerations, was\nconceived as the law of \"the persistence of force\" by Robert Meyer, who\nfirst formulated it, and Helmholtz, who continued the work. Another\nGerman scientist, Friedrich Mohr, of Bonn, had clearly outlined it in\nits main features ten years earlier (1837). The old idea of _force_\nwas, after a time, differentiated by modern physics from that of\n_energy_, which was at first synonymous with it. Hence the law is\nnow usually called the \"law of the persistence of energy.\" However,\nthis finer distinction need not enter into the general consideration,\nto which I must confine myself here, and into the question of the\ngreat principle of the \"persistence of substance.\" The interested\nreader will find a very clear treatment of the question in Tyndall's\nexcellent paper on \"The Fundamental Law of Nature,\" in his _Fragments\nof Science_. It fully explains the broad significance of this profound\ncosmic law, and points out its application to the main problems of\nvery different branches of science. We shall confine our attention to\nthe important fact that the \"principle of energy\" and the correlative\nidea of the unity of natural forces, on the basis of a common origin,\nare now accepted by all competent physicists, and are regarded as the\ngreatest advance of physics in the nineteenth century. We now know that\nheat, sound, light, chemical action, electricity, and magnetism are all\nmodes of motion. We can, by a certain apparatus, convert any one of\nthese forces into another, and prove by an accurate measurement that\nnot a single particle of energy is lost in the process.\n\nThe sum-total of force or energy in the universe remains constant, no\nmatter what changes take place around us; it is eternal and infinite,\nlike the matter on which it is inseparably dependent. The whole drama\nof nature apparently consists in an alternation of movement and\nrepose; yet the bodies at rest have an inalienable quantity of force,\njust as truly as those that are in motion. It is in this movement\nthat the potential energy of the former is converted into the kinetic\nenergy of the latter. \"As the principle of the persistence of force\ntakes into account repulsion as well as attraction, it affirms that\nthe mechanical value of the potential energy and the kinetic energy\nin the material world is a constant quantity. To put it briefly, the\nforce of the universe is divided into two parts, which may be mutually\nconverted, according to a fixed relation of value. The diminution of\nthe one involves the increase of the other; the total value remains\nunchanged in the universe.\" The potential energy and the actual, or\nkinetic, energy are being continually transformed from one condition to\nthe other; but the infinite sum of force in the world at large never\nsuffers the slightest curtailment.\n\nOnce modern physics had established the law of substance as far as\nthe simpler relations of inorganic bodies are concerned, physiology\ntook up the story, and proved its application to the entire province\nof the organic world. It showed that all the vital activities of the\norganism--without exception--are based on a constant \"reciprocity\nof force\" and a correlative change of material, or metabolism, just\nas much as the simplest processes in \"lifeless\" bodies. Not only\nthe growth and the nutrition of plants and animals, but even their\nfunctions of sensation and movement, their sense-action and psychic\nlife, depend on the conversion of potential into kinetic energy,\nand _vice vers\u00e2_. This supreme law dominates also those elaborate\nperformances of the nervous system which we call, in the higher animals\nand man, \"the action of the mind.\"\n\nOur monistic view, that the great cosmic law applies throughout the\nwhole of nature, is of the highest moment. For it not only involves,\non its positive side, the essential unity of the cosmos and the\ncausal connection of all phenomena that come within our cognizance,\nbut it also, in a negative way, marks the highest intellectual\nprogress, in that it definitely rules out the three central dogmas of\nmetaphysics--God, freedom, and immortality. In assigning mechanical\ncauses to phenomena everywhere, the law of substance comes into line\nwith the universal law of causality.\n\n\n\n\nCHAPTER XIII\n\nTHE EVOLUTION OF THE WORLD\n\n    The Notion of Creation--Miracles--Creation of the Whole Universe\n    and of its Various Parts--Creation of Substance (Cosmological\n    Creation)--Deism: One Creative Day--Creation of Separate\n    Entities--Five Forms of Ontological Creationism--Theory of\n    Evolution--I. Monistic Cosmogony--Beginning and End of the\n    World--The Infinity and Eternity of the Universe--Space and\n    Time--_Universum perpetuum mobile_--Entropy of the Universe--II.\n    Monistic Geogeny--History of the Inorganic and Organic Worlds--III.\n    Monistic Biogeny--Transformism and the Theory of Descent: Lamarck\n    and Darwin--IV. Monistic Anthropogeny--Origin of Man\n\n\nThe greatest, vastest, and most difficult of all cosmic problems is\nthat of the origin and development of the world--the \"question of\ncreation,\" in a word. Even to the solution of this most difficult\nworld-riddle the nineteenth century has contributed more than all its\npredecessors; in a certain sense, indeed, it has found the solution. We\nhave at least attained to a clear view of the fact that all the partial\nquestions of creation are indivisibly connected, that they represent\none single, comprehensive \"cosmic problem,\" and that the key to this\nproblem is found in the one magic word--evolution. The great questions\nof the creation of man, the creation of the animals and plants, the\ncreation of the earth and the sun, etc., are all parts of the general\nquestion, What is the origin of the whole world? Has it been _created_\nby supernatural power, or has it been _evolved_ by a natural process?\nWhat are the causes and the manner of this evolution? If we succeed\nin finding the correct answer to one of these questions, we have,\naccording to our monistic conception of the world, cast a brilliant\nlight on the solution of them all, and on the entire cosmic problem.\n\nThe current opinion as to the origin of the world in earlier ages was\nalmost a universal belief in creation. This belief has been expressed\nin thousands of interesting, more or less fabulous, legends, poems,\ncosmogonies, and myths. A few great philosophers were devoid of it,\nespecially those remarkable free-thinkers of classical antiquity who\nfirst conceived the idea of natural evolution. All the creation-myths,\non the contrary, were of a supernatural, miraculous, and transcendental\ncharacter. Incompetent, as it was, to investigate for itself the\nnature of the world and its origin by natural causes, the undeveloped\nmind naturally had recourse to the idea of miracle. In most of these\ncreation-myths _anthropism_ was blended with the belief in the\nmiraculous. The creator was supposed to have constructed the world on a\ndefinite plan, just as man accomplishes his artificial constructions;\nthe conception of the creator was generally completely anthropomorphic,\na palpable \"anthropistic creationism.\" The \"all-mighty maker of heaven\nand earth,\" as he is called in Genesis and the Catechism, is just as\nhumanly conceived as the modern creator of Agassiz and Reinke, or the\nintelligent \"engineer\" of other recent biologists.\n\nEntering more fully into the notion of creation, we can distinguish\nas two entirely different acts the production of the universe as a\nwhole and the partial production of its various parts, in harmony with\nSpinoza's idea of _substance_ (the universe) and _accidents_ (or\n_modes_, the individual phenomena of substance). This distinction is of\ngreat importance, because there are many eminent philosophers who admit\nthe one and reject the other.\n\nAccording to this creationist theory, then, God has \"made the world\nout of nothing.\" It is supposed that God (a rational, but immaterial,\nbeing) existed by himself for an eternity before he resolved to create\nthe world. Some supporters of the theory restrict God's creative\nfunction to one single act; they believe that this extramundane God\n(the rest of whose life is shrouded in mystery) created the substance\nof the world in a single moment, endowed it with the faculty of\nthe most extensive evolution, and troubled no further about it.\nThis view may be found, for instance, in the English Deists in many\nforms. It approaches very close to our monistic theory of evolution,\nonly abandoning it in the one instant in which God accomplished the\ncreation. Other creationists contend that God did not confine himself\nto the mere creation of matter, but that he continues to be operative\nas the \"sustainer and ruler of the world.\" Different modifications of\nthis belief are found, some approaching very close to _pantheism_ and\nothers to complete _theism_. All these and similar forms of belief in\ncreation are incompatible with the law of the persistence of matter and\nforce; that law knows nothing of a beginning.\n\nIt is interesting to note that E. du Bois-Reymond has identified\nhimself with this cosmological creationism in his latest speech\n(on \"Neovitalism,\" 1894). \"It is more consonant with the divine\nomnipotence,\" he says, \"to assume that it created the whole material\nof the world in one creative act unthinkable ages ago in such\nwise that it should be endowed with inviolable laws to control the\norigin and the progress of living things--that, for instance, here\non earth rudimentary organisms should arise from which, without\nfurther assistance, the whole of living nature could be evolved, from\na primitive bacillus to the graceful palm-wood, from a primitive\nmicrococcus to Solomon's lovely wives or to the brain of Newton.\nThus we are content with _one_ creative day, and we derive organic\nnature mechanically, without the aid of either old or new vitalism.\"\nDu Bois-Reymond here shows, as in the question of consciousness, the\nshallow and illogical character of his monistic thought.\n\nAccording to another still prevalent theory, which may be called\n\"ontological creationism,\" God not only created the world at large,\nbut also its separate contents. In the Christian world the old Semitic\nlegend of creation, taken from Genesis, is still very widely accepted;\neven among modern scientists it finds an adherent here and there. I\nhave fully entered into the criticism of it in the first chapter of my\n_Natural History of Creation_. The following theories may be enumerated\nas the most interesting modifications of this ontological creationism:\n\nI. _Dualistic creation._--God restricted his interference to _two_\ncreative acts. First he created the inorganic world, mere dead\nsubstance, to which alone the law of energy applies, working blindly\nand aimlessly in the mechanism of material things and the building of\nthe mountains; then God attained intelligence and communicated it to\nthe purposive intelligent forces which initiate and control organic\nevolution.[26]\n\nII. _Trialistic creation._--God made the world in _three_ creative\nacts: (_a_) the creation of the heavens--the extra-terrestrial world,\n(_b_) the creation of the earth (as the centre of the world) and of\nits living inhabitants, and (_c_) the creation of man (in the image\nand likeness of God). This dogma is still widely prevalent among\ntheologians and other \"educated\" people; it is taught as the truth in\nmany of our schools.\n\nIII. _Heptameral creation_; a creation in seven days (_teste_\nMoses).--Although few educated people really believe in this Mosaic\nmyth now, it is still firmly impressed on our children in the biblical\nlessons of their earliest years. The numerous attempts that have been\nmade, especially in England, to harmonize it with the modern theory of\nevolution have entirely failed. It obtained some importance in science\nwhen Linn\u00e9 adopted it in the establishment of his system, and based his\ndefinition of organic species (which he considered to be unchangeable)\non it: \"There are as many different species of animals and plants as\nthere were different forms created in the beginning by the Infinite.\"\nThis dogma was pretty generally held until the time of Darwin (1859),\nalthough Lamarck had already proved its untenability in 1809.\n\nIV. _Periodic creation._--At the beginning of each period of the\nearth's history the whole population of animals and plants was created\nanew, and destroyed by a general catastrophe at its close; there were\nas many general creative acts as there are distinct geological periods\n(the catastrophic theory of Cuvier [1818] and Louis Agassiz [1858]).\nPal\u00e6ontology, which seemed to support this theory in its more imperfect\nstage, has since completely refuted it.\n\nV. _Individual creation._--Every single man--and every individual\nanimal and plant--does not arise by a natural process of growth, but\nis created by the favor of God. This view of creation is still often\nmet with in journals, especially in the \"births\" column. The special\ntalents and features of our children are often gratefully acknowledged\nto be \"gifts of God\"; their hereditary defects fit into another theory.\n\nThe error of these creation-legends and the cognate belief in miracles\nmust have been apparent to thoughtful minds at an early period; more\nthan two thousand years ago we find that many attempts were made\nto replace them by a rational theory, and to explain the origin of\nthe world by natural causes. In the front rank, once more, we must\nplace the leaders of the Ionic school, with Democritus, Heraclitus,\nEmpedocles, Aristotle, Lucretius, and other ancient philosophers. The\nfirst imperfect attempts which they made astonish us, in a measure,\nby the flashes of mental light in which they anticipate modern ideas.\nIt must be remembered that classical antiquity had not that solid\ngroundwork for scientific speculation which has been provided by the\ncountless observations and experiments of modern scientists. During the\nMiddle Ages--especially during the domination of the papacy--scientific\nwork in this direction entirely ceased. The torture and the stake of\nthe Inquisition insured that an unconditional belief in the Hebrew\nmythology should be the final answer to all the questions of creation.\nEven the phenomena which led directly to the observation of the _facts_\nof evolution--the embryology of the plant and the animal, and of\nman--remained unnoticed, or only excited the interest of an occasional\nkeen observer; but their discoveries were ignored or forgotten.\nMoreover, the path to a correct knowledge of natural development was\nbarred by the dominant theory of preformation, the dogma which held\nthat the characteristic form and structure of each animal and plant\nwere already sketched in miniature in the germ (cf. p. 54).\n\nThe science which we now call the science of evolution (in the broadest\nsense) is, both in its general outline and in its separate parts,\na child of the nineteenth century; it is one of its most momentous\nand most brilliant achievements. Almost unknown in the preceding\ncentury, this theory has now become the sure foundation of our whole\nworld-system. I have treated it exhaustively in my _General Morphology_\n(1866), more popularly in my _Natural History of Creation_ (1868), and\nin its special application to man in my _Anthropogeny_ (1874). Here I\nshall restrict myself to a brief survey of the chief advances which\nthe science has made in the course of the century. It falls into four\nsections, according to the nature of its object; that is, it deals with\nthe natural origin of (1) the cosmos, (2) the earth, (3) terrestrial\nforms of life, and (4) man.\n\n\nI.--MONISTIC COSMOGONY\n\nThe first attempt to explain the constitution and the mechanical\norigin of the world in a simple manner by \"Newtonian laws\"--that is,\nby mathematical and physical laws--was made by Immanuel Kant in the\nfamous work of his youth (1755), _General History of the Earth and\nTheory of the Heavens_. Unfortunately, this distinguished and daring\nwork remained almost unknown for ninety years; it was only disinterred\nin 1845 by Alexander Humboldt in the first volume of his _Cosmos_. In\nthe mean time the great French mathematician, Pierre Laplace, had\narrived independently at similar views to those of Kant, and he gave\nthem a mathematical foundation in his _Exposition du Syst\u00e8me du Monde_\n(1796). His chief work, the _M\u00e9canique C\u00e9leste_, appeared a hundred\nyears ago. The analogous features of the cosmogony of Kant and Laplace\nconsist, as is well known, in a mechanical explanation of the movements\nof the planets, and the conclusion which is drawn therefrom, that all\nthe cosmic bodies were formed originally by a condensation of rotating\nnebulous spheres. This \"nebular hypothesis\" has been much improved\nand supplemented since, but it is still the best of all the attempts\nto explain the origin of the world on monistic and mechanical lines.\nIt has recently been strongly confirmed and enlarged by the theory\nthat this cosmogonic process did not simply take place once, but is\nperiodically repeated. While new cosmic bodies arise and develop out\nof rotating masses of nebula in some parts of the universe, in other\nparts old, extinct, frigid suns come into collision, and are once more\nreduced by the heat generated to the condition of nebul\u00e6.\n\nNearly all the older and the more recent cosmogonies, including most\nof those which were inspired by Kant and Laplace, started from the\npopular idea that the world had had a beginning. Hence, according to\na widespread version of the nebular hypothesis, \"in the beginning\"\nwas made a vast nebula of infinitely attenuated and light material,\nand at a certain moment (\"countless ages ago\") a movement of rotation\nwas imparted to this mass. Given this \"first beginning\" of the\ncosmogonic movement, it is easy, on mechanical principles, to deduce\nand mathematically establish the further phenomena of the formation of\nthe cosmic bodies, the separation of the planets, and so forth. This\nfirst \"origin of movement\" is Du Bois-Reymond's second \"world-enigma\";\nhe regards it as transcendental. Many other scientists and philosophers\nare equally helpless before this difficulty; they resign themselves to\nthe notion that we have here a primary \"supernatural impetus\" to the\nscheme of things, a \"miracle.\"\n\nIn our opinion, this second \"world-enigma\" is solved by the recognition\nthat movement is as innate and original a property of substance as\nis sensation. The proof of this monistic assumption is found, first,\nin the law of substance, and, secondly, in the discoveries which\nastronomy and physics have made in the latter half of the century. By\nthe spectral analysis of Bunsen and Kirchhoff (1860) we have found, not\nonly that the millions of bodies, which fill the infinity of space, are\nof the same material as our own sun and earth, but also that they are\nin various stages of evolution; we have obtained by its aid information\nas to the movements and distances of the stars, which the telescope\nwould never have given us. Moreover, the telescope itself has been\nvastly improved, and has, in alliance with photography, made a host\nof scientific discoveries of which no one dreamed at the beginning\nof the century. In particular, a closer acquaintance with comets,\nmeteorites, star-clusters, and nebul\u00e6 has helped us to realize the\ngreat significance of the smaller bodies which are found in millions in\nthe space between the stars.\n\nWe now know that the _paths_ of the millions of heavenly bodies are\n_changeable_, and to some extent irregular, whereas the planetary\nsystem was formerly thought to be constant, and the rotating spheres\nwere described as pursuing their orbits in eternal regularity.\nAstro-physics owes much of its triumph to the immense progress of other\nbranches of physics, of optics, and electricity, and especially of\nthe theory of ether. And here, again, our supreme law of substance is\nfound to be one of the most valuable achievements of modern science.\nWe now know that it rules unconditionally in the most distant reaches\nof space, just as it does in our planetary system, in the most minute\nparticle of the earth as well as in the smallest cell of our human\nframe. We are, moreover, justified in concluding, if we are not\nlogically compelled to conclude, that the persistence of matter and\nforce has held good throughout all time as it does to-day. Through all\neternity the infinite universe has been, and is, subject to the law of\nsubstance.\n\nFrom this great progress of astronomy and physics, which mutually\nelucidate and supplement each other, we draw a series of most important\nconclusions with regard to the constitution and evolution of the\ncosmos, and the persistence and transformation of substance. Let us put\nthem briefly in the following theses:\n\nI. The _extent_ of the universe is infinite and unbounded; it is empty\nin no part, but everywhere filled with substance.\n\nII. The _duration_ of the world is equally infinite and unbounded; it\nhas no beginning and no end: it is eternity.\n\nIII. Substance is everywhere and always in uninterrupted movement and\ntransformation: nowhere is there perfect repose and rigidity; yet the\ninfinite quantity of matter and of eternally changing force remains\nconstant.\n\nIV. This universal movement of substance in space takes the form of an\neternal cycle or of a periodical process of evolution.\n\nV. The phases of this evolution consist in a periodic change of\nconsistency, of which the first outcome is the primary division into\nmass and ether--the ergonomy of ponderable and imponderable matter.\n\nVI. This division is effected by a progressive condensation of matter\nas the formation of countless infinitesimal \"centres of condensation,\"\nin which the inherent primitive properties of substance--feeling and\ninclination--are the active causes.\n\nVII. While minute and then larger bodies are being formed by this\npyknotic process in one part of space, and the intermediate ether\nincreases its strain, the opposite process--the destruction of cosmic\nbodies by collision--is taking place in another quarter.\n\nVIII. The immense quantity of heat which is generated in this\nmechanical process of the collision of swiftly moving bodies represents\nthe new kinetic energy which effects the movement of the resultant\nnebul\u00e6 and the construction of new rotating bodies. The eternal drama\nbegins afresh. Even our mother earth, which was formed of part of the\ngyrating solar system millions of ages ago, will grow cold and lifeless\nafter the lapse of further millions, and, gradually narrowing its\norbit, will fall eventually into the sun.\n\nIt seems to me that these modern discoveries as to the periodic decay\nand re-birth of cosmic bodies, which we owe to the most recent advance\nof physics and astronomy, associated with the law of substance, are\nespecially important in giving us a clear insight into the universal\ncosmic process of evolution. In their light our earth shrinks into the\nslender proportions of a \"mote in the sunbeam,\" of which unnumbered\nmillions chase each other through the vast depths of space. Our own\n\"human nature,\" which exalted itself into an image of God in its\nanthropistic illusion, sinks to the level of a placental mammal, which\nhas no more value for the universe at large than the ant, the fly of\na summer's day, the microscopic infusorium, or the smallest bacillus.\nHumanity is but a transitory phase of the evolution of an eternal\nsubstance, a particular phenomenal form of matter and energy, the true\nproportion of which we soon perceive when we set it on the background\nof infinite space and eternal time.\n\nSince Kant explained space and time to be merely \"forms of\nperception\"--space the form of external, time of internal,\nsensitivity--there has been a keen controversy, which still continues,\nover this important problem. A large section of modern metaphysicians\nhave persuaded themselves that this \"critical fact\" possesses a great\nimportance as the starting-point of \"a purely idealist theory of\nknowledge,\" and that, consequently, the natural opinion of the ordinary\nhealthy mind as to the _reality_ of time and space is swept aside. This\nnarrow and ultra-idealist conception of time and space has become a\nprolific source of error. It overlooks the fact that Kant only touched\none side of the problem, the _subjective_ side, in that theory, and\nrecognized the equal validity of its _objective_ side. \"Time and\nspace,\" he said, \"have empirical reality, but transcendental ideality.\"\nOur modern monism is quite compatible with this thesis of Kant's,\nbut not with the one-sided exaggeration of the subjective aspect of\nthe problem; the latter leads logically to the absurd idealism that\nculminates in Berkeley's thesis, \"Bodies are but ideas; their essence\nis in their perception.\" The thesis should be read thus: \"Bodies are\nonly ideas for my personal consciousness; their existence is just\nas real as that of my organs of thought, the ganglionic cells in\nthe gray bed of my brain, which receive the impress of bodies on my\nsense-organs and form those ideas by association of the impressions.\" It\nis just as easy to doubt or to deny the reality of my own consciousness\nas to doubt that of time and space. In the delirium of fever, in\nhallucinations, in dreams, and in double-consciousness, I take ideas\nto be true which are merely fancies. I mistake my own personality for\nanother (_vide_ p. 185); Descartes' famous _Cogito ergo sum_ applies no\nlonger. On the other hand, the reality of time and space is now fully\nestablished by that expansion of our philosophy which we owe to the\nlaw of substance and to our monistic cosmogony. When we have happily\ngot rid of the untenable idea of \"empty space,\" there remains as the\ninfinite \"space-filling\"-medium matter, in its two forms of ether and\nmass. So also we find a \"time-filling\" event in the eternal movement,\nor genetic energy, which reveals itself in the uninterrupted evolution\nof substance, in the _perpetuum mobile_ of the universe.\n\nAs a body which has been set in motion continues to move as long as no\nexternal agency interferes with it, the idea was conceived long ago of\nconstructing an apparatus which should illustrate perpetual motion. The\nfact was overlooked that every movement meets with external impediments\nand gradually ceases, unless a new impetus is given to it from without\nand a new force is introduced to counteract the impediments. Thus, for\ninstance, a pendulum would swing backward and forward for an eternity\nat the same speed if the resistance of the atmosphere and the friction\nat the point it hangs from did not gradually deprive it of the\nmechanical kinetic energy of its motion and convert it into heat. We\nhave to furnish it with fresh mechanical energy by a spring (or, as in\nthe pendulum-clock, by the drag of a weight). Hence it is impossible to\nconstruct a machine that would produce, without external aid, a surplus\nof energy by which it could keep itself going. Every attempt to make\nsuch a _perpetuum mobile_ must necessarily fail; the discovery of the\nlaw of substance showed, in addition, the theoretical impossibility of\nit.\n\nThe case is different, however, when we turn to the world at large, the\nboundless universe that is in eternal movement. The infinite matter,\nwhich fills it objectively, is what we call _space_ in our subjective\nimpression of it; _time_ is our subjective conception of its eternal\nmovement, which is, objectively, a periodic, cyclic evolution. These\ntwo \"forms of perception\" teach us the infinity and eternity of the\nuniverse. That is, moreover, equal to saying that the universe itself\nis a _perpetuum mobile_. This infinite and eternal \"machine of the\nuniverse\" sustains itself in eternal and uninterrupted movement,\nbecause every impediment is compensated by an \"equivalence of energy,\"\nand the unlimited sum of kinetic and potential energy remains always\nthe same. The law of the persistence of force proves also that the idea\nof a _perpetuum mobile_ is just as applicable to, and as significant\nfor, the cosmos as a whole as it is impossible for the isolated action\nof any part of it. Hence the theory of _entropy_ is likewise untenable.\n\nThe able founder of the mechanical theory of heat (1850), Clausius,\nembodied the momentous contents of this important theory in two theses.\nThe first runs: \"The energy of the universe is constant\"--that is\none-half of our law of substance, the principle of energy (_vide_ p.\n230). The second thesis is: \"The energy of the universe tends towards\na maximum.\" In my opinion this second assertion is just as erroneous\nas the first is true. In the theory of Clausius the entire energy of\nthe universe is of two kinds, one of which (heat of the higher degree,\nmechanical, electrical, chemical energy, etc.) is partly convertible\ninto work, but the other is not; the latter energy, already converted\ninto heat and distributed in the cooler masses, is irrevocably lost as\nfar as any further work is concerned. Clausius calls this unconsumed\nenergy, which is no longer available for mechanical work, _entropy_\n(that is, force that is directed _inward_); it is continually\nincreasing at the cost of the other half. As, therefore, the mechanical\nenergy of the universe is daily being transformed into heat, and this\ncannot be reconverted into mechanical force, the sum of heat and energy\nin the universe must continually tend to be reduced and dissipated. All\ndifference of temperature must ultimately disappear, and the completely\nlatent heat must be equally distributed through one inert mass of\nmotionless matter. All organic life and movement must cease when this\nmaximum of _entropy_ has been reached. That would be a real \"end of the\nworld.\"\n\nIf this theory of entropy were true, we should have a \"beginning\"\ncorresponding to this assumed \"end\" of the world--a minimum of\nentropy, in which the differences in temperature of the various parts\nof the cosmos would be at a maximum. Both ideas are quite untenable\nin the light of our monistic and consistent theory of the eternal\ncosmogenetic process; both contradict the law of substance. There is\nneither beginning nor end of the world. The universe is infinite, and\neternally in motion; the conversion of kinetic into potential energy,\nand _vicissim_, goes on uninterruptedly; and the sum of this actual and\npotential energy remains constant. The second thesis of the mechanical\ntheory of heat contradicts the first, and so must be rejected.\n\nThe representatives of the theory of entropy are quite correct as long\nas they confine themselves to distinct processes, in which, _under\ncertain conditions_, the latent heat cannot be reconverted into work.\nThus, for instance, in the steam-engine the heat can only be converted\ninto mechanical work when it passes from a warmer body (steam) into a\ncooler (water); the process cannot be reversed. In the world at large,\nhowever, quite other conditions obtain--conditions which permit the\nreconversion of latent heat into mechanical work. For instance, in the\ncollision of two heavenly bodies, which rush towards each other at\ninconceivable speed, enormous quantities of heat are liberated, while\nthe pulverized masses are hurled and scattered about space. The eternal\ndrama begins afresh--the rotating mass, the condensation of its parts,\nthe formation of new meteorites, their combination into larger bodies,\nand so on.\n\n\nII.--MONISTIC GEOGENY\n\nThe history of the earth, of which we are now going to make a brief\nsurvey, is only a minute section of the history of the cosmos. Like\nthe latter, it has been the object of philosophic speculation and\nmythological fantasy for many thousand years. Its true scientific\nstudy, however, is much younger; it belongs, for the most part, to\nthe nineteenth century. The fact that the earth is a planet revolving\nround the sun was determined by the system of Copernicus (1543);\nGalilei, Kepler, and other great astronomers, mathematically determined\nits distance from the sun, the laws of its motion, and so forth.\nKant and Laplace indicated, in their cosmogony, the way in which the\nearth had been developed from the parent sun. But the later history\nof the earth, the formation of its crust, the origin of its seas and\ncontinents, its mountains and deserts, was rarely made the subject\nof serious scientific research in the eighteenth century, and in the\nfirst two decades of the nineteenth. As a rule, men were satisfied with\nunreliable conjectures or with the traditional story of creation; once\nmore the Mosaic legend barred the way to an independent investigation.\n\nIn 1822 an important work appeared, which followed the same method\nin the scientific investigation of the history of the earth that\nhad already proved the most fertile--the _ontological_ method, or\nthe principle of \"actualism.\" It consists in a careful study and\nmanipulation of _actual_ phenomena with a view to the elucidation of\nthe analogous historical processes of the past. The Society of Science\nat G\u00f6ttingen had offered a prize in 1818 for \"the most searching and\ncomprehensive inquiry into the changes in the earth's crust which are\nhistorically demonstrable, and the application which may be made of a\nknowledge of them in the investigation of the terrestrial revolutions\nwhich lie beyond the range of history.\" This prize was obtained by Karl\nHoff, of Gotha, for his distinguished work, _History of the Natural\nChanges in the Crust of the Earth in the Light of Tradition_ (1822-34).\nSir Charles Lyell then applied this _ontological_ or _actualistic_\nmethod with great success to the whole province of geology; his\n_Principles of Geology_ (1830) laid the firm foundation on which\nthe fabric of the history of the earth was so happily erected. The\nimportant geogenetic research of Alexander Humboldt, Leopold Buch,\nGustav Bischof, Edward S\u00fcss, and other geologists, were wholly based\non the empirical foundation and the speculative principles of Karl\nHoff and Charles Lyell. They cleared the way for purely rational\nscience in the field of geology; they removed the obstacles that had\nbeen put in the path by mythological fancy and religious tradition,\nespecially by the Bible and its legends. I have already discussed the\nmerits of Lyell, and his relations with his friend Charles Darwin,\nin the sixteenth and seventeenth chapters of my _Natural History of\nCreation_, and must refer the reader to the standard works on geology\nfor a further acquaintance with the history of the earth and the great\nprogress which dynamical and historical geology have made during the\ncentury.\n\nThe first division of the history of the earth must be a separation\nof inorganic and organic geogeny; the latter begins with the first\nappearance of living things on our planet. The earlier section, the\ninorganic history of the earth, ran much the same course as that of the\nother planets of our system. They were all cast off as rings of nebula\nat the equator of the rotating solar mass, and gradually condensed\ninto independent bodies. After cooling down a little, the glowing ball\nof the earth was formed out of the gaseous mass, and eventually, as\nthe heat continued to radiate out into space, there was formed at its\nsurface the thin solid crust on which we live. When the temperature at\nthe surface had gone down to a certain point, the water descended upon\nit from the environing clouds of steam, and thus the first condition\nwas secured for the rise of organic life. Many million years--certainly\nmore than a hundred--have passed since this important process of\nthe formation of water took place, introducing the third section of\ncosmogony, which we call _biogeny_.\n\n\nIII.--MONISTIC BIOGENY\n\nThe third phase of the evolution of the world opens with the advent of\norganisms on our planet, and continues uninterrupted from that point\nuntil the present day. The great problems which this most interesting\npart of the earth's history suggests to us were still thought insoluble\nat the beginning of the nineteenth century, or, at least, so difficult\nthat their solution seemed to be extremely remote. Now, at the close of\nthe century, we can affirm with legitimate pride that they have been\nsubstantially solved by modern biology and its theory of transformism;\nindeed, many of the phenomena of the organic world are now interpreted\non physical principles as completely as the familiar physical phenomena\nof inorganic nature. The merit of making the first important step\nin this difficult path and of pointing out the way to the monistic\nsolution of all the problems of biology must be accorded to the great\nFrench scientist, Jean Lamarck; it was in 1809, the year of the\nbirth of Charles Darwin, that he published his famous _Philosophie\nZoologique_. In this original work not only is a splendid effort made\nto interpret all the phenomena of organic life from a monistic and\nphysical point of view, but the path is opened which alone leads to\nthe solution of the greatest enigma of this branch of science--the\nproblem of the natural origin of organic species. Lamarck, who had an\nequally extensive empirical acquaintance with zoology and botany, drew\nthe first sketch of the theory of descent; he showed that all the\ncountless members of the plant and animal kingdoms have arisen by slow\ntransformation from simple, common ancestral types, and that it is the\ngradual modification of forms by _adaptation_, in reciprocal action\nwith _heredity_, which has brought about this secular metamorphosis.\n\nI have fully appreciated the merit of Lamarck in the fifth chapter, and\nof Darwin in the sixth and seventh chapters, of the _Natural History\nof Creation_. Darwin, fifty years afterwards, not only gave a solid\nfoundation to all the essential parts of the theory of descent, but he\nfilled up the _lacunae_ of Lamarck's work by his theory of selection.\nDarwin reaped abundantly the success that Lamarck had never seen,\nwith all his merit. His epoch-making work on _The Origin of Species\nby Natural Selection_ has transformed modern biology from its very\nfoundations, in the course of the last forty years, and has raised it\nto a stage of development that yields to no other science in existence.\nDarwin is _the Copernicus of the organic world_, as I said in 1868, and\nE. du Bois-Reymond repeated fifteen years afterwards.[27]\n\n\nIV.--MONISTIC ANTHROPOGENY\n\nThe fourth and last phase of the world's history must be for us men\nthat latest period of time which has witnessed the development of our\nown race. Lamarck (1809) had already recognized that this evolution is\nonly rationally conceivable as the outcome of a natural process, by\n\"descent from the apes,\" our next of kin among the mammals. Huxley then\nproved, in his famous essay on _The Place of Man in Nature_, that this\nmomentous thesis is an inevitable consequence of the theory of descent,\nand is thoroughly established by the facts of anatomy, embryology, and\npal\u00e6ontology. He considered this \"question of all questions\" to be\nsubstantially answered. Darwin followed with a brilliant discussion\nof the question under many aspects in his _Descent of Man_ (1871).\nI had myself devoted a special chapter to this important problem of\nthe science of evolution in my _General Morphology_ (1866). In 1874 I\npublished my _Anthropogeny_, which contains the first attempt to trace\nthe descent of man through the entire chain of his ancestry right up to\nthe earliest archigonous monera; the attempt was based equally on the\nthree great \"documents\" of evolutionary science--anatomy, embryology,\nand pal\u00e6ontology. The progress we have made in anthropogenetic research\nduring the last few years is described in the paper which I read on\n\"Our Present Knowledge of the Origin of Man\" at the International\nCongress of Zoologists at Cambridge in 1898.[28]\n\n\n\n\nCHAPTER XIV\n\nTHE UNITY OF NATURE\n\n    The Monism of the Cosmos--Essential Unity of Organic\n    and Inorganic Nature--Carbon-Theory--The Hypothesis of\n    Abiogenesis--Mechanical and Purposive Causes--Mechanicism and\n    Teleology in Kant's Works--Design in the Organic and Inorganic\n    Worlds--Vitalism--Neovitalism--Dysteleology (the Moral of the\n    Rudimentary Organs)--Absence of Design in, and Imperfection of,\n    Nature--Telic Action in Organized Bodies--Its Absence in Ontogeny\n    and Phylogeny--The Platonist \"Ideas\"--No Moral Order Discoverable\n    in the History of the Organic World, of the Vertebrates, or of the\n    Human Race--Prevision--Design and Chance\n\n\nOne of the first things to be proved by the law of substance is the\nbasic fact that any natural force can be directly or indirectly\nconverted into any other. Mechanical and chemical energy, sound and\nheat, light and electricity, are mutually convertible; they seem to be\nbut different modes of one and the same fundamental force or _energy_.\nThence follows the important thesis of the unity of all natural\nforces, or, as it may also be expressed, the \"monism of energy.\"\nThis fundamental principle is now generally recognized in the entire\nprovince of physics and chemistry, as far as it applies to inorganic\nsubstances.\n\nIt seems to be otherwise with the organic world and its wealth of\ncolor and form. It is, of course, obvious that a great part of the\nphenomena of life may be immediately traced to mechanical and chemical\nenergy, and to the effects of electricity and light. For other vital\nprocesses, however, especially for psychic activity and consciousness,\nsuch an interpretation is vigorously contested. Yet the modern science\nof evolution has achieved the task of constructing a bridge between\nthese two apparently irreconcilable provinces. We are now certain that\nall the phenomena of organic life are subject to the universal law of\nsubstance no less than the phenomena of the inorganic universe.\n\nThe unity of nature which necessarily follows, and the demolition of\nthe earlier dualism, are certainly among the most valuable results of\nmodern evolution. Thirty-three years ago I made an exhaustive effort\nto establish this \"monism of the cosmos\" and the essential unity of\norganic and inorganic nature by a thorough, critical demonstration,\nand a comparison of the accordance of these two great divisions of\nnature with regard to matter, form, and force.[29] A short epitome of\nthe result is given in the fifteenth chapter of my _Natural History\nof Creation_. The views I put forward are accepted by the majority\nof modern scientists, but an attempt has been made in many quarters\nlately to dispute them and to maintain the old antithesis of the two\ndivisions of nature. The ablest of these is to be found in the recent\n_Welt als That_ of the botanist Reinke. It defends _pure cosmological_\ndualism with admirable lucidity and consistency, and only goes to prove\nhow utterly untenable the teleological system is that is connected\ntherewith. According to the author, physical and chemical forces alone\nare at work in the entire field of inorganic nature, while in the\norganic world we find \"intelligent forces,\" regulative or dominant\nforces. The law of substance is supposed to apply to the one, but not\nto the other. On the whole, it is a question of the old antithesis of\na mechanical and a teleological system. But before we go more fully\ninto it, let us glance briefly at two other theories, which seem to\nme to be of great importance in the decision of that controversy--the\ncarbon-theory and the theory of spontaneous generation.\n\nPhysiological chemistry has, after countless analyses, established the\nfollowing five facts during the last forty years:\n\nI. No other elements are found in organic bodies than those of the\ninorganic world.\n\nII. The combinations of elements which are peculiar to organisms,\nand which are responsible for their vital phenomena, are compound\nprotoplasmic substances, of the group of albuminates.\n\nIII. Organic life itself is a chemico-physical process, based on the\nmetabolism (or interchange of material) of these albuminates.\n\nIV. The only element which is capable of building up these compound\nalbuminates, in combination with other elements (oxygen, hydrogen,\nnitrogen, and sulphur), is carbon.\n\nV. These protoplasmic compounds of carbon are distinguished from\nmost other chemical combinations by their very intricate molecular\nstructure, their instability, and their jelly-like consistency.\n\nOn the basis of these five fundamental facts the following\n\"carbon-theory\" was erected thirty-three years ago: \"The peculiar\nchemico-physical properties of carbon--especially the fluidity and\nthe facility of decomposition of the most elaborate albuminoid\ncompounds of carbon--are the sole and the mechanical causes of\nthe specific phenomena of movement, which distinguish organic from\ninorganic substances, and which are called life, in the usual sense\nof the word\" (see _The Natural History of Creation_). Although this\n\"carbon-theory\" is warmly disputed in some quarters, no better monistic\ntheory has yet appeared to replace it. We have now a much better and\nmore thorough knowledge of the physiological relations of cell-life,\nand of the chemistry and physics of the living protoplasm, than we had\nthirty-three years ago, and so it is possible to make a more confident\nand effective defence of the carbon-theory.\n\nThe old idea of spontaneous generation is now taken in many different\nsenses. It is owing to this indistinctness of the idea, and its\napplication to so many different hypotheses, that the problem is one\nof the most contentious and confused of the science of the day. I\nrestrict the idea of spontaneous generation--also called abiogenesis\nor archigony--to the first development of living protoplasm out of\ninorganic carbonates, and distinguish two phases in this \"beginning\nof biogenesis\": (1) _autogony_, or the rise of the simplest\nprotoplasmic substances in a formative fluid, and (2) _plasmogony_,\nthe differentiation of individual primitive organisms out of these\nprotoplasmic compounds, in the form of _monera_. I have treated this\nimportant, though difficult, problem so exhaustively in the fifteenth\nchapter of my _Natural History of Creation_ that I may content myself\nhere with referring to it. There is also a very searching and severely\nscientific inquiry into it in my _General Morphology_ (1866). Naegeli\nhas also treated the hypothesis in quite the same sense in his\nmechanico-physiological theory of descent (1884), and has represented\nit to be an indispensable thesis in any natural theory of evolution.\nI entirely agree with his assertion that \"to reject abiogenesis is to\nadmit a miracle.\"\n\nThe hypothesis of spontaneous generation and the allied carbon-theory\nare of great importance in deciding the long-standing conflict between\nthe _teleological_ (dualistic) and the _mechanical_ (monistic)\ninterpretation of phenomena. Since Darwin gave us the key to the\nmonistic explanation of organization in his theory of selection forty\nyears ago, it has become possible for us to trace the splendid variety\nof orderly tendencies of the organic world to mechanical, natural\ncauses, just as we could formerly in the inorganic world alone. Hence\nthe supernatural and telic forces, to which the scientist had had\nrecourse, have been rendered superfluous. Modern metaphysics, however,\ncontinues to regard the latter as indispensable and the former as\ninadequate.\n\nNo philosopher has done more than Immanuel Kant in defining the\nprofound distinction between efficient and final causes, with relation\nto the interpretation of the whole cosmos. In his well-known earlier\nwork on _The General Natural History and Theory of the Heavens_ he\nmade a bold attempt \"to treat the constitution and the mechanical\norigin of the entire fabric of the universe according to Newtonian\nlaws.\" This \"cosmological nebular theory\" was based entirely on the\nmechanical phenomena of gravitation. It was expanded and mathematically\nestablished later on by Laplace. When the famous French astronomer\nwas asked by Napoleon I. where God, the creator and sustainer of all\nthings, came in in his system, he clearly and honestly replied: \"Sire,\nI have managed without that hypothesis.\" That indicated the atheistic\ncharacter which this mechanical cosmogony shares with all the other\ninorganic sciences. This is the more noteworthy because the theory of\nKant and Laplace is now almost universally accepted; every attempt to\nsupersede it has failed. When atheism is denounced as a grave reproach,\nas it so often is, it is well to remember that the reproach extends to\nthe whole of modern science, in so far as it gives a purely mechanical\ninterpretation of the inorganic world.\n\nMechanicism (in the Kantian sense) alone can give us a true explanation\nof natural phenomena, for it traces them to their real efficient\ncauses, to blind and unconscious agencies, which are determined in\ntheir action only by the material constitution of the bodies we are\ninvestigating. Kant himself emphatically affirms that \"there can be\nno science without this mechanicism of nature,\" and that the capacity\nof human reason to give a mechanical interpretation of phenomena is\nunlimited. But when he came subsequently to give an elucidation of\nthe complex phenomena of organic nature in his _critique_ of the\nteleological system, he declared that these mechanical causes were\ninadequate; that in this we must call _final causes_ to our assistance.\nIt is true, he said, that even here we must recognize the theoretical\nfaculty of the mind to give a mechanical interpretation, but its actual\ncompetence to do so is restricted. He grants it this capacity to some\nextent; but for the majority of the vital processes (and especially for\nman's psychic activity) he thinks we are bound to postulate _final_\ncauses. The remarkable \u00a779 of the _critique_ of judgment bears the\ncharacteristic heading: \"On the Necessity for the Subordination of\nthe Mechanical Principle to the Teleological in the Explanation of a\nThing as a Natural End.\" It seemed to Kant so impossible to explain\nthe orderly processes in the living organism without postulating\nsupernatural final causes (that is, a purposive creative force) that\nhe said: \"It is quite certain that we cannot even satisfactorily\nunderstand, much less elucidate, the nature of an organism and its\ninternal faculty on purely mechanical natural principles; it is so\ncertain, indeed, that we may confidently say, 'It is absurd for a man\nto conceive the idea even that some day a Newton will arise who can\nexplain the origin of a single blade of grass by natural laws which are\nuncontrolled by design'--such a hope is entirely forbidden us.\" Seventy\nyears afterwards this impossible \"Newton of the organic world\" appeared\nin the person of Charles Darwin, and achieved the great task that Kant\nhad deemed impracticable.\n\nSince Newton (1682) formulated the law of gravitation, and Kant (1755)\nestablished \"the constitution and mechanical origin of the entire\nfabric of the world on Newtonian laws,\" and Laplace (1796) provided\na mathematical foundation for this law of cosmic mechanicism, the\nwhole of the inorganic sciences have become purely _mechanical_, and\nat the same time purely _atheistic_. Astronomy, cosmogony, geology,\nmeteorology, and inorganic physics and chemistry are now absolutely\nruled by mechanical laws on a mathematical foundation. The idea of\n\"design\" has wholly disappeared from this vast province of science.\nAt the close of the nineteenth century, now that this monistic view\nhas fought its way to general recognition, no scientist ever asks\nseriously of the \"purpose\" of any single phenomenon in the whole of\nthis great field. Is any astronomer likely to inquire seriously to-day\ninto the purpose of planetary motion, or a mineralogist to seek design\nin the structure of a crystal? Does the physicist investigate the\npurpose of electric force, or the chemist that of atomic weight? We\nmay confidently answer in the negative--certainly not, in the sense\nthat God, or a purposive natural force, had at some time created these\nfundamental laws of the mechanism of the universe with a definite\ndesign, and causes them to work daily in accordance with his rational\nwill. The anthropomorphic notion of a deliberate architect and ruler of\nthe world has gone forever from this field; the \"eternal, iron laws of\nnature\" have taken his place.\n\nBut the idea of design has a very great significance and application\nin the _organic_ world. We do undeniably perceive a purpose in the\nstructure and in the life of an organism. The plant and the animal\nseem to be controlled by a definite design in the combination of their\nseveral parts, just as clearly as we see in the machines which man\ninvents and constructs; as long as life continues the functions of the\nseveral organs are directed to definite ends, just as is the operation\nof the various parts of a machine. Hence it was quite natural that the\nolder na\u00efve study of nature, in explaining the origin and activity\nof the living being, should postulate a creator who had \"arranged\nall things with wisdom and understanding,\" and had constructed each\nplant and animal according to the special purpose of its life. The\nconception of this \"almighty creator of heaven and earth\" was usually\nquite anthropomorphic; he created \"everything after its kind.\" As long\nas the creator seemed to man to be of human shape, to think with his\nbrain, see with his eyes, and fashion with his hands, it was possible\nto form a definite picture of this \"divine engineer\" and his artistic\nwork in the great workshop of creation. This was not so easy when\nthe idea of God became refined, and man saw in his \"invisible God\" a\ncreator without organs--a gaseous being. Still more unintelligible\ndid these anthropomorphic ideas become when physiology substituted\nfor the conscious, divine architect an unconscious, creative \"vital\nforce\"--a mysterious, purposive, natural force, which differed from the\nfamiliar forces of physics and chemistry, and only took these in part,\nduring life, into its service. This vitalism prevailed until about the\nmiddle of the nineteenth century. Johannes M\u00fcller, the great Berlin\nphysiologist, was the first to menace it with a destructive dose of\nfacts. It is true that the distinguished biologist had himself (like\nall others in the first half of the century) been educated in a belief\nin this vital force, and deemed it indispensable for an elucidation of\nthe ultimate sources of life; nevertheless, in his classical and still\nunrivalled _Manual of Physiology_ (1833) he gave a demonstrative proof\nthat there is really nothing to be said for this vital force. M\u00fcller\nhimself, in a long series of remarkable observations and experiments,\nshowed that most of the vital processes in the human organism (and in\nthe other animals) take place according to physical and chemical laws,\nand that many of them are capable of mathematical determination. That\nwas no less true of the animal functions of the muscles and nerves,\nand of both the higher and the lower sense-organs, than of the vegetal\nfunctions of digestion, assimilation, and circulation. Only two\nbranches of the life of the organism, mental action and reproduction,\nretained any element of mystery, and seemed inexplicable without\nassuming a vital force. But immediately after M\u00fcller's death such\nimportant discoveries and advances were made in these two branches\nthat the uneasy \"phantom of vital force\" was driven from its last\nrefuge. By a very remarkable coincidence Johannes M\u00fcller died in the\nyear 1858, which saw the publication of Darwin's first communication\nconcerning his famous theory. The theory of selection solved the great\nproblem that had mastered M\u00fcller--the question of the origin of orderly\narrangements from purely mechanical causes.\n\nDarwin, as we have often said, had a twofold immortal merit in the\nfield of philosophy--firstly, the reform of Lamarck's theory of\ndescent, and its establishment on the mass of facts accumulated in the\ncourse of the half-century; secondly, the conception of the theory\nof selection, which first revealed to us the true causes of the\ngradual formation of species. Darwin was the first to point out that\nthe \"struggle for life\" is the unconscious regulator which controls\nthe reciprocal action of heredity and adaptation in the gradual\ntransformation of species; it is the great \"selective divinity\" which,\nby a purely \"natural choice,\" without preconceived design, creates\nnew forms, just as selective man creates new types by an \"artificial\nchoice\" with a definite design. That gave us the solution of the great\nphilosophic problem: \"How can purposive contrivances be produced by\npurely mechanical processes without design?\" Kant held the problem to\nbe insoluble, although Empedocles had pointed out the direction of the\nsolution two thousand years before. His principle of \"teleological\nmechanism\" has become more and more accepted of late years, and\nhas furnished a mechanical explanation even of the finest and most\nrecondite processes of organic life by \"the functional self-production\nof the purposive structure.\" Thus have we got rid of the transcendental\n\"design\" of the ideological philosophy of the schools, which was the\ngreatest obstacle to the growth of a rational and monistic conception\nof nature.\n\nVery recently, however, this ancient phantom of a mystic vital force,\nwhich seemed to be effectually banished, has put in a fresh appearance;\na number of distinguished biologists have attempted to reintroduce it\nunder another name. The clearest presentation of it is to be found in\nthe _Welt als That_, of the Kiel botanist, J. Reinke. He takes upon\nhimself the defence of the notion of miracle, of theism, of the Mosaic\nstory of creation, and of the constancy of species; he calls \"vital\nforces,\" in opposition to physical forces, the directive or dominant\nforces. Other neovitalists prefer, in the good old anthropomorphic\nstyle, a \"supreme\" engineer, who has endowed organic substance with a\npurposive structure, directed to the realization of a definite plan.\nThese curious teleological hypotheses, and the objections to Darwinism\nwhich generally accompany them, do not call for serious scientific\nrefutation to-day.\n\nThirty-three years ago I gave the title of \"dysteleology\" to the\nscience of those extremely interesting and significant biological\nfacts, which, in the most striking fashion, give a direct contradiction\nto the teleological idea \"of the purposive arrangement of the living\norganism.\"[30] This \"science of rudimentary, abortive, arrested,\ndistorted, atrophied, and cataplastic individuals\" is based on an\nimmense quantity of remarkable phenomena, which were long familiar to\nzoologists and botanists, but were not properly interpreted, and their\ngreat philosophic significance appreciated, until Darwin.\n\nAll the higher animals and plants, or, in general, all organisms which\nare not entirely simple in structure, but are made up of a number of\norgans in orderly co-operation, are found, on close examination, to\npossess a number of useless or inoperative members, sometimes, indeed,\nhurtful and dangerous. In the flowers of most plants we find, besides\nthe actual sex-leaves that effect reproduction, a number of other\nleaf-organs which have no use or meaning (arrested or \"miscarried\"\npistils, fruit, corona, and calix-leaves, etc.). In the two large and\nvariegated classes of flying animals, birds and insects, there are,\nbesides the forms which make constant use of their wings, a number of\nspecies which have undeveloped wings and cannot fly. In nearly every\nclass of the higher animals which have eyes there are certain types\nthat live in the dark; they have eyes, as a rule, but undeveloped and\nuseless for vision. In our own human organism we have similar useless\nrudimentary structures in the muscles of the ear, in the eye-lid, in\nthe nipple and milk-gland of the male, and in other parts of the body;\nindeed, the vermiform appendix of our c\u00e6cum is not only useless, but\nextremely dangerous, and inflammation of it is responsible for a number\nof deaths every year.\n\nNeither the old mystic vitalism nor the new, equally irrational,\nneovitalism can give any explanation of these and many other\npurposeless contrivances in the structure of the plant and the animal;\nbut they are very simple in the light of the theory of descent. It\nshows that these rudimentary organs are atrophied, owing to disuse.\nJust as our muscles, nerves, and organs of sense are strengthened by\nexercise and frequent use, so, on the other hand, they are liable to\ndegenerate more or less by disuse or suspended exercise. But, although\nthe development of the organs is promoted by exercise and adaptation,\nthey by no means disappear without leaving a trace after neglect; the\nforce of heredity retains them for many generations, and only permits\ntheir gradual disappearance after the lapse of a considerable time.\nThe blind \"struggle for existence between the organs\" determines their\nhistorical disappearance, just as it effected their first origin and\ndevelopment. There is no internal \"purpose\" whatever in the drama.\n\nThe life of the animal and the plant bears the same universal character\nof incompleteness as the life of man. This is directly attributable\nto the circumstance that nature--organic as well as inorganic--is\nin a perennial state of evolution, change, and transformation. This\nevolution seems on the whole--at least as far as we can survey the\ndevelopment of organic life on our planet--to be a progressive\nimprovement, an historical advance from the simple to the complex,\nthe lower to the higher, the imperfect to the perfect. I have proved\nin my _General Morphology_ that this historical progress--or gradual\nperfecting (_teleosis_)--is the inevitable result of selection, and not\nthe outcome of a preconceived design. That is clear from the fact that\nno organism is perfect; even if it does perfectly adapt itself to its\nenvironment at a given moment, this condition would not last very long;\nthe conditions of existence of the environment are themselves subject\nto perpetual change and they thus necessitate a continuous adaptation\non the part of the organism.\n\nUnder the title of _Design in the Living Organism_, the famous\nembryologist, Karl Ernst Baer, published a work in 1876 which, together\nwith the article on Darwinism which accompanied it, proved very\nacceptable to our opponents, and is still much quoted in opposition\nto evolution. It was a revival of the old teleological system under\na new name, and we must devote a line of criticism to it. We must\npremise that, though Baer was a scientist of the highest order, his\noriginal monistic views were gradually marred by a tinge of mysticism\nwith the advance of age, and he eventually became a thorough dualist.\nIn his profound work on \"the evolution of animals\" (1828), which he\nhimself entitled _Observation and Experiment_, these two methods of\ninvestigation are equally applied. By careful observation of the\nvarious phenomena of the development of the animal ovum Baer succeeded\nin giving the first consistent presentation of the remarkable changes\nwhich take place in the growth of the vertebrate from a simple\negg-cell. At the same time he endeavored, by far-seeing comparison\nand keen reflection, to learn the causes of the transformation, and\nto reduce them to general constructive laws. He expressed the general\nresult of his research in the following thesis: \"The evolution of\nthe individual is the story of the growth of individuality in every\nrespect.\" He meant that \"the one great thought that controls all the\ndifferent aspects of animal evolution is the same that gathered the\nscattered fragments of space into spheres and linked them into solar\nsystems. This thought is no other than life itself, and the words and\nsyllables in which it finds utterance are the varied forms of living\nthings.\"\n\nBaer, however, did not attain to a deeper knowledge of this great\ngenetic truth and a clearer insight into the real efficient causes of\norganic evolution, because his attention was exclusively given to\none half of evolutionary science, the science of the evolution of the\nindividual, embryology, or, in a wider sense, _ontogeny_. The other\nhalf, the science of the evolution of species, _phylogeny_, was not yet\nin existence, although Lamarck had already pointed out the way to it in\n1809. When it was established by Darwin in 1859, the aged Baer was no\nlonger in a position to appreciate it; the fruitless struggle which he\nled against the theory of selection clearly proved that he understood\nneither its real meaning nor its philosophic importance. Teleological\nand, subsequently, theological speculations had incapacitated the\nageing scientist from appreciating this greatest reform of biology. The\nteleological observations which he published against it in his _Species\nand Studies_ in his eighty-fourth year are mere repetitions of errors\nwhich the teleology of the dualists has opposed to the mechanical or\nmonistic system for more than two thousand years. The \"telic idea\"\nwhich, according to Baer, controls the entire evolution of the animal\nfrom the ovum, is only another expression for the eternal \"idea\" of\nPlato and the _entelecheia_ of his pupil Aristotle.\n\nOur modern biogeny gives a purely physiological explanation of the\nfacts of embryology, in assigning the functions of heredity and\nadaptation as their causes. The great biogenetic law, which Baer\nfailed to appreciate, reveals the intimate causal connection between\nthe _ontogenesis_ of the individual and the _phylogenesis_ of its\nancestors; the former seems to be a recapitulation of the latter.\nNowhere, however, in the evolution of animals and plants do we find any\ntrace of design, but merely the inevitable outcome of the struggle for\nexistence, the blind controller, instead of the provident God, that\neffects the changes of organic forms by a mutual action of the laws of\nheredity and adaptation. And there is no more trace of \"design\" in the\nembryology of the individual plant, animal, or man. This _ontogeny_\nis but a brief epitome of _phylogeny_, an abbreviated and condensed\nrecapitulation of it, determined by the physiological laws of heredity.\n\nBaer ended the preface to his classical _Evolution of Animals_ (1828)\nwith these words: \"The palm will be awarded to the fortunate scientist\nwho succeeds in reducing the constructive forces of the animal body\nto the general forces or life-processes of the entire world. The tree\nhas not yet been planted which is to make his cradle.\" The great\nembryologist erred once more. That very year, 1828, witnessed the\narrival of Charles Darwin at Cambridge University (for the purpose of\nstudying theology!)--the \"fortunate scientist\" who richly earned the\npalm thirty years afterwards by his theory of selection.\n\nIn the philosophy of history--that is, in the general reflections which\nhistorians make on the destinies of nations and the complicated course\nof political evolution--there still prevails the notion of a \"moral\norder of the universe.\" Historians seek in the vivid drama of history\na leading design, an ideal purpose, which has ordained one or other\nrace or state to a special triumph, and to dominion over the others.\nThis teleological view of history has recently become more strongly\ncontrasted with our monistic view in proportion as monism has proved\nto be the only possible interpretation of inorganic nature. Throughout\nthe whole of astronomy, geology, physics, and chemistry there is no\nquestion to-day of a \"moral order,\" or a personal God, whose \"hand hath\ndisposed all things in wisdom and understanding.\" And the same must\nbe said of the entire field of biology, the whole constitution and\nhistory of organic nature, if we set aside the question of man for the\nmoment. Darwin has not only proved by his theory of selection that the\norderly processes in the life and structure of animals and plants have\narisen by mechanical laws without any preconceived design, but he has\nshown us in the \"struggle for life\" the powerful natural force which\nhas exerted supreme control over the entire course of organic evolution\nfor millions of years. It may be said that the struggle for life is the\n\"survival of the fittest\" or the \"victory of the best\"; that is only\ncorrect when we regard the strongest as the best (in a moral sense).\nMoreover, the whole history of the organic world goes to prove that,\nbesides the predominant advance towards perfection, there are at all\ntimes cases of retrogression to lower stages. Even Baer's notion of\n\"design\" has no moral feature whatever.\n\nDo we find a different state of things in the history of peoples, which\nman, in his anthropocentric presumption, loves to call \"the history of\nthe world\"? Do we find in every phase of it a lofty moral principle or\na wise ruler, guiding the destinies of nations? There can be but one\nanswer in the present advanced stage of natural and human history: No.\nThe fate of those branches of the human family, those nations and races\nwhich have struggled for existence and progress for thousands of years,\nis determined by the same \"eternal laws of iron\" as the history of the\nwhole organic world which has peopled the earth for millions of years.\n\nGeologists distinguish three great epochs in the organic history of\nthe earth, as far as we can read it in the monuments of the science of\nfossils--the primary, secondary, and tertiary epochs. According to a\nrecent calculation, the first occupied at least thirty-four million,\nthe second eleven million, and the third three million years. The\nhistory of the family of vertebrates, from which our own race has\nsprung, unfolds clearly before our eyes during this long period. Three\ndifferent stages in the evolution of the vertebrate correspond to the\nthree epochs; the _fishes_ characterized the primary (pal\u00e6ozoic) age,\nthe _reptiles_ the secondary (mesozoic), and the _mammals_ the tertiary\n(c\u00e6nozoic). Of the three groups the fishes rank lowest in organization,\nthe reptiles come next, and the mammals take the highest place. We\nfind, on nearer examination of the history of the three classes, that\ntheir various orders and families also advanced progressively during\nthe three epochs towards a higher stage of perfection. May we consider\nthis progressive development as the outcome of a conscious design or\na moral order of the universe? Certainly not. The theory of selection\nteaches us that this organic progress, like the earlier organic\ndifferentiation, is an inevitable consequence of the struggle for\nexistence. Thousands of beautiful and remarkable species of animals and\nplants have perished during those forty-eight million years, to give\nplace to stronger competitors, and the victors in this struggle for\nlife were not always the noblest or most perfect forms in a moral sense.\n\nIt has been just the same with the history of humanity. The splendid\ncivilization of classical antiquity perished because Christianity,\nwith its faith in a loving God and its hope of a better life beyond\nthe grave, gave a fresh, strong impetus to the soaring human mind. The\nPapal Church quickly degenerated into a pitiful caricature of real\nChristianity, and ruthlessly scattered the treasures of knowledge\nwhich the Hellenic philosophy had gathered; it gained the dominion\nof the world through the ignorance of the credulous masses. In time\nthe Reformation broke the chains of this mental slavery, and assisted\nreason to secure its right once more. But in the new, as in the\nolder, period the great struggle for existence went on in its eternal\nfluctuation, with no trace of a moral order.\n\nAnd it is just as impossible for the impartial and critical observer\nto detect a \"wise providence\" in the fate of individual human beings\nas a moral order in the history of peoples. Both are determined with\niron necessity by a mechanical causality which connects every single\nphenomenon with one or more antecedent causes. Even the ancient Greeks\nrecognized _ananke_, the blind _heimarmene_, the fate \"that rules\ngods and men,\" as the supreme principle of the universe. Christianity\nreplaced it by a conscious Providence, which is not blind, but sees,\nand which governs the world in patriarchal fashion. The anthropomorphic\ncharacter of this notion, generally closely connected with belief in\na personal God, is quite obvious. Belief in a \"loving Father,\" who\nunceasingly guides the destinies of one billion five hundred million\nmen on our planet, and is attentive at all times to their millions of\ncontradictory prayers and pious wishes, is absolutely impossible; that\nis at once perceived on laying aside the colored spectacles of \"faith\"\nand reflecting rationally on the subject.\n\nAs a rule, this belief in Providence and the tutelage of a \"loving\nFather\" is more intense in the modern civilized man--just as in the\nuncultured savage--when some good fortune has fallen him: an escape\nfrom peril of life, recovery from a severe illness, the winning of the\nfirst prize in a lottery, the birth of a long-delayed child, and so\nforth. When, on the other hand, a misfortune is met with, or an ardent\nwish is not fulfilled, \"Providence\" is forgotten. The wise ruler of the\nworld slumbered--or refused his blessing.\n\nIn the extraordinary development of commerce of the nineteenth century\nthe number of catastrophes and accidents has necessarily increased\nbeyond all imagination; of that the journal is a daily witness.\nThousands are killed every year by shipwreck, railway accidents, mine\naccidents, etc. Thousands slay each other every year in war, and the\npreparation for this wholesale massacre absorbs much the greater part\nof the revenue in the highest civilized nations, the chief professors\nof \"Christian charity.\" And among these hundreds of thousands of annual\nvictims of modern civilization strong, industrious, courageous workers\npredominate. Yet the talk of a \"moral order\" goes on.\n\nSince impartial study of the evolution of the world teaches us that\nthere is no definite aim and no special purpose to be traced in it,\nthere seems to be no alternative but to leave everything to \"blind\nchance.\" This reproach has been made to the transformism of Lamarck and\nDarwin, as it had been to the previous systems of Kant and Laplace;\nthere are a number of dualist philosophers who lay great stress on it.\nIt is, therefore, worth while to make a brief remark upon it.\n\nOne group of philosophers affirms, in accordance with its teleological\nconception, that the whole cosmos is an orderly system, in which every\nphenomenon has its aim and purpose; there is no such thing as chance.\nThe other group, holding a mechanical theory, expresses itself thus:\nThe development of the universe is a monistic mechanical process, in\nwhich we discover no aim or purpose whatever; what we call design in\nthe organic world is a special result of biological agencies; neither\nin the evolution of the heavenly bodies nor in that of the crust of\nour earth do we find any trace of a controlling purpose--all is the\nresult of chance. Each party is right--according to its definition of\nchance. The general law of causality, taken in conjunction with the law\nof substance, teaches us that every phenomenon has a mechanical cause;\nin this sense there is no such thing as chance. Yet it is not only\nlawful, but necessary, to retain the term for the purpose of expressing\nthe simultaneous occurrence of two phenomena, which are not causally\nrelated to each other, but of which each has its own mechanical cause,\nindependent of that of the other. Everybody knows that chance, in its\nmonistic sense, plays an important part in the life of man and in the\nuniverse at large. That, however, does not prevent us from recognizing\nin each \"chance\" event, as we do in the evolution of the entire\ncosmos, the universal sovereignty of nature's supreme law, _the law of\nsubstance_.\n\n\n\n\nCHAPTER XV\n\nGOD AND THE WORLD\n\n    The Idea of God in General--Antithesis of God and the World; the\n    Supernatural and Nature--Theism and Pantheism--Chief Forms of\n    Theism--Polytheism--Triplotheism--Amphitheism--Monotheism--Religious\n    Statistics--Naturalistic Monotheism--Solarism--Anthropistic\n    Monotheism--The Three Great Mediterranean\n    Religions--Mosaism--Christianity--The Cult of the Madonna and\n    the Saints--Papal Polytheism--Islam--Mixotheism--Nature of\n    Theism--An Extra-mundane and Anthropomorphic God; a Gaseous\n    Vertebrate--Pantheism--Intramundane God (Nature)--The Hylozoism\n    of the Ionic Monists (Anaximander)--Conflict of Pantheism and\n    Christianity--Spinoza--Modern Monism--Atheism\n\n\nFor thousands of years humanity has placed the last and supreme basis\nof all phenomena in an efficient cause, to which it gives the title of\nGod (_deus_, _theos_). Like all general ideas, this notion of God has\nundergone a series of remarkable modifications and transformations in\nthe course of the evolution of reason. Indeed, it may be said that no\nother idea has had so many metamorphoses; for no other belief affects\nin so high a degree the chief objects of the mind and of rational\nscience, as well as the deepest interests of the emotion and poetic\nfancy of the believer.\n\nA comparative criticism of the many different forms of the idea of God\nwould be extremely interesting and instructive; but we have not space\nfor it in the present work. We must be content with a passing glance\nat the most important forms of the belief and their relation to the\nmodern thought that has been evoked by a sound study of nature. For\nfurther information on this interesting question the reader would do\nwell to consult the distinguished work of Adalbert Svoboda, _Forms of\nFaith_ (1897).\n\nWhen we pass over the finer shades and the variegated clothing of\nthe God-idea and confine our attention to its chief element, we can\ndistribute all the different presentations of it in two groups--the\n_theistic_ and _pantheistic_ group. The latter is closely connected\nwith the monistic, or rational, view of things, and the former is\nassociated with dualism and mysticism.\n\n\nI.--THEISM\n\nIn this view God is distinct from, and opposed to, the world as its\ncreator, sustainer, and ruler. He is always conceived in a more or\nless human form, as an organism which thinks and acts like a man--only\non a much higher scale. This anthropomorphic God, polyphyletically\nevolved by the different races, assumes an infinity of shapes in their\nimagination, from fetichism to the refined monotheistic religions\nof the present day. The chief forms of theism are polytheism,\ntriplotheism, amphitheism, and monotheism.\n\nThe polytheist peoples the world with a variety of gods and goddesses,\nwhich enter into its machinery more or less independently. _Fetichism_\nsees such subordinate deities in the lifeless body of nature, in rocks,\nin water, in the air, in human productions of every kind (pictures,\nstatues, etc.). _Demonism_ sees gods in living organisms of every\nspecies--trees, animals, and men. This kind of polytheism is found in\ninnumerable forms even in the lowest tribes. It reaches the highest\nstage in Hellenic polytheism, in the myths of ancient Greece, which\nstill furnish the finest images to the modern poet and artist. At a\nmuch lower stage we have Catholic polytheism, in which innumerable\n\"saints\" (many of them of very equivocal repute) are venerated as\nsubordinate divinities, and prayed to to exert their mediation with the\nsupreme divinity.\n\nThe dogma of the \"Trinity,\" which still comprises three of the chief\narticles of faith in the creed of Christian peoples, culminates in the\nnotion that the one God of Christianity is really made up of _three_\ndifferent persons: (1) God the Father, the omnipotent creator of heaven\nand earth (this untenable myth was refuted long ago by scientific\ncosmogony, astronomy, and geology); (2) Jesus Christ; and (3) the Holy\nGhost, a mystical being, over whose incomprehensible relation to the\nFather and the Son millions of Christian theologians have racked their\nbrains in vain for the last nineteen hundred years. The Gospels, which\nare the only clear sources of this _triplotheism_, are very obscure as\nto the relation of these three persons to each other, and do not give a\nsatisfactory answer to the question of their unity. On the other hand,\nit must be carefully noted what confusion this obscure and mystic dogma\nof the Trinity must necessarily cause in the minds of our children even\nin the earlier years of instruction. One morning they learn (in their\nreligious instruction) that three times one are one, and the very next\nhour they are told in their arithmetic class that three times one are\nthree. I remember well the reflection that this confusion led me to in\nmy early school-days.\n\nFor the rest, the \"Trinity\" is not an original element in Christianity;\nlike most of the other Christian dogmas, it has been borrowed from\nearlier religions. Out of the sun-worship of the Chaldean magi was\nevolved the Trinity of Ilu, the mysterious source of the world; its\nthree manifestations were Anu, primeval chaos; Bel, the architect of\nthe world; and Aa, the heavenly light, the all-enlightening wisdom.\nIn the Brahmanic religion the Trimurti is also conceived as a \"divine\nunity\" made up of three persons--Brahma (the creator), Vishnu (the\nsustainer), and Shiva (the destroyer). It would seem that in this\nand other ideas of a Trinity the \"sacred number, three,\" as such--as\na \"symbolical number\"--has counted for something. The three first\nChristian virtues--Faith, Hope, and Charity--form a similar _triad_.\n\nAccording to the _amphitheists_, the world is ruled by two different\ngods, a good and an evil principle, God and the Devil. They are engaged\nin a perpetual struggle, like rival emperors, or pope and anti-pope.\nThe condition of the world is the result of this conflict. The\nloving God, or good principle, is the source of all that is good and\nbeautiful, of joy and of peace. The world would be perfect if His work\nwere not continually thwarted by the evil principle, the Devil; this\nbeing is the cause of all that is bad and hateful, of contradiction and\nof pain.\n\nAmphitheism is undoubtedly the most rational of all forms of belief in\nGod, and the one which is least incompatible with a scientific view\nof the world. Hence we find it elaborated in many ancient peoples\nthousands of years before Christ. In ancient India Vishnu, the\npreserver, struggles with Shiva, the destroyer. In ancient Egypt the\ngood Osiris is opposed by the wicked Typhon. The early Hebrews had a\nsimilar dualism of Aschera (or Keturah), the fertile mother-earth,\nand Elion (Moloch or Sethos), the stern heavenly father. In the Zend\nreligion of the ancient Persians, founded by Zoroaster two thousand\nyears before Christ, there is a perpetual struggle between Ormuzd, the\ngood god of light, and Ahriman, the wicked god of darkness.\n\nIn Christian mythology the Devil is scarcely less conspicuous as the\nadversary of the good deity, the tempter and seducer, the prince of\nhell, and lord of darkness. A personal devil was still an important\nelement in the belief of most Christians at the beginning of the\nnineteenth century. Towards the middle of the century he was gradually\neliminated by being progressively explained away, or he was restricted\nto the subordinate _r\u00f4le_ he plays as Mephistopheles in Goethe's great\ndrama. To-day the majority of educated people look upon \"belief in a\npersonal devil\" as a medi\u00e6val superstition, while \"belief in God\" (that\nis, the personal, good, and loving God) is retained as an indispensable\nelement of religion. Yet the one belief is just as much (or as little)\njustified as the other. In any case, the much-lamented \"imperfection of\nour earthly life,\" the \"struggle for existence,\" and all that pertains\nto it, are explained much more simply and naturally by this struggle of\na good and an evil god than by any other form of theism.\n\nThe dogma of the unity of God may in some respects be regarded as the\nsimplest and most natural type of theism; it is popularly supposed to\nbe the most widely accepted element of religion, and to predominate\nin the ecclesiastical systems of civilized countries. In reality,\nthat is not the case, because this alleged \"monotheism\" usually turns\nout on closer inquiry to be one of the other forms of theism we have\nexamined, a number of subordinate deities being generally introduced\nbesides the supreme one. Most of the religions which took a purely\nmonotheistic stand-point have become more or less polytheistic in the\ncourse of time. Modern statistics assure us that of the one billion\nfive hundred million men who people the earth the great majority\nare monotheists; of these, _nominally_, about six hundred millions\nare Brahma-Buddhists, five hundred millions are called Christians,\ntwo hundred millions are heathens (of various types), one hundred\nand eighty millions are Mohammedans, ten millions are Jews, and ten\nmillions have no religion at all. However, the vast majority of\nthese nominal monotheists have very confused ideas about the deity,\nor believe in a number of gods and goddesses besides the chief\ngod--angels, devils, etc.\n\nThe different forms which monotheism has assumed in the course of its\npolyphyletic development may be distributed in two groups--those of\n_naturalistic_ and _anthropistic_ monotheism. Naturalistic monotheism\nfinds the embodiment of the deity in some lofty and dominating natural\nphenomenon. The sun, the deity of light and warmth, on whose influence\nall organic life insensibly and directly depends, was taken to be\nsuch a phenomenon many thousand years ago. Sun-worship (solarism,\nor heliotheism) seems to the modern scientist to be the best of all\nforms of theism, and the one which may be most easily reconciled\nwith modern monism. For modern astrophysics and geogeny have taught\nus that the earth is a fragment detached from the sun, and that it\nwill eventually return to the bosom of its parent. Modern physiology\nteaches us that the first source of organic life on the earth is the\nformation of protoplasm, and that this synthesis of simple inorganic\nsubstances, water, carbonic acid, and ammonia, only takes place under\nthe influence of sunlight. On the primary evolution of the plasmodomous\nplants followed, secondarily, that of the plasmophagous animals, which\ndirectly or indirectly depend on them for nourishment; and the origin\nof the human race itself is only a later stage in the development of\nthe animal kingdom. Indeed, the whole of our bodily and mental life\ndepends, in the last resort, like all other organic life, on the\nlight and heat rays of the sun. Hence in the light of pure reason,\nsun-worship, as a form of naturalistic monotheism, seems to have a much\nbetter foundation than the anthropistic worship of Christians and of\nother monotheists who conceive their god in human form. As a matter of\nfact, the sun-worshippers attained, thousands of years ago, a higher\nintellectual and moral standard than most of the other theists. When\nI was in Bombay, in 1881, I watched with the greatest sympathy the\nelevating rites of the pious Parsees, who, standing on the sea-shore,\nor kneeling on their prayer-rugs, offered their devotion to the sun at\nits rise and setting.[31]\n\nMoon-worship (lunarism and selenotheism) is of much less importance\nthan sun-worship. There are a few uncivilized races that have adored\nthe moon as their only deity, but it has generally been associated with\na worship of the stars and the sun.\n\nThe humanization of God, or the idea that the \"Supreme Being\" feels,\nthinks, and acts like man (though in a higher degree), has played a\nmost important part, as _anthropomorphic monotheism_, in the history\nof civilization. The most prominent in this respect are the three\ngreat religions of the Mediterranean peoples--the old Mosaic religion,\nthe intermediate Christian religion, and the younger Mohammedanism.\nThese three great Mediterranean religions, all three arising on the\neast coast of the most interesting of all seas, and originating in an\nimaginative enthusiast of the Semitic race, are intimately connected,\nnot only by this external circumstance of an analogous origin, but by\nmany common features of their internal contents. Just as Christianity\nborrowed a good deal of its mythology directly from ancient Judaism, so\nIslam has inherited much from both its predecessors. All the three were\noriginally monotheistic; all three were subsequently overlaid with a\ngreat variety of polytheistic features, in proportion as they extended,\nfirst along the coast of the Mediterranean with its heterogeneous\npopulation, and eventually into every part of the world.\n\nThe Hebrew monotheism, as it was founded by Moses (about 1600 B.C.), is\nusually regarded as the ancient faith which has been of the greatest\nimportance in the ethical and religious development of humanity.\nThis high historical appreciation is certainly valid in the sense\nthat the two other world-conquering Mediterranean religions issued\nfrom it; Christ was just as truly a pupil of Moses as Mohammed was\nafterwards of Christ. So also the New Testament, which has become the\nfoundation of the belief of the highest civilized nations in the short\nspace of nineteen hundred years, rests on the venerable basis of the\nOld Testament. The Bible, which the two compose, has had a greater\ninfluence and a wider circulation than any other book in the world.\nEven to-day the Bible--in spite of its curious mingling of the best and\nthe worst elements--is in a certain sense the \"book of books.\" Yet when\nwe make an impartial and unprejudiced study of this notable historical\nsource, we find it very different in several important respects from\nthe popular impression. Here again modern criticism and history have\ncome to certain conclusions which destroy the prevalent tradition in\nits very foundations.\n\nThe monotheism which Moses endeavored to establish in the worship\nof Jehovah, and which the prophets--the philosophers of the Hebrew\nrace--afterwards developed with great success, had at first to sustain\na long and severe struggle with the dominant polytheism which was\nin possession. Jehovah, or Yahveh, was originally derived from the\nheaven-god, which, under the title of Moloch or Baal, was one of\nthe most popular of the Oriental deities (the Sethos or Typhon of\nthe Egyptians, and the Saturn or Cronos of the Greeks). There were,\nhowever, other gods in great favor with the Jewish people, and so the\nstruggle with \"idolatry\" continued. Still, Jehovah was, in principle,\nthe only God, explicitly claiming, in the first precept of the\ndecalogue: \"I am the Lord thy God; thou shalt have no other gods beside\nme.\"\n\nChristian monotheism shared the fate of its mother, Mosaism; it was\ngenerally only monotheistic in theory, while it degenerated practically\ninto every kind of polytheism. In point of fact, monotheism was\nlogically abandoned in the very dogma of the Trinity, which was adopted\nas an indispensable foundation of the Christian religion. The three\npersons, which are distinguished as Father, Son, and Holy Ghost, are\nthree distinct individuals (and, indeed, anthropomorphic persons), just\nas truly as the three Indian deities of the Trimurti (Brahma, Vishnu,\nand Shiva) or the Trinity of the ancient Hebrews (Anu, Bel, and Aa).\nMoreover, in the most widely distributed form of Christianity the\n\"virgin\" mother of Christ plays an important part as a fourth deity;\nin many Catholic countries she is practically taken to be much more\npowerful and influential than the three male persons of the celestial\nadministration. The cult of the madonna has been developed to such an\nextent in these countries that we may oppose it to the usual masculine\nform of monotheism as one of a feminine type. The \"Queen of Heaven\"\nbecomes so prominent, as is seen in so many pictures and legends of the\nmadonna, that the three male persons practically disappear.\n\nIn addition, the imagination of the pious Christian soon came to\nincrease this celestial administration by a numerous company of\n\"saints\" of all kinds, and bands of musical angels, who should see\nthat \"eternal life\" should not prove too dull. The popes--the greatest\ncharlatans that any religion ever produced--have constantly studied to\nincrease this band of celestial satellites by repeated canonizations.\nThis curious company received its most interesting acquisition in 1870,\nwhen the Vatican Council pronounced the popes, as the vicars of Christ,\nto be infallible, and thus raised them to a divine dignity. When we add\nthe \"personal Devil\" that they acknowledge, and the \"bad angels\" who\nform his court, we have in modern Catholicism, still the most extensive\nbranch of Christianity, a rich and variegated polytheism that dwarfs\nthe Olympic family of the Greeks.\n\nIslam, or the Mohammedan monotheism, is the youngest and purest form of\nmonotheism. When the young Mohammed (born 570) learned to despise the\npolytheistic idolatry of his Arabian compatriots, and became acquainted\nwith Nestorian Christianity, he adopted its chief doctrines in a\ngeneral way; but he could not bring himself to see anything more than\na prophet in Christ, like Moses. He found in the dogma of the Trinity\nwhat every emancipated thinker finds on impartial reflection--an\nabsurd legend which is neither reconcilable with the first principles\nof reason nor of any value whatever for our religious advancement. He\njustly regarded the worship of the immaculate mother of God as a piece\nof pure idolatry, like the veneration of pictures and images. The\nlonger he reflected on it, and the more he strove after a purified idea\nof deity, the clearer did the certitude of his great maxim appear: \"God\nis the only God\"--there are no other gods beside him.\n\nYet Mohammed could not free himself from the anthropomorphism of the\nGod-idea. His one only God was an idealized, almighty man, like the\nstern, vindictive God of Moses, and the gentle, loving God of Christ.\nStill, we must admit that the Mohammedan religion has preserved the\ncharacter of pure monotheism throughout the course of its historical\ndevelopment and its inevitable division much more faithfully than the\nMosaic and Christian religions. We see that to-day, even externally,\nin its forms of prayer and preaching, and in the architecture and\nadornment of its mosques. When I visited the East for the first time,\nin 1873, and admired the noble mosques of Cairo, Smyrna, Brussa, and\nConstantinople, I was inspired with a feeling of real devotion by the\nsimple and tasteful decoration of the interior, and the lofty and\nbeautiful architectural work of the exterior. How noble and inspiring\ndo these mosques appear in comparison with the majority of Catholic\nchurches, which are covered internally with gaudy pictures and gilt,\nand are outwardly disfigured by an immoderate crowd of human and\nanimal figures! Not less elevated are the silent prayers and the\nsimple devotional acts of the Koran when compared with the loud,\nunintelligible verbosity of the Catholic Mass and the blatant music of\ntheir theatrical processions.\n\nUnder the title of _mixotheism_ we may embrace all the forms of\ntheistic belief which contain mixtures of religious notions of\ndifferent, sometimes contradictory, kinds. In theory this most widely\ndiffused type of religion is not recognized at all; in the concrete\nit is the most important and most notable of all. The vast majority\nof men who have religious opinions have always been, and still are,\n_mixotheists_; their idea of God is picturesquely compounded from the\nimpressions received in childhood from their own sect, and a number\nof other impressions which are received later on, from contact with\nmembers of other religions, and which modify the earlier notions. In\neducated people there is also sometimes the modifying influence of\nphilosophic studies in maturer years, and especially the unprejudiced\nstudy of natural phenomena, which reveals the futility of the theistic\nidea. The conflict of these contradictory impressions, which is\nvery painful to a sensitive soul, and which often remains undecided\nthroughout life, clearly shows the immense power of the _heredity_ of\nancient myths on the one hand and the early _adaptation_ to erroneous\ndogmas on the other. The particular faith in which the child has been\nbrought up generally remains in power, unless a \"conversion\" takes\nplace subsequently, owing to the stronger influence of some other\nreligion. But even in this supersession of one faith by another the new\nname, like the old one, proves to be merely an outward label covering\na mixture of the most diverse opinions and errors. The greater part\nof those who call themselves Christians are not monotheists (as they\nthink), but amphitheists, triplotheists, or polytheists. And the same\nmust be said of Islam and Mosaism, and other monotheistic religions.\nEverywhere we find associated with the original idea of a \"sole and\ntriune God\" later beliefs in a number of subordinate deities--angels,\ndevils, saints, etc.--a picturesque assortment of the most diverse\ntheistic forms.\n\nAll the above forms of theism, in the proper sense of the word--whether\nthe belief assumes a naturalistic or an anthropistic form--represent\nGod to be an extramundane or a supernatural being. He is always opposed\nto the world, or nature, as an independent being; generally as its\ncreator, sustainer, and ruler. In most religions he has the additional\ncharacter of personality, or, to put it more definitely still, God as\na person is likened to man. \"In his gods man paints himself.\" This\nanthropomorphic conception of God as one who thinks, feels, and acts\nlike man prevails with the great majority of theists, sometimes in a\ncruder and more na\u00efve form, sometimes in a more refined and abstract\ndegree. In any case the form of theosophy we have described is sure\nto affirm that God, the supreme being, is infinite in perfection, and\ntherefore far removed from the imperfection of humanity. Yet, when we\nexamine closely, we always find the same psychic or mental activity in\nthe two. God feels, thinks, and acts as man does, although it be in an\ninfinitely more perfect form.\n\nThe _personal anthropism_ of God has become so natural to the majority\nof believers that they experience no shock when they find God\npersonified in human form in pictures and statues, and in the varied\nimages of the poet, in which God takes human form--that is, is changed\ninto a vertebrate. In some myths, even, God takes the form of other\nmammals (an ape, lion, bull, etc.), and more rarely of a bird (eagle,\ndove, or stork), or of some lower vertebrate (serpent, crocodile,\ndragon, etc.).\n\nIn the higher and more abstract forms of religion this idea of bodily\nappearance is entirely abandoned, and God is adored as a \"pure spirit\"\nwithout a body. \"God is a spirit, and they who worship him must worship\nhim in spirit and in truth.\" Nevertheless, the psychic activity of this\n\"pure spirit\" remains just the same as that of the anthropomorphic\nGod. In reality, even this immaterial spirit is not conceived to be\nincorporeal, but merely invisible, gaseous. We thus arrive at the\nparadoxical conception of God as a _gaseous vertebrate_.\n\n\nII.--PANTHEISM\n\nPantheism teaches that God and the world are one. The idea of God is\nidentical with that of nature or substance. This pantheistic view is\nsharply opposed in principle to all the systems we have described, and\nto all possible forms of theism although there have been many attempts\nmade from both sides to bridge over the deep chasm that separates the\ntwo. There is always this fundamental contradiction between them, that\nin theism God is opposed to nature as an _extramundane_ being, as\ncreating and sustaining the world, and acting upon it from without,\nwhile in pantheism God, as an _intramundane_ being, is everywhere\nidentical with nature itself, and is operative _within_ the world\nas \"force\" or \"energy.\" The latter view alone is compatible with\nour supreme law--the law of substance. It follows necessarily that\npantheism is _the world-system of the modern scientist_. There are,\nit is true, still a few men of science who contest this, and think it\npossible to reconcile the old theistic theory of human nature with the\npantheistic truth of the law of substance. All these efforts rest on\nconfusion or sophistry--when they are honest.\n\nAs pantheism is a result of an advanced conception of nature in the\ncivilized mind, it is naturally much younger than theism, the crudest\nforms of which are found in great variety in the uncivilized races of\nten thousand years ago. We do, indeed, find the germs of pantheism in\ndifferent religions at the very dawn of philosophy in the earliest\ncivilized peoples (in India, Egypt, China, and Japan), several thousand\nyears before the time of Christ; still, we do not meet a definite\nphilosophical expression of it until the hylozoism of the Ionic\nphilosophers, in the first half of the sixth century before Christ.\nAll the great thinkers of this flourishing period of Hellenic thought\nare surpassed by the famous Anaximander, of Miletus, who conceived the\nessential unity of the infinite universe (_apeiron_) more profoundly\nand more clearly than his master, Thales, or his pupil, Anaximenes.\nNot only the great thought of the original unity of the cosmos and the\ndevelopment of all phenomena out of the all-pervading primitive matter\nfound expression in Anaximander, but he even enunciated the bold idea\nof countless worlds in a periodic alternation of birth and death.\n\nMany other great philosophers of classical antiquity, especially\nDemocritus, Heraclitus, and Empedocles, had, in the same or an\nanalogous sense, a profound conception of this unity of nature and\nGod, of body and spirit, which has obtained its highest expression\nin the law of substance of our modern monism. The famous Roman poet\nand philosopher, Lucretius Carus, has presented it in a highly poetic\nform in his poem \"De Rerum Natura.\" However, this true pantheistic\nmonism was soon entirely displaced by the mystic dualism of Plato, and\nespecially by the powerful influence which the idealistic philosophy\nobtained by its blending with Christian dogmas. When the papacy\nattained to its spiritual despotism over the world, pantheism was\nhopelessly crushed; Giordano Bruno, its most gifted defender, was\nburned alive by the \"Vicar of Christ\" in the Campo dei Fiori at Rome on\nFebruary 17, 1600.\n\nIt was not until the middle of the seventeenth century that pantheism\nwas exhibited in its purest form by the great Baruch Spinoza; he gave\nfor the totality of things a definition of substance in which God\nand the world are inseparably united. The clearness, confidence, and\nconsistency of Spinoza's monistic system are the more remarkable when\nwe remember that this gifted thinker of two hundred and fifty years\nago was without the support of all those sound empirical bases which\nhave been obtained in the second half of the nineteenth century. We\nhave already spoken, in the first chapter, of Spinoza's relation to the\nmaterialism of the eighteenth and the monism of the nineteenth century.\nThe propagation of his views, especially in Germany, is due, above\nall, to the immortal works of our greatest poet and thinker, Wolfgang\nGoethe. His splendid _God and the World_, _Prometheus_, _Faust_, etc.,\nembody the great thoughts of pantheism in the most perfect poetic\ncreations.\n\nAtheism affirms that there are no gods or goddesses, assuming that\ngod means a personal, extramundane entity. This \"godless world-system\"\nsubstantially agrees with the monism or pantheism of the modern\nscientist; it is only another expression for it, emphasizing its\nnegative aspect, the non-existence of any supernatural deity. In this\nsense Schopenhauer justly remarks: \"Pantheism is only a polite form\nof atheism. The truth of pantheism lies in its destruction of the\ndualist antithesis of God and the world, in its recognition that the\nworld exists in virtue of its own inherent forces. The maxim of the\npantheist, 'God and the world are one,' is merely a polite way of\ngiving the Lord God his _cong\u00e9_.\"\n\nDuring the whole of the Middle Ages, under the bloody despotism of the\npopes, atheism was persecuted with fire and sword as a most pernicious\nsystem. As the \"godless\" man is plainly identified with the \"wicked\"\nin the Gospel, and is threatened--simply on account of his \"want of\nfaith\"--with the eternal fires of hell, it was very natural that every\ngood Christian should be anxious to avoid the suspicion of atheism.\nUnfortunately, the idea still prevails very widely. The atheistic\nscientist who devotes his strength and his life to the search for\nthe truth, is freely credited with all that is evil; the theistic\nchurch-goer, who thoughtlessly follows the empty ceremonies of Catholic\nworship, is at once assumed to be a good citizen, even if there be no\nmeaning whatever in his faith and his morality be deplorable. This\nerror will only be destroyed when, in the twentieth century, the\nprevalent superstition gives place to rational knowledge and to a\nmonistic conception of the unity of God and the world.\n\n\n\n\nCHAPTER XVI\n\nKNOWLEDGE AND BELIEF\n\n    The Knowledge of the Truth and Its Sources: the Activity of the\n    Senses and the Association of Presentations--Organs of Sense and\n    Organs of Thought--Sense-Organs and their Specific Energy--Their\n    Evolution--The Philosophy of Sensibility--Inestimable Value of the\n    Senses--Limits of Sensitive Knowledge--Hypothesis and Faith--Theory\n    and Faith--Essential Difference of Scientific (Natural) and\n    Religious (Supernatural) Faith--Superstition of Savage and of\n    Civilized Races--Confessions of Faith--Unsectarian Schools--The\n    Faith of Our Fathers--Spiritism--Revelation\n\n\nEvery effort of genuine science makes for a knowledge of the truth. Our\nonly real and valuable knowledge is a knowledge of nature itself, and\nconsists of presentations which correspond to external things. We are\nincompetent, it is true, to penetrate into the innermost nature of this\nreal world--the \"thing in itself\"--but impartial critical observation\nand comparison inform us that, in the normal action of the brain and\nthe organs of sense, the impressions received by them from the outer\nworld are the same in all rational men, and that in the normal function\nof the organs of thought certain presentations are formed which are\neverywhere the same. These presentations we call _true_, and we are\nconvinced that their content corresponds to the knowable aspect of\nthings. We _know_ that these facts are not imaginary, but real.\n\nAll knowledge of the truth depends on two different, but intimately\nconnected, groups of human physiological functions: firstly, on the\n_sense-impressions_ of the object by means of sense-action, and,\nsecondly, on the combination of these impressions by an association\ninto _presentations_ in the subject. The instruments of sensation are\nthe sense-organs (_sensilla_ or _aestheta_); the instruments which\nform and link together the presentations are the organs of thought\n(_phroneta_). The latter are part of the central, and the former part\nof the peripheral, nervous system--that important and elaborate system\nof organs in the higher animals which alone effects their entire\npsychic activity.\n\nMan's sense-activity, which is the starting-point of all knowledge,\nhas been slowly and gradually developed from that of his nearest\nmammal relatives, the primates. The sense-organs are of substantially\nthe same construction throughout this highest animal group, and their\nfunction takes place always according to the same physical and chemical\nlaws. They have had the same historical development in all cases. In\nthe mammals, as in the case of all other animals, the _sensilla_ were\noriginally parts of the skin; the sensitive cells of the epidermis are\nthe sources of all the different sense-organs, which have acquired\ntheir specific energy by adaptation to different stimuli (light, heat,\nsound, chemical action, etc.). The rod-cells in the retina of the eye,\nthe auditory cells in the cochlea of the ear, the olfactory cells in\nthe nose, and the taste-cells on the tongue, are all originally derived\nfrom the simple, indifferent cells of the epidermis, which cover the\nentire surface of the body. This significant fact can be directly\nproved by observation of the embryonic development of man or any of the\nhigher animals. And from this ontogenetic fact we confidently infer,\nin virtue of the great biogenetic law, the important phylogenetic\nproposition, that in the long historical evolution of our ancestors,\nlikewise, the higher sense-organs with their specific energies were\noriginally derived from the epidermis of lower animals, from a simple\nlayer of cells which had no trace of such differentiated sensilla.\n\nA particular importance attaches to the circumstance that different\nnerves are qualified to perceive different properties of the\nenvironment, and these only. The optic nerve accomplishes only the\nperception of light, the auditory nerve the perception of sound, the\nolfactory nerve the perception of smell, and so on. No matter what\nstimuli impinge on and irritate a given sense-organ, its reaction\nis always of the same character. From this specific energy of the\nsense-nerves, which was first fully appreciated by Johannes M\u00fcller,\nvery erroneous inferences have been drawn, especially in favor of a\ndualistic and _\u00e0 priori_ theory of knowledge. It has been affirmed\nthat the brain, or the soul, only perceives a certain condition of the\nstimulated nerve, and that, consequently, no conclusion can be drawn\nfrom the process as to the existence and nature of the stimulating\nenvironment. Sceptical philosophy concluded that the very existence of\nan outer world is doubtful, and extreme idealism went on positively to\ndeny it, contending that things only exist in our impressions of them.\n\nIn opposition to these erroneous views, we must recall the fact that\nthe \"specific energy\" was not originally an innate, special quality of\nthe various nerves, but it has arisen by adaptation to the particular\nactivity of the epidermic cells in which they terminate. In harmony\nwith the great law of \"division of labor\" the originally indifferent\n\"sense-cells of the skin\" undertook different tasks, one group of them\ntaking over the stimulus of the light rays, another the impress of the\nsound waves, a third the chemical impulse of odorous substances, and so\non. In the course of a very long period these external stimuli effected\na gradual change in the physiological, and later in the morphological,\nproperties of these parts of the epidermis, and there was a correlative\nmodification of the sensitive nerves which conduct the impressions they\nreceive to the brain. Selection improved, step by step, such particular\nmodifications as proved to be useful, and thus eventually, in the\ncourse of many million years, created those wonderful instruments,\nthe eye and the ear, which we prize so highly; their structure is\nso remarkably purposive that they might well lead to the erroneous\nassumption of a \"creation on a preconceived design.\" The peculiar\ncharacter of each sense-organ and its specific nerve has thus been\ngradually evolved by use and exercise--that is, by _adaptation_--and\nhas then been transmitted by _heredity_ from generation to generation.\nAlbrecht Rau has thoroughly established this view in his excellent\nwork on _Sensation and Thought_, a physiological inquiry into the\nnature of the human understanding (1896). It points out the correct\nsignificance of M\u00fcller's law of specific sense-energies, adding\nsearching investigations into their relation to the brain, and in the\nlast chapter there is an able \"philosophy of sensitivity\" based on the\nideas of Ludwig Feuerbach. I thoroughly agree with his convincing work.\n\nCritical comparison of sense-action in man and the other vertebrates\nhas brought to light a number of extremely important facts, the\nknowledge of which we owe to the penetrating research of the\nnineteenth century, especially of the second half of the century. This\nis particularly true of the two most elaborate \"\u00e6sthetic\" organs,\nthe eye and the ear. They present a different and more complicated\nstructure in the vertebrates than in the other animals, and have also\na characteristic development in the embryo. This typical ontogenesis\nand structure of the sensilla of all the vertebrates is only explained\nby _heredity_ from a common ancestor. Within the vertebrate group,\nhowever, we find a great variety of structure in points of detail, and\nthis is due to _adaptation_ to their manner of life on the part of the\nvarious species, to the increasing or diminishing use of various parts.\n\nIn respect of the structure of his sense-organs man is by no means\nthe most perfect and most highly-developed vertebrate. The eye of the\neagle is much keener, and can distinguish small objects at a distance\nmuch more clearly than the human eye. The hearing of many mammals,\nespecially of the carnivora, ungulata, and rodentia of the desert, is\nmuch more sensitive than that of man, and perceives slight noises at a\nmuch greater distance; that may be seen at a glance by their large and\nvery sensitive cochlea. Singing birds have attained a higher grade of\ndevelopment, even in respect of musical endowment, than the majority of\nmen. The sense of smell is much more developed in most of the mammals,\nespecially in the carnivora and the ungulata, than in man; if the dog\ncould compare his own fine scent with that of man, he would look down\non us with compassion. Even with regard to the lower senses--taste,\nsex-sense, touch, and temperature--man has by no means reached the\nhighest stage in every respect.\n\nWe can naturally only pass judgment on the sensations which we\nourselves experience. However, anatomy informs us of the presence in\nthe bodies of many animals of other senses than those we are familiar\nwith. Thus fishes and other lower aquatic vertebrates have peculiar\nsensilla in the skin which are in connection with special sense-nerves.\nOn the right and left sides of the fish's body there is a long canal,\nbranching into a number of smaller canals at the head. In this \"mucous\ncanal\" there are nerves with numerous branches, the terminations of\nwhich are connected with peculiar nerve-aggregates. This extensive\nepidermic sense-organ probably serves for the perception of changes in\nthe pressure, or in other properties, of the water. Some groups are\ndistinguished by the possession of other peculiar sensilla, the meaning\nof which is still unknown to us.\n\nBut it is already clear from the above facts that our human\nsense-activity is limited, not only in quantity, but in quality also.\nWe can thus only perceive with our senses, especially with the eye\nand the sense of touch, a part of the qualities of the objects in our\nenvironment. And even this partial perception is incomplete, in the\nsense that our organs are imperfect, and our sensory nerves, acting\nas interpreters, communicate to the brain only a translation of the\nimpressions received.\n\nHowever, this acknowledged imperfection of our senses should not\nprevent us from recognizing their instruments, and especially the eye,\nto be organs of the highest type; together with the thought-organs in\nthe brain, they are nature's most valuable gift to man. Very truly does\nAlbrecht Rau say: \"All science is sensitive knowledge in the ultimate\nanalysis; it does not deny, but interpret, the data of the senses.\nThe senses are our first and best friends. Long before the mind is\ndeveloped the senses tell man what he must do and avoid. He who makes\na general disavowal of the senses in order to meet their dangers acts\nas thoughtlessly and as foolishly as the man who plucks out his eyes\nbecause they once fell on shameful things, or the man who cuts off\nhis hand lest at any time it should reach out to the goods of his\nneighbor.\" Hence Feuerbach is quite right in calling all philosophies,\nreligions, and systems which oppose the principle of sense-action not\nonly erroneous, but really pernicious. Without the senses there is\nno knowledge--\"_Nihil est in intellectu, quod non fuerit in sensu_,\"\nas Locke said. Twenty years ago I pointed out, in my chapter \"On the\nOrigin and Development of the Sense-Organs,\"[32] the great service of\nDarwinism in giving us a profounder knowledge and a juster appreciation\nof the senses.\n\nThe thirst for knowledge of the educated mind is not contented with\nthe defective acquaintance with the outer world which is obtained\nthrough our imperfect sense-organs. He endeavors to build up the\nsense-impressions which they have brought him into valuable knowledge.\nHe transforms them into specific sense-perceptions in the sense-centres\nof the cortex of the brain, and combines them into presentations,\nby association, in the thought-centres. Finally, by a further\nconcatenation of the groups of presentations he attains to connected\nknowledge. But this knowledge remains defective and unsatisfactory\nuntil the imagination supplements the inadequate power of combination\nof the intelligence, and, by the association of stored-up images,\nunites the isolated elements into a connected whole. Thus are produced\nnew general presentative images, and these suffice to interpret the\nfacts perceived and satisfy \"reason's feeling of causality.\"\n\nThe presentations which fill up the gaps in our knowledge, or take its\nplace, may be called, in a broad sense, \"faith.\" That is what happens\ncontinually in daily life. When we are not sure about a thing we say, I\nbelieve it. In this sense we are compelled to make use of faith even in\nscience itself; we conjecture or assume that a certain relation exists\nbetween two phenomena, though we do not know it for certain. If it is\na question of a _cause_, we form a _hypothesis_; though in science\nonly such hypotheses are admitted as lie within the sphere of human\ncognizance, and do not contradict known facts. Such hypotheses are, for\ninstance--in physics the theory of the vibratory movement of ether, in\nchemistry the hypothesis of atoms and their affinity, in biology the\ntheory of the molecular structure of living protoplasm, and so forth.\n\nThe explanation of a great number of connected phenomena by the\nassumption of a common cause is called a _theory_. Both in theory and\nhypothesis \"faith\" (in the scientific sense) is indispensable; for\nhere again it is the imagination that fills up the gaps left by the\nintelligence in our knowledge of the connection of things. A theory,\ntherefore, must always be regarded only as an approximation to the\ntruth; it must be understood that it may be replaced in time by another\nand better-grounded theory. But, in spite of this admitted uncertainty,\ntheory is indispensable for all true science; it elucidates facts by\npostulating a cause for them. The man who renounces theory altogether,\nand seeks to construct a pure science with certain facts alone\n(as often happens with wrong-headed representatives of our \"exact\nsciences\"), must give up the hope of any knowledge of causes, and,\nconsequently, of the satisfaction of reason's demand for causality.\n\nThe theory of gravitation in astronomy (Newton), the nebular theory\nin cosmogony (Kant and Laplace), the principle of energy in physics\n(Meyer and Helmholtz), the atomic theory in chemistry (Dalton), the\nvibratory theory in optics (Huyghens), the cellular theory in histology\n(Schleiden and Schwann), and the theory of descent in biology (Lamarck\nand Darwin), are all important theories of the first rank; they explain\na whole world of natural phenomena by the assumption of a common cause\nfor all the several facts of their respective provinces, and by showing\nthat all the phenomena thereof are inter-connected and controlled by\nlaws which issue from this common cause. Yet the cause itself may\nremain obscure in character, or be merely a \"provisional hypothesis.\"\nThe \"force of gravity\" in the theory of gravitation and in cosmogony,\n\"energy\" itself in its relation to matter, the \"ether\" of optics\nand electricity, the \"atom\" of the chemist, the living \"protoplasm\"\nof histology, the \"heredity\" of the evolutionist--these and similar\nconceptions of other great theories may be regarded by a sceptical\nphilosophy as \"mere hypotheses\" and the outcome of scientific \"faith,\"\nyet they are indispensable for us, until they are replaced by better\nhypotheses.\n\nThe dogmas which are used for the explanation of phenomena in the\nvarious religions, and which go by the name of \"faith\" (in the narrower\nsense), are of a very different character from the forms of scientific\nfaith we have enumerated. The two types, however--the \"natural\"\nfaith of science and the \"supernatural\" faith of religion--are not\ninfrequently confounded, so that we must point out their fundamental\ndifference. Religious faith means always belief in a miracle, and as\nsuch is in hopeless contradiction with the natural faith of reason.\nIn opposition to reason it postulates supernatural agencies, and,\ntherefore, may be justly called superstition. The essential difference\nof this superstition from rational faith lies in the fact that it\nassumes supernatural forces and phenomena, which are unknown and\ninadmissible to science, and which are the outcome of illusion and\nfancy; moreover, superstition contradicts the well-known laws of\nnature, and is therefore _irrational_.\n\nOwing to the great progress of ethnology during the century, we\nhave learned a vast quantity of different kinds and practices of\nsuperstition, as they still survive in uncivilized races. When they are\ncompared with each other and with the mythological notion of earlier\nages, a manifold analogy is discovered, frequently a common origin, and\neventually one simple source for them all. This is found in the \"demand\nof causality in reason,\" in the search for an explanation of obscure\nphenomena by the discovery of a cause. That applies particularly to\nsuch phenomena as threaten us with danger and excite fear, like thunder\nand lightning, earthquakes, eclipses, etc. The demand for a causal\nexplanation of such phenomena is found in uncivilized races of the\nlowest grade, transmitted from their primate ancestors by heredity. It\nis even found in many other vertebrates. When a dog barks at the full\nmoon, or at a ringing bell, of which it sees the hammer moving, or at a\nflag that flutters in the breeze, it expresses not only fear, but also\nthe mysterious impulse to learn the cause of the obscure phenomenon.\nThe crude beginnings of religion among primitive races spring partly\nfrom this hereditary superstition of their primate ancestors, and\npartly from the worship of ancestors, from various emotional impulses,\nand from habits which have become traditional.\n\nThe religious notions of modern civilized peoples, which they esteem\nso highly, profess to be on a much higher level than the \"crude\nsuperstition\" of the savage; we are told of the great advance which\ncivilization has made in sweeping it aside. That is a great mistake.\nImpartial comparison and analysis show that they only differ in\ntheir special \"form of faith\" and the outer shell of their creed.\nIn the clear light of reason the refined faith of the most liberal\necclesiastical religion--inasmuch as it contradicts the known and\ninviolable laws of nature--is no less irrational a superstition than\nthe crude spirit-faith of primitive fetichism on which it looks down\nwith proud disdain.\n\nAnd if, from this impartial stand-point, we take a critical glance at\nthe kinds of faith that prevail to-day in civilized countries, we find\nthem everywhere saturated with traditional superstition. The Christian\nbelief in Creation, the Trinity, the Immaculate Conception, the\nRedemption, the Resurrection and Ascension of Christ, and so forth, is\njust as purely imaginative as the belief in the various dogmas of the\nMohammedan, Mosaic, Buddhistic, and Brahmanic religions, and is just\nas incapable of reconciliation with a rational knowledge of nature.\nEach of these religions is for the sincere believer an indisputable\ntruth, and each regards the other as heresy and damnable error. The\nmore confidently a particular sect considers itself \"the only ark\nof salvation,\" and the more ardently this conviction is cherished,\nthe more zealously does it contend against all other sects and give\nrise to the fearful religious wars that form the saddest pages in the\nbook of history. And all the time the unprejudiced \"critique of pure\nreason\" teaches us that all these different forms of faith are equally\nfalse and irrational, mere creatures of poetic fancy and uncritical\ntradition. Rational science must reject them all alike as the outcome\nof superstition.\n\nThe incalculable injury which irrational superstition has done\nto credulous humanity is conspicuously revealed in the ceaseless\nconflict of confessions of faith. Of all the wars which nations have\nwaged against each other with fire and sword the religious wars have\nbeen the bloodiest; of all the forms of discord that have shattered\nthe happiness of families and of individuals those that arise from\nreligious differences are still the most painful. Think of the millions\nwho have lost their lives in Christian persecutions, in the religious\nconflicts of Islam and of the Reformation, by the Inquisition, and\nunder the charge of witchcraft. Or think of the still greater number\nof luckless men who, through religious differences, have been plunged\ninto family troubles, have lost the esteem of their fellow-citizens\nand their position in the community, or have even been compelled to\nfly from their country. The official confession of faith becomes most\npernicious of all when it is associated with the political aims of\na modern state, and is enforced as \"religious instruction\" in our\nschools. The child's mind is thus early diverted from the pursuit of\nthe truth and impregnated with superstition. Every friend of humanity\nshould do all in his power to promote unsectarian schools as one of the\nmost valuable institutions of the modern state.\n\nThe great value which is, none the less, still very widely attached\nto sectarian instruction is not only due to the compulsion of a\nreactionary state and its dependence on a dominant clericalism, but\nalso to the weight of old traditions and \"emotional cravings\" of\nvarious kinds. One of the strongest of these is the devout reverence\nwhich is extended everywhere to sectarian tradition, to the \"faith\nof our fathers.\" In thousands of stories and poems fidelity to it\nis extolled as a spiritual treasure and a sacred duty. Yet a little\nimpartial study of the history of faith suffices to show the absurdity\nof the notion. The dominant evangelical faith of the second half of\nthe nineteenth century is essentially different from that of the first\nhalf, and this again from that of the eighteenth century. The faith of\nthe eighteenth century diverges considerably from the \"faith of our\nfathers\" of the seventeenth, and still more from that of the sixteenth,\ncentury. The Reformation, releasing enslaved reason from the tyranny of\nthe popes, is naturally regarded by them as darkest heresy; but even\nthe faith of the papacy itself had been completely transformed in the\ncourse of a century. And how different is the faith of the Christian\nfrom that of his heathen ancestors. Every man with some degree of\nindependent thought frames a more or less personal religion for\nhimself, which is always different from that of his fathers; it depends\nlargely on the general condition of thought in his day. The further we\ngo back in the history of civilization, the more clearly do we find\nthis esteemed \"faith of our fathers\" to be an indefensible superstition\nwhich is undergoing continual transformation.\n\nOne of the most remarkable forms of superstition, which still takes a\nvery active part in modern life, is _spiritism_. It is a surprising\nand a lamentable fact that millions of educated people are still\ndominated by this dreary superstition; even distinguished scientists\nare entangled in it. A number of spiritualist journals spread the\nfaith far and wide, and our \"superior circles\" do not scruple to hold\n_s\u00e9ances_ in which \"spirits\" appear, rapping, writing, giving messages\nfrom \"the beyond,\" and so on. It is a frequent boast of spiritists that\neven eminent men of science defend their superstition. In Germany, A.\nZ\u00f6llner and Fechner are quoted as instances; in England, Wallace and\nCrookes. The regrettable circumstance that physicists and biologists\nof such distinction have been led astray by spiritism is accounted\nfor, partly by their excess of imagination and defect of critical\nfaculty, and partly by the powerful influence of dogmas which a\nreligious education imprinted on the brain in early youth. Moreover,\nit was precisely through the famous _s\u00e9ances_ at Leipzig, in which the\nphysicists, Z\u00f6llner, Fechner, and Wilhelm Weber, were imposed on by\nthe clever American conjuror, Slade, that the fraud of the latter was\nafterwards fully exposed; he was discovered to be a common impostor.\nIn other cases, too, where the alleged marvels of spiritism have been\nthoroughly investigated, they have been traced to a more or less clever\ndeception; the mediums (generally of the weaker sex) have been found to\nbe either smart swindlers or nervous persons of abnormal irritability.\nTheir supposed gift of \"telepathy\" (or \"action at a distance of thought\nwithout material medium\") has no more existence than the \"voices\" or\nthe \"groans\" of spirits, etc. The vivid pictures which Carl du Prel, of\nMunich, and other spiritists give of their phenomena must be regarded\nas the outcome of a lively imagination, together with a lack of\ncritical power and of knowledge of physiology.\n\nThe majority of religions have, in spite of their great differences,\none common feature, which is, at the same time, one of their strongest\nsupports in many quarters. They declare that they can elucidate the\nproblem of existence, the solution of which is beyond the natural power\nof reason, by the supernatural way of revelation; from that they derive\nthe authority of the dogmas which in the guise of \"divine laws\" control\nmorality and the practical conduct of life. \"Divine\" inspirations of\nthat kind form the basis of many myths and legends, the human origin of\nwhich is perfectly clear. It is true that the God who reveals himself\ndoes not always appear in human shape, but in thunder and lightning,\nstorm and earthquake, fiery bush or menacing cloud. But the revelation\nwhich he is supposed to bring to the credulous children of men is\nalways anthropomorphic; it invariably takes the form of a communication\nof ideas or commands which are formulated and expressed precisely as is\ndone in the normal action of the human brain and larynx. In the Indian\nand Egyptian religions, in the mythologies of Greece and Rome, in the\nOld and the New Testaments, the gods think, talk, and act just as men\ndo; the revelations, in which they are supposed to unveil for us the\nsecrets of existence and the solution of the great world-enigma, are\ncreations of the human imagination. The \"truth\" which the credulous\ndiscover in them is a human invention; the \"childlike faith\" in these\nirrational revelations is mere superstition.\n\nThe true revelation--that is, the true source of rational knowledge--is\nto be sought in nature alone. The rich heritage of truth which forms\nthe most valuable part of human culture is derived exclusively from\nthe experiences acquired in a searching study of nature, and from the\nrational conclusions which it has reached by the just association of\nthese empirical presentations. Every intelligent man with normal brain\nand senses finds this true revelation in nature on impartial study, and\nthus frees himself from the superstition with which the \"revelations\"\nof religion had burdened him.\n\n\n\n\nCHAPTER XVII\n\nSCIENCE AND CHRISTIANITY\n\n    Increasing Opposition between Modern Science and Christian\n    Theology--The Old and the New Faith--Defence of Rational Science\n    against the Attacks of Christian Superstition, especially against\n    Catholicism--Four Periods in the Evolution of Christianity:\n    I. Primitive Christianity (the First Three Centuries)--The\n    Four Canonical Gospels--The Epistles of Paul--II. The Papacy\n    (Ultramontane Christianity)--Retrogression of Civilization in the\n    Middle Ages--Ultramontane Falsification of History--The Papacy and\n    Science--The Papacy and Christianity--III. The Reformation--Luther\n    and Calvin--The Year of Emancipation--IV. The Pseudo-Christianity\n    of the Nineteenth Century--The Papal Declaration of War against\n    Reason and Science: (_a_) Infallibility, (_b_) The Encyclica, (_c_)\n    The Immaculate Conception\n\n\nOne of the most distinctive features of the expiring century is\nthe increasing vehemence of the opposition between science and\nChristianity. That is both natural and inevitable. In the same\nproportion in which the victorious progress of modern science has\nsurpassed all the scientific achievements of earlier ages has the\nuntenability been proved of those mystic views which would subdue\nreason under the yoke of an alleged revelation; and the Christian\nreligion belongs to that group. The more solidly modern astronomy,\nphysics, and chemistry have established the sole dominion of inflexible\nnatural laws in the universe at large, and modern botany, zoology,\nand anthropology have proved the validity of those laws in the entire\nkingdom of organic nature, so much the more strenuously has the\nChristian religion, in association with dualistic metaphysics, striven\nto deny the application of these natural laws in the province of the\nso-called \"spiritual life\"--that is, in one section of the physiology\nof the brain.\n\nNo one has more clearly, boldly, and unanswerably enunciated this\nopen and irreconcilable opposition between the modern scientific and\nthe outworn Christian view than David Friedrich Strauss, the greatest\ntheologian of the nineteenth century. His last work, _The Old Faith\nand the New_, is a magnificent expression of the honest conviction of\nall educated people of the present day who understand this unavoidable\nconflict between the discredited, dominant doctrines of Christianity\nand the illuminating, rational revelation of modern science--all\nthose who have the courage to defend the right of reason against the\npretensions of superstition, and who are sensible of the philosophic\ndemand for a unified system of thought. Strauss, as an honorable and\ncourageous free-thinker, has expounded far better than I could the\nprincipal points of difference between \"the old and the new faith.\"\nThe absolute irreconcilability of the opponents and the inevitability\nof their struggle (\"for life or death\") have been ably presented on\nthe philosophic side by E. Hartmann, in his interesting work on _The\nSelf-Destruction of Christianity_.\n\nWhen the works of Strauss and Feuerbach and _The History of the\nConflict between Religion and Science_ of J. W. Draper have been read,\nit may seem superfluous for us to devote a special chapter to the\nsubject. Yet we think it useful, and even necessary for our purpose,\nto cast a critical glance at the historical course of this great\nstruggle; especially seeing that the attacks of the \"Church militant\"\non science in general, and on the theory of evolution in particular,\nhave become extremely bitter and menacing of late years. Unfortunately,\nthe mental relaxation which has lately set in, and the rising flood of\nreaction in the political, social, and ecclesiastical world, are only\ntoo well calculated to give point to those dangers. If any one doubts\nit, he has only to look over the conduct of Christian synods and of the\nGerman Reichstag during the last few years. Quite in harmony are the\nrecent efforts of many secular governments to get on as good a footing\nas possible with the \"spiritual regiment,\" their deadly enemy--that\nis, to submit to its yoke. The two forces find a common aim in the\nsuppression of free thought and free scientific research, for the\npurpose of thus more easily securing a complete despotism.\n\nLet us first emphatically protest that it is a question for us of the\nnecessary defence of science and reason against the vigorous attacks\nof the Christian Church and its vast army, not of an unprovoked\nattack of science on religion. And, in the first place, our defence\nmust be prepared against Romanism or Ultramontanism. This \"one ark\nof salvation,\" this Catholic Church \"destined for all,\" is not only\nmuch larger and more powerful than the other Christian sects, but it\nhas the exceptional advantage of a vast, centralized organization\nand an unrivalled political ability. Men of science are often heard\nto say that the Catholic superstition is no more astute than the\nother forms of supernatural faith, and that all these insidious\ninstitutions are equally inimical to reason and science. As a matter\nof general theoretical principle the statement may pass, but it is\ncertainly wrong when we look to its practical side. The deliberate and\nindiscriminate attacks of the ultramontane Church on science, supported\nby the apathy and ignorance of the masses, are, on account of its\npowerful organization, much more severe and dangerous than those of\nother religions.\n\nIn order to appreciate correctly the extreme importance of Christianity\nin regard to the entire history of civilization, and particularly\nits fundamental opposition to reason and science, we must briefly\nrun over the principal stages of its historical evolution. It may be\ndivided into four periods: (1) primitive Christianity (the first three\ncenturies), (2) papal Christianity (twelve centuries, from the fourth\nto the fifteenth), (3) the Reformation (three centuries, from the\nsixteenth to the eighteenth), and (4) modern pseudo-Christianity.\n\n\nI.--PRIMITIVE CHRISTIANITY\n\nPrimitive Christianity embraces the first three centuries. Christ\nhimself, the noble prophet and enthusiast, so full of the love of\nhumanity, was far below the level of classical culture; he knew nothing\nbeyond the Jewish traditions; he has not left a single line of writing.\nHe had, indeed, no suspicion of the advanced stage to which Greek\nphilosophy and science had progressed five hundred years before.\n\nAll that we know of him and of his original teaching is taken from the\nchief documents of the New Testament--the four gospels and the Pauline\nepistles. As to the four canonical gospels, we now know that they were\nselected from a host of contradictory and forged manuscripts of the\nfirst three centuries by the three hundred and eighteen bishops who\nassembled at the Council of Nic\u00e6a in 327. The entire list of gospels\nnumbered forty; the canonical list contains four. As the contending\nand mutually abusive bishops could not agree about the choice, they\ndetermined to leave the selection to a miracle. They put all the books\n(according to the _Synodicon_ of Pappus) together underneath the\naltar, and prayed that the apocryphal books, of human origin, might\nremain there, and the genuine, inspired books might be miraculously\nplaced on the table of the Lord. And that, says tradition, really\noccurred! The three synoptic gospels (Matthew, Mark, and Luke--all\nwritten _after_ them, not _by_ them, at the beginning of the second\ncentury) and the very different fourth gospel (ostensibly \"after\"\nJohn, written about the middle of the second century) leaped on the\ntable, and were thenceforth recognized as the inspired (with their\nthousand mutual contradictions) foundations of Christian doctrine. If\nany modern \"unbeliever\" finds this story of the \"leap of the sacred\nbooks\" incredible, we must remind him that it is just as credible as\nthe table-turning and spirit-rapping that are believed to take place\nto-day by millions of educated people; and that hundreds of millions of\nChristians believe just as implicitly in their personal immortality,\ntheir \"resurrection from the dead,\" and the Trinity of God--dogmas that\ncontradict pure reason no more and no less than that miraculous bound\nof the gospel manuscripts.\n\nThe most important sources after the gospels are the fourteen separate\n(and generally forged) epistles of Paul. The genuine Pauline epistles\n(_three_ in number, according to recent criticism--to the Romans,\nGalatians, and Corinthians) were written before the canonical gospels,\nand contain less incredible miraculous matter than they. They are\nalso more concerned than the gospels to adjust themselves with a\nrational view of the world. Hence the advanced theology of modern times\nconstructs its \"ideal Christianity\" rather on the base of the Pauline\nepistles than on the gospels, so that it has been called \"Paulinism.\"\n\nThe remarkable personality of Paul, who possessed much more culture\nand practical sense than Christ, is extremely interesting, from the\nanthropological point of view, from the fact that the racial origin\nof the two great religious founders is very much the same. Recent\nhistorical investigation teaches that Paul's father was of Greek\nnationality, and his mother of Jewish.[33] The half-breeds of these two\nraces, which are so very distant in origin (although they are branches\nof the same species, the _homo mediterraneus_), are often distinguished\nby a happy blending of talents and temperament, as we find in many\nrecent and actual instances. The plastic Oriental imagination and the\ncritical Western reason often admirably combine and complete each\nother. That is visible in the Pauline teaching, which soon obtained a\ngreater influence than the earliest Christian notions. Hence it is not\nincorrect to consider Paulinism a new phenomenon, of which the father\nwas the philosophy of the Greeks, and the mother the religion of the\nJews. Neoplatonism is an analogous combination.\n\nAs to the real teaching and aims of Christ (and as to many important\naspects of his life) the views of conflicting theologians diverge\nmore and more, as historical criticism (Strauss, Feuerbach, Baur,\nRenan, etc.) puts the accessible facts in their true light, and draws\nimpartial conclusions from them. Two things, certainly, remain beyond\ndispute--the lofty principle of universal charity and the fundamental\nmaxim of ethics, the \"golden rule,\" that issues therefrom; both,\nhowever, existed in theory and in practice centuries before the time\nof Christ (cf. chap. xix.). For the rest, the Christians of the early\ncenturies were generally pure Communists, sometimes \"Social Democrats,\"\nwho, according to the prevailing theory in Germany to-day, ought to\nhave been exterminated with fire and sword.\n\n\nII.--PAPAL CHRISTIANITY\n\nLatin Christianity, variously called Papistry, Romanism, Vaticanism,\nUltramontanism, or the Roman Catholic Church, is one of the most\nremarkable phenomena in the history of civilized man; in spite of\nthe storms that have swept over it, it still exerts a most powerful\ninfluence. Of the four hundred and ten million Christians who are\nscattered over the earth the majority--that is, two hundred and\ntwenty-five millions--are Roman Catholics; there are seventy-five\nmillion Greek Catholics and one hundred and ten million Protestants.\nDuring a period of one thousand two hundred years, from the fourth to\nthe sixteenth century, the papacy has almost absolutely controlled and\ntainted the spiritual life of Europe; on the other hand, it has won but\nlittle territory from the ancient religions of Asia and Africa. In Asia\nBuddhism still counts five hundred and three million followers, the\nBrahmanic religion one hundred and thirty-eight millions, and Islam one\nhundred and twenty millions.\n\nIt is the despotism of the papacy that lent its darkest character to\nthe Middle Ages; it meant death to all freedom of mental life, decay\nto all science, corruption to all morality. From the noble height to\nwhich the life of the human mind had attained in classical antiquity,\nin the centuries before Christ and the first century after Christ,\nit soon sank, under the rule of the papacy, to a level which, in\nrespect of the knowledge of the truth, can only be termed barbarism.\nIt is often protested that other aspects of mental life--poetry and\narchitecture, scholastic learning and patristic philosophy--were richly\ndeveloped in the Middle Ages. But this activity was in the service of\nthe Church; it did not tend to the cultivation, but to the suppression,\nof free mental research. The exclusive preparing for an unknown\neternity beyond the tomb, the contempt of nature, the withdrawal from\nthe study of it, which are essential elements of Christianity, were\nurged as a sacred duty by the Roman hierarchy. It was not until the\nbeginning of the sixteenth century that a change for the better came in\nwith the Reformation.\n\nIt is impossible for us here to describe the pitiful retrogression\nof culture and morality during the twelve centuries of the spiritual\ndespotism of Rome. It is very pithily expressed in a saying of the\ngreatest and the ablest of the Hohenzollerns; Frederick the Great\ncondensed his judgment in the phrase that the study of history led\none to think that from Constantine to the date of the Reformation the\nwhole world was insane. L. B\u00fcchner has given us an admirable, brief\ndescription of this \"period of insanity\" in his work on _Religious\nand Scientific Systems_. The reader who desires a closer acquaintance\nwith the subject would do well to consult the historical works of\nRanke, Draper, Kolb, Svoboda, etc. The truthful description of the\nawful condition of the Christian Middle Ages, which is given by these\nand other unprejudiced historians, is confirmed by all the reliable\nsources of investigation, and by the historical monuments which\nhave come down from the saddest period of human history. Educated\nCatholics, who are sincere truth-seekers, cannot be too frequently\nrecommended to study these historical sources for themselves. This is\nthe more necessary as ultramontane literature has still a considerable\ninfluence. The old trick of deceiving the faithful by a complete\nreversal of facts and an invention of miraculous circumstances is\nstill worked by it with great success. We will only mention Lourdes\nand the \"Holy Coat\" of Tr\u00eaves. The ultramontane professor of history\nat Frankfurt, Johannes Janssen, affords a striking example of the\nlength they will go in distorting historical truth; his much-read works\n(especially his _History of the German People since the Middle Ages_)\nare marred by falsification to an incredible extent. The untruthfulness\nof these Jesuitical productions is on a level with the credulity and\nthe uncritical judgment of the simple German nation that takes them for\ngospel.\n\nOne of the most interesting of the historical facts which clearly prove\nthe evil of the ultramontane despotism is its vigorous and consistent\nstruggle with science. This was determined on, in principle, from the\nvery beginning of Christianity, inasmuch as it set faith above reason\nand preached the blind subjection of the one to the other; that was\nnatural, seeing that our whole life on earth was held to be only a\npreparation for the legendary life beyond, and thus scientific research\nwas robbed of any real value. The deliberate and successful attack on\nscience began in the early part of the fourth century, particularly\nafter the Council of Nic\u00e6a (327), presided over by Constantine--called\nthe \"Great\" because he raised Christianity to the position of a state\nreligion, and founded Constantinople, though a worthless character,\na false-hearted hypocrite, and a murderer. The success of the papacy\nin its conflict with independent scientific thought and inquiry is\nbest seen in the distressing condition of science and its literature\nduring the Middle Ages. Not only were the rich literary treasures\nthat classical antiquity had bequeathed to the world destroyed for\nthe most part, or withdrawn from circulation, but the rack and the\nstake insured the silence of every heretic--that is, every independent\nthinker. If he did not keep his thoughts to himself, he had to look\nforward to being burned alive, as was the fate of the great monistic\nphilosopher, Giordano Bruno, the reformer, John Huss, and more than a\nhundred thousand other \"witnesses to the truth.\" The history of science\nin the Middle Ages teaches us on every page that independent thought\nand empirical research were completely buried for twelve sad centuries\nunder the oppression of the omnipotent papacy.\n\nAll that we esteem in true Christianity, in the sense of its founder\nand of his noblest followers, and that we must endeavor to save from\nthe inevitable wreck of this great world religion for our new monistic\nreligion, lies on its ethical and social planes. The principles of\ntrue humanism, the golden rule, the spirit of tolerance, the love\nof man, in the best and highest sense of the word--all these true\ngraces of Christianity were not, indeed, first discovered and given\nto the world by that religion, but were successfully developed in the\ncritical period when classical antiquity was hastening to its doom.\nThe papacy, however, has attempted to convert all those virtues into\nthe direct contrary, and still to hang out the sign of the old firm.\nInstead of Christian charity, it introduced a fanatical hatred of the\nfollowers of all other religions; with fire and sword it has pursued,\nnot only the heathen, but every Christian sect that dared resist the\nimposition of ultramontane dogma. Tribunals for heretics were erected\nall over Europe, yielding unnumbered victims, whose torments seemed\nonly to fill their persecutors, with all their Christian charity, with\na peculiar satisfaction. The power of Rome was directed mercilessly\nfor centuries against everything that stood in its way. Under the\nnotorious Torquemada (1481-98), in Spain alone eight thousand heretics\nwere burned alive and ninety thousand punished with the confiscation\nof their goods and the most grievous ecclesiastical fines; in the\nNetherlands, under the rule of Charles V., at least fifty thousand\nmen fell victims to the clerical bloodthirst. And while the heavens\nresounded with the cry of the martyrs, the wealth of half the world was\npouring into Rome, to which the whole of Christianity paid tribute, and\nthe self-styled representatives of God on earth and their accomplices\n(not infrequently Atheists themselves) wallowed in pleasure and vice\nof every description. \"And all these privileges,\" said the frivolous,\nsyphilitic Pope, Leo X., \"have been secured to us by the fable of Jesus\nChrist.\"\n\nYet, with all the discipline of the Church and the fear of God, the\ncondition of European society was pitiable. Feudalism, serfdom, the\ngrace of God, and the favor of the monks ruled the land; the poor\nhelots were only too glad to be permitted to raise their miserable\nhuts under the shadow of the castle or the cloister, their secular and\nspiritual oppressors and exploiters. Even to-day we suffer from the\naftermath of these awful ages and conditions, in which there was no\nquestion of care for science or higher mental culture save in rare\ncircumstances and in secret. Ignorance, poverty, and superstition\ncombined with the immoral operation of the law of celibacy, which\nhad been introduced in the eleventh century, to consolidate the\never-growing power of the papacy. It has been calculated that there\nwere more than ten million victims of fanatical religious hatred during\nthis \"Golden Age\" of papal domination; and how many more million human\nvictims must be put to the account of celibacy, oral confession, and\nmoral constraint, the most pernicious and accursed institutions of\nthe papal despotism! Unbelieving philosophers, who have collected\ndisproofs of the existence of God, have overlooked one of the strongest\narguments in that sense--the fact that the Roman \"Vicar of Christ\"\ncould for twelve centuries perpetrate with impunity the most shameful\nand horrible deeds \"in the name of God.\"\n\n\nIII.--THE REFORMATION\n\nThe history of civilization, which we are so fond of calling \"the\nhistory of the world,\" enters upon its third period with the\nReformation of the Christian Church, just as its second period begins\nwith the founding of Christianity. With the Reformation begins the\nnew birth of fettered reason, the reawakening of science, which the\niron hand of the Christian papacy had relentlessly crushed for twelve\nhundred years. At the same time the spread of general education had\nalready commenced, owing to the invention of printing about the\nmiddle of the fifteenth century; and towards its close several great\nevents occurred, especially the discovery of America in 1492, which\nprepared the way for the \"renaissance\" of science in company with\nthat of art. Indeed, certain very important advances were made in the\nknowledge of nature during the first half of the sixteenth century,\nwhich shook the prevailing system to its very foundations. Such were\nthe circumnavigation of the globe by Magellan in 1522, which afforded\nempirical proof of its rotundity, and the founding of the new system of\nthe world by Copernicus in 1543.\n\nYet the 31st of October in the year 1517, the day on which Martin\nLuther nailed his ninety-five theses to the wooden door of Wittenburg\nCathedral, must be regarded as the commencement of a new epoch; for\non that day was forced the iron door of the prison in which the Papal\nChurch had detained fettered reason for twelve hundred years. The\nmerits of the great reformer have been partly exaggerated, partly\nunderestimated. It has been justly pointed out that Luther, like all\nthe other reformers, remained in manifold subjection to the deepest\nsuperstition. Thus he was throughout life a supporter of the rigid\ndogma of the verbal inspiration of the Bible; he zealously maintained\nthe doctrines of the resurrection, original sin, predestination,\njustification by faith, etc. He rejected as folly the great discovery\nof Copernicus, because in the Bible \"Joshua bade the sun, not the\nearth, stand still.\" He utterly failed to appreciate the great\npolitical revolutions of his time, especially the profound and just\nagitation of the peasantry. Worse still was the fanatical Calvin, of\nGeneva, who had the talented Spanish physician, Serveto, burned alive\nin 1553, because he rejected the absurd dogma of the Trinity. The\nfanatical \"true believers\" of the reformed Church followed only too\nfrequently in the blood-stained footsteps of their papal enemies; as\nthey do even in our own day. Deeds of unparalleled cruelty followed\nin the train of the Reformation--the massacre of St. Bartholomew and\nthe persecution of the Huguenots in France, bloody heretic-hunts in\nItaly, civil war in England, and the Thirty Years War in Germany. Yet,\nin spite of those grave blemishes, to the sixteenth and seventeenth\ncenturies belongs the honor of once more opening a free path to the\nthoughtful mind, and delivering reason from the oppressive yoke of the\npapacy. Thus only was made possible that great development of different\ntendencies in critical philosophy and of new paths in science which\nwon for the subsequent eighteenth century the honorable title of \"the\ncentury of enlightenment.\"\n\n\nIV.--THE PSEUDO-CHRISTIANITY OF THE NINETEENTH CENTURY\n\nAs the fourth and last stage in the history of Christianity we oppose\nour nineteenth century to all its predecessors. It is true that the\nenlightenment of preceding centuries had promoted critical thought in\nevery direction, and the rise of science itself had furnished powerful\nempirical weapons; yet it seems to us that our progress along both\nlines has been quite phenomenal during the nineteenth century. It\nhas inaugurated an entirely new period in the history of the human\nmind, characterized by the development of the monistic philosophy\nof nature. At its very commencement the foundations were laid of a\nnew anthropology (by the comparative anatomy of Cuvier) and of a new\nbiology (by the _Philosophie Zoologique_ of Lamarck). The two great\nFrench scientists were quickly succeeded by two contemporary German\nscholars--Baer, the founder of the science of evolution, and Johannes\nM\u00fcller, the founder of comparative morphology and physiology. A\npupil of M\u00fcller, Theodor Schwann, created the far-reaching cellular\ntheory in 1838, in conjunction with M. Schleiden. Lyell had already\ntraced the evolution of the earth to natural causes, and thus proved\nthe application to our planet of the mechanical cosmogony which Kant\nhad sketched with so much insight in 1755. Finally, Robert Mayer and\nHelmholtz established the principle of energy in 1842--the second,\ncomplementary half of the great law of substance, the first half of\nwhich (the persistence of matter) had been previously discovered by\nLavoisier. Forty years ago Charles Darwin crowned all these profound\nrevelations of the intimate nature of the universe by his new theory\nof evolution, the greatest natural-philosophical achievement of our\ncentury.\n\nWhat is the relation of modern Christianity to this vast and\nunparalleled progress of science? In the first place, the deep gulf\nbetween its two great branches, conservative Romanism and progressive\nProtestantism, has naturally widened. The ultramontane clergy (and\nwe must associate with them the orthodox \"evangelical alliance\") had\nnaturally to offer a strenuous opposition to this rapid advance of\nthe emancipated mind; they continued unmoved in their rigid literal\nbelief, demanding the unconditional surrender of reason to dogma.\nLiberal Protestantism, on the other hand, took refuge in a kind of\nmonistic pantheism, and sought a means of reconciling two contradictory\nprinciples. It endeavored to combine the unavoidable recognition of\nthe established laws of nature, and the philosophic conclusions that\nfollowed from them, with a purified form of religion, in which scarcely\nanything remained of the distinctive teaching of faith. There were\nmany attempts at compromise to be found between the two extremes; but\nthe conviction rapidly spread that dogmatic Christianity had lost every\nfoundation, and that only its valuable ethical contents should be saved\nfor the new monistic religion of the twentieth century. As, however,\nthe existing external forms of the dominant Christian religion remained\nunaltered, and as, in spite of a progressive political development,\nthey are more intimately than ever connected with the practical needs\nof the State, there has arisen that widespread religious profession\nin educated spheres which we can only call \"pseudo-Christianity\"--at\nthe bottom it is a \"religious lie\" of the worst character. The great\ndangers which attend this conflict between sincere conviction and the\nhypocritical profession of modern pseudo-Christians are admirably\ndescribed in Max Nordau's interesting work on _The Conventional Lies of\nCivilization_.\n\nIn the midst of this obvious falseness of prevalent pseudo-Christianity\nthere is one favorable circumstance for the progress of a rational\nstudy of nature: its most powerful and bitterest enemy, the Roman\nChurch, threw off its mask of ostensible concern for higher mental\ndevelopment about the middle of the nineteenth century, and declared\na _guerre \u00e0 l'outrance_ against independent science. This happened\nin three important challenges to reason, for the explicitness and\nresoluteness of which modern science and culture cannot but be\ngrateful to the \"Vicar of Christ.\" (1) In December, 1854, the pope\npromulgated the dogma of the immaculate conception of Mary. (2) Ten\nyears afterwards--in December, 1864--the pope published, in his\nfamous _encyclica_, an absolute condemnation of the whole of modern\ncivilization and culture; in the _syllabus_ that accompanied it he\nenumerated and anathematized all the rational theses and philosophical\nprinciples which are regarded by modern science as lucid truths. (3)\nFinally, six years afterwards--on July 13, 1870--the militant head of\nthe Church crowned his folly by claiming _infallibility_ for himself\nand all his predecessors in the papal chair. This triumph of the Roman\n_curia_ was communicated to the astonished world five days afterwards,\non the very day on which France declared war with Prussia. Two months\nlater the temporal power of the pope was taken from him in consequence\nof the war.\n\nThese three stupendous acts of the papacy were such obvious assaults on\nthe reason of the nineteenth century that they gave rise, from the very\nbeginning, to a most heated discussion even within orthodox Catholic\ncircles. When the Vatican Council proceeded to define the dogma of\ninfallibility on July 13, 1870, only three-fourths of the bishops\ndeclared in its favor, 451 out of 601 assenting; many other bishops,\nwho wished to keep clear of the perilous definition, were absent from\nthe council. But the shrewd pontiff had calculated better than the\ntimid \"discreet Catholics\": even this extraordinary dogma was blindly\naccepted by the credulous and uneducated masses of the faithful.\n\nThe whole history of the papacy, as it is substantiated by a thousand\nreliable sources and accessible documents, appears to the impartial\nstudent as an unscrupulous tissue of lying and deceit, a reckless\npursuit of absolute mental despotism and secular power, a frivolous\ncontradiction of all the high moral precepts which true Christianity\nenunciates--charity and toleration, truth and chastity, poverty and\nself-denial. When we judge the long series of popes and of the Roman\nprinces of the Church, from whom the pope is chosen, by the standard of\npure Christian morality, it is clear that the great majority of them\nwere pitiful impostors, many of them utterly worthless and vicious.\nThese well-known historical facts, however, do not prevent millions\nof educated Catholics from admitting the infallibility which the pope\nhas claimed for himself; they do not prevent Protestant princes from\ngoing to Rome, and doing reverence to the pontiff (their most dangerous\nenemy); they do not prevent the fate of the German people from being\nintrusted to-day to the hands of the servants and followers of this\n\"pious impostor\" in the Reichstag--thanks to the incredible political\nindolence and credulity of the nation.\n\nThe most interesting of the three great events by which the papacy has\nendeavored to maintain and strengthen its despotism in the nineteenth\ncentury is the publication of the encyclica and the syllabus in\nDecember, 1864. In these remarkable documents all independent action\nwas forbidden to reason and science, and they were commanded to submit\nimplicitly to faith--that is, to the decrees of the infallible pope.\nThe great excitement which followed this sublime piece of effrontery in\neducated and independent circles was in proportion with the stupendous\ncontents of the encyclica. Draper has given us an excellent discussion\nof its educational and political significance in his _History of the\nConflict between Science and Religion_.\n\nThe dogma of the immaculate conception seems, perhaps, to be less\naudacious and significant than the encyclica and the dogma of the\ninfallibility of the pope. Yet not only the Roman hierarchy, but\neven some of the orthodox Protestants (the Evangelical Alliance, for\ninstance), attach great importance to this thesis. What is known\nas the \"immaculate oath\"--that is, the confirmation of faith by an\noath taken on the immaculate conception of Mary--is still regarded by\nmillions of Christians as a sacred obligation. Many believers take the\ndogma in a twofold application; they think that the mother of Mary was\nimpregnated by the Holy Ghost as well as Mary herself. Comparative and\ncritical theology has recently shown that this myth has no greater\nclaim to originality than most of the other stories in the Christian\nmythology; it has been borrowed from older religions, especially\nBuddhism. Similar myths were widely circulated in India, Persia,\nAsia Minor, and Greece several centuries before the birth of Christ.\nWhenever a king's unwedded daughter, or some other maid of high degree,\ngave birth to a child, the father was always pronounced to be a god, or\na demi-god; in the Christian case it was the Holy Ghost.\n\nThe special endowments of mind or body which often distinguished these\n\"children of love\" above ordinary offspring were thus partly explained\nby \"heredity.\" Distinguished \"sons of God\" of this kind were held in\nhigh esteem both in antiquity and during the Middle Ages, while the\nmoral code of modern civilization reproaches them with their want of\nhonorable parentage. This applies even more forcibly to \"daughters of\nGod,\" though the poor maidens are just as little to blame for their\nwant of a father. For the rest, every one who is familiar with the\nbeautiful mythology of classical antiquity knows that these sons and\ndaughters of the Greek and Roman gods often approach nearest to the\nhighest ideal of humanity. Recollect the large legitimate family, and\nthe still more numerous illegitimate offspring, of Zeus.\n\nTo return to the particular question of the impregnation of the Virgin\nMary by the Holy Ghost, we are referred to the gospels for testimony\nto the fact. The only two evangelists who speak of it, Matthew and\nLuke, relate in harmony that the Jewish maiden Mary was betrothed to\nthe carpenter Joseph, but became pregnant without his co-operation,\nand, indeed, \"by the Holy Ghost.\" As we have already related, the\nfour canonical gospels which are regarded as the only genuine ones\nby the Christian Church, and adopted as the foundation of faith,\nwere deliberately chosen from a much larger number of gospels, the\ndetails of which contradict each other sometimes just as freely as the\nassertions of the four. The fathers of the Church enumerate from forty\nto fifty of these spurious or apocryphal gospels; some of them are\nwritten both in Greek and Latin--for instance, the gospel of James, of\nThomas, of Nicodemus, and so forth. The details which these apocryphal\ngospels give of the life of Christ, especially with regard to his birth\nand childhood, have just as much (or, on the whole, just as little)\nclaim to historical validity as the four canonical gospels.\n\nNow we find in one of these documents an historical statement,\nconfirmed, moreover, in the _Sepher Toldoth Jeschua_, which probably\nfurnishes the simple and natural solution of the \"world-riddle\" of the\nsupernatural conception and birth of Christ. The author curtly gives us\nin one sentence the remarkable statement which contains this solution:\n\"Josephus Pandera, the Roman officer of a Calabrian legion which was in\nJud\u00e6a, seduced Miriam of Bethlehem, and was the father of Jesus.\" Other\ndetails given about Miriam (the Hebrew name for Mary) are far from\nbeing to the credit of the \"Queen of Heaven.\"\n\nNaturally, these historical details are carefully avoided by the\nofficial theologian, but they assort badly with the traditional myth,\nand lift the veil from its mystery in a very simple and natural\nfashion. That makes it the more incumbent on impartial research and\npure reason to make a critical examination of these statements. It\nmust be admitted that they have much more title to credence than all\nthe other statements about the birth of Christ. When, on familiar\nprinciples of science, we put aside the notion of supernatural\nconception through an \"overshadowing of the Most High\" as a pure myth,\nthere only remains the widely accepted version of modern rational\ntheology--that Joseph, the Jewish carpenter, was the true father of\nChrist. But this assumption is explicitly contradicted by many texts\nof the gospels; Christ himself was convinced that he was a \"Son of\nGod,\" and he never recognized his foster-father, Joseph, as his real\nparent. Joseph, indeed, wanted to leave his betrothed when he found her\npregnant without his interference. He gave up this idea when an angel\nappeared to him in a dream and pacified him. As it is expressly stated\nin the first chapter of Matthew (vv. 24, 25), there was no sexual\nintercourse between Joseph and Mary until after Jesus was born.\n\nThe statement of the apocryphal gospels, that the Roman officer,\nPandera, was the true father of Christ, seems all the more credible\nwhen we make a careful anthropological study of the personality\nof Christ. He is generally regarded as purely Jewish. Yet the\ncharacteristics which distinguish his high and noble personality,\nand which give a distinct impress to his religion, are certainly not\nSemitical; they are rather features of the higher Arian race, and\nespecially of its noblest branch, the Hellenes. Now, the name of\nChrist's real father, \"Pandera,\" points unequivocally to a Greek\norigin; in one manuscript, in fact, it is written \"Pandora.\" Pandora\nwas, according to the Greek mythology, the first woman, born of\nthe earth by Vulcan and adorned with every charm by the gods, who\nwas espoused by Epimetheus, and sent by Zeus to men with the dread\n\"Pandora-box,\" containing every evil, in punishment for the stealing of\ndivine fire from heaven by Prometheus.\n\nAnd it is interesting to see the different reception that the\nlove-story of Miriam has met with at the hands of the four great\nChristian nations of civilized Europe. The stern morality of the\nTeutonic races entirely repudiates it; the righteous German and the\nprudish Briton prefer to believe blindly in the impossible thesis of a\nconception \"by the Holy Ghost.\" It is well known that this strenuous\nand carefully paraded prudery of the higher classes (especially in\nEngland) is by no means reflected in the true condition of sexual\nmorality in high quarters. The revelations which the _Pall Mall\nGazette_, for instance, made on the subject twelve years ago vividly\nrecalled the condition of Babylon.\n\nThe Romantic races, which ridicule this prudery and take sexual\nrelations less seriously, find _Mary's Romance_ attractive enough;\nthe special cult which \"Our Lady\" enjoys in France and Italy is often\nassociated with this love-story with curious na\u00efvet\u00e9. Thus, for\nexample, Paul de Regla (Dr. Desjardin), author of _Jesus of Nazareth\nconsidered from a Scientific, Historical, and Social Standpoint_\n(1894), finds precisely in the illegitimate birth of Christ a special\n\"title to the halo that irradiates his noble form.\"\n\nIt seemed to me necessary to enter fully into this important question\nof the origin of Christ in the sense of impartial historical science,\nbecause the Church militant itself lays great emphasis on it, and\nbecause it regards the miraculous structure which has been founded\non it as one of its strongest weapons against modern thought. The\nhighest ethical value of pure primitive Christianity and the ennobling\ninfluence of this \"religion of love\" on the history of civilization are\nquite independent of those mythical dogmas. The so-called \"revelations\"\non which these myths are based are incompatible with the firmest\nresults of modern science.\n\n\n\n\nCHAPTER XVIII\n\nOUR MONISTIC RELIGION\n\n    Monism as a Connecting Link between Religion and Science--The\n    _Cultur-Kampf_--The Relations of Church and State--Principles\n    of the Monistic Religion--Its Three-fold Ideal: the Good, the\n    True, and the Beautiful--Contradiction between Scientific and\n    Christian Truth--Harmony of the Monistic and the Christian Idea\n    of Virtue--Opposition between Monistic and Christian Views\n    of Art--Modern Expansion and Enrichment of Our Idea of the\n    World--Landscape-Painting and the Modern Enjoyment of Nature--The\n    Beauties of Nature--This World and Beyond--Monistic Churches\n\n\nMany distinguished scientists and philosophers of the day, who share\nour monistic views, consider that religion is generally played out.\nTheir meaning is that the clear insight into the evolution of the world\nwhich the great scientific progress of the nineteenth century has\nafforded us will satisfy, not only the causal feeling of our reason,\nbut even our highest emotional cravings. This view is correct in the\nsense that the two ideas, religion and science, would indeed blend\ninto one if we had a perfectly clear and consecutive system of monism.\nHowever, there are but a few resolute thinkers who attain to this most\npure and lofty conception of Spinoza and Goethe. Most of the educated\npeople of our time (as distinct from the uncultured masses) remain in\nthe conviction that religion is a separate branch of our mental life,\nindependent of science, and not less valuable and indispensable.\n\nIf we adopt this view, we can find a means of reconciling the two\ngreat and apparently quite distinct branches in the idea I put forward\nin \"Monism, as a Connecting-Link between Religion and Science,\"\nin 1892. In the preface to this _Confession of Faith of a Man of\nScience_ I expressed myself in the following words with regard to\nits double object: \"In the first place, I must give expression to\nthe rational system which is logically forced upon us by the recent\nprogress of science; it dwells in the intimate thoughts of nearly every\nimpartial and thoughtful scientist, though few have the courage or\nthe disposition to avow it. In the second place, I would make of it a\nconnecting-link between religion and science, and thus do away with\nthe antithesis which has been needlessly maintained between these two\nbranches of the highest activity of the human mind. The ethical craving\nof our emotion is satisfied by monism no less than the logical demand\nfor causality on the part of reason.\"\n\nThe remarkable interest which the discourse enkindled is a proof that\nin this monistic profession of faith I expressed the feeling not only\nof many scientists, but of a large number of cultured men and women\nof very different circles. Not only was I rewarded by hundreds of\nsympathetic letters, but by a wide circulation of the printed address,\nof which six editions were required within six months. I had the more\nreason to be content with this unexpected success, as this \"confession\nof faith\" was originally merely an occasional speech which I delivered\nunprepared on October 9, 1892, at Altenburg, during the jubilee of the\nScientific Society of East Germany. Naturally there was the usual\ndemonstration on the other side; I was fiercely attacked, not only by\nthe ultramontane press, the sworn defenders of superstition, but also\nby the \"liberal\" controversialists of evangelical Christianity, who\nprofess to defend both scientific truth and purified faith. In the\nseven years that have ensued since that time the great struggle between\nmodern science and orthodox Christianity has become more threatening;\nit has grown more dangerous for science in proportion as Christianity\nhas found support in an increasing mental and political reaction. In\nsome countries the Church has made such progress that the freedom\nof thought and conscience, which is guaranteed by the laws, is in\npractice gravely menaced (for instance, in Bavaria). The great historic\nstruggle which Draper has so admirably depicted in his _Conflict\nbetween Religion and Science_ is to-day more acute and significant than\never. For the last twenty-seven years it has been rightly called the\n\"_cultur-kampf_.\"\n\nThe famous encyclica and syllabus which the militant pope, Pius IX.,\nsent out into the entire world in 1864 were a declaration of war on\nthe whole of modern science; they demanded the blind submission of\nreason to the dogmas of the infallible pope. The enormity of this\ncrude assault on the highest treasures of civilization even roused\nmany indolent minds from the slumber of belief. Together with the\nsubsequent promulgation of the papal infallibility (1870), the\nencyclica provoked a deep wave of irritation and an energetic repulse\nwhich held out high hopes. In the new German empire, which had attained\nits indispensable national unity by the heavy sacrifices of the wars\nof 1866 and 1871, the insolent attacks of the pope were felt to be\nparticularly offensive. On the one hand, Germany is the cradle of\nthe Reformation and the modern emancipation of reason; on the other\nhand, it unfortunately has in its 18,000,000 Catholics a vast host of\nmilitant believers, who are unsurpassed by any other civilized people\nin blind obedience to their chief shepherd.\n\nThe dangers of such a situation were clearly recognized by the\ngreat statesman who had solved the political \"world-riddle\" of the\ndismemberment of Germany, and had led us by a marvellous statecraft\nto the long-desired goal of national unity and power. Prince Bismarck\nbegan the famous struggle with the Vatican, which is known as the\n_cultur-kampf_, in 1872, and it was conducted with equal ability and\nenergy by the distinguished Minister of Worship, Falk, author of the\nMay laws of 1873. Unfortunately, Bismarck had to desist six years\nafterwards. Although the great statesman was a remarkable judge of men\nand a realistic politician of immense tact, he had underestimated the\nforce of three powerful obstacles--first, the unsurpassed cunning and\nunscrupulous treachery of the Roman _curia_; secondly, the correlative\ningratitude and credulity of the uneducated Catholic masses, on which\nthe papacy built; and, thirdly, the power of apathy, the continuance\nof the irrational, simply because it is in possession. Hence, in 1878,\nwhen the abler Leo XIII. had ascended the pontifical throne, the fatal\n\"To Canossa\" was heard once more. From that time the newly established\npower of Rome grew in strength; partly through the unscrupulous\nintrigues and serpentine bends of its slippery Jesuitical politics,\npartly through the false Church-politics of the German government and\nthe marvellous political incompetence of the German people. We have,\ntherefore, at the close of the nineteenth century to endure the\npitiful spectacle of the Catholic \"Centre\" being the most important\nsection of the Reichstag, and the fate of our humiliated country\ndepending on a papal party, which does not constitute numerically a\nthird part of the nation.\n\nWhen the _cultur-kampf_ began in 1872, it was justly acclaimed by\nall independent thinkers as a political renewal of the Reformation,\na vigorous attempt to free modern civilization from the yoke of\npapal despotism. The whole of the Liberal press hailed Bismarck as a\n\"political Luther\"--as the great hero, not only of the national unity,\nbut also of the rational emancipation of Germany. Ten years afterwards,\nwhen the papacy had proved victorious, the same \"Liberal press\" changed\nits colors, and denounced the _cultur-kampf_ as a great mistake; and\nit does the same thing to-day. The facts show how short is the memory\nof our journalists, how defective their knowledge of history, and how\npoor their philosophic education. The so-called \"Peace between Church\nand State\" is never more than a suspension of hostilities. The modern\npapacy, true to the despotic principles it has followed for the last\nsixteen hundred years, is determined to wield sole dominion over the\ncredulous souls of men; it must demand the absolute submission of\nthe cultured State, which, as such, defends the rights of reason and\nscience. True and enduring peace there cannot be until one of the\ncombatants lies powerless on the ground. Either the Church wins, and\nthen farewell to all \"free science and free teaching\"--then are our\nuniversities no better than jails, and our colleges become cloistral\nschools; or else the modern rational State proves victorious--then,\nin the twentieth century, human culture, freedom, and prosperity will\ncontinue their progressive development until they far surpass even the\nheight of the nineteenth century.\n\nIn order to compass these high aims, it is of the first importance that\nmodern science not only shatter the false structures of superstition\nand sweep their ruins from the path, but that it also erect a new\nabode for human emotion on the ground it has cleared--a \"palace of\nreason,\" in which, under the influence of our new monistic views, we do\nreverence to the real trinity of the nineteenth century--the trinity of\n\"the true, the good, and the beautiful.\" In order to give a tangible\nshape to the cult of this divine ideal, we must first of all compare\nour position with the dominant forms of Christianity, and realize\nthe changes that are involved in the substitution of the one for the\nother. For, in spite of its errors and defects, the Christian religion\n(in its primitive and purer form) has so high an ethical value, and\nhas entered so deeply into the most important social and political\nmovements of civilized history for the last fifteen hundred years,\nthat we must appeal as much as possible to its existing institutions\nin the establishment of our monistic religion. We do not seek a mighty\n_revolution_, but a rational _reformation_, of our religious life. And\njust as, two thousand years ago, the classic poetry of the ancient\nGreeks incarnated their ideals of virtue in divine shapes, so may\nwe, too, lend the character of noble goddesses to our three rational\nideals. We must inquire into the features of the three goddesses of the\nmonist--truth, beauty, and virtue; and we must study their relation\nto the three corresponding ideals of Christianity which they are to\nreplace.\n\nI. The preceding inquiries (especially those of the first and third\nsections) have convinced us that truth unadulterated is only to be\nfound in the temple of the study of nature, and that the only available\npaths to it are critical observation and reflection--the empirical\ninvestigation of facts and the rational study of their efficient\ncauses. In this way we arrive, by means of pure reason, at true\nscience, the highest treasure of civilized man. We must, in accordance\nwith the arguments of our sixteenth chapter, reject what is called\n\"revelation,\" the poetry of faith, that affirms the discovery of truth\nin a supernatural fashion, without the assistance of reason. And since\nthe entire structure of the Jud\u00e6o-Christian religion, like that of the\nMohammedan and the Buddhistic, rests on these so-called revelations,\nand these mystic fruits of the imagination directly contradict the\nclear results of empirical research, it is obvious that we shall\nonly attain to a knowledge of the truth by the rational activity of\ngenuine science, not by the poetic imagining of a mystic faith. In this\nrespect it is quite certain that the Christian system must give way\nto the monistic. The goddess of truth dwells in the temple of nature,\nin the green woods, on the blue sea, and on the snowy summits of the\nhills--not in the gloom of the cloister, nor in the narrow prisons of\nour jail-like schools, nor in the clouds of incense of the Christian\nchurches. The paths which lead to the noble divinity of truth and\nknowledge are the loving study of nature and its laws, the observation\nof the infinitely great star-world with the aid of the telescope, and\nthe infinitely tiny cell-world with the aid of the microscope--not\nsenseless ceremonies and unthinking prayers, not alms and Peter's\nPence. The rich gifts which the goddess of truth bestows on us are the\nnoble fruits of the tree of knowledge and the inestimable treasure of a\nclear, unified view of the world--not belief in supernatural miracles\nand the illusion of an eternal life.\n\nII. It is otherwise with the divine ideal of eternal goodness. In our\nsearch for the truth we have entirely to exclude the \"revelation\" of\nthe churches, and devote ourselves solely to the study of nature; but,\non the other hand, the idea of the good, which we call virtue, in\nour monistic religion coincides for the most part with the Christian\nidea of virtue. We are speaking, naturally, of the primitive and\npure Christianity of the first three centuries, as far as we learn\nits moral teaching from the gospels and the epistles of Paul; it\ndoes not apply to the Vatican caricature of that pure doctrine which\nhas dominated European civilization, to its infinite prejudice, for\ntwelve hundred years. The best part of Christian morality, to which we\nfirmly adhere, is represented by the humanist precepts of charity and\ntoleration, compassion and assistance. However, these noble commands,\nwhich are set down as \"Christian\" morality (in its best sense), are by\nno means original discoveries of Christianity; they are derived from\nearlier religions. The Golden Rule, which sums up these precepts in\none sentence, is centuries older than Christianity. In the conduct of\nlife this law of natural morality has been followed just as frequently\nby non-Christians and atheists as it has been neglected by pious\nbelievers. Moreover, Christian ethics was marred by the great defect\nof a narrow insistence on altruism and a denunciation of egoism. Our\nmonistic ethics lays equal emphasis on the two, and finds perfect\nvirtue in the just balance of love of self and love of one's neighbor\n(cf. chap. xix.).\n\nIII. But monism enters into its strongest opposition to Christianity\non the question of beauty. Primitive Christianity preached the\nworthlessness of earthly life, regarding it merely as a preparation\nfor an eternal life beyond. Hence it immediately followed that all we\nfind in the life of man here below, all that is beautiful in art and\nscience, in public and in private life, is of no real value. The true\nChristian must avert his eyes from them; he must think only of a worthy\npreparation for the life beyond. Contempt of nature, aversion from all\nits inexhaustible charms, rejection of every kind of fine art, are\nChristian duties; and they are carried out to perfection when a man\nseparates himself from his fellows, chastises his body, and spends all\nhis time in prayer in the cloister or the hermit's cell.\n\nHistory teaches us that this ascetical morality that would scorn the\nwhole of nature had, as a natural consequence, the very opposite effect\nto that it intended. Monasteries, the homes of chastity and discipline,\nsoon became dens of the wildest orgies; the sexual commerce of monks\nand nuns has inspired shoals of novels, as it is so faithfully depicted\nin the literature of the Renaissance. The cult of the \"beautiful,\"\nwhich was then practised, was in flagrant contradiction with the\nvaunted \"abandonment of the world\"; and the same must be said of the\npomp and luxury which soon developed in the immoral private lives of\nthe higher ecclesiastics and in the artistic decoration of Christian\nchurches and monasteries.\n\nIt may be objected that our view is refuted by the splendor of\nChristian art, which, especially in the best days of the Middle Ages,\ncreated works of undying beauty. The graceful Gothic cathedrals and\nByzantine basilicas, the hundreds of magnificent chapels, the thousands\nof marble statues of saints and martyrs, the millions of fine pictures\nof saints, of profoundly conceived representations of Christ and the\nmadonna--all are proofs of the development of a noble art in the Middle\nAges, which is unique of its kind. All these splendid monuments of\nmedi\u00e6val art are untouched in their high \u00e6sthetic value, whatever we\nsay of their mixture of truth and fancy. Yes; but what has all that\nto do with the pure teaching of Christianity--with that religion of\nsacrifice that turned scornfully away from all earthly parade and\nglamour, from all material beauty and art; that made light of the life\nof the family and the love of woman; that urged an exclusive concern as\nto the immaterial goods of eternal life? The idea of a Christian art\nis a contradiction in terms--a _contradictio in adjecto_. The wealthy\nprinces of the Church who fostered it were candidly aiming at very\ndifferent ideals, and they completely attained them. In directing the\nwhole interest and activity of the human mind in the Middle Ages to the\nChristian Church and its distinctive art they were diverting it _from\nnature_ and from the knowledge of the treasures that were hidden in it,\nand would have conducted to independent science. Moreover, the daily\nsight of the huge images of the saints and of the scenes of \"sacred\nhistory\" continually reminded the faithful of the vast collection of\nmyths that the Church had made. The legends themselves were taught\nand believed to be true narratives, and the stories of miracles to be\nrecords of actual events. It cannot be doubted that in this respect\nChristian art has exercised an immense influence on general culture,\nand especially in the strengthening of Christian belief--an influence\nwhich still endures throughout the entire civilized world.\n\nThe diametrical opposite of this dominant Christian art is the new\nartistic tendency which has been developed during the present century\nin connection with science. The remarkable expansion of our knowledge\nof nature, and the discovery of countless beautiful forms of life,\nwhich it includes, have awakened quite a new \u00e6sthetic sense in our\ngeneration, and thus given a new tone to painting and sculpture.\nNumerous scientific voyages and expeditions for the exploration\nof unknown lands and seas, partly in earlier centuries, but more\nespecially in the nineteenth, have brought to light an undreamed\nabundance of new organic forms. The number of new species of animals\nand plants soon became enormous, and among them (especially among the\nlower groups that had been neglected before) there were thousands\nof forms of great beauty and interest, affording an entirely new\ninspiration for painting, sculpture, architecture, and technical\nart. In this respect a new world was revealed by the great advance\nof microscopic research in the second half of the century, and\nespecially by the discovery of the marvellous inhabitants of the\ndeep sea, which were first brought to light by the famous expedition\nof the _Challenger_ (1872-76). Thousands of graceful radiolaria and\nthalamophora, of pretty medus\u00e6 and corals, of extraordinary molluscs,\nand crabs, suddenly introduced us to a wealth of hidden organisms\nbeyond all anticipation, the peculiar beauty and diversity of which\nfar transcend all the creations of the human imagination. In the\nfifty large volumes of the account of the _Challenger_ expedition a\nvast number of these beautiful forms are delineated on three thousand\nplates; and there are millions of other lovely organisms described in\nother great works that are included in the fast-growing literature of\nzoology and botany of the last ten years. I began on a small scale to\nselect a number of these beautiful forms for more popular description\nin my _Art Forms in Nature_ (1899).\n\nHowever, there is now no need for long voyages and costly works to\nappreciate the beauties of this world. A man needs only to keep his\neyes open and his mind disciplined. Surrounding nature offers us\neverywhere a marvellous wealth of lovely and interesting objects of all\nkinds. In every bit of moss and blade of grass, in every beetle and\nbutterfly, we find, when we examine it carefully, beauties which are\nusually overlooked. Above all, when we examine them with a powerful\nglass or, better still, with a good microscope, we find everywhere in\nnature a new world of inexhaustible charms.\n\nBut the nineteenth century has not only opened our eyes to the \u00e6sthetic\nenjoyment of the microscopic world; it has shown us the beauty of\nthe greater objects in nature. Even at its commencement it was the\nfashion to regard the mountains as magnificent but forbidding, and\nthe sea as sublime but dreaded. At its close the majority of educated\npeople--especially they who dwell in the great cities--are delighted\nto enjoy the glories of the Alps and the crystal splendor of the\nglacier world for a fortnight every year, or to drink in the majesty\nof the ocean and the lovely scenery of its coasts. All these sources\nof the keenest enjoyment of nature have only recently been revealed\nto us in all their splendor, and the remarkable progress we have\nmade in facility and rapidity of conveyance has given even the less\nwealthy an opportunity of approaching them. All this progress in the\n\u00e6sthetic enjoyment of nature--and, proportionately, in the scientific\nunderstanding of nature--implies an equal advance in higher mental\ndevelopment and, consequently, in the direction of our monistic\nreligion.\n\nThe opposite character of our _naturalistic_ century to that of the\n_anthropistic_ centuries that preceded is especially noticeable in\nthe different appreciation and spread of illustrations of the most\ndiverse natural objects. In our own days a lively interest in artistic\nwork of that kind has been developed, which did not exist in earlier\nages; it has been supported by the remarkable progress of commerce\nand technical art which have facilitated a wide popularization of\nsuch illustrations. Countless illustrated periodicals convey along\nwith their general information a sense of the inexhaustible beauty of\nnature in all its departments. In particular, landscape-painting has\nacquired an importance that surpassed all imagination. In the first\nhalf of the century one of our greatest and most erudite scientists,\nAlexander Humboldt, had pointed out that the development of modern\nlandscape-painting is not only of great importance as an incentive\nto the study of nature and as a means of geographical description,\nbut that it is to be commended in other respects as a noble educative\nmedium. Since that time the taste for it has considerably increased.\nIt should be the aim at every school to teach the children to enjoy\nscenery at an early age, and to give them the valuable art of\nimprinting on the memory by a drawing or water-color sketch.\n\nThe infinite wealth of nature in what is beautiful and sublime offers\nevery man with open eyes and an \u00e6sthetic sense an incalculable sum of\nchoicest gifts. Still, however valuable and agreeable is the immediate\nenjoyment of each single gift, its worth is doubled by a knowledge of\nits meaning and its connection with the rest of nature. When Humboldt\ngave us the \"outline of a physical description of the world\" in his\nmagnificent _Cosmos_ forty years ago, and when he combined scientific\nand \u00e6sthetic consideration so happily in his standard _Prospects of\nNature_, he justly indicated how closely the higher enjoyment of nature\nis connected with the \"scientific establishment of cosmic laws,\" and\nthat the conjunction of the two serves to raise human nature to a\nhigher stage of perfection. The astonishment with which we gaze upon\nthe starry heavens and the microscopic life in a drop of water, the awe\nwith which we trace the marvellous working of energy in the motion of\nmatter, the reverence with which we grasp the universal dominance of\nthe law of substance throughout the universe--all these are part of our\nemotional life, falling under the heading of \"natural religion.\"\n\nThis progress of modern times in knowledge of the true and enjoyment\nof the beautiful expresses, on the one hand, a valuable element of our\nmonistic religion, but is, on the other hand, in fatal opposition to\nChristianity. For the human mind is thus made to live on this side of\nthe grave; Christianity would have it ever gaze beyond. Monism teaches\nthat we are perishable children of the earth, who for one or two,\nor, at the most, three generations, have the good fortune to enjoy\nthe treasures of our planet, to drink of the inexhaustible fountain\nof its beauty, and to trace out the marvellous play of its forces.\nChristianity would teach us that the earth is \"a vale of tears,\" in\nwhich we have but a brief period to chasten and torment ourselves in\norder to merit the life of eternal bliss beyond. Where this \"beyond\"\nis, and of what joys the glory of this eternal life is compacted, no\nrevelation has ever told us. As long as \"heaven\" was thought to be the\nblue vault that hovers over the disk of our planet, and is illumined\nby the twinkling light of a few thousand stars, the human imagination\ncould picture to itself the ambrosial banquets of the Olympic gods\nabove or the laden tables of the happy dwellers in Valhalla. But now\nall these deities and the immortal souls that sat at their tables are\n\"houseless and homeless,\" as David Strauss has so ably described; for\nwe know from astrophysical science that the immeasurable depths of\nspace are filled with a prosaic ether, and that millions of heavenly\nbodies, ruled by eternal laws of iron, rush hither and thither in the\ngreat ocean, in their eternal rhythm of life and death.\n\nThe places of devotion, in which men seek the satisfaction of their\nreligious emotions and worship the objects of their reverence, are\nregarded as sacred \"churches.\" The pagodas of Buddhistic Asia, the\nGreek temples of classical antiquity, the synagogues of Palestine,\nthe mosques of Egypt, the Catholic cathedrals of the south, and the\nProtestant cathedrals of the north, of Europe--all these \"houses of\nGod\" serve to raise man above the misery and the prose of daily life,\nto lift him into the sacred, poetic atmosphere of a higher, ideal\nworld. They attain this end in a thousand different ways, according\nto their various forms of worship and their age. The modern man who\n\"has science and art\"--and, therefore, \"religion\"--needs no special\nchurch, no narrow, enclosed portion of space. For through the length\nand breadth of free nature, wherever he turns his gaze, to the whole\nuniverse or to any single part of it, he finds, indeed, the grim\n\"struggle for life,\" but by its side are ever \"the good, the true, and\nthe beautiful\"; his church is commensurate with the whole of glorious\nnature. Still, there will always be men of special temperament who will\ndesire to have decorated temples or churches as places of devotion\nto which they may withdraw. Just as the Catholics had to relinquish a\nnumber of churches to the Reformation in the sixteenth century, so a\nstill larger number will pass over to \"free societies\" of monists in\nthe coming years.\n\n\n\n\nCHAPTER XIX\n\nOUR MONISTIC ETHICS\n\n    Monistic and Dualistic Ethics--Contradiction of Pure and\n    Practical Reason in Kant--His Categorical Imperative--The\n    Neo-Kantians--Herbert Spencer--Egoism and Altruism--Equivalence\n    of the Two Instincts--The Fundamental Law of Ethics: the Golden\n    Rule--Its Antiquity--Christian Ethics--Contempt of Self, the\n    Body, Nature, Civilization, the Family, Woman--Roman Catholic\n    Ethics--Immoral Results of Celibacy--Necessity for the Abolition of\n    the Law of Celibacy, Oral Confession, and Indulgences--State and\n    Church--Religion a Private Concern--Church and School--State and\n    School--Need of School Reform\n\n\nThe practical conduct of life makes a number of definite ethical claims\non a man which can only be duly and naturally satisfied when they are\nin complete harmony with his view of the world. In accordance with this\nfundamental principle of our monistic philosophy, our whole system of\nethics must be rationally connected with the unified conception of the\ncosmos which we have formed by our advanced knowledge of the laws of\nnature. Just as the infinite universe is one great whole in the light\nof our monistic teaching, so the spiritual and moral life of man is\na part of this cosmos, and our naturalistic ordering of it must also\nbe monistic. There are not two different, separate worlds--the one\nphysical and material, and the other moral and immaterial.\n\nThe great majority of philosophers and theologians still hold the\ncontrary opinion. They affirm, with Kant, that the moral world is quite\nindependent of the physical, and is subject to very different laws;\nhence a man's conscience, as the basis of his moral life, must also be\nquite independent of our scientific knowledge of the world, and must be\nbased rather on his religious faith. On that theory the study of the\nmoral world belongs to _practical_ reason, while that of nature, or of\nthe physical world, is referred to _pure_ or theoretical reason. This\nunequivocal and conscious dualism of Kant's philosophy was its greatest\ndefect; it has caused, and still causes, incalculable mischief. First\nof all the \"critical Kant\" had built up the splendid and marvellous\npalace of pure reason, and convincingly proved that the three great\ncentral dogmas of metaphysics--a personal God, free will, and the\nimmortal soul--had no place whatever in it, and that no rational proof\ncould be found of their reality. Afterwards, however, the \"dogmatic\nKant\" superimposed on this true crystal palace of _pure_ reason the\nglittering, ideal castle in the air of _practical_ reason, in which\nthree imposing church-naves were designed for the accommodation of\nthose three great mystic divinities. When they had been put out at the\nfront door by rational knowledge they returned by the back door under\nthe guidance of irrational faith.\n\nThe cupola of his great cathedral of faith was crowned by Kant with his\ncurious idol, the famous \"categorical imperative.\" According to it,\nthe demand of the universal moral law is unconditional, independent of\nany regard to actuality or potentiality. It runs: \"Act at all times in\nsuch wise that the maxim (or the subjective law of thy will) may hold\ngood as a principle of a universal law.\" On that theory all normal men\nwould have the same sense of duty. Modern anthropology has ruthlessly\ndissipated that pretty dream; it has shown that conceptions of duty\ndiffer even more among uncivilized than among civilized nations. All\nthe actions and customs which we regard as sins or loathsome crimes\n(theft, fraud, murder, adultery, etc.) are considered by other nations\nin certain circumstances to be virtues, or even sacred duties.\n\nAlthough the obvious contradiction of the two forms of reason in Kant's\nteaching, the fundamental antagonism of pure and practical reason, was\nrecognized and attacked at the very beginning of the century, it is\nstill pretty widely accepted. The modern school of neo-Kantians urges a\n\"return to Kant\" so pressingly precisely on account of this agreeable\ndualism; the Church militant zealously supports it because it fits\nin admirably with its own mystic faith. But it met with an effective\nreverse at the hands of modern science in the second half of the\nnineteenth century, which entirely demolished the theses of the system\nof practical reason. Monistic cosmology proved, on the basis of the law\nof substance, that there is no personal God; comparative and genetic\npsychology showed that there cannot be an immortal soul; and monistic\nphysiology proved the futility of the assumption of \"free will.\"\nFinally, the science of evolution made it clear that the same eternal\niron laws that rule in the inorganic world are valid too in the organic\nand moral world.\n\nBut modern science gives not only a negative support to practical\nphilosophy and ethics in demolishing the Kantian dualism, but it\nrenders the positive service of substituting for it the new structure\nof ethical monism. It shows that the feeling of duty does not rest\non an illusory \"categorical imperative,\" but on the solid ground of\n_social instinct_, as we find in the case of all social animals. It\nregards as the highest aim of all morality the re-establishment of a\nsound harmony between egoism and altruism, between self-love and the\nlove of one's neighbor. It is to the great English philosopher, Herbert\nSpencer, that we owe the founding of this monistic ethics on a basis of\nevolution.\n\nMan belongs to the social vertebrates, and has, therefore, like all\nsocial animals, two sets of duties--first to himself, and secondly\nto the society to which he belongs. The former are the behests of\nself-love or egoism, the latter of love for one's fellows or altruism.\nThe two sets of precepts are equally just, equally natural, and equally\nindispensable. If a man desire to have the advantage of living in an\norganized community, he has to consult not only his own fortune, but\nalso that of the society, and of the \"neighbors\" who form the society.\nHe must realize that its prosperity is his own prosperity, and that it\ncannot suffer without his own injury. This fundamental law of society\nis so simple and so inevitable that one cannot understand how it can be\ncontradicted in theory or in practice; yet that is done to-day, and has\nbeen done for thousands of years.\n\nThe equal appreciation of these two natural impulses, or the moral\nequivalence of self-love and love of others, is the chief and the\nfundamental principle of our morality. Hence the highest aim of all\nethics is very simple--it is the re-establishment of \"the natural\nequality of egoism and altruism, of the love of one's self and the\nlove of one's neighbor.\" The Golden Rule says: \"Do unto others as you\nwould that they should do unto you.\" From this highest precept of\nChristianity it follows of itself that we have just as sacred duties\ntowards ourselves as we have towards our fellows. I have explained\nmy conception of this principle in my _Monism_, and laid down three\nimportant theses. (1) Both these concurrent impulses are natural\nlaws, of equal importance and necessity for the preservation of the\nfamily and the society; egoism secures the self-preservation of the\nindividual, altruism that of the species which is made up of the chain\nof perishable individuals. (2) The social duties which are imposed\nby the social structure of the associated individuals, and by means\nof which it secures its preservation, are merely higher evolutionary\nstages of the social instincts, which we find in all higher social\nanimals (as \"habits which have become hereditary\"). (3) In the case of\ncivilized man all ethics, theoretical or practical, being \"a science\nof rules,\" is connected with his view of the world at large, and\nconsequently with his religion.\n\nFrom the recognition of the fundamental principle of our morality\nwe may immediately deduce its highest precept, that noble command,\nwhich is often called the Golden Rule of morals, or, briefly, the\nGolden Rule. Christ repeatedly expressed it in the simple phrase:\n\"Thou shalt love thy neighbor as thyself.\" Mark adds that \"there is\nno greater commandment than this,\" and Matthew says: \"In these two\ncommandments is the whole law and the prophets.\" In this greatest and\nhighest commandment our monistic ethics is completely at one with\nChristianity. We must, however, recall the historical fact that the\nformulation of this supreme command is not an original merit of Christ,\nas the majority of Christian theologians affirm and their uncritical\nsupporters blindly accept. The Golden Rule is five hundred years\nolder than Christ; it was laid down as the highest moral principle by\nmany Greek and Oriental sages. Pittacus, of Mylene, one of the seven\nwise men of Greece, said six hundred and twenty years before Christ:\n\"Do not that to thy neighbor that thou wouldst not suffer from him.\"\nConfucius, the great Chinese philosopher and religious founder (who\nrejected the idea of a personal God and of the immortality of the\nsoul), said five hundred years B.C.: \"Do to every man as thou wouldst\nhave him do to thee; and do not to another what thou wouldst not have\nhim do to thee. This precept only dost thou need; it is the foundation\nof all other commandments.\" Aristotle taught about the middle of the\nfourth century B.C.: \"We must act towards others as we wish others\nto act towards us.\" In the same sense, and partly in the same words,\nthe Golden Rule was given by Thales, Isocrates, Aristippus, Sextus,\nthe Pythagorean, and other philosophers of classic antiquity--several\ncenturies before Christ. From this collection it is clear that the\nGolden Rule had a _polyphyletic_ origin--that is, it was formulated by\na number of philosophers at different times and in different places,\nquite independently of each other. Otherwise it must be assumed that\nJesus derived it from some other Oriental source, from ancient Semitic,\nIndian, Chinese, or especially Buddhistic traditions, as has been\nproved in the case of most of the other Christian doctrines.\n\nAs the great ethical principle is thus twenty-five hundred years old,\nand as Christianity itself has put it at the head of its moral teaching\nas the highest and all-embracing commandment, it follows that our\nmonistic ethics is in complete harmony on this important point, not\nonly with the ethics of the ancient heathens, but also with that of\nChristianity. Unfortunately this harmony is disturbed by the fact that\nthe gospels and the Pauline epistles contain many other points of moral\nteaching, which contradict our first and supreme commandment. Christian\ntheologians have fruitlessly striven to explain away these striking\nand painful contradictions by their ingenious interpretations. We need\nnot enter into that question now, but we must briefly consider those\nunfortunate aspects of Christian ethics which are incompatible with the\nbetter thought of the modern age, and which are distinctly injurious\nin their practical consequences. Of that character is the contempt\nwhich Christianity has shown for self, for the body, for nature, for\ncivilization, for the family, and for woman.\n\nI. The supreme mistake of Christian ethics, and one which runs\ndirectly counter to the Golden Rule, is its exaggeration of love of\none's neighbor at the expense of self-love. Christianity attacks and\ndespises egoism on principle. Yet that natural impulse is absolutely\nindispensable in view of self-preservation; indeed, one may say that\neven altruism, its apparent opposite, is only an enlightened egoism.\nNothing great or elevated has ever taken place without egoism, and\nwithout the passion that urges us to great sacrifices. It is only\nthe excesses of the impulse that are injurious. One of the Christian\nprecepts that were impressed upon us in our early youth as of great\nimportance, and that are glorified in millions of sermons, is: \"Love\nyour enemies, bless them that curse you, do good to them that hate you,\nand pray for them which despitefully use you and persecute you.\" It is\na very ideal precept, but as useless in practice as it is unnatural.\nSo it is with the counsel, \"If any man will take away thy coat, let\nhim have thy cloak also.\" Translated into the terms of modern life,\nthat means: \"When some unscrupulous scoundrel has defrauded thee of\nhalf thy goods, let him have the other half also.\" Or, again, in the\nlanguage of modern politics: \"When the pious English take from you\nsimple Germans one after another of your new and valuable colonies in\nAfrica, let them have all the rest of your colonies also--or, best of\nall, give them Germany itself.\" And, while we touch on the marvellous\nworld-politics of modern England, we may note in passing its direct\ncontradiction of every precept of Christian charity, which is more\nfrequently on the lips of that great nation than of any other nation in\nthe world. However, the glaring contradiction between the theoretical,\n_ideal_, altruistic morality of the human individual and the _real_,\npurely selfish morality of the human community, and especially of the\ncivilized Christian state, is a familiar fact. It would be interesting\nto determine mathematically in what proportion among organized men the\naltruistic ethical ideal of the individual changes into its contrary,\nthe purely egoistic \"real politics\" of the state and the nation.\n\nII. Since the Christian faith takes a wholly dualistic view of the\nhuman organism and attributes to the immortal soul only a temporary\nsojourn in the mortal frame, it very naturally sets a much greater\nvalue on the soul than on the body. Hence results that neglect of the\ncare of the body, of training, and of cleanliness which contrasts the\nlife of the Christian Middle Ages so unfavorably with that of pagan\nclassical antiquity. Christian ethics contains none of those firm\ncommands as to daily ablutions which are theoretically laid down and\npractically fulfilled in the Mohammedan, Hindoo, and other religions.\nIn many monasteries the ideal of the pious Christian is the man who\ndoes not wash and clothe himself properly, who never changes his\nmalodorous gown, and who, instead of regular work, fills up his useless\nlife with mechanical prayers, senseless fasts, and so forth. As a\nspecial outgrowth of this contempt of the body we have the disgusting\ndiscipline of the flagellants and other ascetics.\n\nIII. One source of countless theoretical errors and practical\nblemishes, of deplorable crudity and privation, is found in the false\nanthropism of Christianity--that is, in the unique position which\nit gives to man, as the image of God, in opposition to all the rest\nof nature. In this way it has contributed, not only to an extremely\ninjurious isolation from our glorious mother \"nature,\" but also to\na regrettable contempt of all other organisms. Christianity has no\nplace for that well-known love of animals, that sympathy with the\nnearly related and friendly mammals (dogs, horses, cattle, etc.),\nwhich is urged in the ethical teaching of many of the older religions,\nespecially Buddhism. Whoever has spent much time in the south of Europe\nmust have often witnessed those frightful sufferings of animals which\nfill us friends of animals with the deepest sympathy and indignation.\nAnd when one expostulates with these brutal \"Christians\" on their\ncruelty, the only answer is, with a laugh: \"But the beasts are not\nChristians.\" Unfortunately Descartes gave some support to the error in\nteaching that man only has a sensitive soul, not the animal.\n\nHow much more elevated is our monistic ethics than the Christian in\nthis regard! Darwinism teaches us that we have descended immediately\nfrom the primates, and, in a secondary degree, from a long series\nof earlier mammals, and that, therefore, they are \"our brothers\";\nphysiology informs us that they have the same nerves and sense-organs\nas we, and the same feelings of pleasure and pain. No sympathetic\nmonistic scientist would ever be guilty of that brutal treatment of\nanimals which comes so lightly to the Christian in his anthropistic\nillusion--to the \"child of the God of love.\" Moreover, this Christian\ncontempt of nature on principle deprives man of an abundance of the\nhighest earthly joys, especially of the keen, ennobling enjoyment of\nnature.\n\nIV. Since, according to Christ's teaching, our planet is \"a vale of\ntears,\" and our earthly life is valueless and a mere preparation for a\nbetter life to come, it has succeeded in inducing men to sacrifice all\nhappiness on this side of eternity and make light of all earthly goods.\nAmong these \"earthly goods,\" in the case of the modern civilized man,\nwe must include the countless great and small conveniences of technical\nscience, hygiene, commerce, etc., which have made modern life cheerful\nand comfortable; we must include all the gratifications of painting,\nsculpture, music, and poetry, which flourished exceedingly even during\nthe Middle Ages (in spite of its principles), and which we esteem\nas \"ideal pleasures\"; we must include all that invaluable progress\nof science, especially the study of nature, of which the nineteenth\ncentury is justly proud. All these \"earthly goods,\" that have so high a\nvalue in the eyes of the monist, are worthless--nay, injurious--for the\nmost part, according to Christian teaching; the stern code of Christian\nmorals should look just as unfavorably on the pursuit of these\npleasures as our humanistic ethics fosters and encourages it. Once\nmore, therefore, Christianity is found to be an enemy to civilization,\nand the struggle which modern thought and science are compelled to\nconduct with it is, in this additional sense, a \"_cultur-kampf_.\"\n\nV. Another of the most deplorable aspects of Christian morality is\nits belittlement of the life of the family, of that natural living\ntogether with our next of kin which is just as necessary in the case\nof man as in the case of all the higher social animals. The family\nis justly regarded as the \"foundation of society,\" and the healthy\nlife of the family is a necessary condition of the prosperity of the\nState. Christ, however, was of a very different opinion: with his gaze\never directed to \"the beyond,\" he thought as lightly of woman and the\nfamily as of all other goods of \"this life.\" Of his infrequent contact\nwith his parents and sisters the gospels have very little to say; but\nthey are far from representing his relations with his mother to have\nbeen so tender and intimate as they are poetically depicted in so many\nthousands of pictures. He was not married himself. Sexual love, the\nfirst foundation of the family union, seems to have been regarded by\nJesus as a necessary evil. His most enthusiastic apostle, Paul, went\nstill farther in the same direction, declaring it to be better not to\nmarry than to marry: \"It is good for a man not to touch a woman.\" If\nhumanity were to follow this excellent counsel, it would soon be rid\nof all earthly misery and suffering: it would be killed off by such a\n\"radical cure\" within half a century.\n\nVI. As Christ never knew the love of woman, he had no personal\nacquaintance with that refining of man's true nature that comes only\nfrom the intimate life of man with woman. The intimate sexual union, on\nwhich the preservation of the human race depends, is just as important\non that account as the spiritual penetration of the two sexes, or\nthe mutual complement which they bring to each other in the practical\nwants of daily life as well as in the highest ideal functions of the\nsoul. For man and woman are two different organisms, equal in worth,\neach having its characteristic virtues and defects. As civilization\nadvanced, this ideal value of sexual love was more appreciated, and\nwoman held in higher honor, especially among the Teutonic races; she\nis the inspiring source of the highest achievements of art and poetry.\nBut Christ was as far from this view as nearly the whole of antiquity;\nhe shared the idea that prevailed everywhere in the East--that\nwoman is subordinate to man, and intercourse with her is \"unclean.\"\nLong-suffering nature has taken a fearful revenge for this blunder; its\nsad consequences are written in letters of blood in the history of the\npapal Middle Ages.\n\nThe marvellous hierarchy of the Roman Church, that never disdained any\nmeans of strengthening its spiritual despotism, found an exceptionally\npowerful instrument in the manipulation of this \"unclean\" idea, and in\nthe promotion of the ascetic notion that abstinence from intercourse\nwith women is a virtue of itself. In the first few centuries after\nChrist a number of priests voluntarily abstained from marriage, and\nthe supposed value of this celibacy soon rose to such a degree that it\nwas made obligatory. In the Middle Ages the seduction of women of good\nrepute and of their daughters by Catholic priests (the confessional\nwas an active agency in the business) was a public scandal: many\ncommunities, in order to prevent such things, pressed for a license\nof concubinage to be given to the clergy. And it was done in many,\nand sometimes very romantic, ways. Thus, for instance, the canon law\nthat the priest's cook should not be less than forty years old was\nvery cleverly \"explained\" in the sense that the priest might have two\ncooks, one in the presbytery, another without; if one was twenty-four\nand the other eighteen, that made forty-two together--two years above\nthe prescribed age. At the Christian councils, at which heretics were\nburned alive, the cardinals and bishops sat down with whole troops\nof prostitutes. The private and public debauchery of the Catholic\nclergy was so scandalous and dangerous to the commonwealth that there\nwas a general rebellion against it before the time of Luther, and a\nloud demand for a \"reformation of the church in head and members.\" It\nis well known that these immoral relations still continue in Roman\nCatholic lands, although more in secret. Formerly proposals were\nmade from time to time for the definitive abrogation of celibacy, as\nwas done, for instance, in the chambers of Baden, Bavaria, Hesse,\nSaxony, and other lands; but they have, unfortunately, hitherto proved\nunavailing. In the German Reichstag, in which the ultramontane Centre\nis now proposing the most ridiculous measures for the suppression of\nsexual immorality, there is now no party that will urge the abolition\nof celibacy in the interest of public morality. The so-called\n\"Freethought\" Party and the utopian social democracy coquette with the\nfavor of the Centre.\n\nThe modern state that would lift not only the material, but the moral,\nlife of its people to a higher level is entitled, and indeed bound,\nto sweep away such unworthy and harmful conditions. The obligatory\ncelibacy of the Catholic clergy is as pernicious and immoral as the\npractice of auricular confession or the sale of indulgences. All\nthree have nothing whatever to do with primitive Christianity. All\nthree are directly opposed to true Christian morality. All three are\ndisreputable inventions of the papacy, designed for the sole purpose of\nstrengthening its despotic rule over the credulous masses and making as\nmuch material profit as possible out of them.\n\nThe Nemesis of history will sooner or later exact a terrible account\nof the Roman papacy, and the millions who have been robbed of their\nhappiness by this degenerate religion will help to give it its\ndeath-blow in the coming twentieth century--at least, in every truly\ncivilized state. It has been recently calculated that the number of\nmen who lost their lives in the papal persecutions of heretics, the\nInquisition, the Christian religious wars, etc., is much more than\nten millions. But what is this in comparison with the tenfold greater\nnumber of the unfortunate _moral_ victims of the institutions and\nthe priestly domination of the degenerate Christian Church--with the\nunnumbered millions whose higher mental life was extinguished, whose\nconscience was tortured, whose family life was destroyed, by the\nChurch? We may with truth apply the words of Goethe in his _Bride of\nCorinth_:\n\n    \"Victims fall, nor lambs nor bulls,\n    But human victims numberless.\"\n\nIn the great _cultur-kampf_, which must go on as long as these sad\nconditions exist, the first aim must be the absolute separation of\nChurch and State. There shall be \"a free Church in a free State\"--that\nis, every Church shall be free in the practice of its special worship\nand ceremonies, and in the construction of its fantastic poetry and\nsuperstitious dogmas--with the sole condition that they contain no\ndanger to social order or morality. Then there will be equal rights\nfor all. Free societies and monistic religious bodies shall be equally\ntolerated, and just as free in their movements as Liberal Protestant\nand orthodox ultramontane congregations. But for all these \"faithful\"\nof the most diverse sects religion will have to be a private concern.\nThe state shall supervise them, and prevent excesses; but it must\nneither oppress nor support them. Above all, the ratepayers shall not\nbe compelled to contribute to the support and spread of a \"faith\" which\nthey honestly believe to be a harmful superstition. In the United\nStates such a complete separation of Church and State has been long\naccomplished, greatly to the satisfaction of all parties. They have\nalso the equally important separation of the Church from the school;\nthat is, undoubtedly, a powerful element in the great advance which\nscience and culture have recently made in America.\n\nIt goes without saying that this exclusion of the Church from the\nschool only refers to its sectarian principles, the particular form\nof belief which each Church has evolved in the course of its life.\nThis sectarian education is purely a private concern, and should be\nleft to parents and tutors, or to such priests or teachers as may\nhave the personal confidence of the parents. Instead of the rejected\nsectarian instruction, two important branches of education will be\nintroduced--monistic or humanist ethics and comparative religion.\nDuring the last thirty years an extensive literature has appeared\ndealing with the new system of ethics which has been raised on the\nbasis of modern science--especially evolutionary science. Comparative\nreligion will be a natural companion to the actual elementary\ninstruction in \"biblical history\" and in the mythology of Greece and\nRome. Both of these will remain in the curriculum. The reason for\nthat is obvious enough; the whole of our painting and sculpture, the\nchief branches of monistic \u00e6sthetics, are intimately blended with\nthe Christian, Greek, and Roman mythologies. There will only be this\nimportant difference--that the Christian myths and legends will not\nbe taught as truths, but as poetic fancies, like the Greek and Roman\nmyths; the high value of the ethical and \u00e6sthetical material they\ncontain will not be lessened, but increased, by this means. As regards\nthe Bible, the \"book of books\" will only be given to the children in\ncarefully selected extracts (a sort of \"school Bible\"); in this way we\nshall avoid the besmirching of the child's imagination with the unclean\nstories and passages which are so numerous in the Old Testament.\n\nOnce the modern State has freed itself and its schools from the\nfetters of the Church, it will be able to devote more attention to the\nimprovement of education. The incalculable value of a good system of\neducation has forced itself more and more upon us as the many aspects\nof modern civilized life have been enlarged and enriched in the\ncourse of the century. But the development of the educational methods\nhas by no means kept pace with life in general. The necessity for a\ncomprehensive reform of our schools is making itself felt more and\nmore. On this question, too, a number of valuable works have appeared\nin the course of the last forty years. We shall restrict ourselves to\nmaking a few general observations which we think of special importance.\n\n1. In all education up to the present time _man_ has played the chief\npart, and especially the grammatical study of his language; the study\nof _nature_ was entirely neglected.\n\n2. In the school of the future nature will be the chief object of the\nstudy; a man shall learn a correct view of the world he lives in; he\nwill not be made to stand outside of and opposed to nature, but be\nrepresented as its highest and noblest product.\n\n3. The study of the classical tongues (Latin and Greek), which has\nhitherto absorbed most of the pupils' time and energy, is indeed\nvaluable; but it will be much restricted, and confined to the mere\nelements (obligatory for Latin, optional for Greek).\n\n4. In consequence, modern languages must be all the more cultivated in\nall the higher schools (English and French to be obligatory, Italian\noptional).\n\n5. Historical instruction must pay more attention to the inner\nmental and spiritual life of a nation, and to the development of its\ncivilization, and less to its external history (the vicissitudes of\ndynasties, wars, and so forth).\n\n6. The elements of evolutionary science must be learned in conjunction\nwith cosmology, geology must go with geography, and anthropology with\nbiology.\n\n7. The first principles of biology must be familiar to every educated\nman; the modern training in observation furnishes an attractive\nintroduction to the biological sciences (anthropology, zoology, and\nbotany). A start must be made with descriptive system (in conjunction\nwith \u00e6tiology or bionomy); the elements of anatomy and physiology to be\nadded later on.\n\n8. The first principles of physics and chemistry must also be taught,\nand their exact establishment with the aid of mathematics.\n\n9. Every pupil must be taught to draw well, and from nature; and,\nwherever it is possible, the use of water-colors. The execution of\ndrawings and of water-color sketches from nature (of flowers, animals,\nlandscapes, clouds, etc.) not only excites interest in nature and helps\nmemory to enjoy objects, but it gives the pupil his first lesson in\n_seeing_ correctly and understanding what he has seen.\n\n10. Much more care and time must be devoted than has been done hitherto\nto corporal exercise, to gymnastics and swimming; but it is especially\nimportant to have walks in common every week, and journeys on foot\nduring the holidays. The lesson in observation which they obtain in\nthis way is invaluable.\n\nThe chief aim of higher education up to the present time, in most\ncountries, has been a preparation for the subsequent profession, and\nthe acquisition of a certain amount of information and direction\nfor civic duties. The school of the twentieth century will have for\nits main object the formation of independent thought, the clear\nunderstanding of the knowledge acquired, and an insight into the\nnatural connection of phenomena. If the modern state gives every\ncitizen a vote, it should also give him the means of developing his\nreason by a proper education, in order to make a rational use of his\nvote for the commonweal.\n\n\n\n\nCHAPTER XX\n\nSOLUTION OF THE WORLD-PROBLEMS\n\n    A Glance at the Progress of the Nineteenth Century in Solving\n    Cosmic Problems--I. Progress of Astronomy and Cosmology--Physical\n    and Chemical Unity of the Universe--Cosmic Metamorphoses--Evolution\n    of the Planetary System--Analogy of the Phylogenetic Processes\n    on the Earth and on Other Planets--Organic Inhabitants of\n    Other Heavenly Bodies--Periodic Variation in the Making of\n    Worlds--II. Progress of Geology and Pal\u00e6ontology--Neptunism and\n    Vulcanism--Theory of Continuity--III. Progress of Physics and\n    Chemistry--IV. Progress of Biology--Cellular Theory and Theory of\n    Descent--V. Anthropology--Origin of Man--General Conclusion\n\n\nAt the close of our philosophic study of the riddles of the universe\nwe turn with confidence to the answer to the momentous question, How\nnearly have we approached to a solution of them? What is the value of\nthe immense progress which the passing nineteenth century has made in\nthe knowledge of nature? And what prospect does it open out to us for\nthe future, for the further development of our system in the twentieth\ncentury, at the threshold of which we pause? Every unprejudiced thinker\nwho impartially considers the solid progress of our empirical science,\nand the unity and clearness of our philosophic interpretation of it,\nwill share our view: the nineteenth century has made greater progress\nin knowledge of the world and in grasp of its nature than all its\npredecessors; it has solved many great problems that seemed insoluble a\nhundred years ago; it has opened out to us new provinces of learning,\nthe very existence of which was unsuspected at the beginning of the\ncentury. Above all, it has put clearly before our eyes the lofty aim of\nmonistic cosmology, and has pointed out the path which alone will lead\nus towards it--the way of the exact empirical investigation of facts,\nand of the critical genetic study of their causes. The great abstract\nlaw of mechanical causality, of which our cosmological law--the law\nof substance--is but another and a concrete expression, now rules\nthe entire universe, as it does the mind of man; it is the steady,\nimmovable pole-star, whose clear light falls on our path through the\ndark labyrinth of the countless separate phenomena. To see the truth\nof this more clearly, let us cast a brief glance at the astonishing\nprogress which the chief branches of science have made in this\nremarkable period.\n\n\nI.--PROGRESS OF ASTRONOMY\n\nThe study of the heavens is the oldest, the study of man the youngest,\nof the sciences. With regard to himself and the character of his being\nman only obtained a clear knowledge in the second half of the present\ncentury; with regard to the starry heavens, the motions of the planets,\nand so on, he had acquired astonishing information forty-five hundred\nyears ago. The ancient Chinese, Hindoos, Egyptians, and Chald\u00e6ans in\nthe distant East knew more of the science of the spheres than the\nmajority of educated Christians did in the West four thousand years\nafter them. An eclipse of the sun was astronomically observed in China\nin the year 2697 B.C., and the plane of the ecliptic was determined\nby means of a gnome eleven hundred years B.C., while Christ himself\nhad no knowledge whatever of astronomy--indeed, he looked out upon\nheaven and earth, nature and man, from the very narrowest geocentric\nand anthropocentric point of view. The greatest advance of astronomy\nis generally, and rightly, said to be the founding of the heliocentric\nsystem of Copernicus, whose famous work, _De Revolutionibus Orbium\nCelestium_, of itself caused a profound revolution in the minds of\nthoughtful men. In overthrowing the Ptolemaic system, he destroyed the\nfoundation of the Christian theory, which regarded the earth as the\ncentre of the universe and man as the godlike ruler of the earth. It\nwas natural, therefore, that the Christian clergy, with the pope at its\nhead, should enter upon a fierce struggle with the invaluable discovery\nof Copernicus. Yet it soon cleared a path for itself, when Kepler and\nGalileo grounded on it their true \"mechanics of the heavens,\" and\nNewton gave it a solid foundation by his theory of gravitation (1686).\n\nA further great advance, comprehending the entire universe, was the\napplication of the idea of evolution to astronomy. It was done by\nthe youthful Kant in 1755; in his famous general natural history and\ntheory of the heavens he undertook the discussion, not only of the\n\"constitution,\" but also of the \"mechanical origin\" of the whole\nworld-structure on Newtonian principles. The splendid _Syst\u00e8me du\nMonde_ of Laplace, who had independently come to the same conclusions\nas Kant on the world-problem, gave so firm a basis to this new\n_M\u00e9canique C\u00e9leste_ in 1796 that it looked as if nothing entirely\nnew of equal importance was left to be discovered in the nineteenth\ncentury. Yet here again it had the honor of opening out entirely\nnew paths and infinitely enlarging our outlook on the universe. The\ninvention of photography and photometry, and especially of spectral\nanalysis (in 1860 by Bunsen and Kirchoff), introduced physics and\nchemistry into astronomy and led to cosmological conclusions of the\nutmost importance. It was now made perfectly clear that matter is\nthe same throughout the universe, and that its physical and chemical\nproperties in the most distant stars do not differ from those of the\nearth under our feet.\n\nThe monistic conviction, which we thus arrived at, of the physical\nand chemical unity of the entire cosmos is certainly one of the most\nvaluable general truths which we owe to astrophysics, the new branch\nof astronomy which is honorably associated with the name of Friedrich\nZ\u00f6llner. Not less important is the clear knowledge we have obtained\nthat the same laws of mechanical development that we have on the\nearth rule throughout the infinite universe. A vast, all-embracing\nmetamorphosis goes on continuously in all parts of the universe,\njust as it is found in the geological history of the earth; it can\nbe traced in the evolution of its living inhabitants as surely as in\nthe history of peoples or in the life of each human individual. In\none part of space we perceive, with the aid of our best telescopes,\nvast nebul\u00e6 of glowing, infinitely attenuated gas; we see in them the\nembryos of heavenly bodies, billions of miles away, in the first stage\nof their development. In some of these \"stellar embryos\" the chemical\nelements do not seem to be differentiated yet, but still buried in the\nhomogeneous primitive matter (_prothyl_) at an enormous temperature\n(calculated to run into millions of degrees); it is possible that the\noriginal basic \"substance\" (_vide_ p. 229) is not yet divided into\nponderable and imponderable matter. In other parts of space we find\nstars that have cooled down into glowing fluid, and yet others that\nare cold and rigid; we can tell their stage of evolution approximately\nby their color. We find stars that are surrounded with rings and moons\nlike Saturn; and we recognize in the luminous ring of the nebula the\nembryo of a new moon, which has detached itself from the mother-planet,\njust as the planet was released from the sun.\n\nMany of the stars, the light of which has taken thousands of years to\nreach us, are certainly suns like our own mother-sun, and are girt\nabout with planets and moons, just as in our own solar system. We\nare justified in supposing that thousands of these planets are in a\nsimilar stage of development to that of our earth--that is, they have\narrived at a period when the temperature at the surface lies between\nthe freezing and boiling point of water, and so permits the existence\nof water in its liquid condition. That makes it possible that carbon\nhas entered into the same complex combinations on those planets as\nit has done on our earth, and that from its nitrogenous compounds\nprotoplasm has been evolved--that wonderful substance which alone,\nas far as our knowledge goes, is the possessor of organic life. The\nmonera (for instance, chromacea and bacteria), which consist only of\nthis primitive protoplasm, and which arise by spontaneous generation\nfrom these inorganic nitrocarbonates, may thus have entered upon the\nsame course of evolution on many other planets as on our own; first of\nall, living cells of the simplest character would be formed from their\nhomogeneous protoplasmic body by the separation of an inner nucleus\nfrom the outer cell body (cytostoma). Further, the analogy that we\nfind in the life of all cells--whether plasmodomous plant-cells or\nplasmophagous animal-cells--justifies the inference that the further\ncourse of organic evolution on these other planets has been analogous\nto that of our own earth--always, of course, given the same limits of\ntemperature which permit water in a liquid form. In the glowing liquid\nbodies of the stars, where water can only exist in the form of steam,\nand on the cold extinct suns, where it can only be in the shape of ice,\nsuch organic life as we know is impossible.\n\nThe similarity of phylogeny, or the analogy of organic evolution,\nwhich we may thus assume in many stars which are at the same stage of\nbiogenetic development, naturally opens out a wide field of brilliant\nspeculation to the constructive imagination. A favorite subject for\nsuch speculation has long been the question whether there are men, or\nliving beings like ourselves, perhaps much more highly developed, in\nother planets? Among the many works which have sought to answer the\nquestion, those of Camille Flammarion, the Parisian astronomer, have\nrecently been extremely popular; they are equally distinguished by\nexuberant imagination and brilliant style, and by a deplorable lack\nof critical judgment and biological knowledge. We may condense in the\nfollowing thesis the present condition of our knowledge on the subject:\n\nI. It is very probable that a similar biogenetic process to that of our\nown earth is taking place on some of the other planets of our solar\nsystem (Mars and Venus), and on many planets of other solar systems;\nfirst simple monera are formed by spontaneous generation, and from\nthese arise unicellular protists (first plasmodomous primitive plants,\nand then plasmophagous primitive animals).\n\nII. It is very probable that from these unicellular protists arise,\nin the further course of evolution, first social cell-communities\n(coenobia), and subsequently tissue-forming plants and animals\n(metaphyta and metazoa).\n\nIII. It is also very probable that thallophyta (alg\u00e6 and fungi) were\nthe first to appear in the plant-kingdom, then diaphyta (mosses and\nferns), finally anthophyta (gymnosperm and angiosperm flowering plants).\n\nIV. It is equally probable that the biogenetic process took a similar\ncourse in the animal kingdom--that from the blast\u00e6ads (catallacta)\nfirst gastr\u00e6ads were formed, and from these lower animal forms\n(coelenteria) higher organisms (coelomaria) were afterwards evolved.\n\nV. On the other hand, it is very questionable whether the different\nstems of these higher animals (and those of the higher plants as well)\nrun through the same course of development on other planets as on our\nearth.\n\nVI. In particular, it is wholly uncertain whether there are vertebrates\non other planets, and whether, in the course of their phyletic\ndevelopment, taking millions of years, mammals are formed as on earth,\nreaching their highest point in the formation of man; in such an event,\nmillions of changes would have to be just the same in both cases.\n\nVII. It is much more probable, on the contrary, that other planets\nhave produced other types of the higher plants and animals, which are\nunknown on our earth; perhaps from some higher animal stem, which is\nsuperior to the vertebrate in formation, higher beings have arisen who\nfar transcend us earthly men in intelligence.\n\nVIII. The possibility of our ever entering into direct communication\nwith such inhabitants of other planets seems to be excluded by the\nimmense distance of our earth from the other heavenly bodies, and the\nabsence of the requisite atmosphere in the intervening space, which\ncontains only ether.\n\nBut while many of the stars are probably in a similar stage of\nbiogenetic development to that of our earth (for the last one hundred\nmillion years at least), others have advanced far beyond this stage,\nand, in their planetary old age, are hastening towards their end--the\nsame end that inevitably awaits our own globe. The radiation of heat\ninto space gradually lowers the temperature until all the water is\nturned into ice; that is the end of all organic life. The substance\nof the rotating mass contracts more and more; the rapidity of its\nmotion gradually falls off. The orbits of the planets and of their\nmoons grow narrower. At length the moons fall upon the planets, and\nthe planets are drawn into the sun that gave them birth. The collision\nagain produces an enormous quantity of heat. The pulverized mass of the\ncolliding bodies is distributed freely through infinite space, and the\neternal drama of sun-birth begins afresh.\n\nThe sublime picture which modern astrophysics thus unveils before the\nmind's eye shows us an eternal birth and death of countless heavenly\nbodies, a periodic change from one to the other of the different\ncosmogenetic conditions, which we observe side by side in the universe.\nWhile the embryo of a new world is being formed from a nebula in\none corner of the vast stage of the universe, another has already\ncondensed into a rotating sphere of liquid fire in some far distant\nspot; a third has already cast off rings at its equator, which round\nthemselves into planets; a fourth has become a vast sun whose planets\nhave formed a secondary retinue of moons, and so on. And between them\nare floating about in space myriads of smaller bodies, meteorites,\nor shooting-stars, which cross and recross the paths of the planets\napparently like lawless vagabonds, and of which a great number fall\nonto the planets every day. Thus there is a continuous but slow change\nin the velocities and the orbits of the revolving spheres. The frozen\nmoons fall onto the planets, the planets onto their suns. Two distant\nsuns, perhaps already stark and cold, rush together with inconceivable\nforce and melt away into nebulous clouds. And such prodigious heat\nis generated by the collision that the nebula is once more raised to\nincandescence, and the old drama begins again. Yet in this \"perpetual\nmotion\" the infinite substance of the universe, the sum total of its\nmatter and energy, remains eternally unchanged, and we have an eternal\nrepetition in infinite time of the periodic dance of the worlds, the\nmetamorphosis of the cosmos that ever returns to its starting-point.\nOver all rules the law of substance.\n\n\nII.--PROGRESS OF GEOLOGY\n\nThe earth and its origin were much later than the heavens in becoming\nthe object of scientific investigation. The numerous ancient and modern\ncosmogonies do, indeed, profess to give us as good an insight into the\norigin of the earth as into that of the heavens; but the mythological\nraiment, in which all alike are clothed, betrays their origin in\npoetic fancy. Among the countless legends of creation which we find in\nthe history of religions and of thought there is one that soon took\nprecedence of all the rest--the Mosaic story of creation as told in\nthe first book of the Hexateuch. It did not exist in its present form\nuntil long after the death of Moses (probably not until eight hundred\nyears afterwards); but its sources are much older, and are to be found\nfor the most part in Assyrian, Babylonian, and Hindoo legends. This\nHebrew legend of creation obtained its great influence through its\nadoption into the Christian faith and its consecration as the \"Word of\nGod.\" Greek philosophers had already, five hundred years before Christ,\nexplained the natural origin of the earth in the same way as that of\nother cosmic bodies. Xenophanes of Colophon had even recognized the\ntrue character of the fossils which were afterwards to prove of such\nmoment; the great painter, Leonardo da Vinci, of the fifteenth century,\nalso explained the fossils as the petrified remains of animals which\nhad lived in earlier periods of the earth's history. But the authority\nof the Bible, especially the myth of the deluge, prevented any further\nprogress in this direction, and insured the triumph of the Mosaic\nlegend until about the middle of the last century. It survives even at\nthe present day among orthodox theologians. However, in the second half\nof the eighteenth century, scientific inquiry into the structure of the\ncrust of the earth set to work independently of the Mosaic story, and\nit soon led to certain conclusions as to the origin of the earth. The\nfounder of geology, Werner of Freiberg, thought that all the rocks were\nformed in water, while Voigt and Hutton (1788) rightly contended that\nonly the stratified, fossil-bearing rocks had had an aquatic origin,\nand that the Vulcanic or Plutonic mountain ranges had been formed by\nthe cooling down of molten matter.\n\nThe heated conflict of these \"Neptunian\" and \"Plutonic\" schools was\nstill going on during the first three decades of the present century;\nit was only settled when Karl Hoff (1822) established the principle of\n\"actualism,\" and Sir Charles Lyell applied it with signal success to\nthe entire natural evolution of the earth. The _Principles of Geology_\nof Lyell (1830) secured the full recognition of the supremely important\ntheory of continuity in the formation of the earth's crust, as opposed\nto the catastrophic theory of Cuvier.[34] Pal\u00e6ontology, which had\nbeen founded by Cuvier's work on fossil bones (1812), was of the\ngreatest service to geology; by the middle of the present century it\nhad advanced so far that the chief periods in the history of the earth\nand its inhabitants could be established. The comparatively thin crust\nof the earth was now recognized with certainty to be the hard surface\nformed by the cooling of an incandescent fluid planet, which still\ncontinues its slow, unbroken course of refrigeration and condensation.\nThe crumpling of the stiffened crust, \"the reaction of the molten fiery\ncontents on the cool surface,\" and especially the unceasing geological\naction of water, are the natural causes which are daily at work in the\nsecular formation of the crust of the earth and its mountains.\n\nTo the brilliant progress of modern geology we owe three extremely\nimportant results of general import. In the first place, it has\nexcluded from the story of the earth all questions of miracle, all\nquestions of supernatural agencies, in the building of the mountains\nand the shaping of the continents. In the second place, our idea of\nthe length of the vast period of time which had been absorbed in their\nformation has been considerably enlarged. We now know that the huge\nmountains of the pal\u00e6ozoic, mesozoic, and cenozoic formations have\ntaken, not thousands, but millions of years in their growth. In the\nthird place, we now know that all the countless fossils that are found\nin those formations are not \"sports of nature,\" as was believed one\nhundred and fifty years ago, but the petrified remains of organisms\nthat lived in earlier periods of the earth's history, and arose by\ngradual transformation from a long series of ancestors.\n\n\nIII.--PROGRESS OF PHYSICS AND CHEMISTRY\n\nThe many important discoveries which these fundamental sciences have\nmade during the nineteenth century are so well known, and their\npractical application in every branch of modern life is so obvious,\nthat we need not discuss them in detail here. In particular, the\napplication of steam and electricity has given to our nineteenth\ncentury its characteristic \"machinist-stamp.\" But the colossal\nprogress of inorganic and organic chemistry is not less important. All\nbranches of modern civilization--medicine and technology, industry\nand agriculture, mining and forestry, land and water transport--have\nbeen so much improved in the course of the century, especially in the\nsecond half, that our ancestors of the eighteenth century would find\nthemselves in a new world, could they return. But more valuable and\nimportant still is the great theoretical expansion of our knowledge\nof nature, which we owe to the establishment of the law of substance.\nOnce Lavoisier (1789) had established the law of the persistence of\nmatter, and Dalton (1808) had founded his new atomic theory with its\nassistance, a way was open to modern chemistry along which it has\nadvanced with a rapidity and success beyond all anticipation. The same\nmust be said of physics in respect of the law of the conservation of\nenergy. Its discovery by Robert Mayer (1842) and Hermann Helmholtz\n(1847) inaugurated for this science also a new epoch of the most\nfruitful development; for it put physics in a position to grasp the\nuniversal unity of the forces of nature and the eternal play of natural\nprocesses, in which one force may be converted into another at any\nmoment.\n\n\nIV.--PROGRESS OF BIOLOGY\n\nThe great discoveries which astronomy and geology have made during the\nnineteenth century, and which are of extreme importance to our whole\nsystem, are, nevertheless, far surpassed by those of biology. Indeed,\nwe may say that the greater part of the many branches which this\ncomprehensive science of organic life has recently produced have seen\nthe light in the course of the present century. As we saw in the first\nsection, during the century all branches of anatomy and physiology,\nbotany and zoology, ontogeny and phylogeny, have been so marvellously\nenriched by countless discoveries that the present condition of\nbiological science is immeasurably superior to its condition a hundred\nyears ago. That applies first of all _quantitatively_ to the colossal\ngrowth of our positive information in all those provinces and their\nseveral parts. But it applies with even greater force _qualitatively_\nto the deepening of our comprehension of biological phenomena, and\nour knowledge of their efficient causes. In this Charles Darwin\n(1859) takes the palm of victory; by his theory of selection he has\nsolved the great problem of \"organic creation,\" of the natural\norigin of the countless forms of life by gradual transformation. It\nis true that Lamarck had recognized fifty years earlier that the\nmode of this transformation lay in the reciprocal action of heredity\nand adaptation. However, Lamarck was hampered by his lack of the\nprinciple of selection, and of that deeper insight into the true\nnature of organization which was only rendered possible after the\nfounding of the theory of evolution and the cellular theory. When we\ncollated the results of these and other disciplines, and found the\nkey to their harmonious interpretation in the ancestral development\nof living beings, we succeeded in establishing the monistic biology,\nthe principles of which I have endeavored to lay down securely in my\n_General Morphology_.\n\n\nV.--PROGRESS OF ANTHROPOLOGY\n\nIn a certain sense, the true science of man, rational anthropology,\ntakes precedence of every other science. The saying of the ancient\nsage, \"Man, know thyself,\" and that other famous maxim, \"Man is the\nmeasure of all things,\" have been accepted and applied from all time.\nAnd yet this science--taking it in its widest sense--has languished\nlonger than all other sciences in the fetters of tradition and\nsuperstition. We saw in the first section how slowly and how late\nthe science of the human organism was developed. One of its chief\nbranches--embryology--was not firmly established until 1828 (by Baer),\nand another, of equal importance--the cellular theory--until 1838 (by\nSchwann). And it was even later still when the answer was given to the\n\"question of all questions,\" the great riddle of the origin of man.\nAlthough Lamarck had pointed out the only path to a correct solution\nof it in 1809, and had affirmed the descent of man from the ape, it\nfell to Darwin to establish the affirmation securely fifty years\nafterwards, and to Huxley to collect the most important proofs of it\nin 1863, in his _Place of Man in Nature_. I have myself made the first\nattempt, in my _Anthropogeny_ (1874), to present in their historical\nconnection the entire series of ancestors through which our race has\nbeen slowly evolved from the animal kingdom in the course of many\nmillions of years.\n\n\n\n\nCONCLUSION\n\n\nThe number of world-riddles has been continually diminishing in the\ncourse of the nineteenth century through the aforesaid progress of a\ntrue knowledge of nature. Only one comprehensive riddle of the universe\nnow remains--the problem of substance. What is the real character of\nthis mighty world-wonder that the realistic scientist calls Nature or\nthe Universe, the idealist philosopher calls Substance or the Cosmos,\nthe pious believer calls Creator or God? Can we affirm to-day that the\nmarvellous progress of modern cosmology has solved this \"problem of\nsubstance,\" or at least that it has brought us nearer to the solution?\n\nThe answer to this final question naturally varies considerably\naccording to the stand-point of the philosophic inquirer and his\nempirical acquaintance with the real world. We grant at once that the\ninnermost character of nature is just as little understood by us as it\nwas by Anaximander and Empedocles twenty-four hundred years ago, by\nSpinoza and Newton two hundred years ago, and by Kant and Goethe one\nhundred years ago. We must even grant that this essence of substance\nbecomes more mysterious and enigmatic the deeper we penetrate into the\nknowledge of its attributes, matter and energy, and the more thoroughly\nwe study its countless phenomenal forms and their evolution. We do not\nknow the \"thing in itself\" that lies behind these knowable phenomena.\nBut why trouble about this enigmatic \"thing in itself\" when we have\nno means of investigating it, when we do not even clearly know whether\nit exists or not? Let us, then, leave the fruitless brooding over this\nideal phantom to the \"pure metaphysician,\" and let us instead, as \"real\nphysicists,\" rejoice in the immense progress which has been actually\nmade by our monistic philosophy of nature.\n\nTowering above all the achievements and discoveries of the century\nwe have the great, comprehensive \"law of substance,\" the fundamental\nlaw of the constancy of matter and force. The fact that substance is\neverywhere subject to eternal movement and transformation gives it the\ncharacter also of the universal law of evolution. As this supreme law\nhas been firmly established, and all others are subordinate to it, we\narrive at a conviction of the universal unity of nature and the eternal\nvalidity of its laws. From the gloomy _problem_ of substance we have\nevolved the clear _law_ of substance. The monism of the cosmos which we\nestablish thereon proclaims the absolute dominion of \"the great eternal\niron laws\" throughout the universe. It thus shatters, at the same time,\nthe three central dogmas of the dualistic philosophy--the personality\nof God, the immortality of the soul, and the freedom of the will.\n\nMany of us certainly view with sharp regret, or even with a profound\nsorrow, the death of the gods that were so much to our parents and\nancestors. We must console ourselves in the words of the poet:\n\n    \"The times are changed, old systems fall,\n    And new life o'er their ruins dawns.\"\n\nThe older view of idealistic dualism is breaking up with all its mystic\nand anthropistic dogmas; but upon the vast field of ruins rises,\nmajestic and brilliant, the new sun of our realistic monism, which\nreveals to us the wonderful temple of nature in all its beauty. In the\nsincere cult of \"the true, the good, and the beautiful,\" which is the\nheart of our new monistic religion, we find ample compensation for the\nanthropistic ideals of \"God, freedom, and immortality\" which we have\nlost.\n\nThroughout this discussion of the riddles of the universe I have\nclearly defined my consistent monistic position and its opposition\nto the still prevalent dualistic theory. In this I am supported by\nthe agreement of nearly all modern scientists who have the courage to\naccept a rounded philosophical system. I must not, however, take leave\nof my readers without pointing out in a conciliatory way that this\nstrenuous opposition may be toned down to a certain degree on clear\nand logical reflection--may, indeed, even be converted into a friendly\nharmony. In a thoroughly logical mind, applying the highest principles\nwith equal force in the entire field of the cosmos--in both organic and\ninorganic nature--the antithetical positions of theism and pantheism,\nvitalism and mechanism, approach until they touch each other.\nUnfortunately, consecutive thought is a rare phenomenon in nature. The\ngreat majority of philosophers are content to grasp with the right hand\nthe pure knowledge that is built on experience, but they will not part\nwith the mystic faith based on revelation, to which they cling with the\nleft. The best type of this contradictory dualism is the conflict of\npure and practical reason in the critical philosophy of the most famous\nof modern thinkers, Immanuel Kant.\n\nOn the other hand, the number is always small of the thinkers who\nwill boldly reject dualism and embrace pure monism. That is equally\ntrue of consistent idealists and theists, and of logical realists and\npantheists. However, the reconciliation of these apparent antitheses,\nand, consequently, the advance towards the solution of the fundamental\nriddle of the universe, is brought nearer to us every year in the\never-increasing growth of our knowledge of nature. We may, therefore,\nexpress a hope that the approaching twentieth century will complete\nthe task of resolving the antitheses, and, by the construction of a\nsystem of pure monism, spread far and wide the long-desired unity\nof world-conception. Germany's greatest thinker and poet, whose one\nhundred and fiftieth anniversary will soon be upon us--Wolfgang\nGoethe--gave this \"philosophy of unity\" a perfect poetic expression,\nat the very beginning of the century, in his immortal poems, _Faust_,\n_Prometheus_, and _God and the World_:\n\n    \"By eternal laws\n    Of iron ruled,\n    Must all fulfil\n    The cycle of\n    Their destiny.\"\n\n\n\n\nFOOTNOTES:\n\n[1] There are two English translations, _The Evolution of Man_ (1879)\nand _The Pedigree of Man_ (1880).\n\n[2] The English translation, by Dr. Hans Gadow, bears the title of _The\nLast Link_.\n\n[3] English translation, by J. Gilchrist, with the title of _Monism_.\n\n[4] E. Haeckel, _Systematische Phylogenie_, 1895, vol. iii., pp.\n646-50. (Anthropolatry means \"A divine worship of human nature.\")\n\n[5] Cf. my Cambridge lecture, _The Last Link_, \"Geological Time and\nEvolution.\"\n\n[6] As to induction and deduction, _vide_ _The Natural History of\nCreation_.\n\n[7] Rudolph Virchow, _Die Gr\u00fcndung der Berliner Universit\u00e4t und der\nUebergang aus dem Philosophischen in das naturwissenschaftliche\nZeitalter_. (Berlin; 1893.)\n\n[8] Cf. chap. iv. of my _General Morphology_, 1866; _Kritik der\nnaturwissenschaftlichen Methoden_.\n\n[9] _Systematische Phylogenie_, 1896, part iii., pp. 490, 494, and 496.\n\n[10] Translated in the International Science Series, 1872.\n\n[11] _Zell-Seelen und Seelen-Zellen._ Ernst Haeckel, _Gesammelte\npopul\u00e4re Vortr\u00e4ge. I. Heft._ 1878.\n\n[12] Cf. E. Haeckel, _The Systems of Darwin, Goethe, and Lamarck_.\nLecture given at Eisenach in 1882.\n\n[13] _Vide_ the translation of Dr. Hans Gadow: _The Last Link_. (A. &\nC. Black.)\n\n[14] Cf. Max Verworn, _Psychophysiologische Protisten-Studien_, pp.\n135, 140.\n\n[15] E. Haeckel, \"General Natural History of the Radiolaria\"; 1887.\n\n[16] _Vide Natural History of Creation_, E. Haeckel.\n\n[17] Law of individual variation. _Vide_ _Natural History of Creation_.\n\n[18] Cf. E. Haeckel, _Systematic Phylogeny_, vol. i.\n\n[19] Cf. _Anthropogeny_ and _Natural History of Creation_.\n\n[20] Cf. _Natural History of Creation_.\n\n[21] See chaps. xvi. and xvii. of my _Anthropogeny_.\n\n[22] E. Haeckel, _A Visit to Ceylon_.\n\n[23] Cf. _Monism_, by Ernst Haeckel.\n\n[24] Cf. _Monism_, by Ernst Haeckel.\n\n[25] Cf. _Monism_, by Ernst Haeckel.\n\n[26] Reinke, _Die Welt als That_ (1899).\n\n[27] Cf. _Monism_, by Ernst Haeckel.\n\n[28] _The Last Link_, translated by Dr. Gadow.\n\n[29] _General Morphology_, book 2, chap. v.\n\n[30] Cf. _General Morphology_, vol. ii., and _The Natural History of\nCreation._\n\n[31] _Vide_ _A Visit to Ceylon_, E. Haeckel, translated by C. Bell.\n\n[32] _Collected Popular Lectures_; Bonn, 1878.\n\n[33] As to the Greek paternity of Christ, _vide_ p. 328.\n\n[34] Cf. _The Natural History of Creation_, chaps. iii., vi., xv., and\nxvi.\n\n\n\n\nINDEX\n\n\n Abiogenesis, 257, 369.\n\n Abortive organs, 264.\n\n Accidents, 216.\n\n Acrania, 166.\n\n Action at a distance, 217.\n\n Actualism, 249.\n\n \u00c6sthesis, 225.\n\n Affinity, 224.\n\n Altruism, 350.\n\n Amphibia, 167.\n\n Amphimixis, 141.\n\n Ampitheism, 278.\n\n Ananke, 272.\n\n Anatomy, 22, etc.\n   comparative, 24.\n\n Anaximander, 289, 379.\n\n Anthropism, 11.\n\n Anthropistic illusion, 14, etc.\n   world-theory, 13.\n\n Anthropocentric dogma, 11, etc.\n\n Anthropogeny, 83.\n\n Anthropolatric dogma, 12.\n\n Anthropomorpha, 36.\n\n Anthropomorphic dogma, 12.\n\n Apes, 36, 37, 167.\n   anthropoid, 37.\n\n Arch\u00e6us, 43.\n\n Archigony, 257.\n\n Aristotle, 23, 268.\n\n Association, centres of, 183.\n   of ideas, 121.\n   of presentations, 121, 122.\n\n Astronomy, progress of, 366.\n\n Astro-physics, 368.\n\n Atavism, 142.\n\n Athanatism, 189.\n\n Athanatistic illusions, 205.\n\n Atheism, 290.\n\n Atheistic science, 260.\n\n Atom, the, 222.\n\n Atomism, 223.\n\n Atomistic consciousness, 187.\n\n Attributes of ether, 227.\n   of substance, 216.\n\n Augustine of Hippo, 130.\n\n Auricular confession, 319, 359.\n\n Autogony, 257.\n\n\n Baer (Carl Ernst), 57.\n\n Bastian (Adolf), 103.\n\n Beginning of the world, 240, 247.\n\n Bible, the, 282, 362.\n\n Biogenesis, 257.\n\n Biogenetic law, 81, 143.\n\n Bismarck, 334.\n\n Blastoderm, 150, 155.\n\n Blastosphere, 153.\n\n Blastula, 153.\n\n Bruno (Giordano), 290, 317.\n\n B\u00fcchner (Ludwig), 93.\n\n Buddhism, 326, 355.\n\n\n Calvin, 130.\n\n Canonical gospels, 312.\n\n Carbon as creator, 256.\n   theory, 257.\n\n Catarrhin\u00e6, 35.\n\n Catastrophic theory, 74.\n\n Categorical imperative, 350.\n\n Causes, efficient, 258.\n   final, 258.\n\n Celibacy, 358.\n\n Cell-love, 137.\n   community, soul of the, 155.\n   soul, 151.\n   state, 157.\n\n Cellular pathology, 50.\n   physiology, 48.\n   psychology, 153, 177.\n   theory, 26.\n\n Cenobitic soul, 155.\n\n Cenogenesis, 82.\n   of the psyche, 144.\n\n Chance, 274.\n\n Chemicotropism, 64, 136.\n\n Chordula, 64.\n\n Chorion, 68.\n\n Christ, father of, 327.\n\n Christian art, 339.\n   civilization, 356.\n   contempt of the body, 354.\n     animals, 355.\n     nature, 355.\n     self, 353.\n     the family, 357.\n     woman, 358.\n   ethics, 352.\n\n Christianity, 347.\n\n Church and school, 362.\n   state, 361.\n\n Cnidaria, 161.\n\n Conception, 64.\n\n Concubinage of the clergy, 358.\n\n Confession of faith, 302.\n\n Consciousness, 170.\n   animal, 176.\n   atomistic, 178.\n   biological, 176.\n   cellular, 177.\n   development of, 185.\n   dualistic, 182.\n   human, 173.\n   monistic, 182.\n   neurological, 174.\n   ontogeny of, 186.\n   pathology of, 182.\n   physiological, 180.\n   transcendental, 180.\n\n Constancy of energy, 212, 231.\n   matter, 212.\n\n Constantine the Great, 316.\n\n Constellations of substance, 218.\n\n Conventional lies, 323.\n\n Copernicus, 24, 320, 367.\n\n Cosmic immortality, 191.\n\n Cosmogonies, 234.\n\n Cosmological dualism, 257.\n   creationism, 235.\n   law, 211.\n   perspective, 14.\n\n Cosmos, the, 229.\n\n Creation, 73, 79, 234.\n   cosmological, 235.\n   dualistic, 236.\n   heptameral, 237.\n   individual, 237.\n   myths of, 236.\n   periodic, 237.\n   trialistic, 237.\n\n Cultur-kampf, 334.\n\n Cuvier, 74.\n\n Cyclostomata, 167.\n\n Cynopitheci, 46.\n\n Cytology, 26, etc.\n\n Cytopsyche, 151.\n\n Cytula, 64.\n\n\n Darwin (Charles), 78, etc.\n\n Decidua, 69.\n\n Deduction, 16.\n\n Demonism, 276.\n\n Descartes, 99, 355.\n\n Descent of the ape, 85, etc.\n   of man, 87.\n   theory of, 77.\n\n Design, 264, 266.\n   in nature, 260.\n   in organisms, 266.\n   in selection, 261.\n\n Destruction of heavenly bodies, 243.\n\n Determinists, 130.\n\n Diaphragm, 31.\n\n Division of labor in matter, 229.\n\n Draper, 309, 333.\n\n Dualism, 20, etc.\n\n Du Bois-Reymond, 15 180, 235.\n\n Du Prel (Carl), 305.\n\n Duty, feeling of, 350.\n\n Dynamodes, 216.\n\n Dysteleology, 260.\n\n Echinodermata, 62.\n\n Ectoderm, 160.\n   sense-cells in the, 293.\n\n Egoism, 350.\n\n Elements, chemical, 222.\n   system of the, 222.\n\n Embryo, human, 64.\n\n Embryology, 54.\n\n Embryonic psychogeny, 144.\n   sleep, 146.\n\n Empedocles, 23, 224.\n\n Encyclica (of Pius IX.), 323.\n\n End of the world, 247.\n\n Energy, kinetic, 231.\n   potential, 231.\n   principle of, 230.\n   specific, 294.\n\n Entelecheia, 268.\n\n Entoderm, 160.\n\n Entropy of the universe, 247.\n\n Epigenesis, 56, 133.\n\n Ergonomy of matter, 229.\n\n Eternity of the world, 242.\n\n Ether, 225.\n\n Etheric souls, 199.\n\n Ethics, fundamental law of, 350.\n\n Evolution, theory of, 54, 239, 243.\n   chief element in, 267.\n\n Experience, 16.\n\n Extra-mundane God, 288.\n\n\n Faith, confession of, 303.\n   of our fathers, 304.\n\n Family, the, and Christianity, 357.\n\n Fate, 272.\n\n Fechner, 97, etc.\n\n Fecundation, 63.\n\n Fetishism, 276.\n\n Feuerbach (Ludwig), 295.\n\n Flechsig, 183.\n\n Foetal membranes, 66.\n\n Folk-psychology, 103.\n\n Forces, conversion of, 231.\n\n Frederick the Great, 194, 315.\n\n\n Galen, 23, 40.\n\n Gaseous souls, 199.\n   vertebrates, 288.\n\n Gastr\u00e6a, 160.\n   theory of the, 60.\n\n Gastr\u00e6ads, 159.\n\n Gastrula, 61.\n\n Gegenbaur, 25, 30.\n\n Generation, theory of, 55.\n\n Genus, 73.\n\n Geology, periods of, 270.\n   progress of, 373.\n\n Germinal disk, 57.\n\n Gills, 65.\n\n God, 275.\n   the father, 277.\n   the son, 277, 328.\n\n Goethe, 20, etc.\n\n Goethe's monism, 331.\n\n Golden Rule, the, 351.\n\n Gospels, 312.\n\n Gravitation, theory of, 217.\n\n Gut-layer, 159.\n\n\n Haller, 42.\n\n Harvey, 42.\n\n Helmholtz (Hermann), 213, 230.\n\n Heredity, psychic, 138.\n\n Hertz (Heinrich), 225.\n\n Hippocrates, 23.\n\n Histology, 26.\n\n Histopsyche, 156.\n\n Hoff (Carl), 250.\n\n Holbach (Paul), 193.\n\n Holy Ghost, 277, 326.\n\n Humboldt (Alexander), 343.\n\n Hydra, 161.\n\n Hylozoism, 289.\n\n Hypothesis, 299.\n\n\n Iatrochemicists, 45.\n\n Iatromechanicists, 45.\n\n Ideal of beauty, 338.\n   of truth, 337.\n   of virtue, 339.\n\n Ignorabimus, 180.\n\n Immaculate conception, 326.\n\n Immaterial substance, 221.\n\n Immortality of animals, 201.\n   of the human soul, 188.\n   of unicellular organisms, 190.\n   personal, 192.\n\n Imperfection of nature, 264.\n\n Imponderable matter, 225.\n\n Impregnation, 64.\n\n Indeterminists, 130.\n\n Induction, 16.\n\n Indulgences, 359.\n\n Infallibility of the pope, 324.\n\n Instinct, 105, 123.\n\n Intellect, 125, etc.\n\n Intramundane God, 288.\n\n Introspective psychology, 95.\n\n Islam, 284.\n\n\n Janssen (Johannes), 316.\n\n Jehovah, 283.\n\n Journeys on foot, 364.\n\n\n Kant, 258, etc.\n\n Kant's metamorphosis, 92, etc.\n\n Kinetic energy, 231.\n   theory of substance, 216.\n\n K\u00f6lliker, 26, 48.\n\n\n Lamarck, 76, etc.\n\n Lamettrie, 194.\n\n Landscape-painting, 343.\n\n Language, 126.\n   study of, 363.\n\n Last judgment, 209.\n\n Lavoisier, 212.\n\n Leap of the gospels, miraculous, 312.\n\n Leydig, 27.\n\n Life, definition of, 39.\n\n Limits of our knowledge, 182.\n\n Love, 357.\n   of animals, 355.\n   of neighbor, 350.\n   of self, 350.\n\n Lucretius Carus, 290.\n\n Lunarism, 281.\n\n Luther, 320.\n\n Lyell, 77, 250.\n\n\n Madonna, cult of the, 284, 327.\n\n Malphigi, 54.\n\n Mammals, 30, etc.\n\n Mammary glands, 31.\n\n Man, ancestors of, 82.\n\n Marsupials, 32, 86.\n\n Mass, 222.\n\n Materialism, 20.\n\n Mayer (Robert), 213, 377.\n\n Mechanical causality, 366.\n   explanation, 259.\n   theory of heat, 247.\n\n Mechanicism, 259.\n\n Mediterranean religions, the, 282.\n\n Memory, cellular, 12O.\n   conscious, 121.\n   histionic, 121.\n   unconscious, 121.\n\n Mephistopheles, 279.\n\n Metabolism, 232.\n\n Metamorphoses of the cosmos, 372.\n   of philosophers, 92.\n\n Metaphyta, 156.\n\n Metasitism, 153.\n\n Metazoa, 60, 157.\n\n Middle Ages, 315, 358.\n\n Mixotheism, 286.\n\n Mohammedanism, 284.\n\n Mohr (Friedrich), 213.\n\n Monera, 257, 369.\n\n Monism, 20, and _passim_.\n   of energy, 254.\n   of Spinoza, 331.\n   of the cosmos, 255.\n\n Monistic anthropogeny, 252.\n   art, 341.\n   biogeny, 251.\n   churches, 345.\n   cosmology, 368.\n   ethics, 347.\n   geogeny, 248.\n\n Monotheism, 279.\n\n Monotrema, 32.\n\n Moon-worship, 281.\n\n Moral order of the universe, 269.\n\n Morula, 155.\n\n Mosaism, 283.\n\n M\u00fcller (Johannes), 25, 45, 262.\n\n Mythology of the soul, 135.\n\n\n Natural religion, 344.\n\n Navel-cord, 69.\n\n Neokantians, 349.\n\n Neovitalism, 264.\n\n Neptunian geology, 375.\n\n Neuro-muscular cells, 114.\n\n Neuroplasm, 91, 109.\n\n Neuropsyche, 162.\n\n Nomocracy, 9.\n\n\n Ontogenetic psychology, 103.\n\n Ontological creationism, 235.\n   methods, 249.\n\n Orbits of the heavenly bodies, 241.\n\n Origin of movement, 15, 241.\n   of feeling, 15, 241.\n\n Ovary, 63.\n\n\n Palingenesis, 82.\n   of the psyche, 143.\n\n Pandera (the father of Christ), 328.\n\n Pantheism, 288.\n\n Papacy, 314.\n\n Papal ethics, 359.\n\n Papiomorpha, 37.\n\n Paul, 313, 357.\n   epistles of, 312.\n\n Paulinism, 313.\n\n Pedicle of the allantois, 69.\n\n Perpetual motion, 245.\n\n Persistence of force, 212, 231.\n   of matter, 212.\n\n Phroneta, 293.\n\n Phylogeny, 71, 81.\n   of the apes, 51.\n   systematic, 81.\n\n Physiology, 39.\n\n Phytopsyche, 157.\n\n Pithecanthropus, 87.\n\n Pithecoid theory, 82, etc.\n\n Pithecometra-thesis, 69, 85.\n\n Placenta, 32, 68.\n\n Placentals, 32, 86.\n\n Plasmodoma, 153.\n\n Plasmogony, 257.\n\n Plasmophaga, 154.\n\n Plato, 99, 197.\n\n Plato's theory of ideas, 269.\n\n Platodaria, 160.\n\n Platodes, 160.\n\n Platyrrhin\u00e6, 35.\n\n Pneuma zoticon, 40.\n\n Polytheism, 276.\n\n Ponderable matter, 222.\n\n Preformation theory, 54.\n\n Primaria, 33.\n\n Primates, 33, 86.\n\n Primitive Christianity, 311.\n   gut, 61, 161.\n\n Prodynamis, 216.\n\n Progaster, 161.\n\n Proplacentals, 85.\n\n Prosimi\u00e6, 34.\n\n Prostoma, 161.\n\n Prothyl, 223.\n\n Protoplasm, 90.\n\n Protozoa, 60.\n\n Provertebr\u00e6, 166.\n\n Pseudo-Christianity, 321.\n\n Psychade theory, 178.\n\n Psyche, 88.\n\n Psychogeny, 135.\n   phyletic, 149.\n   post-embryonic, 146.\n\n Psychology, 88 et seqq.\n   ontogenetic, 104.\n   phylogenetic, 104.\n\n Psychomonism, 226.\n\n Psychophysics, 97.\n\n Psychoplasm, 91, 110.\n\n Pupa, sleep of the, 146.\n\n Pyknosis, 218.\n\n Pyknotic theory of substance, 218.\n\n\n Reason, 17, 125.\n\n Reflex action, 112.\n   arches, 114.\n\n Reformation, the, 319.\n\n Religion a private concern, 361.\n\n Remak, 58.\n\n Revelation, 306.\n\n Reversion, 142.\n\n Romance of the Virgin Mary, 327.\n\n Romanes, 106.\n\n Rudimentary organs, 264.\n\n\n Saints, 284.\n\n Scale of emotion, 127.\n   of memory, 120.\n   of movement, 111.\n   of presentation, 118.\n   of reason, 122.\n   of reflex action, 113.\n   of will, 127.\n\n Scatulation theory, 55.\n\n Schleiden, 26, 47.\n\n School, and Church, 361.\n   and State, 362.\n   reform of the, 363.\n\n Schwann, 26, 47.\n\n Selachii, 166.\n\n Selection, theory of, 79.\n\n Self-consciousness, 171.\n\n Sense-knowledge, 297.\n   organs, 293.\n\n Senses, philosophy of the, 295.\n\n Sentiment, 17, etc., 331.\n\n Siebold, 27.\n\n Simi\u00e6, 34.\n\n Social duties, 351.\n   instincts, 350.\n\n Solar systems, 241, 369.\n\n Solarism, 280.\n\n Soul, 88 _et seqq._\n   apparatus of the, 162.\n   blending of the, 141.\n   creation of the, 135.\n   division of the, 135.\n   etheric, 199.\n   gaseous, 199.\n   histionic, 157.\n   history of the, 167.\n   hydra, 161.\n   life of the, 90.\n   liquid, 200.\n   mammal, 167.\n   nerve, 162.\n   origin of the, 135.\n   of the plant, 157.\n   personal, 162.\n   solid, 201.\n   substance of the, 198.\n   transmigration of the, 135.\n\n Sources of knowledge, 293.\n\n Space and time, 244.\n   infinity of, 242.\n   reality of, 244.\n\n Species, 73.\n\n Spectral analysis, 241.\n\n Spermarium, 63.\n\n Spermatozoa, 58.\n\n Spinal cord, 165.\n\n Spinoza, 21, 215, 290.\n\n Spirit world, 221.\n\n Spirit-rapping, 305.\n\n Spiritism, 304.\n\n Spiritualism, 20.\n\n Sponge, soul of the, 161.\n\n Stem-cell, 63, 138, 151.\n\n Stimulated movement, 113, 116.\n\n Stimuli, conduction of, 158.\n\n Strauss (David), 309, 313.\n\n Struggle for life, 270.\n\n Substance, 215.\n   law of, 211, etc.\n   structure of, 229.\n\n Superstition, 301.\n\n S\u00fcss (Edward), 250.\n\n Syllabus, 323.\n\n Synodikon (of Pappus), 312.\n\n\n Table-turning, 305.\n\n Teleological explanation, 259.\n\n Teleology, 258.\n\n Tetrapoda, 29.\n\n Thanatism, 189.\n   primary, 192.\n   secondary, 192.\n\n Theism, 276.\n\n Theocracy, 9.\n\n Theory, 299.\n\n Thought, organs of, 126, 183, 293.\n\n Time and space, 244.\n   reality of, 246.\n\n Tissue, theory of, 26.\n\n Tissue-forming animals, 157.\n   plants, 156.\n\n Transformism, 76.\n\n Trimurti, 278.\n\n Trinity, dogma of the, 277.\n   monistic, 336.\n\n Triplotheism, 277.\n\n Tropesis, 225.\n\n Tropismata, 128.\n\n Tunicata, 165.\n\n Turbellaria, 161.\n\n\n Ultramontanism, 310.\n\n Understanding, 125.\n\n Unity of natural forces, 231.\n   of substance, 214.\n\n Universum perpetuum mobile, 245.\n\n Uterus, 34.\n\n\n Vaticanism, 314.\n\n Vertebrates, 27, _passim_.\n\n Verworn (Max), 48, 116.\n\n Vesalius, 24.\n\n Vibration, theory of, 216.\n\n Virchow, 26, 50.\n\n Virchow's metamorphosis, 93.\n\n Vital force, 42, 262.\n\n Vitalism, 43, 262.\n\n Vivisection, 41.\n\n Vogt (Carl), 93.\n\n Vogt (J.E.), 218.\n\n\n Water-color drawing, 364.\n\n Weismann, 190.\n\n Will, liberty of the, 129.\n   scale of the, 128.\n\n Wolff (C.F.), 56.\n\n Woman and Christianity, 358.\n\n World-consciousness, 171.\n\n World-riddles, number of, 15.\n\n Wundt (Wilhelm), 100, 171.\n\n\n                                THE END\n\n\n\n\n    Transcriber's notes:\n\n    The following is a list of changes made to the original.\n    The first line is the original line, the second the corrected one.\n\n    (12) Consequently, the so-called history of the world\"\n    (12) Consequently, the so-called \"history of the world\"\n\n    structure of the primates forces us to distingiush two\n    structure of the primates forces us to distinguish two\n\n    of the geneaology of our race; for man bears all the\n    of the genealogy of our race; for man bears all the\n\n    world of which we have direct and certain cognizanze\n    world of which we have direct and certain cognizance\n\n    the law of substance by Robert Mayer and Helmholz\n    the law of substance by Robert Mayer and Helmholtz\n\n    The more impotant of these works we owe to Romanes\n    The more important of these works we owe to Romanes\n\n    Formerly assistant and pupil of Helmholz, Wundt had early\n    Formerly assistant and pupil of Helmholtz, Wundt had early\n\n    all other viviporous animals, precisely because the complete\n    all other viviparous animals, precisely because the complete\n\n    recent students of the protists, afford conlcusive evidence\n    recent students of the protists, afford conclusive evidence\n\n    a thinker is very striking; in explaning it, it is not\n    a thinker is very striking; in explaining it, it is not\n\n    \"have no individuals and no generations in the matazoic sense.\"\n    \"have no individuals and no generations in the metazoic sense.\"\n\n    in his _Species and Studies_ in his eighty-fouth year\n    in his _Species and Studies_ in his eighty-fourth year\n\n    Chief Forms of Theism--Polytheism--Tritheism--Ampitheism\n    Chief Forms of Theism--Polytheism--Triplotheism--Amphitheism\n\n    faith, and that all these insiduous institutions are\n    faith, and that all these insidious institutions are\n\n    nor in the narnow prisons of our jail-like schools,\n    nor in the narrow prisons of our jail-like schools,\n\n    And it was done in many, and sometimes very romatic, ways.\n    And it was done in many, and sometimes very romantic, ways.","title":"The Riddle of the Universe at the close of the nineteenth century","tradition":"scripture-revelation","translated_text":null,"word_count":109117}