{"collection":"philosophy-ethics","full_text_available":true,"graph_url":"https://unchartedknowledge.5gfusion.net/v2/api/page/gutenberg_52344/graph","html_url":"https://unchartedknowledge.5gfusion.net/v2/page/gutenberg_52344","id":"gutenberg_52344","license":"Public Domain (US)","rights_basis":"gutenberg_metadata_copyright_false","source":"gutenberg","source_url":"https://www.gutenberg.org/ebooks/52344","summary":null,"tags":["Category: Essays, Letters & Speeches","Category: Philosophy & Ethics","Category: Teaching & Education","Science"],"text":"SCIENCE AND CULTURE\n\n  AND\n\n  OTHER ESSAYS\n\n[Illustration]\n\n  SCIENCE AND CULTURE\n\n  AND\n\n  OTHER ESSAYS\n\n  BY\n\n  THOMAS HENRY HUXLEY, LL.D., F.R.S.\n\n\n  London\n  MACMILLAN AND CO.\n  AND NEW YORK\n  1888\n\n  _All rights reserved_\n\n\n  _First Edition printed 1881\n  Reprinted 1882, 1888._\n\n\n\n\nPREFACE.\n\n\nThe Addresses, Lectures, and Essays gathered together in this volume\nhave appeared at intervals during the past seven years, and I can give\nno better reason for republishing them in their present form, than\nthe fact that three earlier collections of a similar nature have been\nreceived with favour, and, indeed, have not yet ceased to be in request.\n\nI beg leave to offer my best thanks to the Editors and Publishers of\nthe various publications in which these pieces have appeared, for their\nkindly accorded permission to reprint them.\n\n  LONDON. _October 1881._\n\n\n\n\nCONTENTS.\n\n\n  I.\n\n  SCIENCE AND CULTURE.\n\n  An Address delivered at the Opening of Sir Josiah Mason\u2019s\n  Science College, at Birmingham, on the 1st of October\n  1880                                                   Pages 1 to 23\n\n\n  II.\n\n  UNIVERSITIES: ACTUAL AND IDEAL.\n\n  The Inaugural Address of the Lord Rector of the\n  University of Aberdeen, 27th February 1874.\u2014_Contemporary\n  Review_, 1874                                               24 to 64\n\n\n  III.\n\n  TECHNICAL EDUCATION.\n\n  An Address delivered to the Working Men\u2019s Club and\n  Institute, 1st December 1877.\u2014_Nineteenth Century_, 1878    65 to 85\n\n\n  IV.\n\n  ELEMENTARY INSTRUCTION IN PHYSIOLOGY.\n\n  Read at the Meeting of the Domestic Economy Congress at\n  Birmingham, 1877                                            86 to 93\n\n\n  V.\n\n  JOSEPH PRIESTLEY.\n\n  An Address delivered on the occasion of the Presentation\n  of a Statue of Priestley to the Town of Birmingham, on\n  the 1st of August 1874.\u2014_Macmillan\u2019s Magazine_, 1874       94 to 127\n\n\n  VI.\n\n  ON THE METHOD OF ZADIG.\n\n  A Lecture delivered at the Working Men\u2019s College, Great\n  Ormond Street, 1880.\u2014_Nineteenth Century_, 1880           128 to 148\n\n\n  VII.\n\n  ON THE BORDER TERRITORY BETWEEN THE ANIMAL AND THE\n  VEGETABLE KINGDOMS.\n\n  An Evening Lecture at the Royal Institution, Friday,\n  January 28, 1876.\u2014_Macmillan\u2019s Magazine_, 1874            149 to 179\n\n\n  VIII.\n\n  ON CERTAIN ERRORS RESPECTING THE STRUCTURE OF THE HEART\n  ATTRIBUTED TO ARISTOTLE.\n\n  _Nature_, 6th November 1879                               180 to 198\n\n\n  IX.\n\n  ON THE HYPOTHESIS THAT ANIMALS ARE AUTOMATA, AND ITS\n  HISTORY.\n\n  An Address delivered at the Meeting of the British\n  Association for the Advancement of Science, at Belfast,\n  1874.\u2014_Fortnightly Review_, 1874                          199 to 245\n\n\n  X.\n\n  ON SENSATION AND THE UNITY OF STRUCTURE OF THE\n  SENSIFEROUS ORGANS.\n\n  An Evening Lecture at the Royal Institution, Friday,\n  March 7, 1879.\u2014_Nineteenth Century_, 1879                 246 to 273\n\n\n  XI.\n\n  EVOLUTION IN BIOLOGY.\n\n  The _Encyclop\u00e6dia Britannica_, Ninth Edition, vol. viii.\n  1878                                                      274 to 309\n\n\n  XII.\n\n  THE COMING OF AGE OF \u201cTHE ORIGIN OF SPECIES.\u201d\n\n  An evening Lecture at the Royal Institution, Friday, 9th\n  April 1880.\u2014_Nature_, 1880                                310 to 324\n\n\n  XIII.\n\n  THE CONNECTION OF THE BIOLOGICAL SCIENCES WITH MEDICINE.\n\n  An Address delivered at the Meeting of the International\n  Medical Congress in London, 9th August 1881               325 to 349\n\n\n\n\nI.\n\nSCIENCE AND CULTURE.\n\n\nSix years ago, as some of my present hearers may remember, I had the\nprivilege of addressing a large assemblage of the inhabitants of this\ncity, who had gathered together to do honour to the memory of their\nfamous townsman, Joseph Priestley;[1] and, if any satisfaction attaches\nto posthumous glory, we may hope that the manes of the burnt-out\nphilosopher were then finally appeased.\n\nNo man, however, who is endowed with a fair share of common sense, and\nnot more than a fair share of vanity, will identify either contemporary\nor posthumous fame with the highest good; and Priestley\u2019s life leaves\nno doubt that he, at any rate, set a much higher value upon the\nadvancement of knowledge, and the promotion of that freedom of thought\nwhich is at once the cause and the consequence of intellectual progress.\n\nHence I am disposed to think that, if Priestley could be amongst us\nto-day, the occasion of our meeting would afford him even greater\npleasure than the proceedings which celebrated the centenary of his\nchief discovery. The kindly heart would be moved, the high sense\nof social duty would be satisfied, by the spectacle of well-earned\nwealth, neither squandered in tawdry luxury and vainglorious show,\nnor scattered with the careless charity which blesses neither him\nthat gives nor him that takes, but expended in the execution of a\nwell-considered plan for the aid of present and future generations of\nthose who are willing to help themselves.\n\nWe shall all be of one mind thus far. But it is needful to share\nPriestley\u2019s keen interest in physical science; and to have learned, as\nhe had learned, the value of scientific training in fields of inquiry\napparently far remote from physical science; in order to appreciate, as\nhe would have appreciated, the value of the noble gift which Sir Josiah\nMason has bestowed upon the inhabitants of the Midland district.\n\nFor us children of the nineteenth century, however, the establishment\nof a college under the conditions of Sir Josiah Mason\u2019s Trust, has a\nsignificance apart from any which it could have possessed a hundred\nyears ago. It appears to be an indication that we are reaching the\ncrisis of the battle, or rather of the long series of battles, which\nhave been fought over education in a campaign which began long before\nPriestley\u2019s time, and will probably not be finished just yet.\n\nIn the last century, the combatants were the champions of ancient\nliterature, on the one side, and those of modern literature on the\nother; but, some thirty years[2] ago, the contest became complicated by\nthe appearance of a third army, ranged round the banner of Physical\nScience.\n\nI am not aware that any one has authority to speak in the name of this\nnew host. For it must be admitted to be somewhat of a guerilla force,\ncomposed largely of irregulars, each of whom fights pretty much for\nhis own hand. But the impressions of a full private, who has seen a\ngood deal of service in the ranks, respecting the present position of\naffairs and the conditions of a permanent peace, may not be devoid\nof interest; and I do not know that I could make a better use of the\npresent opportunity than by laying them before you.\n\n\nFrom the time that the first suggestion to introduce physical science\ninto ordinary education was timidly whispered, until now, the advocates\nof scientific education have met with opposition of two kinds. On the\none hand, they have been pooh-poohed by the men of business who pride\nthemselves on being the representatives of practicality; while, on the\nother hand, they have been excommunicated by the classical scholars,\nin their capacity of Levites in charge of the ark of culture and\nmonopolists of liberal education.\n\nThe practical men believed that the idol whom they worship\u2014rule of\nthumb\u2014has been the source of the past prosperity, and will suffice\nfor the future welfare of the arts and manufactures. They were of\nopinion that science is speculative rubbish; that theory and practice\nhave nothing to do with one another; and that the scientific habit of\nmind is an impediment, rather than an aid, in the conduct of ordinary\naffairs.\n\nI have used the past tense in speaking of the practical men\u2014for\nalthough they were very formidable thirty years ago, I am not sure\nthat the pure species has not been extirpated. In fact, so far as mere\nargument goes, they have been subjected to such a _feu d\u2019enfer_ that it\nis a miracle if any have escaped. But I have remarked that your typical\npractical man has an unexpected resemblance to one of Milton\u2019s angels.\nHis spiritual wounds, such as are inflicted by logical weapons, may be\nas deep as a well and as wide as a church door, but beyond shedding a\nfew drops of ichor, celestial or otherwise, he is no whit the worse.\nSo, if any of these opponents be left, I will not waste time in vain\nrepetition of the demonstrative evidence of the practical value of\nscience; but knowing that a parable will sometimes penetrate where\nsyllogisms fail to effect an entrance, I will offer a story for their\nconsideration.\n\nOnce upon a time, a boy, with nothing to depend upon but his own\nvigorous nature, was thrown into the thick of the struggle for\nexistence in the midst of a great manufacturing population. He seems\nto have had a hard fight, inasmuch as, by the time he was thirty\nyears of age, his total disposable funds amounted to twenty pounds.\nNevertheless, middle life found him giving proof of his comprehension\nof the practical problems he had been roughly called upon to solve, by\na career of remarkable prosperity.\n\nFinally, having reached old age with its well-earned surroundings of\n\u201chonour, troops of friends,\u201d the hero of my story bethought himself of\nthose who were making a like start in life, and how he could stretch\nout a helping hand to them.\n\nAfter long and anxious reflection this successful practical man\nof business could devise nothing better than to provide them with\nthe means of obtaining \u201csound, extensive, and practical scientific\nknowledge.\u201d And he devoted a large part of his wealth and five years of\nincessant work to this end.\n\nI need not point the moral of a tale which, as the solid and spacious\nfabric of the Scientific College assures us, is no fable, nor can\nanything which I could say intensify the force of this practical answer\nto practical objections.\n\n\nWe may take it for granted then, that, in the opinion of those best\nqualified to judge, the diffusion of thorough scientific education is\nan absolutely essential condition of industrial progress; and that the\nCollege which has been opened to-day will confer an inestimable boon\nupon those whose livelihood is to be gained by the practice of the arts\nand manufactures of the district.\n\nThe only question worth discussion is, whether the conditions, under\nwhich the work of the College is to be carried out, are such as to give\nit the best possible chance of achieving permanent success.\n\nSir Josiah Mason, without doubt most wisely, has left very large\nfreedom of action to the trustees, to whom he proposes ultimately to\ncommit the administration of the College, so that they may be able to\nadjust its arrangements in accordance with the changing conditions\nof the future. But, with respect to three points, he has laid most\nexplicit injunctions upon both administrators and teachers.\n\nParty politics are forbidden to enter into the minds of either, so\nfar as the work of the College is concerned; theology is as sternly\nbanished from its precincts; and finally, it is especially declared\nthat the College shall make no provision for \u201cmere literary instruction\nand education.\u201d\n\nIt does not concern me at present to dwell upon the first two\ninjunctions any longer than may be needful to express my full\nconviction of their wisdom. But the third prohibition brings us face to\nface with those other opponents of scientific education, who are by no\nmeans in the moribund condition of the practical man, but alive, alert,\nand formidable.\n\nIt is not impossible that we shall hear this express exclusion\nof \u201cliterary instruction and education\u201d from a College which,\nnevertheless, professes to give a high and efficient education, sharply\ncriticised. Certainly the time was that the Levites of culture would\nhave sounded their trumpets against its walls as against an educational\nJericho.\n\nHow often have we not been told that the study of physical science\nis incompetent to confer culture; that it touches none of the higher\nproblems of life; and, what is worse, that the continual devotion to\nscientific studies tends to generate a narrow and bigoted belief in\nthe applicability of scientific methods to the search after truth of\nall kinds. How frequently one has reason to observe that no reply to\na troublesome argument tells so well as calling its author a \u201cmere\nscientific specialist.\u201d And, as I am afraid it is not permissible to\nspeak of this form of opposition to scientific education in the past\ntense; may we not expect to be told that this, not only omission, but\nprohibition, of \u201cmere literary instruction and education\u201d is a patent\nexample of scientific narrow-mindedness?\n\nI am not acquainted with Sir Josiah Mason\u2019s reasons for the action\nwhich he has taken; but if, as I apprehend is the case, he refers to\nthe ordinary classical course of our schools and universities by the\nname of \u201cmere literary instruction and education,\u201d I venture to offer\nsundry reasons of my own in support of that action.\n\nFor I hold very strongly by two convictions\u2014The first is, that neither\nthe discipline nor the subject-matter of classical education is of\nsuch direct value to the student of physical science as to justify\nthe expenditure of valuable time upon either; and the second is, that\nfor the purpose of attaining real culture, an exclusively scientific\neducation is at least as effectual as an exclusively literary education.\n\nI need hardly point out to you that these opinions, especially the\nlatter, are diametrically opposed to those of the great majority of\neducated Englishmen, influenced as they are by school and university\ntraditions. In their belief, culture is obtainable only by a liberal\neducation; and a liberal education is synonymous, not merely with\neducation and instruction in literature, but in one particular form of\nliterature, namely, that of Greek and Roman antiquity. They hold that\nthe man who has learned Latin and Greek, however little, is educated;\nwhile he who is versed in other branches of knowledge, however deeply,\nis a more or less respectable specialist, not admissible into the\ncultured caste. The stamp of the educated man, the University degree,\nis not for him.\n\nI am too well acquainted with the generous catholicity of spirit, the\ntrue sympathy with scientific thought, which pervades the writings\nof our chief apostle of culture to identify him with these opinions;\nand yet one may cull from one and another of those epistles to the\nPhilistines, which so much delight all who do not answer to that name,\nsentences which lend them some support.\n\nMr. Arnold tells us that the meaning of culture is \u201cto know the best\nthat has been thought and said in the world.\u201d It is the criticism of\nlife contained in literature. That criticism regards \u201cEurope as being,\nfor intellectual and spiritual purposes, one great confederation, bound\nto a joint action and working to a common result; and whose members\nhave, for their common outfit, a knowledge of Greek, Roman, and Eastern\nantiquity, and of one another. Special, local, and temporary advantages\nbeing put out of account, that modern nation will in the intellectual\nand spiritual sphere make most progress, which most thoroughly carries\nout this programme. And what is that but saying that we too, all of us,\nas individuals, the more thoroughly we carry it out, shall make the\nmore progress?\u201d[3]\n\nWe have here to deal with two distinct propositions. The first, that\na criticism of life is the essence of culture; the second, that\nliterature contains the materials which suffice for the construction of\nsuch a criticism.\n\nI think that we must all assent to the first proposition. For\nculture certainly means something quite different from learning or\ntechnical skill. It implies the possession of an ideal, and the habit\nof critically estimating the value of things by comparison with a\ntheoretic standard. Perfect culture should supply a complete theory of\nlife, based upon a clear knowledge alike of its possibilities and of\nits limitations.\n\nBut we may agree to all this, and yet strongly dissent from the\nassumption that literature alone is competent to supply this knowledge.\nAfter having learnt all that Greek, Roman, and Eastern antiquity have\nthought and said, and all that modern literatures have to tell us, it\nis not self-evident that we have laid a sufficiently broad and deep\nfoundation for that criticism of life which constitutes culture.\n\nIndeed, to any one acquainted with the scope of physical science, it is\nnot at all evident. Considering progress only in the \u201cintellectual and\nspiritual sphere,\u201d I find myself wholly unable to admit that either\nnations or individuals will really advance, if their common outfit\ndraws nothing from the stores of physical science. I should say that\nan army, without weapons of precision and with no particular base of\noperations, might more hopefully enter upon a campaign on the Rhine,\nthan a man, devoid of a knowledge of what physical science has done in\nthe last century, upon a criticism of life.\n\n\nWhen a biologist meets with an anomaly, he instinctively turns to the\nstudy of development to clear it up. The rationale of contradictory\nopinions may with equal confidence be sought in history.\n\nIt is, happily, no new thing that Englishmen should employ their wealth\nin building and endowing institutions for educational purposes. But,\nfive or six hundred years ago, deeds of foundation expressed or implied\nconditions as nearly as possible contrary to those which have been\nthought expedient by Sir Josiah Mason. That is to say, physical science\nwas practically ignored, while a certain literary training was enjoined\nas a means to the acquirement of knowledge which was essentially\ntheological.\n\nThe reason of this singular contradiction between the actions of men\nalike animated by a strong and disinterested desire to promote the\nwelfare of their fellows, is easily discovered.\n\nAt that time, in fact, if any one desired knowledge beyond such as\ncould be obtained by his own observation, or by common conversation,\nhis first necessity was to learn the Latin language, inasmuch as\nall the higher knowledge of the western world was contained in works\nwritten in that language. Hence, Latin grammar, with logic and\nrhetoric, studied through Latin, were the fundamentals of education.\nWith respect to the substance of the knowledge imparted through this\nchannel, the Jewish and Christian Scriptures, as interpreted and\nsupplemented by the Romish Church, were held to contain a complete and\ninfallibly true body of information.\n\nTheological dicta were, to the thinkers of those days, that which\nthe axioms and definitions of Euclid are to the geometers of these.\nThe business of the philosophers of the middle ages was to deduce\nfrom the data furnished by the theologians, conclusions in accordance\nwith ecclesiastical decrees. They were allowed the high privilege of\nshowing, by logical process, how and why that which the Church said\nwas true, must be true. And if their demonstrations fell short of or\nexceeded this limit, the Church was maternally ready to check their\naberrations, if need be, by the help of the secular arm.\n\nBetween the two, our ancestors were furnished with a compact and\ncomplete criticism of life. They were told how the world began and\nhow it would end; they learned that all material existence was but a\nbase and insignificant blot upon the fair face of the spiritual world,\nand that nature was, to all intents and purposes, the playground of\nthe devil; they learned that the earth is the centre of the visible\nuniverse, and that man is the cynosure of things terrestrial; and more\nespecially was it inculcated that the course of nature had no fixed\norder, but that it could be, and constantly was, altered by the agency\nof innumerable spiritual beings, good and bad, according as they were\nmoved by the deeds and prayers of men. The sum and substance of the\nwhole doctrine was to produce the conviction that the only thing really\nworth knowing in this world was how to secure that place in a better\nwhich, under certain conditions, the Church promised.\n\nOur ancestors had a living belief in this theory of life, and acted\nupon it in their dealings with education, as in all other matters.\nCulture meant saintliness\u2014after the fashion of the saints of those\ndays; the education that led to it was, of necessity, theological; and\nthe way to theology lay through Latin.\n\nThat the study of nature\u2014further than was requisite for the\nsatisfaction of everyday wants\u2014should have any bearing on human life\nwas far from the thoughts of men thus trained. Indeed, as nature had\nbeen cursed for man\u2019s sake, it was an obvious conclusion that those who\nmeddled with nature were likely to come into pretty close contact with\nSatan. And, if any born scientific investigator followed his instincts,\nhe might safely reckon upon earning the reputation, and probably upon\nsuffering the fate, of a sorcerer.\n\nHad the western world been left to itself in Chinese isolation, there\nis no saying how long this state of things might have endured. But,\nhappily, it was not left to itself. Even earlier than the thirteenth\ncentury, the development of Moorish civilisation in Spain and the\ngreat movement of the Crusades had introduced the leaven which, from\nthat day to this, has never ceased to work. At first, through the\nintermediation of Arabic translations, afterwards, by the study of the\noriginals, the western nations of Europe became acquainted with the\nwritings of the ancient philosophers and poets, and, in time, with the\nwhole of the vast literature of antiquity.\n\nWhatever there was of high intellectual aspiration or dominant\ncapacity in Italy, France, Germany, and England, spent itself for\ncenturies in taking possession of the rich inheritance left by the dead\ncivilisations of Greece and Rome. Marvellously aided by the invention\nof printing, classical learning spread and flourished. Those who\npossessed it prided themselves on having attained the highest culture\nthen within the reach of mankind.\n\nAnd justly. For, saving Dante on his solitary pinnacle, there was no\nfigure in modern literature at the time of the Renascence to compare\nwith the men of antiquity; there was no art to compete with their\nsculpture; there was no physical science but that which Greece had\ncreated. Above all, there was no other example of perfect intellectual\nfreedom\u2014of the unhesitating acceptance of reason as the sole guide to\ntruth and the supreme arbiter of conduct.\n\nThe new learning necessarily soon exerted a profound influence upon\neducation. The language of the monks and schoolmen seemed little better\nthan gibberish to scholars fresh from Virgil and Cicero, and the study\nof Latin was placed upon a new foundation. Moreover, Latin itself\nceased to afford the sole key to knowledge. The student who sought the\nhighest thought of antiquity, found only a second-hand reflection of\nit in Roman literature, and turned his face to the full light of the\nGreeks. And after a battle, not altogether dissimilar to that which\nis at present being fought over the teaching of physical science, the\nstudy of Greek was recognised as an essential element of all higher\neducation.\n\nThus the Humanists, as they were called, won the day; and the great\nreform which they effected was of incalculable service to mankind.\nBut the Nemesis of all reformers is finality; and the reformers of\neducation, like those of religion, fell into the profound, however\ncommon, error of mistaking the beginning for the end of the work of\nreformation.\n\nThe representatives of the Humanists, in the nineteenth century, take\ntheir stand upon classical education as the sole avenue to culture, as\nfirmly as if we were still in the age of Renascence. Yet, surely, the\npresent intellectual relations of the modern and the ancient worlds are\nprofoundly different from those which obtained three centuries ago.\nLeaving aside the existence of a great and characteristically modern\nliterature, of modern painting, and, especially, of modern music,\nthere is one feature of the present state of the civilised world which\nseparates it more widely from the Renascence, than the Renascence was\nseparated from the middle ages.\n\nThis distinctive character of our own times lies in the vast and\nconstantly increasing part which is played by natural knowledge. Not\nonly is our daily life shaped by it, not only does the prosperity\nof millions of men depend upon it, but our whole theory of life has\nlong been influenced, consciously or unconsciously, by the general\nconceptions of the universe, which have been forced upon us by physical\nscience.\n\nIn fact, the most elementary acquaintance with the results of\nscientific investigation shows us that they offer a broad and striking\ncontradiction to the opinions so implicitly credited and taught in the\nmiddle ages.\n\nThe notions of the beginning and the end of the world entertained\nby our forefathers are no longer credible. It is very certain that\nthe earth is not the chief body in the material universe, and that\nthe world is not subordinated to man\u2019s use. It is even more certain\nthat nature is the expression of a definite order with which nothing\ninterferes, and that the chief business of mankind is to learn that\norder and govern themselves accordingly. Moreover this scientific\n\u201ccriticism of life\u201d presents itself to us with different credentials\nfrom any other. It appeals not to authority, nor to what anybody\nmay have thought or said, but to nature. It admits that all our\ninterpretations of natural fact are more or less imperfect and\nsymbolic, and bids the learner seek for truth not among words but among\nthings. It warns us that the assertion which outstrips evidence is not\nonly a blunder but a crime.\n\nThe purely classical education advocated by the representatives of\nthe Humanists in our day, gives no inkling of all this. A man may be\na better scholar than Erasmus, and know no more of the chief causes\nof the present intellectual fermentation than Erasmus did. Scholarly\nand pious persons, worthy of all respect, favour us with allocutions\nupon the sadness of the antagonism of science to their medi\u00e6val way\nof thinking, which betray an ignorance of the first principles of\nscientific investigation, an incapacity for understanding what a man\nof science means by veracity, and an unconsciousness of the weight of\nestablished scientific truths, which is almost comical.\n\nThere is no great force in the _tu quoque_ argument, or else the\nadvocates of scientific education might fairly enough retort upon the\nmodern Humanists that they may be learned specialists, but that they\npossess no such sound foundation for a criticism of life as deserves\nthe name of culture. And, indeed, if we were disposed to be cruel,\nwe might urge that the Humanists have brought this reproach upon\nthemselves, not because they are too full of the spirit of the ancient\nGreek, but because they lack it.\n\nThe period of the Renascence is commonly called that of the \u201cRevival of\nLetters,\u201d as if the influences then brought to bear upon the mind of\nWestern Europe had been wholly exhausted in the field of literature.\nI think it is very commonly forgotten that the revival of science,\neffected by the same agency, although less conspicuous, was not less\nmomentous.\n\nIn fact, the few and scattered students of nature of that day picked\nup the clue to her secrets exactly as it fell from the hands of the\nGreeks a thousand years before. The foundations of mathematics were so\nwell laid by them, that our children learn their geometry from a book\nwritten for the schools of Alexandria two thousand years ago. Modern\nastronomy is the natural continuation and development of the work of\nHipparchus and of Ptolemy; modern physics of that of Democritus and of\nArchimedes; it was long before modern biological science outgrew the\nknowledge bequeathed to us by Aristotle, by Theophrastus, and by Galen.\n\nWe cannot know all the best thoughts and sayings of the Greeks unless\nwe know what they thought about natural phenomena. We cannot fully\napprehend their criticism of life unless we understand the extent\nto which that criticism was affected by scientific conceptions. We\nfalsely pretend to be the inheritors of their culture, unless we are\npenetrated, as the best minds among them were, with an unhesitating\nfaith that the free employment of reason, in accordance with scientific\nmethod, is the sole method of reaching truth.\n\nThus I venture to think that the pretensions of our modern Humanists\nto the possession of the monopoly of culture and to the exclusive\ninheritance of the spirit of antiquity must be abated, if not\nabandoned. But I should be very sorry that anything I have said should\nbe taken to imply a desire on my part to depreciate the value of\nclassical education, as it might be and as it sometimes is. The native\ncapacities of mankind vary no less than their opportunities; and while\nculture is one, the road by which one man may best reach it is widely\ndifferent from that which is most advantageous to another. Again,\nwhile scientific education is yet inchoate and tentative, classical\neducation is thoroughly well organised upon the practical experience\nof generations of teachers. So that, given ample time for learning and\ndestination for ordinary life, or for a literary career, I do not think\nthat a young Englishman in search of culture can do better than follow\nthe course usually marked out for him, supplementing its deficiencies\nby his own efforts.\n\nBut for those who mean to make science their serious occupation; or who\nintend to follow the profession of medicine; or who have to enter early\nupon the business of life; for all these, in my opinion, classical\neducation is a mistake; and it is for this reason that I am glad to see\n\u201cmere literary education and instruction\u201d shut out from the curriculum\nof Sir Josiah Mason\u2019s College, seeing that its inclusion would probably\nlead to the introduction of the ordinary smattering of Latin and Greek.\n\nNevertheless, I am the last person to question the importance of\ngenuine literary education, or to suppose that intellectual culture can\nbe complete without it. An exclusively scientific training will bring\nabout a mental twist as surely as an exclusively literary training. The\nvalue of the cargo does not compensate for a ship\u2019s being out of trim;\nand I should be very sorry to think that the Scientific College would\nturn out none but lop-sided men.\n\nThere is no need, however, that such a catastrophe should happen.\nInstruction in English, French, and German is provided, and thus the\nthree greatest literatures of the modern world are made accessible to\nthe student.\n\nFrench and German, and especially the latter language, are absolutely\nindispensable to those who desire full knowledge in any department\nof science. But even supposing that the knowledge of these languages\nacquired is not more than sufficient for purely scientific purposes,\nevery Englishman has, in his native tongue, an almost perfect\ninstrument of literary expression; and, in his own literature, models\nof every kind of literary excellence. If an Englishman cannot get\nliterary culture out of his Bible, his Shakspeare, his Milton, neither,\nin my belief, will the profoundest study of Homer and Sophocles, Virgil\nand Horace, give it to him.\n\nThus, since the constitution of the College makes sufficient provision\nfor literary as well as for scientific education, and since artistic\ninstruction is also contemplated, it seems to me that a fairly complete\nculture is offered to all who are willing to take advantage of it.\n\n\nBut I am not sure that at this point the \u201cpractical\u201d man, scotched but\nnot slain, may ask what all this talk about culture has to do with\nan Institution, the object of which is defined to be \u201cto promote the\nprosperity of the manufactures and the industry of the country.\u201d He\nmay suggest that what is wanted for this end is not culture, nor even\na purely scientific discipline, but simply a knowledge of applied\nscience.\n\nI often wish that this phrase, \u201capplied science,\u201d had never been\ninvented. For it suggests that there is a sort of scientific knowledge\nof direct practical use, which can be studied apart from another sort\nof scientific knowledge, which is of no practical utility, and which\nis termed \u201cpure science.\u201d But there is no more complete fallacy than\nthis. What people call applied science is nothing but the application\nof pure science to particular classes of problems. It consists of\ndeductions from those general principles, established by reasoning and\nobservation, which constitute pure science. No one can safely make\nthese deductions until he has a firm grasp of the principles; and he\ncan obtain that grasp only by personal experience of the operations of\nobservation and of reasoning on which they are founded.\n\nAlmost all the processes employed in the arts and manufactures fall\nwithin the range either of physics or of chemistry. In order to improve\nthem, one must thoroughly understand them; and no one has a chance\nof really understanding them, unless he has obtained that mastery\nof principles and that habit of dealing with facts, which is given\nby long-continued and well-directed purely scientific training in\nthe physical and the chemical laboratory. So that there really is no\nquestion as to the necessity of purely scientific discipline, even if\nthe work of the College were limited by the narrowest interpretation of\nits stated aims.\n\nAnd, as to the desirableness of a wider culture than that yielded\nby science alone, it is to be recollected that the improvement of\nmanufacturing processes is only one of the conditions which contribute\nto the prosperity of industry. Industry is a means and not an end; and\nmankind work only to get something which they want. What that something\nis depends partly on their innate, and partly on their acquired,\ndesires.\n\nIf the wealth resulting from prosperous industry is to be spent upon\nthe gratification of unworthy desires, if the increasing perfection\nof manufacturing processes is to be accompanied by an increasing\ndebasement of those who carry them on, I do not see the good of\nindustry and prosperity.\n\nNow it is perfectly true that men\u2019s views of what is desirable depend\nupon their characters; and that the innate proclivities to which we\ngive that name are not touched by any amount of instruction. But it\ndoes not follow that even mere intellectual education may not, to an\nindefinite extent, modify the practical manifestation of the characters\nof men in their actions, by supplying them with motives unknown to the\nignorant. A pleasure-loving character will have pleasure of some sort;\nbut, if you give him the choice, he may prefer pleasures which do not\ndegrade him to those which do. And this choice is offered to every man,\nwho possesses in literary or artistic culture a never-failing source of\npleasures, which are neither withered by age, nor staled by custom, nor\nembittered in the recollection by the pangs of self-reproach.\n\nIf the Institution opened to-day fulfils the intention of its founder,\nthe picked intelligences among all classes of the population of\nthis district will pass through it. No child born in Birmingham,\nhenceforward, if he have the capacity to profit by the opportunities\noffered to him, first in the primary and other schools, and afterwards\nin the Scientific College, need fail to obtain, not merely the\ninstruction, but the culture most appropriate to the conditions of his\nlife.\n\nWithin these walls, the future employer and the future artisan may\nsojourn together for a while, and carry, through all their lives, the\nstamp of the influences then brought to bear upon them. Hence, it is\nnot beside the mark to remind you, that the prosperity of industry\ndepends not merely upon the improvement of manufacturing processes,\nnot merely upon the ennobling of the individual character, but upon a\nthird condition, namely, a clear understanding of the conditions of\nsocial life on the part of both the capitalist and the operative, and\ntheir agreement upon common principles of social action. They must\nlearn that social phenomena are as much the expression of natural laws\nas any others; that no social arrangements can be permanent unless\nthey harmonise with the requirements of social statics and dynamics;\nand that, in the nature of things, there is an arbiter whose decisions\nexecute themselves.\n\nBut this knowledge is only to be obtained by the application of\nthe methods of investigation adopted in physical researches to the\ninvestigation of the phenomena of society. Hence, I confess, I should\nlike to see one addition made to the excellent scheme of education\npropounded for the College, in the shape of provision for the teaching\nof Sociology. For though we are all agreed that party politics are to\nhave no place in the instruction of the College; yet in this country,\npractically governed as it is now by universal suffrage, every man who\ndoes his duty must exercise political functions. And, if the evils\nwhich are inseparable from the good of political liberty are to be\nchecked, if the perpetual oscillation of nations between anarchy and\ndespotism is to be replaced by the steady march of self-restraining\nfreedom; it will be because men will gradually bring themselves to deal\nwith political, as they now deal with scientific questions; to be as\nashamed of undue haste and partisan prejudice in the one case as in\nthe other; and to believe that the machinery of society is at least\nas delicate as that of a spinning-jenny, and as little likely to be\nimproved by the meddling of those who have not taken the trouble to\nmaster the principles of its action.\n\n\nIn conclusion, I am sure that I make myself the mouthpiece of all\npresent in offering to the venerable founder of the Institution,\nwhich now commences its beneficent career, our congratulations on the\ncompletion of his work; and in expressing the conviction, that the\nremotest posterity will point to it as a crucial instance of the wisdom\nwhich natural piety leads all men to ascribe to their ancestors.\n\n\n\n\nII.\n\nUNIVERSITIES: ACTUAL AND IDEAL.\n\n\nElected by the suffrages of your four Nations, Rector of the ancient\nUniversity of which you are scholars, I take the earliest opportunity\nwhich has presented itself since my restoration to health, of\ndelivering the Address which, by long custom, is expected of the holder\nof my office.\n\nMy first duty in opening that Address, is to offer you my most hearty\nthanks for the signal honour you have conferred upon me\u2014an honour\nof which, as a man unconnected with you by personal or by national\nties, devoid of political distinction, and a plebeian who stands by\nhis order, I could not have dreamed. And it was the more surprising\nto me, as the five-and-twenty years which have passed over my head\nsince I reached intellectual manhood, have been largely spent in no\nhalf-hearted advocacy of doctrines which have not yet found favour\nin the eyes of Academic respectability; so that, when the proposal\nto nominate me for your Rector came, I was almost as much astonished\nas was Hal o\u2019 the Wynd, \u201cwho fought for his own hand,\u201d by the Black\nDouglas\u2019s proffer of knighthood. And I fear that my acceptance must be\ntaken as evidence that, less wise than the Armourer of Perth, I have\nnot yet done with soldiering.\n\nIn fact, if, for a moment, I imagined that your intention was simply,\nin the kindness of your hearts, to do me honour; and that the Rector of\nyour University, like that of some other Universities, was one of those\nhappy beings who sit in glory for three years, with nothing to do for\nit save the making of a speech, a conversation with my distinguished\npredecessor soon dispelled the dream. I found that, by the constitution\nof the University of Aberdeen, the incumbent of the Rectorate is, if\nnot a power, at any rate a potential energy; and that, whatever may\nbe his chances of success or failure, it is his duty to convert that\npotential energy into a living force, directed towards such ends as may\nseem to him conducive to the welfare of the corporation of which he is\nthe theoretical head.\n\nI need not tell you that your late Lord Rector took this view of\nhis position, and acted upon it with the comprehensive, far-seeing\ninsight into the actual condition and tendencies, not merely of his\nown, but of other countries, which is his honourable characteristic\namong statesmen. I have already done my best, and, as long as I hold\nmy office, I shall continue my endeavours, to follow in the path which\nhe trod; to do what in me lies, to bring this University nearer to the\nideal\u2014alas, that I should be obliged to say ideal\u2014of all Universities;\nwhich, as I conceive, should be places in which thought is free from\nall fetters; and in which all sources of knowledge, and all aids to\nlearning, should be accessible to all comers, without distinction of\ncreed or country, riches or poverty.\n\nDo not suppose, however, that I am sanguine enough to expect much to\ncome of any poor efforts of mine. If your annals take any notice of my\nincumbency, I shall probably go down to posterity as the Rector who was\nalways beaten. But if they add, as I think they will, that my defeats\nbecame victories in the hands of my successors, I shall be well content.\n\n\nThe scenes are shifting in the great theatre of the world. The act\nwhich commenced with the Protestant Reformation is nearly played\nout, and a wider and a deeper change than that effected three\ncenturies ago\u2014a reformation, or rather a revolution of thought, the\nextremes of which are represented by the intellectual heirs of John\nof Leyden and of Ignatius Loyola, rather than by those of Luther\nand of Leo\u2014is waiting to come on, nay, visible behind the scenes to\nthose who have good eyes. Men are beginning, once more, to awake to\nthe fact that matters of belief and of speculation are of absolutely\ninfinite practical importance; and are drawing off from that sunny\ncountry \u201cwhere it is always afternoon\u201d\u2014the sleepy hollow of broad\nindifferentism\u2014to range themselves under their natural banners.\nChange is in the air. It is whirling feather-heads into all sorts of\neccentric orbits, and filling the steadiest with a sense of insecurity.\nIt insists on reopening all questions and asking all institutions,\nhowever venerable, by what right they exist, and whether they are, or\nare not, in harmony with the real or supposed wants of mankind. And\nit is remarkable that these searching inquiries are not so much forced\non institutions from without, as developed from within. Consummate\nscholars question the value of learning; priests condemn dogma; and\nwomen turn their backs upon man\u2019s ideal of perfect womanhood, and seek\nsatisfaction in apocalyptic visions of some, as yet unrealised, epicene\nreality.\n\nIf there be a type of stability in this world, one would be inclined\nto look for it in the old Universities of England. But it has been my\nbusiness of late to hear a good deal about what is going on in these\nfamous corporations; and I have been filled with astonishment by the\nevidences of internal fermentation which they exhibit. If Gibbon\ncould revisit the ancient seat of learning of which he has written so\ncavalierly, assuredly he would no longer speak of \u201cthe monks of Oxford\nsunk in prejudice and port.\u201d There, as elsewhere, port has gone out\nof fashion, and so has prejudice\u2014at least that particular fine, old,\ncrusted sort of prejudice to which the great historian alludes.\n\nIndeed, things are moving so fast in Oxford and Cambridge, that, for my\npart, I rejoiced when the Royal Commission, of which I am a member, had\nfinished and presented the Report which related to these Universities;\nfor we should have looked like mere plagiarists, if, in consequence\nof a little longer delay in issuing it, all the measures of reform\nwe proposed had been anticipated by the spontaneous action of the\nUniversities themselves.\n\nA month ago I should have gone on to say that one might speedily\nexpect changes of another kind in Oxford and Cambridge. A Commission\nhas been inquiring into the revenues of the many wealthy societies, in\nmore or less direct connection with the Universities, resident in those\ntowns. It is said that the Commission has reported, and that, for the\nfirst time in recorded history, the nation, and perhaps the Colleges\nthemselves, will know what they are worth. And it was announced that a\nstatesman, who, whatever his other merits or defects, has aims above\nthe level of mere party fighting, and a clear vision into the most\ncomplex practical problems, meant to deal with these revenues.\n\nBut, _Bos locutus est._ That mysterious independent variable of\npolitical calculation, Public Opinion\u2014which some whisper is, in the\npresent case, very much the same thing as publican\u2019s opinion\u2014has willed\notherwise. The Heads may return to their wonted slumbers\u2014at any rate\nfor a space.\n\nIs the spirit of change, which is working thus vigorously in the South,\nlikely to affect the Northern Universities, and if so, to what extent?\nThe violence of fermentation depends, not so much on the quantity of\nthe yeast, as on the composition of the wort, and its richness in\nfermentable material; and, as a preliminary to the discussion of this\nquestion, I venture to call to your minds the essential and fundamental\ndifferences between the Scottish and the English type of University.\n\nDo not charge me with anything worse than official egotism, if I say\nthat these differences appear to be largely symbolised by my own\nexistence. There is no Rector in an English University. Now, the\norganisation of the members of an University into Nations, with their\nelective Rector, is the last relic of the primitive constitution of\nUniversities. The Rectorate was the most important of all offices in\nthat University of Paris, upon the model of which the University of\nAberdeen was fashioned; and which was certainly a great and flourishing\ninstitution in the twelfth century.\n\nEnthusiasts for the antiquity of one of the two acknowledged parents\nof all Universities, indeed, do not hesitate to trace the origin of\nthe \u201cStudium Parisiense\u201d up to that wonderful king of the Franks and\nLombards, Karl, surnamed the Great, whom we all called Charlemagne, and\nbelieved to be a Frenchman, until a learned historian, by beneficent\niteration, taught us better. Karl is said not to have been much of a\nscholar himself, but he had the wisdom of which knowledge is only the\nservitor. And that wisdom enabled him to see that ignorance is one of\nthe roots of all evil.\n\nIn the Capitulary which enjoins the foundation of monasterial and\ncathedral schools, he says: \u201cRight action is better than knowledge;\nbut in order to do what is right, we must know what is right.\u201d[4] An\nirrefragable truth, I fancy. Acting upon it, the king took pretty full\ncompulsory powers, and carried into effect a really considerable and\neffectual scheme of elementary education through the length and breadth\nof his dominions.\n\nNo doubt the idolaters out by the Elbe, in what is now part of Prussia,\nobjected to the Frankish king\u2019s measures; no doubt the priests, who had\nnever hesitated about sacrificing all unbelievers in their fantastic\ndeities and futile conjurations, were the loudest in chanting the\nvirtues of toleration; no doubt they denounced as a cruel persecutor\nthe man who would not allow them, however sincere they might be, to go\non spreading delusions which debased the intellect, as much as they\ndeadened the moral sense, and undermined the bonds of civil allegiance;\nno doubt, if they had lived in these times, they would have been able\nto show, with ease, that the king\u2019s proceedings were totally contrary\nto the best liberal principles. But it may be said, in justification of\nthe Teutonic ruler, first, that he was born before those principles,\nand did not suspect that the best way of getting disorder into order\nwas to let it alone; and, secondly, that his rough and questionable\nproceedings did, more or less, bring about the end he had in view. For,\nin a couple of centuries, the schools he sowed broadcast produced their\ncrop of men, thirsting for knowledge and craving for culture. Such men\ngravitating towards Paris, as a light amidst the darkness of evil days,\nfrom Germany, from Spain, from Britain, and from Scandinavia, came\ntogether by natural affinity. By degrees they banded themselves into a\nsociety, which, as its end was the knowledge of all things knowable,\ncalled itself a \u201c_Studium Generale_;\u201d and when it had grown into a\nrecognised corporation, acquired the name of \u201c_Universitas Studii\nGeneralis_,\u201d which, mark you, means not a \u201cUseful Knowledge Society,\u201d\nbut a \u201cKnowledge-of-things-in-general Society.\u201d\n\nAnd thus the first \u201cUniversity,\u201d at any rate on this side of the Alps,\ncame into being. Originally it had but one Faculty, that of Arts. Its\naim was to be a centre of knowledge and culture; not to be, in any\nsense, a technical school.\n\nThe scholars seem to have studied Grammar, Logic, and Rhetoric;\nArithmetic and Geometry; Astronomy; Theology; and Music. Thus, their\nwork, however imperfect and faulty, judged by modern lights, it may\nhave been, brought them face to face with all the leading aspects of\nthe many-sided mind of man. For these studies did really contain, at\nany rate in embryo\u2014sometimes, it may be, in caricature\u2014what we now call\nPhilosophy, Mathematical and Physical Science, and Art. And I doubt if\nthe curriculum of any modern University shows so clear and generous\na comprehension of what is meant by culture, as this old Trivium and\nQuadrivium does.\n\nThe students who had passed through the University course, and had\nproved themselves competent to teach, became masters and teachers of\ntheir younger brethren. Whence the distinction of Masters and Regents\non the one hand, and Scholars on the other.\n\nRapid growth necessitated organisation. The Masters and Scholars of\nvarious tongues and countries grouped themselves into four Nations; and\nthe Nations, by their own votes at first, and subsequently by those\nof their Procurators, or representatives, elected their supreme head\nand governor, the Rector\u2014at that time the sole representative of the\nUniversity, and a very real power, who could defy Provosts interfering\nfrom without; or could inflict even corporal punishment on disobedient\nmembers within the University.\n\nSuch was the primitive constitution of the University of Paris. It is\nin reference to this original state of things that I have spoken of the\nRectorate, and all that appertains to it, as the sole relic of that\nconstitution.\n\nBut this original organisation did not last long. Society was not\nthen, any more than it is now, patient of culture, as such. It says to\neverything, \u201cBe useful to me, or away with you.\u201d And to the learned,\nthe unlearned man said then, as he does now, \u201cWhat is the use of all\nyour learning, unless you can tell me what I want to know? I am here\nblindly groping about, and constantly damaging myself by collision\nwith three mighty powers, the power of the invisible God, the power\nof my fellow Man, and the power of brute Nature. Let your learning\nbe turned to the study of these powers, that I may know how I am to\ncomport myself with regard to them.\u201d In answer to this demand, some\nof the Masters of the Faculty of Arts devoted themselves to the study\nof Theology, some to that of Law, and some to that of Medicine; and\nthey became Doctors\u2014men learned in those technical, or, as we now call\nthem, professional, branches of knowledge. Like cleaving to like, the\nDoctors formed schools, or Faculties, of Theology, Law, and Medicine,\nwhich sometimes assumed airs of superiority over their parent, the\nFaculty of Arts, though the latter always asserted and maintained its\nfundamental supremacy.\n\nThe Faculties arose by process of natural differentiation out of the\nprimitive University. Other constituents, foreign to its nature,\nwere speedily grafted upon it. One of these extraneous elements was\nforced into it by the Roman Church, which in those days asserted with\neffect, that which it now asserts, happily without any effect in these\nrealms, its right of censorship and control over all teaching. The\nlocal habitation of the University lay partly in the lands attached to\nthe monastery of S. Genevi\u00e8ve, partly in the diocese of the Bishop of\nParis; and he who would teach must have the licence of the Abbot, or of\nthe Bishop, as the nearest representative of the Pope, so to do, which\nlicence was granted by the Chancellors of these Ecclesiastics.\n\nThus, if I am what arch\u00e6ologists call a \u201csurvival\u201d of the primitive\nhead and ruler of the University, your Chancellor stands in the same\nrelation to the Papacy; and, with all respect for his Grace, I think\nI may say that we both look terribly shrunken when compared with our\ngreat originals.\n\nNot so is it with a second foreign element, which silently dropped\ninto the soil of Universities, like the grain of mustard-seed in the\nparable; and, like that grain, grew into a tree, in whose branches\na whole aviary of fowls took shelter. That element is the element\nof Endowment. It differed from the preceding, in its original design\nto serve as a prop to the young plant, not to be a parasite upon it.\nThe charitable and the humane, blessed with wealth, were very early\npenetrated by the misery of the poor student. And the wise saw that\nintellectual ability is not so common or so unimportant a gift that it\nshould be allowed to run to waste upon mere handicrafts and chares.\nThe man who was a blessing to his contemporaries, but who so often has\nbeen converted into a curse, by the blind adherence of his posterity\nto the letter, rather than to the spirit, of his wishes\u2014I mean the\n\u201cpious founder\u201d\u2014gave money and lands, that the student, who was rich in\nbrain and poor in all else, might be taken from the plough or from the\nstithy, and enabled to devote himself to the higher service of mankind;\nand built colleges and halls in which he might be not only housed and\nfed, but taught.\n\nThe Colleges were very generally placed in strict subordination to the\nUniversity by their founders; but, in many cases, their endowment,\nconsisting of land, has undergone an \u201cunearned increment,\u201d which has\ngiven these societies a continually increasing weight and importance\nas against the unendowed, or fixedly endowed, University. In Pharaoh\u2019s\ndream, the seven lean kine eat up the seven fat ones. In the reality of\nhistorical fact, the fat Colleges have eaten up the lean Universities.\n\nEven here in Aberdeen, though the causes at work may have been\nsomewhat different, the effects have been similar; and you see how\nmuch more substantial an entity is the Very Reverend the Principal,\nanalogue, if not homologue, of the Principals of King\u2019s College, than\nthe Rector, lineal representative of the ancient monarchs of the\nUniversity, though now, little more than a \u201cking of shreds and patches.\u201d\n\nDo not suppose that, in thus briefly tracing the process of University\nmetamorphosis, I have had any intention of quarrelling with its\nresults. Practically, it seems to me that the broad changes effected in\n1858 have given the Scottish Universities a very liberal constitution,\nwith as much real approximation to the primitive state of things as\nis at all desirable. If your fat kine have eaten the lean, they have\nnot lain down to chew the cud ever since. The Scottish Universities,\nlike the English, have diverged widely enough from their primitive\nmodel; but I cannot help thinking that the northern form has remained\nmore faithful to its original, not only in constitution, but, what is\nmore to the purpose, in view of the cry for change, in the practical\napplication of the endowments connected with it.\n\nIn Aberdeen, these endowments are numerous, but so small that, taken\naltogether, they are not equal to the revenue of a single third-rate\nEnglish college. They are scholarships, not fellowships; aids to\ndo work\u2014not rewards for such work as it lies within the reach of\nan ordinary, or even an extraordinary, young man to do. You do not\nthink that passing a respectable examination is a fair equivalent\nfor an income, such as many a gray-headed veteran, or clergyman,\nwould envy; and which is larger than the endowment of many Regius\nchairs. You do not care to make your University a school of manners\nfor the rich; of sports for the athletic; or a hot-bed of high-fed,\nhypercritical refinement, more destructive to vigour and originality\nthan are starvation and oppression. No; your little Bursaries of ten\nand twenty (I believe even fifty) pounds a year, enable any boy who\nhas shown ability in the course of his education in those remarkable\nprimary schools, which have made Scotland the power she is, to obtain\nthe highest culture the country can give him; and when he is armed and\nequipped, his Spartan Alma Mater tells him that, so far, he has had his\nwages for his work, and that he may go and earn the rest.\n\nWhen I think of the host of pleasant, monied, well-bred young\ngentlemen, who do a little learning and much boating by Cam and Isis,\nthe vision is a pleasant one; and, as a patriot, I rejoice that the\nyouth of the upper and richer classes of the nation receive a wholesome\nand a manly training, however small may be the modicum of knowledge\nthey gather, in the intervals of this, their serious business. I admit,\nto the full, the social and political value of that training. But, when\nI proceed to consider that these young men may be said to represent\nthe great bulk of what the Colleges have to show for their enormous\nwealth, plus, at least, a hundred and fifty pounds a year apiece which\neach undergraduate costs his parents or guardians, I feel inclined\nto ask, whether the rate-in-aid of the education of the wealthy and\nprofessional classes, thus levied on the resources of the community,\nis not, after all, a little heavy? And, still further, I am tempted\nto inquire what has become of the indigent scholars, the sons of the\nmasses of the people whose daily labour just suffices to meet their\ndaily wants, for whose benefit these rich foundations were largely,\nif not mainly, instituted? It seems as if Pharaoh\u2019s dream had been\nrigorously carried out, and that even the fat scholar has eaten the\nlean one. And when I turn from this picture to the no less real vision\nof many a brave and frugal Scotch boy, spending his summer in hard\nmanual labour, that he may have the privilege of wending his way in\nautumn to this University, with a bag of oatmeal, ten pounds in his\npocket, and his own stout heart to depend upon through the northern\nwinter; not bent on seeking\n\n  \u201cThe bubble reputation at the cannon\u2019s mouth,\u201d\n\nbut determined to wring knowledge from the hard hands of penury; when\nI see him win through all such outward obstacles to positions of wide\nusefulness and well-earned fame; I cannot but think that, in essence,\nAberdeen has departed but little from the primitive intention of the\nfounders of Universities, and that the spirit of reform has so much to\ndo on the other side of the Border, that it may be long before he has\nleisure to look this way.\n\nAs compared with other actual Universities, then, Aberdeen, may,\nperhaps, be well satisfied with itself. But do not think me an\nimpracticable dreamer, if I ask you not to rest and be thankful in\nthis state of satisfaction; if I ask you to consider awhile, how this\nactual good stands related to that ideal better, towards which both men\nand institutions must progress, if they would not retrograde.\n\nIn an ideal University, as I conceive it, a man should be able to\nobtain instruction in all forms of knowledge, and discipline in the\nuse of all the methods by which knowledge is obtained. In such an\nUniversity, the force of living example should fire the student with a\nnoble ambition to emulate the learning of learned men, and to follow\nin the footsteps of the explorers of new fields of knowledge. And the\nvery air he breathes should be charged with that enthusiasm for truth,\nthat fanaticism of veracity, which is a greater possession than much\nlearning; a nobler gift than the power of increasing knowledge; by\nso much greater and nobler than these, as the moral nature of man is\ngreater than the intellectual; for veracity is the heart of morality.\n\nBut the man who is all morality and intellect, although he may be good\nand even great, is, after all, only half a man. There is beauty in the\nmoral world and in the intellectual world; but there is also a beauty\nwhich is neither moral nor intellectual\u2014the beauty of the world of Art.\nThere are men who are devoid of the power of seeing it, as there are\nmen who are born deaf and blind, and the loss of those, as of these,\nis simply infinite. There are others in whom it is an overpowering\npassion; happy men, born with the productive, or at lowest, the\nappreciative, genius of the Artist. But, in the mass of mankind,\nthe \u00c6sthetic faculty, like the reasoning power and the moral sense,\nneeds to be roused, directed, and cultivated; and I know not why the\ndevelopment of that side of his nature, through which man has access to\na perennial spring of ennobling pleasure, should be omitted from any\ncomprehensive scheme of University education.\n\nAll Universities recognise Literature in the sense of the old Rhetoric,\nwhich is art incarnate in words. Some, to their credit, recognise Art\nin its narrower sense, to a certain extent, and confer degrees for\nproficiency in some of its branches. If there are Doctors of Music, why\nshould there be no Masters of Painting, of Sculpture, of Architecture?\nI should like to see Professors of the Fine Arts in every University;\nand instruction in some branch of their work made a part of the Arts\ncurriculum.\n\nI just now expressed the opinion that, in our ideal University, a man\nshould be able to obtain instruction in all forms of knowledge. Now, by\n\u201cforms of knowledge\u201d I mean the great classes of things knowable; of\nwhich the first, in logical, though not in natural, order is knowledge\nrelating to the scope and limits of the mental faculties of man; a form\nof knowledge which, in its positive aspect, answers pretty much to\nLogic and part of Psychology, while, on its negative and critical side,\nit corresponds with Metaphysics.\n\nA second class comprehends all that knowledge which relates to\nman\u2019s welfare, so far as it is determined by his own acts, or what\nwe call his conduct. It answers to Moral and Religious philosophy.\nPractically, it is the most directly valuable of all forms of\nknowledge, but speculatively, it is limited and criticised by that\nwhich precedes and by that which follows it in my order of enumeration.\n\nA third class embraces knowledge of the phenomena of the Universe, as\nthat which lies about the individual man: and of the rules which those\nphenomena are observed to follow in the order of their occurrence,\nwhich we term the laws of Nature.\n\nThis is what ought to be called Natural Science, or Physiology, though\nthose terms are hopelessly diverted from such a meaning; and it\nincludes all exact knowledge of natural fact, whether Mathematical,\nPhysical, Biological, or Social.\n\nKant has said that the ultimate object of all knowledge is to give\nreplies to these three questions: What can I do? What ought I to do?\nWhat may I hope for? The forms of knowledge which I have enumerated,\nshould furnish such replies as are within human reach, to the first\nand second of these questions. While to the third, perhaps the wisest\nanswer is, \u201cDo what you can to do what you ought, and leave hoping and\nfearing alone.\u201d\n\nIf this be a just and an exhaustive classification of the forms of\nknowledge, no question as to their relative importance, or as to the\nsuperiority of one to the other, can be seriously raised.\n\nOn the face of the matter, it is absurd to ask whether it is more\nimportant to know the limits of one\u2019s powers; or the ends for which\nthey ought to be exerted; or the conditions under which they must be\nexerted. One may as well inquire which of the terms of a Rule of Three\nsum one ought to know, in order to get a trustworthy result. Practical\nlife is such a sum, in which your duty multiplied into your capacity,\nand divided by your circumstances, gives you the fourth term in the\nproportion, which is your deserts, with great accuracy. All agree, I\ntake it, that men ought to have these three kinds of knowledge. The\nso-called \u201cconflict of studies\u201d turns upon the question of how they may\nbest be obtained.\n\nThe founders of Universities held the theory that the Scriptures and\nAristotle taken together, the latter being limited by the former,\ncontained all knowledge worth having, and that the business of\nphilosophy was to interpret and co-ordinate these two. I imagine\nthat in the twelfth century this was a very fair conclusion from\nknown facts. Nowhere in the world, in those days, was there such an\nencyclop\u00e6dia of knowledge of all three classes, as is to be found in\nthose writings. The scholastic philosophy is a wonderful monument of\nthe patience and ingenuity with which the human mind toiled to build up\na logically consistent theory of the Universe, out of such materials.\nAnd that philosophy is by no means dead and buried, as many vainly\nsuppose. On the contrary, numbers of men of no mean learning and\naccomplishment, and sometimes of rare power and subtlety of thought,\nhold by it as the best theory of things which has yet been stated. And,\nwhat is still more remarkable, men who speak the language of modern\nphilosophy, nevertheless think the thoughts of the schoolmen. \u201cThe\nvoice is the voice of Jacob, but the hands are the hands of Esau.\u201d\nEvery day I hear \u201cCause,\u201d \u201cLaw,\u201d \u201cForce,\u201d \u201cVitality,\u201d spoken of as\nentities, by people who can enjoy Swift\u2019s joke about the meat-roasting\nquality of the smoke-jack, and comfort themselves with the reflection\nthat they are not even as those benighted schoolmen.\n\nWell, this great system had its day, and then it was sapped and mined\nby two influences. The first was the study of classical literature,\nwhich familiarised men with methods of philosophising; with conceptions\nof the highest Good; with ideas of the order of Nature; with notions of\nLiterary and Historical Criticism; and, above all, with visions of Art,\nof a kind which not only would not fit into the scholastic scheme, but\nshowed them a pre-Christian, and indeed altogether un-Christian world,\nof such grandeur and beauty that they ceased to think of any other.\nThey were as men who had kissed the Fairy Queen, and wandering with her\nin the dim loveliness of the underworld, cared not to return to the\nfamiliar ways of home and fatherland, though they lay, at arm\u2019s length,\noverhead. Cardinals were more familiar with Virgil than with Isaiah;\nand Popes laboured, with great success, to re-paganise Rome.\n\nThe second influence was the slow, but sure, growth of the physical\nsciences. It was discovered that some results of speculative thought,\nof immense practical and theoretical importance, can be verified by\nobservation; and are always true, however severely they may be tested.\nHere, at any rate, was knowledge, to the certainty of which no\nauthority could add, or take away, one jot or tittle, and to which the\ntradition of a thousand years was as insignificant as the hearsay of\nyesterday. To the scholastic system, the study of classical literature\nmight be inconvenient and distracting, but it was possible to hope that\nit could be kept within bounds. Physical science, on the other hand,\nwas an irreconcilable enemy, to be excluded at all hazards. The College\nof Cardinals has not distinguished itself in Physics or Physiology; and\nno Pope has, as yet, set up public laboratories in the Vatican.\n\nPeople do not always formulate the beliefs on which they act. The\ninstinct of fear and dislike is quicker than the reasoning process;\nand I suspect that, taken in conjunction with some other causes, such\ninstinctive aversion is at the bottom of the long exclusion of any\nserious discipline in the physical sciences from the general curriculum\nof Universities; while, on the other hand, classical literature has\nbeen gradually made the backbone of the Arts course.\n\nI am ashamed to repeat here what I have said elsewhere, in season\nand out of season, respecting the value of Science as knowledge and\ndiscipline. But the other day I met with some passages in the Address\nto another Scottish University, of a great thinker, recently lost to\nus, which express so fully, and yet so tersely, the truth in this\nmatter, that I am fain to quote them:\u2014\n\n\u201cTo question all things;\u2014never to turn away from any difficulty;\nto accept no doctrine either from ourselves or from other people\nwithout a rigid scrutiny by negative criticism; letting no fallacy,\nor incoherence, or confusion of thought step by unperceived; above\nall, to insist upon having the meaning of a word clearly understood\nbefore using it, and the meaning of a proposition before assenting\nto it;\u2014these are the lessons we learn\u201d from workers in Science.\n\u201cWith all this vigorous management of the negative element, they\ninspire no scepticism about the reality of truth or indifference to\nits pursuit. The noblest enthusiasm, both for the search after truth\nand for applying it to its highest uses, pervades those writers.\u201d\n\u201cIn cultivating, therefore,\u201d science as an essential ingredient in\neducation, \u201cwe are all the while laying an admirable foundation for\nethical and philosophical culture.\u201d[5]\n\nThe passages I have quoted were uttered by John Stuart Mill; but you\ncannot hear inverted commas, and it is therefore right that I should\nadd, without delay, that I have taken the liberty of substituting\n\u201cworkers in science\u201d for \u201cancient dialecticians,\u201d and \u201cScience as an\nessential ingredient in education\u201d for \u201cthe ancient languages as our\nbest literary education.\u201d Mill did, in fact, deliver a noble panegyric\nupon classical studies. I do not doubt its justice, nor presume to\nquestion its wisdom. But I venture to maintain that no wise or just\njudge, who has a knowledge of the facts, will hesitate to say that it\napplies with equal force to scientific training.\n\nBut it is only fair to the Scottish Universities to point out that\nthey have long understood the value of Science as a branch of general\neducation. I observe, with the greatest satisfaction, that candidates\nfor the degree of Master of Arts in this University are required to\nhave a knowledge, not only of Mental and Moral Philosophy, and of\nMathematics and Natural Philosophy, but of Natural History, in addition\nto the ordinary Latin and Greek course; and that a candidate may take\nhonours in these subjects and in Chemistry.\n\nI do not know what the requirements of your examiners may be, but I\nsincerely trust they are not satisfied with a mere book knowledge of\nthese matters. For my own part, I would not raise a finger, if I could\nthereby introduce mere book work in science into every Arts curriculum\nin the country. Let those who want to study books devote themselves\nto Literature, in which we have the perfection of books, both as to\nsubstance and as to form. If I may paraphrase Hobbes\u2019s well-known\naphorism, I would say that \u201cbooks are the money of Literature, but only\nthe counters of Science,\u201d Science (in the sense in which I now use the\nterm) being the knowledge of fact, of which every verbal description\nis but an incomplete and symbolic expression. And be assured that no\nteaching of science is worth anything, as a mental discipline, which is\nnot based upon direct perception of the facts, and practical exercise\nof the observing and logical faculties upon them. Even in such a simple\nmatter as the mere comprehension of form, ask the most practised and\nwidely informed anatomist what is the difference between his knowledge\nof a structure which he has read about, and his knowledge of the same\nstructure when he has seen it for himself; and he will tell you that\nthe two things are not comparable\u2014the difference is infinite. Thus I\nam very strongly inclined to agree with some learned school-masters\nwho say that, in their experience, the teaching of science is all\nwaste time. As they teach it, I have no doubt it is. But to teach it\notherwise, requires an amount of personal labour and a development of\nmeans and appliances, which must strike horror and dismay into a man\naccustomed to mere book work; and who has been in the habit of teaching\na class of fifty without much strain upon his energies. And this is one\nof the real difficulties in the way of the introduction of physical\nscience into the ordinary University course, to which I have alluded.\nIt is a difficulty which will not be overcome, until years of patient\nstudy have organised scientific teaching as well as, or I hope better\nthan, classical teaching has been organised hitherto.\n\nA little while ago, I ventured to hint a doubt as to the perfection\nof some of the arrangements in the ancient Universities of England;\nbut, in their provision for giving instruction in Science as such,\nand without direct reference to any of its practical applications,\nthey have set a brilliant example. Within the last twenty years,\nOxford alone has sunk more than a hundred and twenty thousand pounds\nin building and furnishing Physical, Chemical, and Physiological\nLaboratories, and a magnificent Museum, arranged with an almost\nluxurious regard for the needs of the student. Cambridge, less rich,\nbut aided by the munificence of her Chancellor, is taking the same\ncourse; and, in a few years, it will be for no lack of the means and\nappliances of sound teaching, if the mass of English University men\nremain in their present state of barbarous ignorance of even the\nrudiments of scientific culture.\n\nYet another step needs to be made before Science can be said to have\ntaken its proper place in the Universities. That is its recognition\nas a Faculty, or branch of study demanding recognition and special\norganisation, on account of its bearing on the wants of mankind. The\nFaculties of Theology, Law, and Medicine, are technical schools,\nintended to equip men who have received general culture, with the\nspecial knowledge which is needed for the proper performance of the\nduties of clergymen, lawyers, and medical practitioners.\n\nWhen the material well-being of the country depended upon rude pasture\nand agriculture, and still ruder mining; in the days when all the\ninnumerable applications of the principles of physical science to\npractical purposes were non-existent even as dreams; days which men\nliving may have heard their fathers speak of; what little physical\nscience could be seen to bear directly upon human life, lay within the\nprovince of Medicine. Medicine was the foster-mother of Chemistry,\nbecause it has to do with the preparation of drugs and the detection\nof poisons; of Botany, because it enabled the physician to recognise\nmedicinal herbs; of Comparative Anatomy and Physiology, because the man\nwho studied Human Anatomy and Physiology for purely medical purposes\nwas led to extend his studies to the rest of the animal world.\n\nWithin my recollection, the only way in which a student could obtain\nanything like a training in Physical Science, was by attending the\nlectures of the Professors of Physical and Natural Science attached to\nthe Medical Schools. But, in the course of the last thirty years, both\nfoster-mother and child have grown so big, that they threaten not only\nto crush one another, but to press the very life out of the unhappy\nstudent who enters the nursery; to the great detriment of all three.\n\nI speak in the presence of those who know practically what medical\neducation is; for I may assume that a large proportion of my hearers\nare more or less advanced students of medicine. I appeal to the most\nindustrious and conscientious among you, to those who are most deeply\npenetrated with a sense of the extremely serious responsibilities which\nattach to the calling of a medical practitioner, when I ask whether,\nout of the four years which you devote to your studies, you ought to\nspare even so much as an hour for any work which does not tend directly\nto fit you for your duties?\n\nConsider what that work is. Its foundation is a sound and practical\nacquaintance with the structure of the human organism, and with the\nmodes and conditions of its action in health. I say a sound and\npractical acquaintance, to guard against the supposition that my\nintention is to suggest that you ought all to be minute anatomists and\naccomplished physiologists. The devotion of your whole four years to\nAnatomy and Physiology alone, would be totally insufficient to attain\nthat end. What I mean is, the sort of practical, familiar, finger-end\nknowledge which a watchmaker has of a watch, and which you expect that\ncraftsman, as an honest man, to have, when you entrust a watch that\ngoes badly, to him. It is a kind of knowledge which is to be acquired,\nnot in the lecture-room, nor in the library, but in the dissecting-room\nand the laboratory. It is to be had, not by sharing your attention\nbetween these and sundry other subjects, but by concentrating your\nminds, week after week, and month after month, six or seven hours a\nday, upon all the complexities of organ and function, until each of the\ngreater truths of anatomy and physiology has become an organic part of\nyour minds\u2014until you would know them if you were roused and questioned\nin the middle of the night, as a man knows the geography of his native\nplace and the daily life of his home. That is the sort of knowledge\nwhich, once obtained, is a life-long possession. Other occupations may\nfill your minds\u2014it may grow dim, and seem to be forgotten\u2014but there it\nis, like the inscription on a battered and defaced coin, which comes\nout when you warm it.\n\nIf I had the power to remodel Medical Education, the first two years of\nthe medical curriculum should be devoted to nothing but such thorough\nstudy of Anatomy and Physiology, with Physiological Chemistry and\nPhysics; the student should then pass a real, practical examination in\nthese subjects; and, having gone through that ordeal satisfactorily,\nhe should be troubled no more with them. His whole mind should then be\ngiven with equal intentness, to Therapeutics, in its broadest sense,\nto Practical Medicine and to Surgery, with instruction in Hygiene and\nin Medical Jurisprudence; and of these subjects only\u2014surely there are\nenough of them\u2014should he be required to show a knowledge in his final\nexamination.\n\nI cannot claim any special property in this theory of what the medical\ncurriculum should be, for I find that views, more or less closely\napproximating these, are held by all who have seriously considered the\nvery grave and pressing question of Medical Reform; and have, indeed,\nbeen carried into practice, to some extent, by the most enlightened\nExamining Boards. I have heard but two kinds of objections to them.\nThere is, first, the objection of vested interests, which I will not\ndeal with here, because I want to make myself as pleasant as I can, and\nno discussions are so unpleasant as those which turn on such points.\nAnd there is, secondly, the much more respectable objection, which\ntakes the general form of the reproach that, in thus limiting the\ncurriculum, we are seeking to narrow it. We are told that the medical\nman ought to be a person of good education and general information,\nif his profession is to hold its own among other professions; that\nhe ought to know Botany, or else, if he goes abroad, he will not be\nable to tell poisonous fruits from edible ones; that he ought to\nknow drugs, as a druggist knows them, or he will not be able to tell\nsham bark and senna from the real articles; that he ought to know\nZoology, because\u2014well, I really have never been able to learn exactly\nwhy he is to be expected to know zoology. There is, indeed, a popular\nsuperstition, that doctors know all about things that are queer or\nnasty to the general mind, and may, therefore, be reasonably expected\nto know the \u201cbarbarous binomials\u201d applicable to snakes, snails, and\nslugs; an amount of information with which the general mind is usually\ncompletely satisfied. And there is a scientific superstition that\nPhysiology is largely aided by Comparative Anatomy\u2014a superstition\nwhich, like most superstitions, once had a grain of truth at bottom;\nbut the grain has become hom\u0153opathic, since Physiology took its modern\nexperimental development, and became what it is now, the application\nof the principles of Physics and Chemistry to the elucidation of the\nphenomena of life.\n\nI hold as strongly as any one can do, that the medical practitioner\nought to be a person of education and good general culture; but I\nalso hold by the old theory of a Faculty, that a man should have his\ngeneral culture before he devotes himself to the special studies of\nthat Faculty; and I venture to maintain, that, if the general culture\nobtained in the Faculty of Arts were what it ought to be, the student\nwould have quite as much knowledge of the fundamental principles of\nPhysics, of Chemistry, and of Biology, as he needs, before he commenced\nhis special medical studies.\n\nMoreover, I would urge, that a thorough study of Human Physiology is,\nin itself, an education broader and more comprehensive than much that\npasses under that name. There is no side of the intellect which it does\nnot call into play, no region of human knowledge into which either its\nroots, or its branches, do not extend; like the Atlantic between the\nOld and the New Worlds, its waves wash the shores of the two worlds\nof matter and of mind; its tributary streams flow from both; through\nits waters, as yet unfurrowed by the keel of any Columbus, lies the\nroad, if such there be, from the one to the other; far away from that\nNorth-west Passage of mere speculation, in which so many brave souls\nhave been hopelessly frozen up.\n\nBut whether I am right or wrong about all this, the patent fact of the\nlimitation of time remains. As the song runs:\u2014\n\n     \u201cIf a man could be sure\n      That his life would endure\n  For the space of a thousand long years\u2014\u2014\u201d\n\nhe might do a number of things not practicable under present\nconditions. Methuselah might, with much propriety, have taken half a\ncentury to get his doctor\u2019s degree; and might, very fairly, have been\nrequired to pass a practical examination upon the contents of the\nBritish Museum, before commencing practice as a promising young fellow\nof two hundred, or thereabouts. But you have four years to do your\nwork in, and are turned loose, to save or slay, at two or three and\ntwenty.\n\nNow, I put it to you, whether you think that, when you come down to\nthe realities of life\u2014when you stand by the sick-bed, racking your\nbrains for the principles which shall furnish you with the means of\ninterpreting symptoms, and forming a rational theory of the condition\nof your patient, it will be satisfactory for you to find that those\nprinciples are not there\u2014although, to use the examination slang which\nis unfortunately too familiar to me, you can quite easily \u201cgive\nan account of the leading peculiarities of the _Marsupialia_,\u201d or\n\u201cenumerate the chief characters of the _Composit\u00e6_,\u201d or \u201cstate the\nclass and order of the animal from which Castoreum is obtained.\u201d\n\nI really do not think that state of things will be satisfactory\nto you; I am very sure it will not be so to your patient. Indeed,\nI am so narrow-minded myself, that if I had to choose between two\nphysicians\u2014one who did not know whether a whale is a fish or not, and\ncould not tell gentian from ginger, but did understand the applications\nof the institutes of medicine to his art; while the other, like\nTalleyrand\u2019s doctor, \u201cknew everything, even a little physic\u201d\u2014with all\nmy love for breadth of culture, I should assuredly consult the former.\n\nIt is not pleasant to incur the suspicion of an inclination to injure\nor depreciate particular branches of knowledge. But the fact that\none of those which I should have no hesitation in excluding from the\nmedical curriculum, is that to which my own life has been specially\ndevoted, should, at any rate, defend me from the suspicion of being\nurged to this course by any but the very gravest considerations of the\npublic welfare.\n\nAnd I should like, further, to call your attention to the important\ncircumstance that, in thus proposing the exclusion of the study of such\nbranches of knowledge as Zoology and Botany, from those compulsory upon\nthe medical student, I am not, for a moment, suggesting their exclusion\nfrom the University. I think that sound and practical instruction in\nthe elementary facts and broad principles of Biology should form part\nof the Arts Curriculum: and here, happily, my theory is in entire\naccordance with your practice. Moreover, as I have already said, I have\nno sort of doubt that, in view of the relation of Physical Science\nto the practical life of the present day, it has the same right as\nTheology, Law, and Medicine, to a Faculty of its own in which men shall\nbe trained to be professional men of science. It may be doubted whether\nUniversities are the places for technical schools of Engineering, or\nApplied Chemistry, or Agriculture. But there can surely be little\nquestion, that instruction in the branches of Science which lie at the\nfoundation of these Arts, of a far more advanced and special character\nthan could, with any propriety, be included in the ordinary Arts\nCurriculum, ought to be obtainable by means of a duly organised Faculty\nof Science in every University.\n\nThe establishment of such a Faculty would have the additional advantage\nof providing, in some measure, for one of the greatest wants of our\ntime and country. I mean the proper support and encouragement of\noriginal research.\n\nThe other day, an emphatic friend of mine committed himself to the\nopinion that, in England, it is better for a man\u2019s worldly prospects\nto be a drunkard, than to be smitten with the divine dipsomania of the\noriginal investigator. I am inclined to think he was not far wrong.\nAnd, be it observed, that the question is not, whether such a man shall\nbe able to make as much out of his abilities as his brother, of like\nability, who goes into Law, or Engineering, or Commerce; it is not a\nquestion of \u201cmaintaining a due number of saddle horses,\u201d as George\nEliot somewhere puts it\u2014it is a question of living or starving.\n\nIf a student of my own subject shows power and originality, I dare not\nadvise him to adopt a scientific career; for, supposing he is able to\nmaintain himself until he has attained distinction, I cannot give him\nthe assurance that any amount of proficiency in the Biological Sciences\nwill be convertible into, even the most modest, bread and cheese.\nAnd I believe that the case is as bad, or perhaps worse, with other\nbranches of Science. In this respect Britain, whose immense wealth\nand prosperity hang upon the thread of Applied Science, is far behind\nFrance, and infinitely behind Germany.\n\nAnd the worst of it is, that it is very difficult to see one\u2019s way to\nany immediate remedy for this state of affairs which shall be free from\na tendency to become worse than the disease.\n\nGreat schemes for the Endowment of Research have been proposed. It has\nbeen suggested, that Laboratories for all branches of Physical Science,\nprovided with every apparatus needed by the investigator, shall be\nestablished by the State: and shall be accessible, under due conditions\nand regulations, to all properly qualified persons. I see no objection\nto the principle of such a proposal. If it be legitimate to spend great\nsums of money on public Libraries and public collections of Painting\nand Sculpture, in aid of the man of letters, or the Artist, or for the\nmere sake of affording pleasure to the general public, I apprehend that\nit cannot be illegitimate to do as much for the promotion of scientific\ninvestigation. To take the lowest ground, as a mere investment of\nmoney, the latter is likely to be much more immediately profitable. To\nmy mind, the difficulty in the way of such schemes is not theoretical,\nbut practical. Given the laboratories, how are the investigators to be\nmaintained? What career is open to those who have been thus encouraged\nto leave bread-winning pursuits? If they are to be provided for by\nendowment, we come back to the College Fellowship system, the results\nof which, for Literature, have not been so brilliant that one would\nwish to see it extended to Science; unless some much better securities,\nthan at present exist, can be taken that it will foster real work.\nYou know that among the Bees, it depends on the kind of cell in which\nthe egg is deposited, and the quantity and quality of food which is\nsupplied to the grub, whether it shall turn out a busy little worker\nor a big idle queen. And, in the human hive, the cells of the endowed\nlarv\u00e6 are always tending to enlarge, and their food to improve, until\nwe get queens, beautiful to behold, but which gather no honey and build\nno comb.\n\nI do not say that these difficulties may not be overcome, but their\ngravity is not to be lightly estimated.\n\nIn the meanwhile, there is one step in the direction of the endowment\nof research which is free from such objections. It is possible to place\nthe scientific inquirer in a position in which he shall have ample\nleisure and opportunity for original work, and yet shall give a fair\nand tangible equivalent for those privileges. The establishment of a\nFaculty of Science in every University, implies that of a corresponding\nnumber of Professorial chairs, the incumbents of which need not be\nso burdened with teaching as to deprive them of ample leisure for\noriginal work. I do not think that it is any impediment to an original\ninvestigator to have to devote a moderate portion of his time to\nlecturing, or superintending practical instruction. On the contrary,\nI think it may be, and often is, a benefit to be obliged to take a\ncomprehensive survey of your subject; or to bring your results to a\npoint, and give them, as it were, a tangible objective existence. The\nbesetting sins of the investigator are two: the one is the desire to\nput aside a subject, the general bearings of which he has mastered\nhimself, and pass on to something which has the attraction of novelty;\nand the other, the desire for too much perfection, which leads him to\n\n  \u201cAdd and alter many times,\n   Till all be ripe and rotten;\u201d\n\nto spend the energies which should be reserved for action, in whitening\nthe decks and polishing the guns.\n\nThe obligation to produce results for the instruction of others, seems\nto me to be a more effectual check on these tendencies, than even the\nlove of usefulness or the ambition for fame.\n\nBut supposing the Professorial forces of our University to be\nduly organised, there remains an important question, relating\nto the teaching power, to be considered. Is the Professorial\nsystem\u2014the system, I mean, of teaching in the lecture-room alone,\nand leaving the student to find his own way when he is outside the\nlecture-room\u2014adequate to the wants of learners? In answering this\nquestion, I confine myself to my own province, and I venture to\nreply for Physical Science, assuredly and undoubtedly, No. As I have\nalready intimated, practical work in the Laboratory is absolutely\nindispensable, and that practical work must be guided and superintended\nby a sufficient staff of Demonstrators, who are for Science what Tutors\nare for other branches of study. And there must be a good supply of\nsuch Demonstrators. I doubt if the practical work of more than twenty\nstudents can be properly superintended by one Demonstrator. If we\ntake the working day at six hours, that is less than twenty minutes\napiece\u2014not a very large allowance of time for helping a dull man, for\ncorrecting an inaccurate one, or even for making an intelligent student\nclearly apprehend what he is about. And, no doubt, the supplying of\na proper amount of this tutorial, practical teaching, is a difficulty\nin the way of giving proper instruction in Physical Science in such\nUniversities as that of Aberdeen, which are devoid of endowments; and,\nunlike the English Universities, have no moral claim on the funds of\nrichly endowed bodies to supply their wants.\n\nExamination\u2014thorough, searching examination\u2014is an indispensable\naccompaniment of teaching; but I am almost inclined to commit myself\nto the very heterodox proposition that it is a necessary evil. I am a\nvery old Examiner, having, for some twenty years past, been occupied\nwith examinations on a considerable scale, of all sorts and conditions\nof men, and women too,\u2014from the boys and girls of elementary schools\nto the candidates for Honours and Fellowships in the Universities. I\nwill not say that, in this case as in so many others, the adage, that\nfamiliarity breeds contempt, holds good; but my admiration for the\nexisting system of examination and its products, does not wax warmer\nas I see more of it. Examination, like fire, is a good servant, but a\nbad master; and there seems to me to be some danger of its becoming our\nmaster. I by no means stand alone in this opinion. Experienced friends\nof mine do not hesitate to say that students whose career they watch,\nappear to them to become deteriorated by the constant effort to pass\nthis or that examination, just as we hear of men\u2019s brains becoming\naffected by the daily necessity of catching a train. They work to pass,\nnot to know; and outraged Science takes her revenge. They do pass,\nand they don\u2019t know. I have passed sundry examinations in my time, not\nwithout credit, and I confess I am ashamed to think how very little\nreal knowledge underlay the torrent of stuff which I was able to pour\nout on paper. In fact, that which examination, as ordinarily conducted,\ntests, is simply a man\u2019s power of work under stimulus, and his capacity\nfor rapidly and clearly producing that which, for the time, he has got\ninto his mind. Now, these faculties are by no means to be despised.\nThey are of great value in practical life, and are the making of many\nan advocate, and of many a so-called statesman. But in the pursuit of\ntruth, scientific or other, they count for very little, unless they are\nsupplemented by that long-continued, patient \u201cintending of the mind,\u201d\nas Newton phrased it, which makes very little show in Examinations. I\nimagine that an Examiner who knows his students personally, must not\nunfrequently have found himself in the position of finding A\u2019s paper\nbetter than B\u2019s, though his own judgment tells him, quite clearly, that\nB is the man who has the larger share of genuine capacity.\n\nAgain, there is a fallacy about Examiners. It is commonly supposed that\nany one who knows a subject is competent to teach it; and no one seems\nto doubt that any one who knows a subject is competent to examine in\nit. I believe both these opinions to be serious mistakes: the latter,\nperhaps, the more serious of the two. In the first place, I do not\nbelieve that any one who is not, or has not been, a teacher is really\nqualified to examine advanced students. And in the second place,\nExamination is an Art, and a difficult one, which has to be learned\nlike all other arts.\n\nBeginners always set too difficult questions\u2014partly because they are\nafraid of being suspected of ignorance if they set easy ones, and\npartly from not understanding their business. Suppose that you want to\ntest the relative physical strength of a score of young men. You do not\nput a hundredweight down before them, and tell each to swing it round.\nIf you do, half of them won\u2019t be able to lift it at all, and only one\nor two will be able to perform the task. You must give them half a\nhundredweight, and see how they man\u0153uvre that, if you want to form any\nestimate of the muscular strength of each. So, a practised Examiner\nwill seek for information respecting the mental vigour and training of\ncandidates from the way in which they deal with questions easy enough\nto let reason, memory, and method have free play.\n\nNo doubt, a great deal is to be done by the careful selection of\nExaminers, and by the copious introduction of practical work, to\nremove the evils inseparable from examination; but, under the best of\ncircumstances, I believe that examination will remain but an imperfect\ntest of knowledge, and a still more imperfect test of capacity, while\nit tells next to nothing about a man\u2019s power as an investigator.\n\nThere is much to be said in favour of restricting the highest degrees\nin each Faculty, to those who have shown evidence of such original\npower, by prosecuting a research under the eye of the Professor in\nwhose province it lies; or, at any rate, under conditions which shall\nafford satisfactory proof that the work is theirs. The notion may sound\nrevolutionary, but it is really very old; for, I take it, that it lies\nat the bottom of that presentation of a thesis by the candidate for a\ndoctorate, which has now, too often, become little better than a matter\nof form.\n\n\nThus far, I have endeavoured to lay before you, in a too brief and\nimperfect manner, my views respecting the teaching half\u2014the Magistri\nand Regentes\u2014of the University of the Future. Now let me turn to the\nlearning half\u2014the Scholares.\n\nIf the Universities are to be the sanctuaries of the highest culture of\nthe country, those who would enter that sanctuary, must not come with\nunwashed hands. If the good seed is to yield its hundredfold harvest,\nit must not be scattered amidst the stones of ignorance, or the tares\nof undisciplined indolence and wantonness. On the contrary, the soil\nmust have been carefully prepared, and the Professor should find that\nthe operations of clod-crushing, draining, and weeding, and even a good\ndeal of planting, have been done by the Schoolmaster.\n\nThat is exactly what the Professor does not find in any University in\nthe three Kingdoms that I can hear of\u2014the reason of which state of\nthings lies in the extremely faulty organisation of the majority of\nsecondary Schools. Students come to the Universities ill-prepared in\nclassics and mathematics, not at all prepared in anything else; and\nhalf their time is spent in learning that which they ought to have\nknown when they came.\n\nI sometimes hear it said that the Scottish Universities differ from\nthe English, in being to a much greater extent places of comparatively\nelementary education for a younger class of students. But it would seem\ndoubtful if any great difference of this kind really exists; for a high\nauthority, himself Head of an English College, has solemnly affirmed\nthat: \u201cElementary teaching of youths under twenty is now the only\nfunction performed by the University;\u201d and that Colleges are \u201cboarding\nschools in which the elements of the learned languages are taught to\nyouths.\u201d[6]\n\nThis is not the first time that I have quoted those remarkable\nassertions. I should like to engrave them in public view, for they\nhave not been refuted; and I am convinced that if their import is once\nclearly apprehended, they will play no mean part when the question of\nUniversity reorganisation, with a view to practical measures, comes\non for discussion. You are not responsible for this anomalous state\nof affairs now; but, as you pass into active life and acquire the\npolitical influence to which your education and your position should\nentitle you, you will become responsible for it, unless each in his\nsphere does his best to alter it, by insisting on the improvement of\nsecondary Schools.\n\nYour present responsibility is of another, though not less serious,\nkind. Institutions do not make men, any more than organisation makes\nlife; and even the ideal University we have been dreaming about will be\nbut a superior piece of mechanism, unless each student strive after the\nideal of the Scholar. And that ideal, it seems to me, has never been\nbetter embodied than by the great Poet, who, though lapped in luxury,\nthe favourite of a Court, and the idol of his countrymen, remained\nthrough all the length of his honoured years a Scholar in Art, in\nScience, and in Life.\n\n  \u201cWould\u2019st shape a noble life? Then cast\n  No backward glances towards the past:\n  And though somewhat be lost and gone,\n  Yet do thou act as one new-born.\n  What each day needs, that shalt thou ask;\n  Each day will set its proper task.\n  Give other\u2019s work just share of praise;\n  Not of thine own the merits raise.\n  Beware no fellow man thou hate:\n  And so in God\u2019s hands leave thy fate.\u201d[7]\n\n\n\n\nIII.\n\nTECHNICAL EDUCATION.\n\n\nAny candid observer of the phenomena of modern society will readily\nadmit that bores must be classed among the enemies of the human race;\nand a little consideration will probably lead him to the further\nadmission, that no species of that extensive genus of noxious creatures\nis more objectionable than the educational bore. Convinced as I am of\nthe truth of this great social generalisation, it is not without a\ncertain trepidation that I venture to address you on an educational\ntopic. For, in the course of the last ten years, to go back no farther,\nI am afraid to say how often I have ventured to speak of education,\nfrom that given in the primary schools to that which is to be had in\nthe universities and medical colleges; indeed, the only part of this\nwide region into which, as yet, I have not adventured is that into\nwhich I propose to intrude to-day.\n\nThus, I cannot but be aware that I am dangerously near becoming the\nthing which all men fear and fly. But I have deliberately elected to\nrun the risk. For when you did me the honour to ask me to address you,\nan unexpected circumstance had led me to occupy myself seriously with\nthe question of technical education; and I had acquired the conviction\nthat there are few subjects respecting which it is more important for\nall classes of the community to have clear and just ideas than this;\nwhile, certainly, there is none which is more deserving of attention by\nthe Working Men\u2019s Club and Institute Union.\n\nIt is not for me to express an opinion whether the considerations,\nwhich I am about to submit to you, will be proved by experience to be\njust or not; but I will do my best to make them clear. Among the many\ngood things to be found in Lord Bacon\u2019s works, none is more full of\nwisdom than the saying that \u201ctruth more easily comes out of error than\nout of confusion.\u201d Clear and consecutive wrong-thinking is the next\nbest thing to right-thinking; so that, if I succeed in clearing your\nideas on this topic, I shall have wasted neither your time nor my own.\n\n\u201cTechnical education,\u201d in the sense in which the term is ordinarily\nused, and in which I am now employing it, means that sort of education\nwhich is specially adapted to the needs of men whose business in\nlife it is to pursue some kind of handicraft; it is, in fact, a fine\nGreco-Latin equivalent for what in good vernacular English would be\ncalled \u201cthe teaching of handicrafts.\u201d And probably, at this stage of\nour progress, it may occur to many of you to think of the story of the\ncobbler and his last, and to say to yourselves, though you will be too\npolite to put the question openly to me, What does the speaker know\npractically about this matter? What is his handicraft? I think the\nquestion is a very proper one, and unless I were prepared to answer it,\nI hope satisfactorily, I should have chosen some other theme.\n\nThe fact is, I am, and have been, any time these thirty years, a man\nwho works with his hands\u2014a handicraftsman. I do not say this in the\nbroadly metaphorical sense in which fine gentlemen, with all the\ndelicacy of Agag about them, trip to the hustings about election time,\nand protest that they too are working men. I really mean my words to be\ntaken in their direct, literal, and straightforward sense. In fact, if\nthe most nimble-fingered watchmaker among you will come to my workshop,\nhe may set me to put a watch together, and I will set him to dissect,\nsay, a blackbeetle\u2019s nerves. I do not wish to vaunt, but I am inclined\nto think that I shall manage my job to his satisfaction sooner than he\nwill do his piece of work to mine.\n\nIn truth, anatomy, which is my handicraft, is one of the most difficult\nkinds of mechanical labour, involving, as it does, not only lightness\nand dexterity of hand, but sharp eyes and endless patience. And you\nmust not suppose that my particular branch of science is especially\ndistinguished for the demand it makes upon skill in manipulation. A\nsimilar requirement is made upon all students of physical science.\nThe astronomer, the electrician, the chemist, the mineralogist, the\nbotanist, are constantly called upon to perform manual operations of\nexceeding delicacy. The progress of all branches of physical science\ndepends upon observation, or on that artificial observation which is\ntermed experiment, of one kind or another; and, the farther we advance,\nthe more practical difficulties surround the investigation of the\nconditions of the problems offered to us; so that mobile and yet steady\nhands, guided by clear vision, are more and more in request in the\nworkshops of science.\n\nIndeed, it has struck me that one of the grounds of that sympathy\nbetween the handicraftsmen of this country and the men of science, by\nwhich it has so often been my good fortune to profit, may, perhaps, lie\nhere. You feel and we feel that, among the so-called learned folks, we\nalone are brought into contact with tangible facts in the way that you\nare. You know well enough that it is one thing to write a history of\nchairs in general, or to address a poem to a throne, or to speculate\nabout the occult powers of the chair of St. Peter; and quite another\nthing to make with your own hands a veritable chair, that will stand\nfair and square, and afford a safe and satisfactory resting-place to a\nframe of sensitiveness and solidity.\n\nSo it is with us, when we look out from our scientific handicrafts\nupon the doings of our learned brethren, whose work is untrammelled\nby anything \u201cbase and mechanical,\u201d as handicrafts used to be called\nwhen the world was younger, and, in some respects, less wise than\nnow. We take the greatest interest in their pursuits; we are edified\nby their histories and are charmed with their poems, which sometimes\nillustrate so remarkably the powers of man\u2019s imagination; some of us\nadmire and even humbly try to follow them in their high philosophical\nexcursions, though we know the risk of being snubbed by the inquiry\nwhether grovelling dissectors of monkeys and blackbeetles can hope\nto enter into the empyreal kingdom of speculation. But still we feel\nthat our business is different; humbler if you will, though the\ndiminution of dignity is, perhaps, compensated by the increase of\nreality; and that we, like you, have to get our work done in a region\nwhere little avails, if the power of dealing with practical tangible\nfacts is wanting. You know that clever talk touching joinery will not\nmake a chair; and I know that it is of about as much value in the\nphysical sciences. Mother Nature is serenely obdurate to honeyed words;\nonly those who understand the ways of things, and can silently and\neffectually handle them, get any good out of her.\n\n\nAnd now, having, as I hope, justified my assumption of a place among\nhandicraftsmen, and put myself right with you as to my qualification,\nfrom practical knowledge, to speak about technical education, I will\nproceed to lay before you the results of my experience as a teacher of\na handicraft, and tell you what sort of education I should think best\nadapted for a boy whom one wanted to make a professional anatomist.\n\nI should say, in the first place, let him have a good English\nelementary education. I do not mean that he shall be able to pass\nin such and such a standard\u2014that may or may not be an equivalent\nexpression\u2014but that his teaching shall have been such as to have given\nhim command of the common implements of learning and to have created a\ndesire for the things of the understanding.\n\nFurther, I should like him to know the elements of physical science,\nand especially of physics and chemistry, and I should take care that\nthis elementary knowledge was real. I should like my aspirant to\nbe able to read a scientific treatise in Latin, French, or German,\nbecause an enormous amount of anatomical knowledge is locked up in\nthose languages. And especially, I should require some ability to\ndraw\u2014I do not mean artistically, for that is a gift which may be\ncultivated but cannot be learned, but with fair accuracy. I will not\nsay that everybody can learn even this; for the negative development\nof the faculty of drawing in some people is almost miraculous. Still\neverybody, or almost everybody, can learn to write; and, as writing is\na kind of drawing, I suppose that the majority of the people who say\nthey cannot draw, and give copious evidence of the accuracy of their\nassertion, could draw, after a fashion, if they tried. And that \u201cafter\na fashion\u201d would be better than nothing for my purposes.\n\nAbove all things, let my imaginary pupil have preserved the freshness\nand vigour of youth in his mind as well as his body. The educational\nabomination of desolation of the present day is the stimulation\nof young people to work at high pressure by incessant competitive\nexaminations. Some wise man (who probably was not an early riser)\nhas said of early risers in general, that they are conceited all the\nforenoon and stupid all the afternoon. Now whether this is true of\nearly risers in the common acceptation of the word or not, I will not\npretend to say; but it is too often true of the unhappy children who\nare forced to rise too early in their classes. They are conceited all\nthe forenoon of life, and stupid all its afternoon. The vigour and\nfreshness, which should have been stored up for the purposes of the\nhard struggle for existence in practical life, have been washed out\nof them by precocious mental debauchery\u2014by book gluttony and lesson\nbibbing. Their faculties are worn out by the strain put upon their\ncallow brains, and they are demoralised by worthless childish triumphs\nbefore the real work of life begins. I have no compassion for sloth,\nbut youth has more need for intellectual rest than age; and the\ncheerfulness, the tenacity of purpose, the power of work which make\nmany a successful man what he is, must often be placed to the credit,\nnot of his hours of industry, but to that of his hours of idleness,\nin boyhood. Even the hardest worker of us all, if he has to deal with\nanything above mere details, will do well, now and again, to let his\nbrain lie fallow for a space. The next crop of thought will certainly\nbe all the fuller in the ear and the weeds fewer.\n\nThis is the sort of education which I should like any one who was\ngoing to devote himself to my handicraft to undergo. As to knowing\nanything about anatomy itself, on the whole I would rather he left that\nalone until he took it up seriously in my laboratory. It is hard work\nenough to teach, and I should not like to have superadded to that the\npossible need of unteaching.\n\nWell, but, you will say, this is Hamlet with the Prince of Denmark left\nout; your \u201ctechnical education\u201d is simply a good education, with more\nattention to physical science, to drawing, and to modern languages,\nthan is common, and there is nothing specially technical about it.\n\nExactly so; that remark takes us straight to the heart of what I have\nto say; which is, that, in my judgment, the preparatory education\nof the handicraftsman ought to have nothing of what is ordinarily\nunderstood by \u201ctechnical\u201d about it.\n\nThe workshop is the only real school for a handicraft. The education\nwhich precedes that of the workshop should be entirely devoted to the\nstrengthening of the body, the elevation of the moral faculties, and\nthe cultivation of the intelligence; and, especially, to the imbuing\nthe mind with a broad and clear view of the laws of that natural world\nwith the components of which the handicraftsman will have to deal. And,\nthe earlier the period of life at which the handicraftsman has to enter\ninto actual practice of his craft, the more important is it that he\nshould devote the precious hours of preliminary education to things of\nthe mind, which have no direct and immediate bearing on his branch of\nindustry, though they lie at the foundation of all realities.\n\n\nNow let me apply the lessons I have learned from my handicraft to\nyours. If any of you were obliged to take an apprentice, I suppose\nyou would like to get a good healthy lad, ready and willing to learn,\nhandy, and with his fingers not all thumbs, as the saying goes. You\nwould like that he should read, write, and cipher well; and, if you\nwere an intelligent master, and your trade involved the application of\nscientific principles, as so many trades do, you would like him to know\nenough of the elementary principles of science to understand what was\ngoing on. I suppose that, in nine trades out of ten, it would be useful\nif he could draw; and many of you must have lamented your inability\nto find out for yourselves what foreigners are doing or have done. So\nthat some knowledge of French and German might, in many cases, be very\ndesirable.\n\nSo it appears to me that what you want is pretty much what I want; and\nthe practical question is, How you are to get what you need, under the\nactual limitations and conditions of life of handicraftsmen in this\ncountry?\n\nI think I shall have the assent both of the employers of labour and of\nthe employed as to one of these limitations; which is, that no scheme\nof technical education is likely to be seriously entertained which will\ndelay the entrance of boys into working life, or prevent them from\ncontributing towards their own support, as early as they do at present.\nNot only do I believe that any such scheme could not be carried out,\nbut I doubt its desirableness, even if it were practicable.\n\nThe period between childhood and manhood is full of difficulties and\ndangers, under the most favourable circumstances; and, even among the\nwell-to-do, who can afford to surround their children with the most\nfavourable conditions, examples of a career ruined, before it has well\nbegun, are but too frequent. Moreover, those who have to live by labour\nmust be shaped to labour early. The colt that is left at grass too\nlong makes but a sorry draught-horse, though his way of life does not\nbring him within the reach of artificial temptations. Perhaps the most\nvaluable result of all education is the ability to make yourself do the\nthing you have to do, when it ought to be done, whether you like it\nor not; it is the first lesson that ought to be learned; and, however\nearly a man\u2019s training begins, it is probably the last lesson that he\nlearns thoroughly.\n\nThere is another reason, to which I have already adverted, and which\nI would reiterate, why any extension of the time devoted to ordinary\nschool-work is undesirable. In the newly awakened zeal for education,\nwe run some risk of forgetting the truth that while under-instruction\nis a bad thing, over-instruction may possibly be a worse.\n\nSuccess in any kind of practical life is not dependent solely, or\nindeed chiefly, upon knowledge. Even in the learned professions,\nknowledge, alone, is of less consequence than people are apt to\nsuppose. And, if much expenditure of bodily energy is involved in the\nday\u2019s work, mere knowledge is of still less importance when weighed\nagainst the probable cost of its acquirement. To do a fair day\u2019s work\nwith his hands, a man needs, above all things, health, strength, and\nthe patience and cheerfulness which, if they do not always accompany\nthese blessings, can hardly in the nature of things exist without them;\nto which we must add honesty of purpose and a pride in doing what is\ndone well.\n\nA good handicraftsman can get on very well without genius, but he will\nfare badly without a reasonable share of that which is a more useful\npossession for workaday life, namely, mother-wit; and he will be all\nthe better for a real knowledge, however limited, of the ordinary laws\nof nature, and especially of those which apply to his own business.\n\nInstruction carried so far as to help the scholar to turn his store of\nmother-wit to account, to acquire a fair amount of sound elementary\nknowledge, and to use his hands and eyes; while leaving him fresh,\nvigorous, and with a sense of the dignity of his own calling, whatever\nit may be, if fairly and honestly pursued, cannot fail to be of\ninvaluable service to all those who come under its influence.\n\nBut, on the other hand, if school instruction is carried so far as to\nencourage bookishness; if the ambition of the scholar is directed, not\nto the gaining of knowledge, but to the being able to pass examinations\nsuccessfully; especially if encouragement is given to the mischievous\ndelusion that brainwork is, in itself, and apart from its quality, a\nnobler or more respectable thing than handiwork\u2014such education may be\na deadly mischief to the workman, and lead to the rapid ruin of the\nindustries it is intended to serve.\n\nI know that I am expressing the opinion of some of the largest as well\nas the most enlightened employers of labour, when I say that there is\na real danger that, from the extreme of no education, we may run to\nthe other extreme of over-education of handicraftsmen. And I apprehend\nthat what is true for the ordinary hand-worker is true for the foreman.\nActivity, probity, knowledge of men, ready mother-wit, supplemented by\na good knowledge of the general principles involved in his business,\nare the making of a good foreman. If he possess these qualities, no\namount of learning will fit him better for his position; while the\ncourse of life and the habit of mind required for the attainment of\nsuch learning may, in various direct and indirect ways, act as direct\ndisqualifications for it.\n\nKeeping in mind, then, that the two things to be avoided are, the delay\nof the entrance of boys into practical life, and the substitution\nof exhausted book-worms for shrewd, handy men, in our works and\nfactories, let us consider what may be wisely and safely attempted in\nthe way of improving the education of the handicraftsman.\n\nFirst, I look to the elementary schools now happily established all\nover the country. I am not going to criticise or find fault with\nthem; on the contrary, their establishment seems to me to be the most\nimportant and the most beneficial result of the corporate action of the\npeople in our day. A great deal is said of British interests just now,\nbut, depend upon it, that no Eastern difficulty needs our intervention\nas a nation so seriously, as the putting down both the Bashi-Bazouks\nof ignorance and the Cossacks of sectarianism at home. What has already\nbeen achieved in these directions is a great thing; you must have lived\nsome time to know how great. An education, better in its processes,\nbetter in its substance, than that which was accessible to the great\nmajority of well-to-do Britons a quarter of a century ago, is now\nobtainable by every child in the land. Let any man of my age go into\nan ordinary elementary school, and, unless he was unusually fortunate\nin his youth, he will tell you that the educational method, the\nintelligence, patience, and good temper on the teacher\u2019s part, which\nare now at the disposal of the veriest waifs and wastrels of society,\nare things of which he had no experience in those costly middle-class\nschools, which were so ingeniously contrived as to combine all the\nevils and shortcomings of the great public schools with none of their\nadvantages. Many a man, whose so-called education cost a good deal of\nvaluable money and occupied many a year of invaluable time, leaves the\ninspection of a well-ordered elementary school devoutly wishing that,\nin his young days, he had had the chance of being as well taught as\nthese boys and girls are.\n\nBut while, in view of such an advance in general education, I willingly\nobey the natural impulse to be thankful, I am not willing altogether\nto rest. I want to see instruction in elementary science and in art\nmore thoroughly incorporated in the educational system. At present, it\nis being administered by driblets, as if it were a potent medicine,\n\u201ca few drops to be taken occasionally in a teaspoon.\u201d Every year I\nnotice that that earnest and untiring friend of yours and of mine,\nSir John Lubbock, stirs up the Government of the day in the House of\nCommons on this subject; and also that, every year, he, and the few\nmembers of the House of Commons, such as Mr. Playfair, who sympathise\nwith him, are met with expressions of warm admiration for science in\ngeneral, and reasons at large for doing nothing in particular. But now\nthat Mr. Forster, to whom the education of the country owes so much,\nhas announced his conversion to the right faith, I begin to hope that,\nsooner or later, things will mend.\n\nI have given what I believe to be a good reason for the assumption,\nthat the keeping at school of boys, who are to be handicraftsmen,\nbeyond the age of thirteen or fourteen is neither practicable nor\ndesirable; and, as it is quite certain, that, with justice to other\nand no less important branches of education, nothing more than the\nrudiments of science and art teaching can be introduced into elementary\nschools, we must seek elsewhere for a supplementary training in these\nsubjects, and, if need be, in foreign languages, which may go on after\nthe workman\u2019s life has begun.\n\nThe means of acquiring the scientific and artistic part of this\ntraining already exists in full working order, in the first place, in\nthe classes of the Science and Art Department, which are, for the most\npart, held in the evening, so as to be accessible to all who choose to\navail themselves of them after working hours. The great advantage of\nthese classes is that they bring the means of instruction to the doors\nof the factories and workshops; that they are no artificial creations,\nbut by their very existence prove the desire of the people for them;\nand finally, that they admit of indefinite development in proportion\nas they are wanted. I have often expressed the opinion, and I repeat\nit here, that, during the eighteen years they have been in existence,\nthese classes have done incalculable good; and I can say, of my own\nknowledge, that the Department spares no pains and trouble in trying to\nincrease their usefulness and ensure the soundness of their work.\n\nNo one knows better than my friend Colonel Donnelly, to whose clear\nviews and great administrative abilities so much of the successful\nworking of the science classes is due, that there is much to be done\nbefore the system can be said to be thoroughly satisfactory. The\ninstruction given needs to be made more systematic and especially more\npractical; the teachers are of very unequal excellence, and not a few\nstand much in need of instruction themselves, not only in the subjects\nwhich they teach, but in the objects for which they teach. I daresay\nyou have heard of that proceeding, reprobated by all true sportsmen,\nwhich is called \u201cshooting for the pot.\u201d Well, there is such a thing\nas \u201cteaching for the pot\u201d\u2014teaching, that is, not that your scholar\nmay know, but that he may count for payment among those who pass the\nexamination; and there are some teachers, happily not many, who have\nyet to learn that the examiners of the Department regard them as\npoachers of the worst description.\n\nWithout presuming in any way to speak in the name of the Department, I\nthink I may say, as a matter which has come under my own observation,\nthat it is doing its best to meet all these difficulties. It\nsystematically promotes practical instruction in the classes; it\naffords facilities to teachers who desire to learn their business\nthoroughly; and it is always ready to aid in the suppression of\npot-teaching.\n\nAll this is, as you may imagine, highly satisfactory to me. I see that\nspread of scientific education, about which I have so often permitted\nmyself to worry the public, become, for all practical purposes, an\naccomplished fact. Grateful as I am for all that is now being done,\nin the same direction, in our higher schools and universities, I have\nceased to have any anxiety about the wealthier classes. Scientific\nknowledge is spreading by what the alchemists called a \u201cdistillatio per\nascensum;\u201d and nothing now can prevent it from continuing to distil\nupwards and permeate English society, until, in the remote future,\nthere shall be no member of the legislature who does not know as much\nof science as an elementary school-boy; and even the heads of houses\nin our venerable seats of learning shall acknowledge that natural\nscience is not merely a sort of University back-door through which\ninferior men may get at their degrees. Perhaps this apocalyptic vision\nis a little wild; and I feel I ought to ask pardon for an outbreak of\nenthusiasm, which, I assure you, is not my commonest failing. I have\nsaid that the Government is already doing a great deal in aid of that\nkind of technical education for handicraftsmen which, to my mind, is\nalone worth seeking. Perhaps it is doing as much as it ought to do,\neven in this direction. Certainly there is another kind of help of the\nmost important character, for which we may look elsewhere than to the\nGovernment. The great mass of mankind have neither the liking, nor the\naptitude, for either literary, or scientific, or artistic pursuits;\nnor, indeed, for excellence of any sort. Their ambition is to go\nthrough life with moderate exertion and a fair share of ease, doing\ncommon things in a common way. And a great blessing and comfort it is\nthat the majority of men are of this mind; for the majority of things\nto be done are common things, and are quite well enough done when\ncommonly done. The great end of life is not knowledge but action. What\nmen need is, as much knowledge as they can assimilate and organise into\na basis for action; give them more and it may become injurious. One\nknows people who are as heavy and stupid from undigested learning as\nothers are from over-fulness of meat and drink. But a small percentage\nof the population is born with that most excellent quality, a desire\nfor excellence, or with special aptitudes of some sort or another; Mr.\nGalton tells us that not more than one in four thousand may be expected\nto attain distinction, and not more than one in a million some share\nof that intensity of instinctive aptitude, that burning thirst for\nexcellence, which is called genius.\n\nNow, the most important object of all educational schemes is to\ncatch these exceptional people, and turn them to account for the\ngood of society. No man can say where they will crop up; like their\nopposites, the fools and knaves, they appear sometimes in the palace,\nand sometimes in the hovel; but the great thing to be aimed at, I was\nalmost going to say the most important end of all social arrangements,\nis to keep these glorious sports of Nature from being either corrupted\nby luxury or starved by poverty, and to put them into the position in\nwhich they can do the work for which they are specially fitted.\n\nThus, if a lad in an elementary school showed signs of special\ncapacity, I would try to provide him with the means of continuing his\neducation after his daily working life had begun; if, in the evening\nclasses, he developed special capabilities in the direction of science\nor of drawing, I would try to secure him an apprenticeship to some\ntrade in which those powers would have applicability. Or, if he chose\nto become a teacher, he should have the chance of so doing. Finally, to\nthe lad of genius, the one in a million, I would make accessible the\nhighest and most complete training the country could afford. Whatever\nthat might cost, depend upon it the investment would be a good one. I\nweigh my words when I say that if the nation could purchase a potential\nWatt, or Davy, or Faraday, at the cost of a hundred thousand pounds\ndown, he would be dirt-cheap at the money. It is a mere commonplace\nand everyday piece of knowledge, that what these three men did has\nproduced untold millions of wealth, in the narrowest economical sense\nof the word.\n\nTherefore, as the sum and crown of what is to be done for technical\neducation, I look to the provision of a machinery for winnowing out the\ncapacities and giving them scope. When I was a member of the London\nSchool Board, I said, in the course of a speech, that our business\nwas to provide a ladder, reaching from the gutter to the university,\nalong which every child in the three kingdoms should have the chance of\nclimbing as far as he was fit to go. This phrase was so much bandied\nabout at the time, that, to say truth, I am rather tired of it; but I\nknow of no other which so fully expresses my belief, not only about\neducation in general, but about technical education in particular.\n\nThe essential foundation of all the organisation needed for the\npromotion of education among handicraftsmen will, I believe, exist in\nthis country, when every working lad can feel that society has done\nas much as lies in its power to remove all needless and artificial\nobstacles from his path; that there is no barrier, except such as\nexists in the nature of things, between himself and whatever place in\nthe social organisation he is fitted to fill; and, more than this,\nthat, if he has capacity and industry, a hand is held out to help him\nalong any path which is wisely and honestly chosen.\n\nI have endeavoured to point out to you that a great deal of such an\norganisation already exists; and I am glad to be able to add that\nthere is a good prospect that what is wanting will, before long, be\nsupplemented.\n\nThose powerful and wealthy societies, the livery companies of the City\nof London, remembering that they are the heirs and representatives of\nthe trade guilds of the Middle Ages, are interesting themselves in the\nquestion. So far back as 1872 the Society of Arts organised a system\nof instruction in the technology of arts and manufactures, for persons\nactually employed in factories and workshops, who desired to extend and\nimprove their knowledge of the theory and practice of their particular\navocations;[8] and a considerable subsidy, in aid of the efforts of\nthe Society, was liberally granted by the Clothworkers\u2019 Company. We\nhave here the hopeful commencement of a rational organisation for the\npromotion of excellence among handicraftsmen. Quite recently, other of\nthe livery companies have determined upon giving their powerful, and,\nindeed, almost boundless, aid to the improvement of the teaching of\nhandicrafts. They have already gone so far as to appoint a committee\nto act for them; and I betray no confidence in adding that, some time\nsince, the committee sought the advice and assistance of several\npersons, myself among the number.\n\nOf course I cannot tell you what may be the result of the deliberations\nof the committee; but we may all fairly hope that, before long, steps\nwhich will have a weighty and a lasting influence on the growth and\nspread of sound and thorough teaching among the handicraftsmen[9] of\nthis country will be taken by the livery companies of London.\n\n  [This hope has been fully justified by the establishment\n  of the Cowper Street Schools, and that of the Central\n  Institution of the City and Guilds of London Institute.\n  September 1881.]\n\n\n\n\nIV.\n\nON ELEMENTARY INSTRUCTION IN PHYSIOLOGY.\n\n\nThe chief ground upon which I venture to recommend that the teaching of\nelementary physiology should form an essential part of any organised\ncourse of instruction in matters pertaining to domestic economy, is,\nthat a knowledge of even the elements of this subject supplies those\nconceptions of the constitution and mode of action of the living body,\nand of the nature of health and disease, which prepare the mind to\nreceive instruction from sanitary science.\n\nIt is, I think, eminently desirable that the hygienist and the\nphysician should find something in the public mind to which they can\nappeal; some little stock of universally acknowledged truths, which may\nserve as a foundation for their warnings, and predispose towards an\nintelligent obedience to their recommendations.\n\nListening to ordinary talk about health, disease, and death, one is\noften led to entertain a doubt whether the speakers believe that the\ncourse of natural causation runs as smoothly in the human body as\nelsewhere. Indications are too often obvious of a strong, though\nperhaps an unavowed and half unconscious, under-current of opinion\nthat the phenomena of life are not only widely different, in their\nsuperficial characters and in their practical importance, from other\nnatural events, but that they do not follow in that definite order\nwhich characterises the succession of all other occurrences, and the\nstatement of which we call a law of nature.\n\nHence, I think, arises the want of heartiness of belief in the value\nof knowledge respecting the laws of health and disease, and of the\nforesight and care to which knowledge is the essential preliminary,\nwhich is so often noticeable; and a corresponding laxity and\ncarelessness in practice, the results of which are too frequently\nlamentable.\n\nIt is said that among the many religious sects of Russia, there is one\nwhich holds that all disease is brought about by the direct and special\ninterference of the Deity, and which, therefore, looks with repugnance\nupon both preventive and curative measures as alike blasphemous\ninterferences with the will of God. Among ourselves, the \u201cPeculiar\nPeople\u201d are, I believe, the only persons who hold the like doctrine\nin its integrity, and carry it out with logical rigour. But many of\nus are old enough to recollect that the administration of chloroform\nin assuagement of the pangs of childbirth was, at its introduction,\nstrenuously resisted upon similar grounds.\n\nI am not sure that the feeling, of which the doctrine to which I have\nreferred is the full expression, does not lie at the bottom of the\nminds of a great many people who yet would vigorously object to give\na verbal assent to the doctrine itself. However this may be, the main\npoint is that sufficient knowledge has now been acquired of vital\nphenomena, to justify the assertion, that the notion, that there is\nanything exceptional about these phenomena, receives not a particle of\nsupport from any known fact. On the contrary, there is a vast and an\nincreasing mass of evidence that birth and death, health and disease,\nare as much parts of the ordinary stream of events as the rising and\nsetting of the sun, or the changes of the moon; and that the living\nbody is a mechanism, the proper working of which we term health;\nits disturbance, disease; its stoppage, death. The activity of this\nmechanism is dependent upon many and complicated conditions, some of\nwhich are hopelessly beyond our control, while others are readily\naccessible, and are capable of being indefinitely modified by our own\nactions. The business of the hygienist and of the physician is to know\nthe range of these modifiable conditions, and how to influence them\ntowards the maintenance of health and the prolongation of life; the\nbusiness of the general public is to give an intelligent assent, and\na ready obedience based upon that assent, to the rules laid down for\ntheir guidance by such experts. But an intelligent assent is an assent\nbased upon knowledge, and the knowledge which is here in question means\nan acquaintance with the elements of physiology.\n\nIt is not difficult to acquire such knowledge. What is true, to\na certain extent, of all the physical sciences, is eminently\ncharacteristic of physiology\u2014the difficulty of the subject begins\nbeyond the stage of elementary knowledge, and increases with every\nstage of progress. While the most highly trained and the best furnished\nintellect may find all its resources insufficient, when it strives to\nreach the heights and penetrate into the depths of the problems of\nphysiology, the elementary and fundamental truths can be made clear to\na child.\n\nNo one can have any difficulty in comprehending the mechanism of\ncirculation or respiration; or the general mode of operation of the\norgan of vision; though the unravelling of all the minuti\u00e6 of these\nprocesses, may, for the present, baffle the conjoined attacks of\nthe most accomplished physicists, chemists, and mathematicians. To\nknow the anatomy of the human body, with even an approximation to\nthoroughness, is the work of a life; but as much as is needed for a\nsound comprehension of elementary physiological truths, may be learned\nin a week.\n\nA knowledge of the elements of physiology is not only easy of\nacquirement, but it may be made a real and practical acquaintance\nwith the facts, as far as it goes. The subject of study is always at\nhand, in oneself. The principal constituents of the skeleton, and the\nchanges of form of contracting muscles, may be felt through one\u2019s\nown skin. The beating of one\u2019s heart, and its connection with the\npulse, may be noted; the influence of the valves of one\u2019s own veins\nmay be shown; the movements of respiration may be observed; while the\nwonderful phenomena of sensation afford an endless field for curious\nand interesting self-study. The prick of a needle will yield, in a drop\nof one\u2019s own blood, material for microscopic observation of phenomena\nwhich lie at the foundation of all biological conceptions; and a cold,\nwith its concomitant coughing and sneezing, may prove the sweet uses\nof adversity by helping one to a clear conception of what is meant by\n\u201creflex action.\u201d\n\nOf course there is a limit to this physiological self-examination.\nBut there is so close a solidarity between ourselves and our poor\nrelations of the animal world, that our inaccessible inward parts\nmay be supplemented by theirs. A comparative anatomist knows that a\nsheep\u2019s heart and lungs, or eye, must not be confounded with those of\na man; but, so far as the comprehension of the elementary facts of the\nphysiology of circulation, of respiration, and of vision goes, the one\nfurnishes the needful anatomical data as well as the other.\n\nThus, it is quite possible to give instruction in elementary physiology\nin such a manner as, not only to confer knowledge, which, for the\nreason I have mentioned, is useful in itself; but to serve the purposes\nof a training in accurate observation, and in the methods of reasoning\nof physical science. But that is an advantage which I mention only\nincidentally, as the present Conference does not deal with education in\nthe ordinary sense of the word.\n\nIt will not be suspected that I wish to make physiologists of all the\nworld. It would be as reasonable to accuse an advocate of the \u201cthree\nR\u2019s\u201d of a desire to make an orator, an author, and a mathematician of\neverybody. A stumbling reader, a pot-hook writer, and an arithmetician\nwho has not got beyond the rule of three, is not a person of brilliant\nacquirements; but the difference between such a member of society and\none who can neither read, write, nor cipher is almost inexpressible;\nand no one now-a-days doubts the value of instruction, even if it goes\nno farther.\n\nThe saying that a little knowledge is a dangerous thing is, to my\nmind, a very dangerous adage. If knowledge is real and genuine, I do\nnot believe that it is other than a very valuable possession, however\ninfinitesimal its quantity may be. Indeed, if a little knowledge is\ndangerous, where is the man who has so much as to be out of danger?\n\nIf William Harvey\u2019s life-long labours had revealed to him a tenth\npart of that which may be made sound and real knowledge to our boys\nand girls, he would not only have been what he was, the greatest\nphysiologist of his age, but he would have loomed upon the seventeenth\ncentury as a sort of intellectual portent. Our \u201clittle knowledge\u201d would\nhave been to him a great, astounding, unlooked-for vision of scientific\ntruth.\n\nI really see no harm which can come of giving our children a little\nknowledge of physiology. But then, as I have said, the instruction\nmust be real, based upon observation, eked out by good explanatory\ndiagrams and models, and conveyed by a teacher whose own knowledge has\nbeen acquired by a study of the facts; and not the mere catechismal\nparrot-work which too often usurps the place of elementary teaching.\n\nIt is, I hope, unnecessary for me to give a formal contradiction to\nthe silly fiction, which is assiduously circulated by fanatics who not\nonly ought to know, but do know, that their assertions are untrue,\nthat I have advocated the introduction of that experimental discipline\nwhich is absolutely indispensable to the professed physiologist, into\nelementary teaching.\n\nBut while I should object to any experimentation which can justly be\ncalled painful, for the purpose of elementary instruction; and, while,\nas a member of a late Royal Commission, I gladly did my best to prevent\nthe infliction of needless pain, for any purpose; I think it is my duty\nto take this opportunity of expressing my regret at a condition of the\nlaw which permits a boy to troll for pike, or set lines with live frog\nbait, for idle amusement; and, at the same time, lays the teacher of\nthat boy open to the penalty of fine and imprisonment, if he uses the\nsame animal for the purpose of exhibiting one of the most beautiful\nand instructive of physiological spectacles, the circulation in the\nweb of the foot. No one could undertake to affirm that a frog is not\ninconvenienced by being wrapped up in a wet rag, and having his toes\ntied out; and it cannot be denied that inconvenience is a sort of pain.\nBut you must not inflict the least pain on a vertebrated animal for\nscientific purposes (though you may do a good deal in that way for gain\nor for sport) without due licence of the Secretary of State for the\nHome Department, granted under the authority of the Vivisection Act.\n\nSo it comes about, that, in this present year of grace 1877, two\npersons may be charged with cruelty to animals. One has impaled a frog,\nand suffered the creature to writhe about in that condition for hours;\nthe other has pained the animal no more than one of us would be pained\nby tying strings round his fingers, and keeping him in the position\nof a hydropathic patient. The first offender says, \u201cI did it because\nI find fishing very amusing,\u201d and the magistrate bids him depart in\npeace; nay, probably wishes him good sport. The second pleads, \u201cI\nwanted to impress a scientific truth, with a distinctness attainable in\nno other way, on the minds of my scholars,\u201d and the magistrate fines\nhim five pounds.\n\nI cannot but think that this is an anomalous and not wholly creditable\nstate of things.\n\n\n\n\nV.\n\nJOSEPH PRIESTLEY.\n\n\nIf the man to perpetuate whose memory we have this day raised a\nstatue had been asked on what part of his busy life\u2019s work he set the\nhighest value, he would undoubtedly have pointed to his voluminous\ncontributions to theology. In season and out of season, he was the\nsteadfast champion of that hypothesis respecting the Divine nature\nwhich is termed Unitarianism by its friends and Socinianism by its\nfoes. Regardless of odds, he was ready to do battle with all comers in\nthat cause; and if no adversaries entered the lists, he would sally\nforth to seek them.\n\nTo this, his highest ideal of duty, Joseph Priestley sacrificed the\nvulgar prizes of life, which, assuredly, were within easy reach of a\nman of his singular energy and varied abilities. For this object, he\nput aside, as of secondary importance, those scientific investigations\nwhich he loved so well, and in which he showed himself so competent\nto enlarge the boundaries of natural knowledge and to win fame. In\nthis cause, he not only cheerfully suffered obloquy from the bigoted\nand the unthinking, and came within sight of martyrdom; but bore with\nthat which is much harder to be borne than all these, the unfeigned\nastonishment and hardly disguised contempt of a brilliant society,\ncomposed of men whose sympathy and esteem must have been most dear to\nhim, and to whom it was simply incomprehensible that a philosopher\nshould seriously occupy himself with any form of Christianity.\n\nIt appears to me that the man who, setting before himself such an ideal\nof life, acted up to it consistently, is worthy of the deepest respect,\nwhatever opinion may be entertained as to the real value of the tenets\nwhich he so zealously propagated and defended.\n\nBut I am sure that I speak not only for myself, but for all this\nassemblage, when I say that our purpose to-day is to do honour, not\nto Priestley, the Unitarian divine, but to Priestley, the fearless\ndefender of rational freedom in thought and in action: to Priestley,\nthe philosophic thinker; to that Priestley who held a foremost place\namong \u201cthe swift runners who hand over the lamp of life,\u201d[10] and\ntransmit from one generation to another the fire kindled, in the\nchildhood of the world, at the Promethean altar of Science.\n\n\nThe main incidents of Priestley\u2019s life are so well known that I need\ndwell upon them at no great length.\n\nBorn in 1733, at Fieldhead, near Leeds, and brought up among Calvinists\nof the straitest orthodoxy, the boy\u2019s striking natural ability led to\nhis being devoted to the profession of a minister of religion; and, in\n1752, he was sent to the Dissenting Academy at Daventry\u2014an institution\nwhich authority left undisturbed, though its existence contravened the\nlaw. The teachers under whose instruction and influence the young man\ncame at Daventry, carried out to the letter the injunction to \u201ctry all\nthings: hold fast that which is good,\u201d and encouraged the discussion\nof every imaginable proposition with complete freedom, the leading\nprofessors taking opposite sides; a discipline which, admirable as\nit may be from a purely scientific point of view, would seem to be\ncalculated to make acute, rather than sound, divines. Priestley tells\nus, in his \u201cAutobiography,\u201d that he generally found himself on the\nunorthodox side: and, as he grew older, and his faculties attained\ntheir maturity, this native tendency towards heterodoxy grew with his\ngrowth and strengthened with his strength. He passed from Calvinism to\nArianism; and finally, in middle life, landed in that very broad form\nof Unitarianism, by which his craving after a credible and consistent\ntheory of things was satisfied.\n\nOn leaving Daventry, Priestley became minister of a congregation, first\nat Needham Market, and secondly at Nantwich; but whether on account\nof his heterodox opinions, or of the stuttering which impeded his\nexpression of them in the pulpit, little success attended his efforts\nin this capacity. In 1761, a career much more suited to his abilities\nbecame open to him. He was appointed \u201ctutor in the languages\u201d in the\nDissenting Academy at Warrington, in which capacity, besides giving\nthree courses of lectures, he taught Latin, Greek, French, and Italian,\nand read lectures on the Theory of Language and Universal Grammar, on\nOratory, Philosophical Criticism, and Civil law. And it is interesting\nto observe that, as a teacher, he encouraged and cherished in those\nwhom he instructed, the freedom which he had enjoyed, in his own\nstudent days, at Daventry. One of his pupils tells us that,\n\n  \u201cAt the conclusion of his lecture, he always encouraged\n  his students to express their sentiments relative to the\n  subject of it, and to urge any objections to what he had\n  delivered, without reserve. It pleased him when any one\n  commenced such a conversation. In order to excite the\n  freest discussion, he occasionally invited the students\n  to drink tea with him, in order to canvass the subjects\n  of his lectures. I do not recollect that he ever showed\n  the least displeasure at the strongest objections that\n  were made to what he delivered, but I distinctly remember\n  the smile of approbation with which he usually received\n  them: nor did he fail to point out, in a very encouraging\n  manner, the ingenuity or force of any remarks that were\n  made, when they merited these characters. His object,\n  as well as Dr. Aikin\u2019s, was to engage the students to\n  examine and decide for themselves, uninfluenced by the\n  sentiments of any other persons.\u201d[11]\n\nIt would be difficult to give a better description of a model teacher\nthan that conveyed in these words.\n\nFrom his earliest days, Priestley had shown a strong bent towards the\nstudy of nature; and his brother Timothy tells us that the boy put\nspiders into bottles, to see how long they would live in the same air\u2014a\ncurious anticipation of the investigations of his later years. At\nNantwich, where he set up a school, Priestley informs us that he bought\nan air pump, an electrical machine, and other instruments, in the use\nof which he instructed his scholars. But he does not seem to have\ndevoted himself seriously to physical science until 1766, when he had\nthe great good fortune to meet Benjamin Franklin, whose friendship he\never afterwards enjoyed. Encouraged by Franklin, he wrote a \u201cHistory of\nElectricity,\u201d which was published in 1767, and appears to have met with\nconsiderable success.\n\nIn the same year, Priestley left Warrington to become the minister of\na congregation at Leeds; and, here, happening to live next door to a\npublic brewery, as he says,\n\n  \u201cI, at first, amused myself with making experiments on\n  the fixed air which I found ready-made in the process\n  of fermentation. When I removed from that house I was\n  under the necessity of making fixed air for myself; and\n  one experiment leading to another, as I have distinctly\n  and faithfully noted in my various publications on the\n  subject, I by degrees contrived a convenient apparatus\n  for the purpose, but of the cheapest kind.\n\n  \u201cWhen I began these experiments I knew very little\n  of _chemistry_, and had, in a manner, no idea on the\n  subject before I attended a course of chemical lectures,\n  delivered in the Academy at Warrington, by Dr. Turner of\n  Liverpool. But I have often thought that, upon the whole,\n  this circumstance was no disadvantage to me; as, in this\n  situation, I was led to devise an apparatus and processes\n  of my own, adapted to my peculiar views; whereas, if I\n  had been previously accustomed to the usual chemical\n  processes, I should not have so easily thought of any\n  other, and without new modes of operation, I should\n  hardly have discovered anything materially new.\u201d[12]\n\nThe first outcome of Priestley\u2019s chemical work, published in 1772, was\nof a very practical character. He discovered the way of impregnating\nwater with an excess of \u201cfixed air,\u201d or carbonic acid, and thereby\nproducing what we now know as \u201csoda water\u201d\u2014a service to naturally,\nand still more to artificially, thirsty souls, which those whose\nparched throats and hot heads are cooled by morning draughts of\nthat beverage, cannot too gratefully acknowledge. In the same year,\nPriestley communicated the extensive series of observations which his\nindustry and ingenuity had accumulated, in the course of four years,\nto the Royal Society, under the title of \u201cObservations on Different\nKinds of Air\u201d\u2014a memoir which was justly regarded of so much merit and\nimportance, that the Society at once conferred upon the author the\nhighest distinction in their power, by awarding him the Copley Medal.\n\nIn 1771 a proposal was made to Priestley to accompany Captain Cook\nin his second voyage to the South Seas. He accepted it, and his\ncongregation agreed to pay an assistant to supply his place during\nhis absence. But the appointment lay in the hands of the Board of\nLongitude, of which certain clergymen were members; and whether these\nworthy ecclesiastics feared that Priestley\u2019s presence among the ship\u2019s\ncompany might expose his Majesty\u2019s Sloop _Resolution_ to the fate which\naforetime befell a certain ship that went from Joppa to Tarshish; or\nwhether they were alarmed lest a Socinian should undermine that piety\nwhich, in the days of Commodore Trunnion, so strikingly characterised\nsailors, does not appear; but, at any rate, they objected to Priestley\n\u201con account of his religious principles,\u201d and appointed the two\nForsters, whose \u201creligious principles,\u201d if they had been known to these\nwell-meaning but not far-sighted persons, would probably have surprised\nthem.\n\nIn 1772 another proposal was made to Priestley. Lord Shelburne,\ndesiring a \u201cliterary companion,\u201d had been brought into communication\nwith Priestley by the good offices of a friend of both, Dr. Price;\nand offered him the nominal post of librarian, with a good house\nand appointments, and an annuity in case of the termination of the\nengagement. Priestley accepted the offer, and remained with Lord\nShelburne for seven years, sometimes residing at Calne, sometimes\ntravelling abroad with the Earl.\n\nWhy the connection terminated has never been exactly known; but it\nis certain that Lord Shelburne behaved with the utmost consideration\nand kindness towards Priestley; that he fulfilled his engagements to\nthe letter; and that, at a later period, he expressed a desire that\nPriestley should return to his old footing in his house. Probably\nenough, the politician, aspiring to the highest offices in the state,\nmay have found the position of the protector of a man who was being\ndenounced all over the country as an infidel and an atheist somewhat\nembarrassing. In fact, a passage in Priestley\u2019s \u201cAutobiography\u201d on the\noccasion of the publication of his \u201cDisquisitions relating to Matter\nand Spirit,\u201d which took place in 1777, indicates pretty clearly the\nstate of the case:\u2014\n\n  \u201c(126) It being probable that this publication would be\n  unpopular, and might be the means of bringing odium on\n  my patron, several attempts were made by his friends,\n  though none by himself, to dissuade me from persisting\n  in it. But being, as I thought, engaged in the cause\n  of important truth, I proceeded without regard to any\n  consequences, assuring them that this publication should\n  not be injurious to his lordship.\u201d\n\nIt is not unreasonable to suppose that his lordship, as a keen,\npractical man of the world, did not derive much satisfaction from this\nassurance. The \u201cevident marks of dissatisfaction\u201d which Priestley says\nhe first perceived in his patron in 1778, may well have arisen from\nthe peer\u2019s not unnatural uneasiness as to what his domesticated, but\nnot tamed, philosopher might write next, and what storm might thereby\nbe brought down on his own head; and it speaks very highly for Lord\nShelburne\u2019s delicacy that, in the midst of such perplexities, he\nmade not the least attempt to interfere with Priestley\u2019s freedom of\naction. In 1780, however, he intimated to Dr. Price that he should be\nglad to establish Priestley on his Irish estates: the suggestion was\ninterpreted, as Lord Shelburne probably intended it should be, and\nPriestley left him, the annuity of \u00a3150 a year, which had been promised\nin view of such a contingency, being punctually paid.\n\nAfter leaving Calne, Priestley spent some little time in London, and\nthen, having settled in Birmingham at the desire of his brother-in-law,\nhe was soon invited to become the minister of a large congregation.\nThis settlement Priestley considered, at the time, to be \u201cthe happiest\nevent of his life.\u201d And well he might think so; for it gave him\ncompetence and leisure; placed him within reach of the best makers\nof apparatus of the day; made him a member of that remarkable \u201cLunar\nSociety,\u201d at whose meetings he could exchange thoughts with such men\nas Watt, Wedgewood, Darwin, and Boulton; and threw open to him the\npleasant house of the Galtons of Barr, where these men, and others of\nless note, formed a society of exceptional charm and intelligence.[13]\n\nBut these halcyon days were ended by a bitter storm. The French\nRevolution broke out. An electric shock ran through the nations;\nwhatever there was of corrupt and retrograde, and, at the same time,\na great deal of what there was of best and noblest, in European\nsociety shuddered at the outburst of long-pent-up social fires.\nMen\u2019s feelings were excited in a way that we, in this generation,\ncan hardly comprehend. Party wrath and virulence were expressed in\na manner unparalleled, and it is to be hoped impossible, in our\ntimes; and Priestley and his friends were held up to public scorn,\neven in Parliament, as fomenters of sedition. A \u201cChurch-and-King\u201d cry\nwas raised against the Liberal Dissenters; and, in Birmingham, it\nwas intensified and specially directed towards Priestley by a local\ncontroversy, in which he had engaged with his usual vigour. In 1791,\nthe celebration of the second anniversary of the taking of the Bastille\nby a public dinner, with which Priestley had nothing whatever to do,\ngave the signal to the loyal and pious mob, who, unchecked, and indeed\nto some extent encouraged, by those who were responsible for order, had\nthe town at their mercy for three days. The chapels and houses of the\nleading Dissenters were wrecked, and Priestley and his family had to\nfly for their lives, leaving library, apparatus, papers, and all their\npossessions, a prey to the flames.\n\nPriestley never returned to Birmingham. He bore the outrages and losses\ninflicted upon him with extreme patience and sweetness,[14] and betook\nhimself to London. But even his scientific colleagues gave him a cold\nshoulder; and though he was elected minister of a congregation at\nHackney, he felt his position to be insecure, and finally determined on\nemigrating to the United States. He landed in America in 1794; lived\nquietly with his sons at Northumberland, in Pennsylvania, where his\nposterity still flourish; and, clear-headed and busy to the last, died\non the 6th of February 1804.\n\n\nSuch were the conditions under which Joseph Priestley did the work\nwhich lay before him, and then, as the Norse Sagas say, went out of the\nstory. The work itself was of the most varied kind. No human interest\nwas without its attraction for Priestley, and few men have ever had\nso many irons in the fire at once; but, though he may have burned his\nfingers a little, very few who have tried that operation have burned\ntheir fingers so little. He made admirable discoveries in science; his\nphilosophical treatises are still well worth reading; his political\nworks are full of insight and replete with the spirit of freedom; and\nwhile all these sparks flew off from his anvil, the controversial\nhammer rained a hail of blows on orthodox priest and bishop. While\nthus engaged, the kindly, cheerful doctor felt no more wrath or\nuncharitableness towards his opponents than a smith does towards his\niron. But if the iron could only speak!\u2014and the priests and bishops\ntook the point of view of the iron.\n\nNo doubt what Priestley\u2019s friends repeatedly urged upon him\u2014that he\nwould have escaped the heavier trials of his life and done more for the\nadvancement of knowledge, if he had confined himself to his scientific\npursuits and let his fellow-men go their way\u2014was true. But it seems to\nhave been Priestley\u2019s feeling that he was a man and a citizen before\nhe was a philosopher, and that the duties of the two former positions\nare at least as imperative as those of the latter. Moreover, there are\nmen (and I think Priestley was one of them) to whom the satisfaction\nof throwing down a triumphant fallacy is as great as that which\nattends the discovery of a new truth; who feel better satisfied with\nthe government of the world, when they have been helping Providence\nby knocking an imposture on the head; and who care even more for\nfreedom of thought than for mere advance of knowledge. These men are\nthe Carnots who organise victory for truth, and they are, at least, as\nimportant as the generals who visibly fight her battles in the field.\n\n\nPriestley\u2019s reputation as a man of science rests upon his numerous and\nimportant contributions to the chemistry of gaseous bodies; and to form\na just estimate of the value of his work\u2014of the extent to which it\nadvanced the knowledge of fact and the development of sound theoretical\nviews\u2014we must reflect what chemistry was in the first half of the\neighteenth century.\n\nThe vast science which now passes under that name had no existence.\nAir, water, and fire were still counted among the elemental bodies;\nand though Van Helmont, a century before, had distinguished different\nkinds of air as _gas ventosum_ and _gas sylvestre_, and Boyle and\nHales had experimentally defined the physical properties of air, and\ndiscriminated some of the various kinds of a\u00ebriform bodies, no one\nsuspected the existence of the numerous totally distinct gaseous\nelements which are now known, or dreamed that the air we breathe and\nthe water we drink are compounds of gaseous elements.\n\nBut, in 1754, a young Scotch physician, Dr. Black, made the first\nclearing in this tangled backwood of knowledge. And it gives one a\nwonderful impression of the juvenility of scientific chemistry to think\nthat Lord Brougham, whom so many of us recollect, attended Black\u2019s\nlectures when he was a student in Edinburgh. Black\u2019s researches gave\nthe world the novel and startling conception of a gas that was a\npermanently elastic fluid like air, but that differed from common air\nin being much heavier, very poisonous, and in having the properties of\nan acid, capable of neutralising the strongest alkalies; and it took\nthe world some time to become accustomed to the notion.\n\nA dozen years later, one of the most sagacious and accurate\ninvestigators who has adorned this, or any other, country, Henry\nCavendish, published a memoir in the \u201cPhilosophical Transactions,\u201d in\nwhich he deals not only with the \u201cfixed air\u201d (now called carbonic acid\nor carbonic anhydride) of Black, but with \u201cinflammable air,\u201d or what we\nnow term hydrogen.\n\nBy the rigorous application of weight and measure to all his processes,\nCavendish implied the belief subsequently formulated by Lavoisier,\nthat, in chemical processes, matter is neither created nor destroyed,\nand indicated the path along which all future explorers must travel.\nNor did he himself halt until this path led him, in 1784, to the\nbrilliant and fundamental discovery that water is composed of two gases\nunited in fixed and constant proportions.\n\nIt is a trying ordeal for any man to be compared with Black and\nCavendish, and Priestley cannot be said to stand on their level.\nNevertheless, his achievements are not only great in themselves, but\ntruly wonderful, if we consider the disadvantages under which he\nlaboured. Without the careful scientific training of Black, without the\nleisure and appliances secured by the wealth of Cavendish, he scaled\nthe walls of science as so many Englishmen have done before and since\nhis day; and trusting to mother wit to supply the place of training,\nand to ingenuity to create apparatus out of washing tubs, he discovered\nmore new gases than all his predecessors put together had done. He\nlaid the foundations of gas analysis; he discovered the complementary\nactions of animal and vegetable life upon the constituents of the\natmosphere; and, finally, he crowned his work, this day one hundred\nyears ago, by the discovery of that \u201cpure dephlogisticated air\u201d to\nwhich the French chemists subsequently gave the name of oxygen. Its\nimportance, as the constituent of the atmosphere which disappears in\nthe processes of respiration and combustion, and is restored by green\nplants growing in sunshine, was proved somewhat later. For these\nbrilliant discoveries, the Royal Society elected Priestley a fellow and\ngave him their medal, while the Academies of Paris and St. Petersburg\nconferred their membership upon him. Edinburgh had made him an\nhonorary doctor of laws at an early period of his career; but, I need\nhardly add, that a man of Priestley\u2019s opinions received no recognition\nfrom the universities of his own country.\n\nThat Priestley\u2019s contributions to the knowledge of chemical fact were\nof the greatest importance, and that they richly deserve all the praise\nthat has been awarded to them, is unquestionable; but it must, at the\nsame time, be admitted that he had no comprehension of the deeper\nsignificance of his work; and, so far from contributing anything to the\ntheory of the facts which he discovered, or assisting in their rational\nexplanation, his influence to the end of his life was warmly exerted\nin favour of error. From first to last, he was a stiff adherent of the\nphlogiston doctrine which was prevalent when his studies commenced;\nand, by a curious irony of fate, the man who by the discovery of what\nhe called \u201cdephlogisticated air\u201d furnished the essential datum for the\ntrue theory of combustion, of respiration, and of the composition of\nwater, to the end of his days fought against the inevitable corollaries\nfrom his own labours. His last scientific work, published in 1800,\nbears the title, \u201cThe Doctrine of Phlogiston established, and that of\nthe Composition of Water refuted.\u201d\n\nWhen Priestley commenced his studies, the current belief was, that\natmospheric air, freed from accidental impurities, is a simple\nelementary substance, indestructible and unalterable, as water was\nsupposed to be. When a combustible burned, or when an animal breathed\nin air, it was supposed that a substance, \u201cphlogiston,\u201d the matter of\nheat and light, passed from the burning or breathing body into it,\nand destroyed its powers of supporting life and combustion. Thus, air\ncontained in a vessel in which a lighted candle had gone out, or a\nliving animal had breathed until it could breathe no longer, was called\n\u201cphlogisticated.\u201d The same result was supposed to be brought about by\nthe addition of what Priestley called \u201cnitrous gas\u201d to common air.\n\nIn the course of his researches, Priestley found that the quantity of\ncommon air which can thus become \u201cphlogisticated,\u201d amounts to about\none-fifth the volume of the whole quantity submitted to experiment.\nHence it appeared that common air consists, to the extent of\nfour-fifths of its volume, of air which is already \u201cphlogisticated;\u201d\nwhile the other fifth is free from phlogiston, or \u201cdephlogisticated.\u201d\nOn the other hand, Priestley found that air \u201cphlogisticated\u201d by\ncombustion or respiration could be \u201cdephlogisticated,\u201d or have the\nproperties of pure common air restored to it, by the action of green\nplants in sunshine. The question, therefore, would naturally arise\u2014as\ncommon air can be wholly phlogisticated by combustion, and converted\ninto a substance which will no longer support combustion, is it\npossible to get air that shall be less phlogisticated than common air,\nand consequently support combustion better than common air does?\n\nNow, Priestley says that, in 1774, the possibility of obtaining air\nless phlogisticated than common air had not occurred to him.[15] But\nin pursuing his experiments on the evolution of air from various bodies\nby means of heat, it happened that, on the 1st of August 1774, he threw\nthe heat of the sun, by means of a large burning glass which he had\nrecently obtained, upon a substance which was then called _mercurius\ncalcinatus per se_, and which is commonly known as red precipitate.\n\n  \u201cI presently found that, by means of this lens, air was\n  expelled from it very readily. Having got about three\n  or four times as much as the bulk of my materials, I\n  admitted water to it, and found that it was not imbibed\n  by it. But what surprised me more than I can well\n  express, was that a candle burned in this air with a\n  remarkably vigorous flame, very much like that enlarged\n  flame with which a candle burns in nitrous air, exposed\n  to iron or lime of sulphur; but as I had got nothing like\n  this remarkable appearance from any kind of air besides\n  this particular modification of nitrous air, and I knew\n  no nitrous acid was used in the preparation of _mercurius\n  calcinatus_, I was utterly at a loss how to account for\n  it.\n\n  \u201cIn this case also, though I did not give sufficient\n  attention to the circumstance at that time, the flame\n  of the candle, besides being larger, burned with more\n  splendour and heat than in that species of nitrous air;\n  and a piece of red-hot wood sparkled in it, exactly like\n  paper dipped in a solution of nitre, and it consumed very\n  fast\u2014an experiment which I had never thought of trying\n  with nitrous air.\u201d[16]\n\nPriestley obtained the same sort of air from red lead, but, as he says\nhimself, he remained in ignorance of the properties of this new kind of\nair for seven months, or until March 1775, when he found that the new\nair behaved with \u201cnitrous gas\u201d in the same way as the dephlogisticated\npart of common air does;[17] but that, instead of being diminished to\nfour-fifths, it almost completely vanished, and, therefore, showed\nitself to be \u201cbetween five and six times as good as the best common\nair I have ever met with.\u201d[18] As this new air thus appeared to be\ncompletely free from phlogiston, Priestley called it \u201cdephlogisticated\nair.\u201d\n\nWhat was the nature of this air? Priestley found that the same kind of\nair was to be obtained by moistening with the spirit of nitre (which he\nterms nitrous acid) any kind of earth that is free from phlogiston, and\napplying heat; and consequently he says: \u201cThere remained no doubt on\nmy mind but that the atmospherical air, or the thing that we breathe,\nconsists of the nitrous acid and earth, with so much phlogiston as is\nnecessary to its elasticity, and likewise so much more as is required\nto bring it from its state of perfect purity to the mean condition in\nwhich we find it.\u201d[19]\n\n\nPriestley\u2019s view, in fact, is that atmospheric air is a kind of\nsaltpetre, in which the potash is replaced by some unknown earth.\nAnd in speculating on the manner in which saltpetre is formed,\nhe enunciates the hypothesis, \u201cthat nitre is formed by a real\n_decomposition of the air itself_, the _bases_ that are presented to\nit having, in such circumstances, a nearer affinity with the spirit\nof nitre than that kind of earth with which it is united in the\natmosphere.\u201d[20]\n\nIt would have been hard for the most ingenious person to have wandered\nfarther from the truth than Priestley does in this hypothesis; and,\nthough Lavoisier undoubtedly treated Priestley very ill, and pretended\nto have discovered dephlogisticated air, or oxygen, as he called it,\nindependently, we can almost forgive him, when we reflect how different\nwere the ideas which the great French chemist attached to the body\nwhich Priestley discovered.\n\nThey are like two navigators of whom the first sees a new country, but\ntakes clouds for mountains and mirage for lowlands; while the second\ndetermines its length and breadth, and lays down on a chart its exact\nplace, so that, thenceforth, it serves as a guide to his successors,\nand becomes a secure outpost whence new explorations may be pushed.\n\nNevertheless, as Priestley himself somewhere remarks, the first object\nof physical science is to ascertain facts, and the service which he\nrendered to chemistry by the definite establishment of a large number\nof new and fundamentally important facts, is such as to entitle him to\na very high place among the fathers of chemical science.\n\n\nIt is difficult to say whether Priestley\u2019s philosophical, political, or\ntheological views were most responsible for the bitter hatred which was\nborne to him by a large body of his countrymen,[21] and which found\nits expression in the malignant insinuations in which Burke, to his\neverlasting shame, indulged in the House of Commons.\n\nWithout containing much that will be new to the readers of Hobbes,\nSpinoza, Collins, Hume, and Hartley, and, indeed, while making no\npretensions to originality, Priestley\u2019s \u201cDisquisitions relating to\nMatter and Spirit,\u201d and his \u201cDoctrine of Philosophical Necessity\nillustrated,\u201d are among the most powerful, clear, and unflinching\nexpositions of materialism and necessarianism which exist in the\nEnglish language, and are still well worth reading.\n\nPriestley denied the freedom of the will in the sense of its\nself-determination; he denied the existence of a soul distinct from the\nbody; and as a natural consequence, he denied the natural immortality\nof man.\n\nIn relation to these matters English opinion, a century ago, was very\nmuch what it is now.\n\nA man may be a necessarian without incurring graver reproach than that\nimplied in being called a gloomy fanatic, necessarianism, though very\nshocking, having a note of Calvinistic orthodoxy; but, if a man is a\nmaterialist; or, if good authorities say he is and must be so, in spite\nof his assertion to the contrary; or, if he acknowledge himself unable\nto see good reasons for believing in the natural immortality of man,\nrespectable folks look upon him as an unsafe neighbour of a cash-box,\nas an actual or potential sensualist, the more virtuous in outward\nseeming, the more certainly loaded with secret \u201cgrave personal sins.\u201d\n\nNevertheless, it is as certain as anything can be, that Joseph\nPriestley was no gloomy fanatic, but as cheerful and kindly a soul as\never breathed, the idol of children; a man who was hated only by those\nwho did not know him, and who charmed away the bitterest prejudices\nin personal intercourse; a man who never lost a friend, and the best\ntestimony to whose worth is the generous and tender warmth with which\nhis many friends vied with one another in rendering him substantial\nhelp, in all the crises of his career.\n\nThe unspotted purity of Priestley\u2019s life, the strictness of\nhis performance of every duty, his transparent sincerity, the\nunostentatious and deep-seated piety which breathes through all his\ncorrespondence, are in themselves a sufficient refutation of the\nhypothesis, invented by bigots to cover uncharitableness, that such\nopinions as his must arise from moral defects. And his statue will do\nas good service as the brazen image that was set upon a pole before\nthe Israelites, if those who have been bitten by the fiery serpents of\nsectarian hatred, which still haunt this wilderness of a world, are\nmade whole by looking upon the image of a heretic, who was yet a saint.\n\nThough Priestley did not believe in the natural immortality of man, he\nheld with an almost na\u00efve realism, that man would be raised from the\ndead by a direct exertion of the power of God, and thenceforward be\nimmortal. And it may be as well for those who may be shocked by this\ndoctrine to know that views, substantially identical with Priestley\u2019s,\nhave been advocated, since his time, by two prelates of the Anglican\nChurch: by Dr. Whately, Archbishop of Dublin, in his well-known\n\u201cEssays;\u201d[22] and by Dr. Courtenay, Bishop of Kingston in Jamaica,\nthe first edition of whose remarkable book \u201cOn the Future States,\u201d\ndedicated to Archbishop Whately, was published in 1843 and the second\nin 1857. According to Bishop Courtenay,\n\n  \u201cThe death of the body will cause a cessation of all the\n  activity of the mind by way of natural consequence; to\n  continue for ever UNLESS the Creator should interfere.\u201d\n\nAnd again:\u2014\n\n  \u201cThe natural end of human existence is the \u2018first death,\u2019\n  the dreamless slumber of the grave, wherein man lies\n  spellbound, soul and body, under the dominion of sin\n  and death\u2014that whatever modes of conscious existence,\n  whatever future states of \u2018life\u2019 or of \u2018torment\u2019 beyond\n  Hades are reserved for man, are results of our blessed\n  Lord\u2019s victory over sin and death; that the resurrection\n  of the dead must be preliminary to their entrance into\n  either of the future states, and that the nature and even\n  existence of these states and even the mere fact that\n  there is a futurity of consciousness, can be known _only_\n  through God\u2019s revelation of Himself in the Person and the\n  Gospel of His Son.\u201d\u2014P. 389.\n\nAnd now hear Priestley:\u2014\n\n  \u201cMan, according to this system (of materialism), is no\n  more than we now see of him. His being commences at\n  the time of his conception, or perhaps at an earlier\n  period. The corporeal and mental faculties, in being in\n  the same substance, grow, ripen, and decay together;\n  and whenever the system is dissolved it continues in a\n  state of dissolution till it shall please that Almighty\n  Being who called it into existence to restore it to life\n  again.\u201d\u2014\u201cMatter and Spirit,\u201d p. 49.\n\nAnd again:\u2014\n\n  \u201cThe doctrine of the Scripture is, that God made man of\n  the dust of the ground, and by simply animating this\n  organised matter, made man that living percipient and\n  intelligent being that he is. According to Revelation,\n  _death_ is a state of rest and insensibility, and our\n  only though sure hope of a future life is founded on\n  the doctrine of the resurrection of the whole man at\n  some distant period; this assurance being sufficiently\n  confirmed to us both by the evident tokens of a Divine\n  commission attending the persons who delivered the\n  doctrine, and especially by the actual resurrection of\n  Jesus Christ, which is more authentically attested than\n  any other fact in history.\u201d\u2014_Ibid._, p. 247.\n\nWe all know that \u201ca saint in crape is twice a saint in lawn;\u201d but\nit is not yet admitted that the views which are consistent with\nsuch saintliness in lawn, become diabolical when held by a mere\ndissenter.[23]\n\nI am not here either to defend or to attack Priestley\u2019s philosophical\nviews, and I cannot say that I am personally disposed to attach much\nvalue to episcopal authority in philosophical questions; but it seems\nright to call attention to the fact, that those of Priestley\u2019s opinions\nwhich have brought most odium upon him, have been openly promulgated,\nwithout challenge, by persons occupying the highest positions in the\nState Church.\n\nI must confess that what interests me most about Priestley\u2019s\nmaterialism, is the evidence that he saw dimly the seed of destruction\nwhich such materialism carries within its own bosom. In the course\nof his reading for his \u201cHistory of Discoveries relating to Vision,\nLight, and Colours,\u201d he had come upon the speculations of Boscovich\nand Michell, and had been led to admit the sufficiently obvious truth\nthat our knowledge of matter is a knowledge of its properties; and that\nof its substance\u2014if it have a substance\u2014we know nothing. And this led\nto the further admission that, so far as we can know, there may be no\ndifference between the substance of matter and the substance of spirit\n(\u201cDisquisitions,\u201d p. 16). A step farther would have shown Priestley\nthat his materialism was, essentially, very little different from the\nIdealism of his contemporary, the Bishop of Cloyne.\n\n\nAs Priestley\u2019s philosophy is mainly a clear statement of the views of\nthe deeper thinkers of his day, so are his political conceptions based\nupon those of Locke. Locke\u2019s aphorism that \u201cthe end of government is\nthe good of mankind,\u201d is thus expanded by Priestley:\u2014\n\n  \u201cIt must necessarily be understood, therefore, whether it\n  be expressed or not, that all people live in society for\n  their mutual advantage; so that the good and happiness\n  of the members, that is, of the majority of the members,\n  of any state, is the great standard by which everything\n  relating to that state must finally be determined.\u201d[24]\n\nThe little sentence here interpolated, \u201cthat is, of the majority of\nthe members of any state,\u201d appears to be that passage which suggested\nto Bentham, according to his own acknowledgment, the famous \u201cgreatest\nhappiness\u201d formula, which by substituting \u201chappiness\u201d for \u201cgood,\u201d has\nconverted a noble into an ignoble principle. But I do not call to\nmind that there is any utterance in Locke quite so outspoken as the\nfollowing passage in the \u201cEssay on the First Principles of Government.\u201d\nAfter laying down as \u201ca fundamental maxim in all governments,\u201d the\nproposition that \u201ckings, senators, and nobles\u201d are \u201cthe servants of the\npublic,\u201d Priestley goes on to say:\u2014\n\n  \u201cBut in the largest states, if the abuses of the\n  government should at any time be great and manifest; if\n  the servants of the people, forgetting their masters and\n  their masters\u2019 interest, should pursue a separate one\n  of their own; if, instead of considering that they are\n  made for the people, they should consider the people as\n  made for them; if the oppressions and violation of right\n  should be great, flagrant, and universally resented; if\n  the tyrannical governors should have no friends but a few\n  sycophants, who had long preyed upon the vitals of their\n  fellow-citizens, and who might be expected to desert a\n  government whenever their interests should be detached\n  from it; if, in consequence of these circumstances, it\n  should become manifest that the risk which would be\n  run in attempting a revolution would be trifling, and\n  the evils which might be apprehended from it were far\n  less than those which were actually suffered and which\n  were daily increasing; in the name of God, I ask, what\n  principles are those which ought to restrain an injured\n  and insulted people from asserting their natural rights,\n  and from changing or even punishing their governors\u2014that\n  is, their servants\u2014who had abused their trust, or from\n  altering the whole form of their government, if it\n  appeared to be of a structure so liable to abuse?\u201d\n\nAs a Dissenter, subject to the operation of the Corporation and Test\nActs, and as a Unitarian, excluded from the benefit of the Toleration\nAct, it is not surprising to find that Priestley had very definite\nopinions about Ecclesiastical Establishments; the only wonder is that\nthese opinions were so moderate as the following passages show them to\nhave been:\u2014\n\n  \u201cEcclesiastical authority may have been necessary in the\n  infant state of society, and, for the same reason, it\n  may perhaps continue to be, in some degree, necessary as\n  long as society is imperfect; and therefore may not be\n  entirely abolished till civil governments have arrived\n  at a much greater degree of perfection. If, therefore,\n  I were asked whether I should approve of the immediate\n  dissolution of all the ecclesiastical establishments in\n  Europe, I should answer, No.... Let experiment be first\n  made of _alterations_, or, which is the same thing, of\n  _better establishments_ than the present. Let them be\n  reformed in many essential articles, and then not thrown\n  aside entirely till it be found by experience that no\n  good can be made of them.\u201d\n\nPriestley goes on to suggest four such reforms of a capital nature:\u2014\n\n  \u201c1. Let the Articles of Faith to be subscribed by\n  candidates for the ministry be greatly reduced. In\n  the formulary of the Church of England, might not\n  thirty-eight out of the thirty-nine be very well spared?\n  It is a reproach to any Christian establishment if every\n  man cannot claim the benefit of it who can say that he\n  believes in the religion of Jesus Christ as it is set\n  forth in the New Testament. You say the terms are so\n  general that even Deists would quibble and insinuate\n  themselves. I answer that all the articles which are\n  subscribed at present, by no means exclude Deists who\n  will prevaricate; and upon this scheme you would at least\n  exclude fewer honest men.\u201d[25]\n\nThe second reform suggested is the equalisation, in proportion to work\ndone, of the stipends of the clergy; the third, the exclusion of the\nbishops from Parliament; and the fourth, complete toleration, so that\nevery man may enjoy the rights of a citizen, and be qualified to serve\nhis country, whether he belong to the Established Church or not.\n\nOpinions such as those I have quoted, respecting the duties and\nthe responsibilities of governors, are the commonplaces of modern\nLiberalism; and Priestley\u2019s views on Ecclesiastical Establishments\nwould, I fear, meet with but a cool reception, as altogether too\nconservative, from a large proportion of the lineal descendants of the\npeople who taught their children to cry \u201cDamn Priestley;\u201d and, with\nthat love for the practical application of science which is the source\nof the greatness of Birmingham, tried to set fire to the doctor\u2019s house\nwith sparks from his own electrical machine; thereby giving the man\nthey called an incendiary and raiser of sedition against Church and\nKing, an appropriately experimental illustration of the nature of arson\nand riot.\n\n\nIf I have succeeded in putting before you the main features of\nPriestley\u2019s work, its value will become apparent, when we compare the\ncondition of the English nation, as he knew it, with its present state.\n\nThe fact that France has been for eighty-five years trying, without\nmuch success, to right herself after the great storm of the Revolution,\nis not unfrequently cited among us, as an indication of some inherent\nincapacity for self-government among the French people. I think,\nhowever, that Englishmen who argue thus, forget that, from the meeting\nof the Long Parliament in 1640, to the last Stuart rebellion in 1745,\nis a hundred and five years, and that, in the middle of the last\ncentury, we had but just safely freed ourselves from our Bourbons and\nall that they represented. The corruption of our state was as bad as\nthat of the Second Empire. Bribery was the instrument of government,\nand peculation its reward. Four-fifths of the seats in the House of\nCommons were more or less openly dealt with as property. A minister\nhad to consider the state of the vote market, and the sovereign secured\na sufficiency of \u201cking\u2019s friends\u201d by payments allotted with retail,\nrather than royal, sagacity.\n\nBarefaced and brutal immorality and intemperance pervaded the land,\nfrom the highest to the lowest classes of society. The Established\nChurch was torpid, so far as it was not a scandal; but those who\ndissented from it came within the meshes of the Act of Uniformity, the\nTest Act, and the Corporation Act. By law, such a man as Priestley,\nbeing a Unitarian, could neither teach nor preach, and was liable to\nruinous fines and long imprisonment.[26] In those days, the guns that\nwere pointed by the Church against the Dissenters were shotted. The law\nwas a cesspool of iniquity and cruelty. Adam Smith was a new prophet\nwhom few regarded, and commerce was hampered by idiotic impediments,\nand ruined by still more absurd help, on the part of government.\n\nBirmingham, though already the centre of a considerable industry, was a\nmere village as compared with its present extent. People who travelled\nwent about armed, by reason of the abundance of highwaymen and the\npaucity and inefficiency of the police. Stage coaches had not reached\nBirmingham, and it took three days to get to London. Even canals were a\nrecent and much opposed invention.\n\nNewton had laid the foundation of a mechanical conception of the\nphysical universe: Hartley, putting a modern face upon ancient\nmaterialism, had extended that mechanical conception to psychology;\nLinn\u00e6us and Haller were beginning to introduce method and order into\nthe chaotic accumulation of biological facts. But those parts of\nphysical science which deal with heat, electricity, and magnetism,\nand above all, chemistry, in the modern sense, can hardly be said\nto have had an existence. No one knew that two of the old elemental\nbodies, air and water, are compounds, and that a third, fire, is not a\nsubstance but a motion. The great industries that have grown out of the\napplications of modern scientific discoveries had no existence, and the\nman who should have foretold their coming into being in the days of his\nson, would have been regarded as a mad enthusiast.\n\nIn common with many other excellent persons, Priestley believed that\nman is capable of reaching, and will eventually attain, perfection.\nIf the temperature of space presented no obstacle, I should be glad\nto entertain the same idea; but judging from the past progress of our\nspecies, I am afraid that the globe will have cooled down so far,\nbefore the advent of this natural millennium, that we shall be, at\nbest, perfected Esquimaux. For all practical purposes, however, it\nis enough that man may visibly improve his condition in the course\nof a century or so. And, if the picture of the state of things\nin Priestley\u2019s time, which I have just drawn, have any pretence\nto accuracy, I think it must be admitted that there has been a\nconsiderable change for the better.\n\nI need not advert to the well-worn topic of material advancement, in\na place in which the very stones testify to that progress\u2014in the town\nof Watt and of Boulton. I will only remark, in passing, that material\nadvancement has its share in moral and intellectual progress. Becky\nSharp\u2019s acute remark that it is not difficult to be virtuous on ten\nthousand a year, has its application to nations; and it is futile to\nexpect a hungry and squalid population to be anything but violent and\ngross. But as regards other than material welfare, although perfection\nis not yet in sight\u2014even from the mast-head\u2014it is surely true that\nthings are much better than they were.\n\nTake the upper and middle classes as a whole, and it may be said\nthat open immorality and gross intemperance have vanished. Four and\nsix bottle men are as extinct as the dodo. Women of good repute\ndo not gamble, and talk modelled upon Dean Swift\u2019s \u201cArt of Polite\nConversation\u201d would be tolerated in no decent kitchen.\n\nMembers of the legislature are not to be bought; and constituents are\nawakening to the fact that votes must not be sold\u2014even for such trifles\nas rabbits and tea and cake. Political power has passed into the hands\nof the masses of the people. Those whom Priestley calls their servants\nhave recognised their position, and have requested the master to be\nso good as to go to school and fit himself for the administration of\nhis property. No civil disability attaches to any one on theological\ngrounds, and the highest offices of the state are open to Papist, Jew,\nor Secularist.[27]\n\nWhatever men\u2019s opinions as to the policy of Establishment, no one\ncan hesitate to admit that the clergy of the Church are men of pure\nlife and conversation, zealous in the discharge of their duties; and,\nat present, apparently, more bent on prosecuting one another than\non meddling with Dissenters. Theology itself has broadened so much,\nthat Anglican divines put forward doctrines more liberal than those\nof Priestley; and, in our state-supported churches, one listener may\nhear a sermon to which Bossuet might have given his approbation, while\nanother may hear a discourse in which Socrates would find nothing new.\n\nBut great as these changes may be, they sink into insignificance\nbeside the progress of physical science, whether we consider the\nimprovement of methods of investigation, or the increase in bulk of\nsolid knowledge. Consider that the labours of Laplace, of Young, of\nDavy, and of Faraday; of Cuvier, of Lamarck, and of Robert Brown; of\nVon Baer, and of Schwann; of Smith and of Hutton, have all been carried\non since Priestley discovered oxygen; and consider that they are now\nthings of the past, concealed by the industry of those who have built\nupon them, as the first founders of a coral reef are hidden beneath the\nlife\u2019s work of their successors; consider that the methods of physical\nscience are slowly spreading into all investigations, and that proofs\nas valid as those required by her canons of investigation, are being\ndemanded of all doctrines which ask for men\u2019s assent; and you will\nhave a faint image of the astounding difference in this respect between\nthe nineteenth century and the eighteenth.\n\nIf we ask what is the deeper meaning of all these vast changes, I\nthink there can be but one reply. They mean that reason has asserted\nand exercised her primacy over all provinces of human activity: that\necclesiastical authority has been relegated to its proper place; that\nthe good of the governed has been finally recognised as the end of\ngovernment, and the complete responsibility of governors to the people\nas its means; and that the dependence of natural phenomena in general,\non the laws of action of what we call matter has become an axiom.\n\nBut it was to bring these things about, and to enforce the recognition\nof these truths, that Joseph Priestley laboured. If the nineteenth\ncentury is other and better than the eighteenth, it is, in great\nmeasure, to him and to such men as he, that we owe the change. If the\ntwentieth century is to be better than the nineteenth, it will be\nbecause there are among us men who walk in Priestley\u2019s footsteps.\n\nSuch men are not those whom their own generation delights to honour;\nsuch men, in fact, rarely trouble themselves about honour, but ask,\nin another spirit than Falstaff\u2019s, \u201cWhat is honour? Who hath it? He\nthat died o\u2019 Wednesday.\u201d But whether Priestley\u2019s lot be theirs, and a\nfuture generation, in justice and in gratitude, set up their statues;\nor whether their names and fame are blotted out from remembrance,\ntheir work will live as long as time endures. To all eternity, the\nsum of truth and right will have been increased by their means; to all\neternity, falsehood and injustice will be the weaker because they have\nlived.\n\n\n\n\nVI.\n\nON THE METHOD OF ZADIG:\n\nRETROSPECTIVE PROPHECY AS A FUNCTION OF SCIENCE.\n\n  \u201cUne marque plus s\u00fbre que toutes celles de Zadig\u201d\u2014CUVIER.[28]\n\n\nIt is a usual and a commendable practice to preface the discussion of\nthe views of a philosophic thinker by some account of the man and of\nthe circumstances which shaped his life and coloured his way of looking\nat things; but, though Zadig is cited in one of the most important\nchapters of Cuvier\u2019s greatest work, little is known about him, and that\nlittle might perhaps be better authenticated than it is.\n\nIt is said that he lived at Babylon in the time of King Moabdar;\nbut the name of Moabdar does not appear in the list of Babylonian\nsovereigns brought to light by the patience and the industry of the\ndecipherers of cuneiform inscriptions in these later years; nor indeed\nam I aware that there is any other authority for his existence than\nthat of the biographer of Zadig, one Arouet de Voltaire, among whose\nmore conspicuous merits strict historical accuracy is perhaps hardly\nto be reckoned.\n\nHappily Zadig is in the position of a great many other philosophers.\nWhat he was like when he was in the flesh, indeed whether he existed at\nall, are matters of no great consequence. What we care about in a light\nis that it shows the way, not whether it is lamp or candle, tallow or\nwax. Our only real interest in Zadig lies in the conceptions of which\nhe is the putative father; and his biographer has stated these with so\nmuch clearness and vivacious illustration, that we need hardly feel a\npang, even if critical research should prove King Moabdar and all the\nrest of the story to be unhistorical, and reduce Zadig himself to the\nshadowy condition of a solar myth.\n\nVoltaire tells us that, disenchanted with life by sundry domestic\nmisadventures, Zadig withdrew from the turmoil of Babylon to a secluded\nretreat on the banks of the Euphrates, where he beguiled his solitude\nby the study of nature. The manifold wonders of the world of life\nhad a particular attraction for the lonely student; incessant and\npatient observation of the plants and animals about him sharpened\nhis naturally good powers of observation and of reasoning; until, at\nlength, he acquired a sagacity which enabled him to perceive endless\nminute differences among objects which, to the untutored eye, appeared\nabsolutely alike.\n\nIt might have been expected that this enlargement of the powers of the\nmind and of its store of natural knowledge could tend to nothing but\nthe increase of a man\u2019s own welfare and the good of his fellow-men.\nBut Zadig was fated to experience the vanity of such expectations.\n\n  One day, walking near a little wood, he saw, hastening\n  that way, one of the Queen\u2019s chief eunuchs, followed by\n  a troop of officials, who appeared to be in the greatest\n  anxiety, running hither and thither like men distraught,\n  in search of some lost treasure.\n\n  \u201cYoung man,\u201d cried the eunuch, \u201chave you seen the Queen\u2019s\n  dog?\u201d Zadig answered modestly, \u201cA bitch, I think, not\n  a dog.\u201d \u201cQuite right,\u201d replied the eunuch; and Zadig\n  continued, \u201cA very small spaniel who has lately had\n  puppies; she limps with the left foreleg, and has very\n  long ears.\u201d \u201cAh! you have seen her then,\u201d said the\n  breathless eunuch. \u201cNo,\u201d answered Zadig, \u201cI have not seen\n  her; and I really was not aware that the Queen possessed\n  a spaniel.\u201d\n\n  By an odd coincidence, at the very same time, the\n  handsomest horse in the King\u2019s stables broke away from\n  his groom in the Babylonian plains. The grand huntsman\n  and all his staff were seeking the horse with as much\n  anxiety as the eunuch and his people the spaniel; and the\n  grand huntsman asked Zadig if he had not seen the King\u2019s\n  horse go that way.\n\n  \u201cA first-rate galloper, small-hoofed, five feet high;\n  tail three feet and a half long; cheek pieces of the bit\n  of twenty-three carat gold; shoes silver?\u201d said Zadig.\n\n  \u201cWhich way did he go? Where is he?\u201d cried the grand\n  huntsman.\n\n  \u201cI have not seen anything of the horse, and I never heard\n  of him before,\u201d replied Zadig.\n\n  The grand huntsman and the chief eunuch made sure that\n  Zadig had stolen both the King\u2019s horse and the Queen\u2019s\n  spaniel, so they haled him before the High Court of\n  Desterham, which at once condemned him to the knout, and\n  transportation for life to Siberia. But the sentence was\n  hardly pronounced when the lost horse and spaniel were\n  found. So the judges were under the painful necessity of\n  reconsidering their decision: but they fined Zadig four\n  hundred ounces of gold for saying he had seen that which\n  he had not seen.\n\n  The first thing was to pay the fine; afterwards Zadig was\n  permitted to open his defence to the court, which he did\n  in the following terms:\n\n  \u201cStars of justice, abysses of knowledge, mirrors\n  of truth, whose gravity is as that of lead, whose\n  inflexibility is as that of iron, who rival the diamond\n  in clearness, and possess no little affinity with gold;\n  since I am permitted to address your august assembly, I\n  swear by Ormuzd that I have never seen the respectable\n  lady dog of the queen, nor beheld the sacrosanct horse of\n  the King of Kings.\n\n  \u201cThis is what happened. I was taking a walk towards the\n  little wood near which I subsequently had the honour to\n  meet the venerable chief eunuch and the most illustrious\n  grand huntsman. I noticed the track of an animal in the\n  sand, and it was easy to see that it was that of a small\n  dog. Long faint streaks upon the little elevations of\n  sand between the footmarks convinced me that it was a\n  she dog with pendent dugs, showing that she must have\n  had puppies not many days since. Other scrapings of\n  the sand, which always lay close to the marks of the\n  forepaws, indicated that she had very long ears; and, as\n  the imprint of one foot was always fainter than those of\n  the other three, I judged that the lady dog of our august\n  Queen was, if I may venture to say so, a little lame.\n\n  \u201cWith respect to the horse of the King of Kings, permit\n  me to observe that, wandering through the paths which\n  traverse the wood, I noticed the marks of horse-shoes.\n  They were all equidistant. \u2018Ah!\u2019 said I, \u2018this is a\n  famous galloper.\u2019 In a narrow alley, only seven feet\n  wide, the dust upon the trunks of the trees was a little\n  disturbed at three feet and a half from the middle of\n  the path. \u2018This horse,\u2019 said I to myself, \u2018had a tail\n  three feet and a half long, and, lashing it from one side\n  to the other, he has swept away the dust.\u2019 Branches of\n  the trees met overhead at the height of five feet, and\n  under them I saw newly fallen leaves; so I knew that the\n  horse had brushed some of the branches, and was therefore\n  five feet high. As to his bit, it must have been made of\n  twenty-three carat gold, for he had rubbed it against\n  a stone, which turned out to be a touchstone, with the\n  properties of which I am familiar by experiment. Lastly,\n  by the marks which his shoes left upon pebbles of another\n  kind, I was led to think that his shoes were of fine\n  silver.\u201d\n\n  All the judges admired Zadig\u2019s profound and subtle\n  discernment; and the fame of it reached even the King and\n  the Queen. From the ante-rooms to the presence-chamber,\n  Zadig\u2019s name was in everybody\u2019s mouth; and, although many\n  of the magi were of opinion that he ought to be burnt\n  as a sorcerer, the King commanded that the four hundred\n  ounces of gold which he had been fined should be restored\n  to him. So the officers of the court went in state with\n  the four hundred ounces; only they retained three hundred\n  and ninety-eight for legal expenses, and their servants\n  expected fees.\n\nThose who are interested in learning more of the fateful history of\nZadig must turn to the original; we are dealing with him only as a\nphilosopher, and this brief excerpt suffices for the exemplification of\nthe nature of his conclusions and of the method by which he arrived at\nthem.\n\nThese conclusions may be said to be of the nature of retrospective\nprophecies; though it is perhaps a little hazardous to employ\nphraseology which perilously suggests a contradiction in terms\u2014the\nword \u201cprophecy\u201d being so constantly in ordinary use restricted to\n\u201cforetelling.\u201d Strictly, however, the term prophecy as much applies to\noutspeaking as to foretelling; and, even in the restricted sense of\n\u201cdivination,\u201d it is obvious that the essence of the prophetic operation\ndoes not lie in its backward or forward relation to the course of time,\nbut in the fact that it is the apprehension of that which lies out of\nthe sphere of immediate knowledge; the seeing of that which to the\nnatural sense of the seer is invisible.\n\nThe foreteller asserts that, at some future time, a properly situated\nobserver will witness certain events; the clairvoyant declares that,\nat this present time, certain things are to be witnessed a thousand\nmiles away; the retrospective prophet (would that there were such a\nword as \u201cbackteller!\u201d) affirms that so many hours or years ago, such\nand such things were to be seen. In all these cases, it is only the\nrelation to time which alters\u2014the process of divination beyond the\nlimits of possible direct knowledge remains the same.\n\nNo doubt it was their instinctive recognition of the analogy between\nZadig\u2019s results and those obtained by authorised inspiration which\ninspired the Babylonian magi with the desire to burn the philosopher.\nZadig admitted that he had never either seen or heard of the horse of\nthe king or of the spaniel of the queen; and yet he ventured to assert\nin the most positive manner that animals answering to their description\ndid actually exist, and ran about the plains of Babylon. If his method\nwas good for the divination of the course of events ten hours old, why\nshould it not be good for those of ten years or ten centuries past;\nnay, might it not extend to ten thousand years and justify the impious\nin meddling with the traditions of Oannes and the fish, and all the\nsacred foundations of Babylonian cosmogony?\n\nBut this was not the worst. There was another consideration which\nobviously dictated to the more thoughtful of the magi the propriety\nof burning Zadig out of hand. His defence was worse than his offence.\nIt showed that his mode of divination was fraught with danger to\nmagianism in general. Swollen with the pride of human reason, he had\nignored the established canons of magian lore; and, trusting to what\nafter all was mere carnal common sense, he professed to lead men to\na deeper insight into nature than magian wisdom, with all its lofty\nantagonism to everything common, had ever reached. What, in fact, lay\nat the foundation of all Zadig\u2019s arguments but the coarse commonplace\nassumption, upon which every act of our daily lives is based, that we\nmay conclude from an effect to the pre-existence of a cause competent\nto produce that effect?\n\nThe tracks were exactly like those which dogs and horses leave;\ntherefore they were the effects of such animals as causes. The marks\nat the sides of the fore prints of the dog track were exactly such\nas would be produced by long trailing ears; therefore the dog\u2019s long\nears were the causes of these marks\u2014and so on. Nothing can be more\nhopelessly vulgar, more unlike the majestic development of a system\nof grandly unintelligible conclusions from sublimely inconceivable\npremisses, such as delights the magian heart. In fact, Zadig\u2019s method\nwas nothing but the method of all mankind. Retrospective prophecies,\nfar more astonishing for their minute accuracy than those of Zadig, are\nfamiliar to those who have watched the daily life of nomadic people.\n\nFrom freshly broken twigs, crushed leaves, disturbed pebbles, and\nimprints hardly discernible by the untrained eye, such graduates in\nthe University of Nature will divine, not only the fact that a party\nhas passed that way, but its strength, its composition, the course\nit took, and the number of hours or days which have elapsed since it\npassed. But they are able to do this because, like Zadig, they perceive\nendless minute differences where untrained eyes discern nothing; and\nbecause the unconscious logic of common sense compels them to account\nfor these effects by the causes which they know to be competent to\nproduce them.\n\nAnd such mere methodised savagery was to discover the hidden things\nof nature better than _\u00e0 priori_ deductions from the nature of\nOrmuzd\u2014perhaps to give a history of the past, in which Oannes would be\naltogether ignored! Decidedly it were better to burn this man at once.\n\nIf instinct, or an unwonted use of reason, led Moabdar\u2019s magi to\nthis conclusion two or three thousand years ago, all that can be\nsaid is that subsequent history has fully justified them. For the\nrigorous application of Zadig\u2019s logic to the results of accurate and\nlong-continued observation has founded all those sciences which\nhave been termed historical or pal\u00e6tiological, because they are\nretrospectively prophetic and strive towards the reconstruction in\nhuman imagination of events which have vanished and ceased to be.\n\nHistory, in the ordinary acceptation of the word, is based upon the\ninterpretation of documentary evidence; and documents would have no\nevidential value unless historians were justified in their assumption\nthat they have come into existence by the operation of causes similar\nto those of which documents are, in our present experience, the\neffects. If a written history can be produced otherwise than by human\nagency, or if the man who wrote a given document was actuated by other\nthan ordinary human motives, such documents are of no more evidential\nvalue than so many arabesques.\n\nArch\u00e6ology, which takes up the thread of history beyond the point at\nwhich documentary evidence fails us, could have no existence, except\nfor our well-grounded confidence that monuments and works of art or\nartifice, have never been produced by causes different in kind from\nthose to which they now owe their origin. And geology, which traces\nback the course of history beyond the limits of arch\u00e6ology, could tell\nus nothing except for the assumption that, millions of years ago,\nwater, heat, gravitation, friction, animal and vegetable life, caused\neffects of the same kind as they do now. Nay, even physical astronomy,\nin so far as it takes us back to the uttermost point of time which\npal\u00e6tiological science can reach, is founded upon the same assumption.\nIf the law of gravitation ever failed to be true, even to the smallest\nextent, for that period, the calculations of the astronomer have no\napplication.\n\nThe power of prediction, of prospective prophecy, is that which is\ncommonly regarded as the great prerogative of physical science. And\ntruly it is a wonderful fact that one can go into a shop and buy for\nsmall price a book, the \u201cNautical Almanac,\u201d which will foretell the\nexact position to be occupied by one of Jupiter\u2019s moons six months\nhence; nay more, that, if it were worth while, the Astronomer Royal\ncould furnish us with as infallible a prediction applicable to 1980 or\n2980.\n\nBut astronomy is not less remarkable for its power of retrospective\nprophecy.\n\nThales, oldest of Greek philosophers, the dates of whose birth and\ndeath are uncertain, but who flourished about 600 B.C., is said to have\nforetold an eclipse of the sun which took place in his time during a\nbattle between the Medes and the Lydians. Sir George Airy has written a\nvery learned and interesting memoir[29] in which he proves that such an\neclipse was visible in Lydia on the afternoon of the 28th of May in the\nyear 585 B.C.\n\nNo one doubts that, on the day and at the hour mentioned by the\nAstronomer Royal, the people of Asia Minor saw the face of the sun\ntotally obscured. But, though we implicitly believe this retrospective\nprophecy, it is incapable of verification. In the total absence of\nhistorical records, it is impossible even to conceive any means of\nascertaining directly whether the eclipse of Thales happened or not.\nAll that can be said is, that the prospective prophecies of the\nastronomer are always verified; and that, inasmuch as his retrospective\nprophecies are the result of following backwards, the very same method\nas that which invariably leads to verified results, when it is worked\nforwards, there is as much reason for placing full confidence in the\none as in the other. Retrospective prophecy is therefore a legitimate\nfunction of astronomical science; and if it is legitimate for one\nscience it is legitimate for all; the fundamental axiom on which\nit rests, the constancy of the order of nature, being the common\nfoundation of all scientific thought. Indeed, if there can be grades\nin legitimacy, certain branches of science have the advantage over\nastronomy, in so far as their retrospective prophecies are not only\nsusceptible of verification, but are sometimes strikingly verified.\n\nSuch a science exists in that application of the principles of biology\nto the interpretation of the animal and vegetable remains imbedded\nin the rocks which compose the surface of the globe, which is called\nPal\u00e6ontology.\n\nAt no very distant time, the question whether these so-called \u201cfossils\u201d\nwere really the remains of animals and plants was hotly disputed. Very\nlearned persons maintained that they were nothing of the kind, but a\nsort of concretion, or crystallisation, which had taken place within\nthe stone in which they are found; and which simulated the forms of\nanimal and vegetable life, just as frost on a window-pane imitates\nvegetation. At the present day, it would probably be impossible\nto find any sane advocate of this opinion; and the fact is rather\nsurprising, that among the people from whom the circle-squarers,\nperpetual-motioners, flat-earth men and the like, are recruited, to say\nnothing of table-turners and spirit-rappers, somebody has not perceived\nthe easy avenue to nonsensical notoriety open to any one who will take\nup the good old doctrine, that fossils are all _lusus natur\u00e6_.\n\nThe position would be impregnable, inasmuch as it is quite impossible\nto prove the contrary. If a man choose to maintain that a fossil\noyster shell, in spite of its correspondence, down to every minutest\nparticular, with that of an oyster fresh taken out of the sea, was\nnever tenanted by a living oyster, but is a mineral concretion, there\nis no demonstrating his error. All that can be done is to show him\nthat, by a parity of reasoning, he is bound to admit that a heap of\noyster shells outside a fishmonger\u2019s door may also be \u201csports of\nnature,\u201d and that a mutton bone in a dust-bin may have had the like\norigin. And when you cannot prove that people are wrong, but only that\nthey are absurd, the best course is to let them alone.\n\nThe whole fabric of pal\u00e6ontology, in fact, falls to the ground unless\nwe admit the validity of Zadig\u2019s great principle, that like effects\nimply like causes; and that the process of reasoning from a shell, or\na tooth, or a bone, to the nature of the animal to which it belonged,\nrests absolutely on the assumption that the likeness of this shell,\nor tooth, or bone, to that of some animal with which we are already\nacquainted, is such that we are justified in inferring a corresponding\ndegree of likeness in the rest of the two organisms. It is on this\nvery simple principle, and not upon imaginary laws of physiological\ncorrelation, about which, in most cases, we know nothing whatever, that\nthe so-called restorations of the pal\u00e6ontologist are based.\n\nAbundant illustrations of this truth will occur to every one who is\nfamiliar with pal\u00e6ontology; none is more suitable than the case of the\nso-called _Belemnites_. In the early days of the study of fossils,\nthis name was given to certain elongated stony bodies, ending at one\nextremity in a conical point, and truncated at the other, which were\ncommonly reputed to be thunderbolts, and as such to have descended\nfrom the sky. They are common enough in some parts of England; and, in\nthe condition in which they are ordinarily found, it might be difficult\nto give satisfactory reasons for denying them to be merely mineral\nbodies.\n\nThey appear, in fact, to consist of nothing but concentric layers\nof carbonate of lime, disposed in subcrystalline fibres, or prisms,\nperpendicular to the layers. Among a great number of specimens of these\nBelemnites, however, it was soon observed that some showed a conical\ncavity at the blunt end; and, in still better preserved specimens, this\ncavity appeared to be divided into chambers by delicate saucer-shaped\npartitions, situated at regular intervals one above the other. Now\nthere is no mineral body which presents any structure comparable to\nthis, and the conclusion suggested itself that the Belemnites must be\nthe effects of causes other than those which are at work in inorganic\nnature. On close examination, the saucer-shaped partitions were proved\nto be all perforated at one point, and the perforations being situated\nexactly in the same line, the chambers were seen to be traversed by\na canal, or _siphuncle_, which thus connected the smallest or apical\nchamber with the largest. There is nothing like this in the vegetable\nworld; but an exactly corresponding structure is met with in the\nshells of two kinds of existing animals, the pearly _Nautilus_ and\nthe _Spirula_, and only in them. These animals belong to the same\ndivision\u2014the _Cephalopoda_\u2014as the cuttle-fish, the squid, and the\noctopus. But they are the only existing members of the group which\npossess chambered, siphunculated shells; and it is utterly impossible\nto trace any physiological connection between the very peculiar\nstructural characters of a cephalopod and the presence of a chambered\nshell. In fact, the squid has, instead of any such shell, a horny\n\u201cpen,\u201d the cuttle-fish has the so-called \u201ccuttle-bone,\u201d and the octopus\nhas no shell, or, at most, a mere rudiment of one.\n\nNevertheless, seeing that there is nothing in nature at all like the\nchambered shell of the Belemnite, except the shells of the _Nautilus_\nand of the _Spirula_, it was legitimate to prophesy that the animal\nfrom which the fossil proceeded must have belonged to the group of the\n_Cephalopoda_. _Nautilus_ and _Spirula_ are both very rare animals,\nbut the progress of investigation brought to light the singular fact,\nthat, though each has the characteristic cephalopodous organisation, it\nis very different from the other. The shell of _Nautilus_ is external,\nthat of _Spirula_ internal; _Nautilus_ has four gills, _Spirula_\ntwo; _Nautilus_ has multitudinous tentacles, _Spirula_ has only ten\narms beset with horny rimmed suckers; _Spirula_, like the squids and\ncuttle-fishes, which it closely resembles, has a bag of ink which it\nsquirts out to cover its retreat when alarmed; _Nautilus_ has none.\n\nNo amount of physiological reasoning could enable any one to say\nwhether the animal which fabricated the Belemnite was more like\n_Nautilus_, or more like _Spirula_. But the accidental discovery of\nBelemnites in due connection with black elongated masses which were\ncertainly fossilised ink-bags, inasmuch as the ink could be ground up\nand used for painting as well as if it were recent sepia, settled the\nquestion; and it became perfectly safe to prophesy that the creature\nwhich fabricated the Belemnite was a two-gilled cephalopod with suckers\non its arms, and with all the other essential features of our living\nsquids, cuttle-fishes, and _Spirul\u00e6_. The pal\u00e6ontologist was, by this\ntime, able to speak as confidently about the animal of the Belemnite,\nas Zadig was respecting the queen\u2019s spaniel. He could give a very fair\ndescription of its external appearance, and even enter pretty fully\ninto the details of its internal organisation, and yet could declare\nthat neither he, nor any one else, had ever seen one. And as the\nqueen\u2019s spaniel was found, so happily has the animal of the Belemnite;\na few exceptionally preserved specimens having been discovered, which\ncompletely verify the retrospective prophecy of those who interpreted\nthe facts of the case by due application of the method of Zadig.\n\nThese Belemnites flourished in prodigious abundance in the seas of the\nmesozoic or secondary age of the world\u2019s geological history; but no\ntrace of them has been found in any of the tertiary deposits, and they\nappear to have died out towards the close of the mesozoic epoch. The\nmethod of Zadig, therefore, applies in full force to the events of a\nperiod which is immeasurably remote, which long preceded the origin\nof the most conspicuous mountain masses of the present world, and\nthe deposition, at the bottom of the ocean, of the rocks which form\nthe greater part of the soil of our present continents. The Euphrates\nitself, at the mouth of which Oannes landed, is a thing of yesterday\ncompared with a Belemnite; and even the liberal chronology of Magian\ncosmogony fixes the beginning of the world only at a time when other\napplications of Zadig\u2019s method afford convincing evidence that, could\nwe have been there to see, things would have looked very much as they\ndo now. Truly the magi were wise in their generation; they foresaw\nrightly that this pestilent application of the principles of common\nsense, inaugurated by Zadig, would be their ruin.\n\nBut it may be said that the method of Zadig, which is simple reasoning\nfrom analogy, does not account for the most striking feats of modern\npal\u00e6ontology\u2014the reconstruction of entire animals from a tooth or\nperhaps a fragment of a bone; and it may be justly urged that Cuvier,\nthe great master of this kind of investigation, gave a very different\naccount of the process which yielded such remarkable results.\n\nCuvier is not the first man of ability who has failed to make his\nown mental processes clear to himself, and he will not be the last.\nThe matter can be easily tested. Search the eight volumes of the\n\u201cRecherches sur les Ossemens fossiles\u201d from cover to cover, and\nnothing but the application of the method of Zadig will be found in\nthe arguments by which a fragment of a skeleton is made to reveal the\ncharacters of the animal to which it belonged.\n\nThere is one well-known case which may represent all. It is an\nexcellent illustration of Cuvier\u2019s sagacity, and he evidently takes\nsome pride in telling his story about it. A split slab of stone arrived\nfrom the quarries of Montmartre, the two halves of which contained the\ngreater part of the skeleton of a small animal. On careful examinations\nof the characters of the teeth and of the lower jaw, which happened\nto be exposed, Cuvier assured himself that they presented such a very\nclose resemblance to the corresponding parts in the living opossums\nthat he at once assigned the fossil to that genus.\n\nNow the opossums are unlike most mammals in that they possess two\nbones attached to the fore part of the pelvis, which are commonly\ncalled \u201cmarsupial bones.\u201d The name is a misnomer, originally conferred\nbecause it was thought that these bones have something to do with the\nsupport of the pouch, or marsupium, with which some, but not all, of\nthe opossums are provided. As a matter of fact, they have nothing to do\nwith the support of the pouch, and they exist as much in those opossums\nwhich have no pouches as in those which possess them. In truth, no one\nknows what the use of these bones may be, nor has any valid theory\nof their physiological import yet been suggested. And if we have no\nknowledge of the physiological importance of the bones themselves, it\nis obviously absurd to pretend that we are able to give physiological\nreasons why the presence of these bones is associated with certain\npeculiarities of the teeth and of the jaws. If any one knows why four\nmolar teeth and an inflected angle of the jaw are very generally found\nalong with marsupial bones, he has not yet communicated that knowledge\nto the world.\n\nIf, however, Zadig was right in concluding from the likeness of the\nhoof-prints which he observed to a horse\u2019s that the creature which made\nthem had a tail like that of a horse, Cuvier, seeing that the teeth\nand jaw of his fossil were just like those of an opossum, had the same\nright to conclude that the pelvis would also be like an opossum\u2019s; and\nso strong was his conviction that this retrospective prophecy, about\nan animal which he had never seen before, and which had been dead and\nburied for millions of years, would be verified, that he went to work\nupon the slab which contained the pelvis in confident expectation of\nfinding and laying bare the \u201cmarsupial bones,\u201d to the satisfaction of\nsome persons whom he had invited to witness their disinterment. As\nhe says:\u2014\u201cCette op\u00e9ration se fit en pr\u00e9sence de quelques personnes \u00e0\nqui j\u2019en avais annonc\u00e9 d\u2019avance le r\u00e9sultat, dans l\u2019intention de leur\nprouver par le fait la justice de nos th\u00e9ories zoologiques; puisque le\nvrai cachet d\u2019une th\u00e9orie est sans contredit la facult\u00e9 qu\u2019elle donne\nde pr\u00e9voir les ph\u00e9nom\u00e8nes.\u201d\n\nIn the \u201cOssemens fossiles\u201d Cuvier leaves his paper just as it first\nappeared in the \u201cAnnales du Mus\u00e9um,\u201d as \u201ca curious monument of the\nforce of zoological laws and of the use which may be made of them.\u201d\n\nZoological laws truly, but not physiological laws. If one sees a\nlive dog\u2019s head, it is extremely probable that a dog\u2019s tail is not\nfar off, though nobody can say why that sort of head and that sort\nof tail go together; what physiological connection there is between\nthe two. So, in the case of the Montmartre fossil, Cuvier, finding a\nthorough opossum\u2019s head, concluded that the pelvis also would be like\nan opossum\u2019s. But, most assuredly, the most advanced physiologist of\nthe present day could throw no light on the question why these are\nassociated, nor could pretend to affirm that the existence of the one\nis necessarily connected with that of the other. In fact, had it so\nhappened that the pelvis of the fossil had been originally exposed,\nwhile the head lay hidden, the presence of the \u201cmarsupial bones,\u201d\nhowever like they might have been to an opossum\u2019s, would by no means\nhave warranted the prediction that the skull would turn out to be that\nof the opossum. It might just as well have been like that of some\nother Marsupial; or even like that of the totally different group of\nMonotremes, of which the only living representatives are the _Echidna_\nand the _Ornithorhynchus_.\n\nFor all practical purposes, however, the empirical laws of\nco-ordination of structures, which are embodied in the generalisations\nof morphology, may be confidently trusted, if employed with due\ncaution, to lead to a just interpretation of fossil remains; or, in\nother words, we may look for the verification of the retrospective\nprophecies which are based upon them.\n\nAnd if this be the case, the late advances which have been made in\npal\u00e6ontological discovery open out a new field for such prophecies.\nFor it has been ascertained with respect to many groups of animals,\nthat, as we trace them back in time, their ancestors gradually cease\nto exhibit those special modifications which at present characterise\nthe type, and more nearly embody the general plan of the group to which\nthey belong.\n\nThus, in the well-known case of the horse, the toes which are\nsuppressed in the living horse are found to be more and more complete\nin the older members of the group, until, at the bottom of the Tertiary\nseries of America, we find an equine animal which has four toes in\nfront and three behind. No remains of the horse tribe are at present\nknown from any Mesozoic deposit. Yet who can doubt that, whenever a\nsufficiently extensive series of lacustrine and fluviatile beds of that\nage becomes known, the lineage which has been traced thus far will be\ncontinued by equine quadrupeds with an increasing number of digits,\nuntil the horse type merges in the five-toed form towards which these\ngradations point?\n\nBut the argument which holds good for the horse, holds good, not only\nfor all mammals, but for the whole animal world. And as the study of\nthe pedigrees, or lines of evolution, to which, at present, we have\naccess, brings to light, as it assuredly will do, the laws of that\nprocess, we shall be able to reason from the facts with which the\ngeological record furnishes us to those which have hitherto remained,\nand many of which, perhaps, may for ever remain, hidden. The same\nmethod of reasoning which enables us, when furnished with a fragment of\nan extinct animal, to prophesy the character which the whole organism\nexhibited, will, sooner or later, enable us, when we know a few of the\nlater terms of a genealogical series, to predict the nature of the\nearlier terms.\n\nIn no very distant future, the method of Zadig, applied to a greater\nbody of facts than the present generation is fortunate enough to\nhandle, will enable the biologist to reconstruct the scheme of life\nfrom its beginning, and to speak as confidently of the character of\nlong extinct living beings, no trace of which has been preserved, as\nZadig did of the queen\u2019s spaniel and the king\u2019s horse. Let us hope that\nthey may be better rewarded for their toil and their sagacity than was\nthe Babylonian philosopher; for perhaps, by that time, the Magi also\nmay be reckoned among the members of a forgotten Fauna, extinguished in\nthe struggle for existence against their great rival, common sense.\n\n\n\n\nVII.\n\nON THE BORDER TERRITORY BETWEEN THE ANIMAL AND THE\nVEGETABLE KINGDOMS.\n\n\nIn the whole history of science there is nothing more remarkable than\nthe rapidity of the growth of biological knowledge within the last\nhalf-century, and the extent of the modification which has thereby been\neffected in some of the fundamental conceptions of the naturalist.\n\nIn the second edition of the \u201cR\u00e8gne Animal,\u201d published in 1828,\nCuvier devotes a special section to the \u201cDivision of Organised Beings\ninto Animals and Vegetables,\u201d in which the question is treated with\nthat comprehensiveness of knowledge and clear critical judgment\nwhich characterise his writings, and justify us in regarding them\nas representative expressions of the most extensive, if not the\nprofoundest, knowledge of his time. He tells us that living beings have\nbeen subdivided from the earliest times into _animated beings_, which\npossess sense and motion, and _inanimated beings_, which are devoid of\nthese functions, and simply vegetate.\n\nAlthough the roots of plants direct themselves towards moisture, and\ntheir leaves towards air and light,\u2014although the parts of some plants\nexhibit oscillating movements without any perceptible cause, and the\nleaves of others retract when touched,\u2014yet none of these movements\njustify the ascription to plants of perception or of will. From the\nmobility of animals, Cuvier, with his characteristic partiality for\nteleological reasoning, deduces the necessity of the existence in them\nof an alimentary cavity, or reservoir of food, whence their nutrition\nmay be drawn by the vessels, which are a sort of internal roots; and,\nin the presence of this alimentary cavity, he naturally sees the\nprimary and the most important distinction between animals and plants.\n\nFollowing out his teleological argument, Cuvier remarks that the\norganisation of this cavity and its appurtenances must needs vary\naccording to the nature of the aliment, and the operations which it\nhas to undergo, before it can be converted into substances fitted for\nabsorption; while the atmosphere and the earth supply plants with\njuices ready prepared, and which can be absorbed immediately. As the\nanimal body required to be independent of heat and of the atmosphere,\nthere were no means by which the motion of its fluids could be produced\nby internal causes. Hence arose the second great distinctive character\nof animals, or the circulatory system, which is less important than the\ndigestive, since it was unnecessary, and therefore is absent, in the\nmore simple animals.\n\nAnimals further needed muscles for locomotion and nerves for\nsensibility. Hence, says Cuvier, it was necessary that the chemical\ncomposition of the animal body should be more complicated than that of\nthe plant; and it is so, inasmuch as an additional substance, nitrogen,\nenters into it as an essential element; while, in plants, nitrogen is\nonly accidentally joined with the three other fundamental constituents\nof organic beings\u2014carbon, hydrogen, and oxygen. Indeed, he afterwards\naffirms that nitrogen is peculiar to animals; and herein he places the\nthird distinction between the animal and the plant. The soil and the\natmosphere supply plants with water, composed of hydrogen and oxygen;\nair, consisting of nitrogen and oxygen; and carbonic acid, containing\ncarbon and oxygen. They retain the hydrogen and the carbon, exhale the\nsuperfluous oxygen, and absorb little or no nitrogen. The essential\ncharacter of vegetable life is the exhalation of oxygen, which is\neffected through the agency of light. Animals, on the contrary,\nderive their nourishment either directly or indirectly from plants.\nThey get rid of the superfluous hydrogen and carbon, and accumulate\nnitrogen. The relations of plants and animals to the atmosphere are\ntherefore inverse. The plant withdraws water and carbonic acid from\nthe atmosphere, the animal contributes both to it. Respiration\u2014that\nis, the absorption of oxygen and the exhalation of carbonic acid\u2014is\nthe specially animal function of animals, and constitutes their fourth\ndistinctive character.\n\nThus wrote Cuvier in 1828. But, in the fourth and fifth decades of\nthis century, the greatest and most rapid revolution which biological\nscience has ever undergone was effected by the application of the\nmodern microscope to the investigation of organic structure; by the\nintroduction of exact and easily manageable methods of conducting the\nchemical analysis of organic compounds; and finally, by the employment\nof instruments of precision for the measurement of the physical forces\nwhich are at work in the living economy.\n\nThat the semi-fluid contents (which we now term protoplasm) of the\ncells of certain plants, such as the _Char\u00e6_, are in constant and\nregular motion, was made out by Bonaventura Corti a century ago; but\nthe fact, important as it was, fell into oblivion, and had to be\nrediscovered by Treviranus in 1807. Robert Brown noted the more complex\nmotions of the protoplasm in the cells of _Tradescantia_ in 1831; and\nnow such movements of the living substance of plants are well known to\nbe some of the most widely-prevalent phenomena of vegetable life.\n\nAgardh, and other of the botanists of Cuvier\u2019s generation, who occupied\nthemselves with the lower plants, had observed that, under particular\ncircumstances, the contents of the cells of certain water-weeds were\nset free, and moved about with considerable velocity, and with all the\nappearances of spontaneity, as locomotive bodies, which, from their\nsimilarity to animals of simple organisation, were called \u201czoospores.\u201d\nEven as late as 1845, however, a botanist of Schleiden\u2019s eminence dealt\nvery sceptically with these statements; and his scepticism was the more\njustified, since Ehrenberg, in his elaborate and comprehensive work\non the _Infusoria_, had declared the greater number of what are now\nrecognised as locomotive plants to be animals.\n\nAt the present day, innumerable plants and free plant cells are known\nto pass the whole or part of their lives in an actively locomotive\ncondition, in no wise distinguishable from that of one of the simpler\nanimals; and, while in this condition, their movements are, to all\nappearance, as spontaneous\u2014as much the product of volition\u2014as those of\nsuch animals.\n\nHence the teleological argument for Cuvier\u2019s first diagnostic\ncharacter\u2014the presence in animals of an alimentary cavity, or internal\npocket, in which they can carry about their nutriment\u2014has broken\ndown, so far, at least, as his mode of stating it goes. And, with the\nadvance of microscopic anatomy, the universality of the fact itself\namong animals has ceased to be predicable. Many animals of even complex\nstructure, which live parasitically within others, are wholly devoid\nof an alimentary cavity. Their food is provided for them, not only\nready cooked, but ready digested, and the alimentary canal, become\nsuperfluous, has disappeared. Again, the males of most Rotifers have no\ndigestive apparatus; as a German naturalist has remarked, they devote\nthemselves entirely to the \u201cMinnedienst,\u201d and are to be reckoned among\nthe few realisations of the Byronic ideal of a lover. Finally, amidst\nthe lowest forms of animal life, the speck of gelatinous protoplasm,\nwhich constitutes the whole body, has no permanent digestive cavity or\nmouth, but takes in its food anywhere; and digests, so to speak, all\nover its body.\n\nBut although Cuvier\u2019s leading diagnosis of the animal from the plant\nwill not stand a strict test, it remains one of the most constant of\nthe distinctive characters of animals. And, if we substitute for the\npossession of an alimentary cavity, the power of taking solid nutriment\ninto the body and there digesting it, the definition so changed\nwill cover all animals, except certain parasites, and the few and\nexceptional cases of non-parasitic animals which do not feed at all. On\nthe other hand, the definition thus amended will exclude all ordinary\nvegetable organisms.\n\nCuvier himself practically gives up his second distinctive mark when he\nadmits that it is wanting in the simpler animals.\n\nThe third distinction is based on a completely erroneous conception of\nthe chemical differences and resemblances between the constituents of\nanimal and vegetable organisms, for which Cuvier is not responsible,\nas it was current among contemporary chemists. It is now established\nthat nitrogen is as essential a constituent of vegetable as of animal\nliving matter; and that the latter is, chemically speaking, just as\ncomplicated as the former. Starchy substances, cellulose and sugar,\nonce supposed to be exclusively confined to plants, are now known to\nbe regular and normal products of animals. Amylaceous and saccharine\nsubstances are largely manufactured, even by the highest animals;\ncellulose is widespread as a constituent of the skeletons of the lower\nanimals; and it is probable that amyloid substances are universally\npresent in the animal organism, though not in the precise form of\nstarch.\n\nMoreover, although it remains true that there is an inverse relation\nbetween the green plant in sunshine and the animal, in so far as, under\nthese circumstances, the green plant decomposes carbonic acid and\nexhales oxygen, while the animal absorbs oxygen and exhales carbonic\nacid; yet, the exact researches of the modern chemical investigators\nof the physiological processes of plants have clearly demonstrated the\nfallacy of attempting to draw any general distinction between animals\nand vegetables on this ground. In fact, the difference vanishes with\nthe sunshine, even in the case of the green plant; which, in the dark,\nabsorbs oxygen and gives out carbonic acid like any animal.[30] On\nthe other hand, those plants, such as the fungi, which contain no\nchlorophyll and are not green, are always, so far as respiration is\nconcerned, in the exact position of animals. They absorb oxygen and\ngive out carbonic acid.\n\nThus, by the progress of knowledge, Cuvier\u2019s fourth distinction\nbetween the animal and the plant has been as completely invalidated as\nthe third and second; and even the first can be retained only in a\nmodified form and subject to exceptions.\n\nBut has the advance of biology simply tended to break down old\ndistinctions, without establishing new ones?\n\nWith a qualification, to be considered presently, the answer to this\nquestion is undoubtedly in the affirmative. The famous researches of\nSchwann and Schleiden in 1837 and the following years, founded the\nmodern science of histology, or that branch of anatomy which deals\nwith the ultimate visible structure of organisms, as revealed by\nthe microscope; and, from that day to this, the rapid improvement\nof methods of investigation, and the energy of a host of accurate\nobservers, have given greater and greater breadth and firmness to\nSchwann\u2019s great generalisation, that a fundamental unity of structure\nobtains in animals and plants; and that, however diverse may be the\nfabrics, or _tissues_, of which their bodies are composed, all these\nvaried structures result from the metamorphosis of morphological units\n(termed _cells_, in a more general sense than that in which the word\n\u201ccells\u201d was at first employed), which are not only similar in animals\nand in plants respectively, but present a close resemblance, when those\nof animals and those of plants are compared together.\n\nThe contractility which is the fundamental condition of locomotion,\nhas not only been discovered to exist far more widely among plants\nthan was formerly imagined; but, in plants, the act of contraction has\nbeen found to be accompanied, as Dr. Burdon Sanderson\u2019s interesting\ninvestigations have shown, by a disturbance of the electrical state of\nthe contractile substance, comparable to that which was found by Du\nBois Reymond to be a concomitant of the activity of ordinary muscle in\nanimals.\n\nAgain, I know of no test by which the reaction of the leaves of the\nSundew and of other plants to stimuli, so fully and carefully studied\nby Mr. Darwin, can be distinguished from those acts of contraction\nfollowing upon stimuli, which are called \u201creflex\u201d in animals.\n\nOn each lobe of the bilobed leaf of Venus\u2019s fly trap (_Dion\u00e6a\nmuscipula_) are three delicate filaments which stand out at right angle\nfrom the surface of the leaf. Touch one of them with the end of a fine\nhuman hair and the lobes of the leaf instantly close together[31] in\nvirtue of an act of contraction of part of their substance, just as the\nbody of a snail contracts into its shell when one of its \u201chorns\u201d is\nirritated.\n\nThe reflex action of the snail is the result of the presence of a\nnervous system in the animal. A molecular change takes place in the\nnerve of the tentacle, is propagated to the muscles by which the body\nis retracted, and causing them to contract, the act of retraction\nis brought about. Of course the similarity of the acts does not\nnecessarily involve the conclusion that the mechanism by which they are\neffected is the same; but it suggests a suspicion of their identity\nwhich needs careful testing.\n\nThe results of recent inquiries into the structure of the nervous\nsystem of animals converge towards the conclusion that the nerve\nfibres, which we have hitherto regarded as ultimate elements of nervous\ntissue, are not such, but are simply the visible aggregations of vastly\nmore attenuated filaments, the diameter of which dwindles down to the\nlimits of our present microscopic vision, greatly as these have been\nextended by modern improvements of the microscope; and that a nerve\nis, in its essence, nothing but a linear tract of specially modified\nprotoplasm between two points of an organism\u2014one of which is able to\naffect the other by means of the communication so established. Hence,\nit is conceivable that even the simplest living being may possess a\nnervous system. And the question whether plants are provided with a\nnervous system or not, thus acquires a new aspect, and presents the\nhistologist and physiologist with a problem of extreme difficulty,\nwhich must be attacked from a new point of view and by the aid of\nmethods which have yet to be invented.\n\nThus it must be admitted that plants may be contractile and locomotive;\nthat, while locomotive, their movements may have as much appearance\nof spontaneity as those of the lowest animals; and that many exhibit\nactions, comparable to those which are brought about by the agency of a\nnervous system in animals. And it must be allowed to be possible that\nfurther research may reveal the existence of something comparable to a\nnervous system in plants. So that I know not where we can hope to find\nany absolute distinction between animals and plants, unless we return\nto their mode of nutrition, and inquire whether certain differences of\na more occult character than those imagined to exist by Cuvier, and\nwhich certainly hold good for the vast majority of animals and plants,\nare of universal application.\n\nA bean may be supplied with water in which salts of ammonia and\ncertain other mineral salts are dissolved in due proportion; with\natmospheric air containing its ordinary minute dose of carbonic acid;\nand with nothing else but sunlight and heat. Under these circumstances,\nunnatural as they are, with proper management, the bean will thrust\nforth its radicle and its plumule; the former will grow down into\nroots, the latter grow up into the stem and leaves of a vigorous bean\nplant; and this plant will, in due time, flower and produce its crop of\nbeans, just as if it were grown in the garden or in the field.\n\nThe weight of the nitrogenous protein compounds, of the oily, starchy,\nsaccharine and woody substances contained in the full-grown plant\nand its seeds, will be vastly greater than the weight of the same\nsubstances contained in the bean from which it sprang. But nothing has\nbeen supplied to the bean save water, carbonic acid, ammonia, potash,\nlime, iron, and the like, in combination with phosphoric, sulphuric,\nand other acids. Neither protein, nor fat, nor starch, nor sugar, nor\nany substance in the slightest degree resembling them, has formed part\nof the food of the bean. But the weights of the carbon, hydrogen,\noxygen, nitrogen, phosphorus, sulphur, and other elementary bodies\ncontained in the bean-plant, and in the seeds which it produces, are\nexactly equivalent to the weights of the same elements which have\ndisappeared from the materials supplied to the bean during its growth.\nWhence it follows that the bean has taken in only the raw materials of\nits fabric, and has manufactured them into bean stuffs.\n\nThe bean has been able to perform this great chemical feat by the\nhelp of its green colouring matter, or chlorophyll; for it is only\nthe green parts of the plant which, under the influence of sunlight,\nhave the marvellous power of decomposing carbonic acid, setting free\nthe oxygen and laying hold of the carbon which it contains. In fact,\nthe bean obtains two of the absolutely indispensable elements of its\nsubstance from two distinct sources; the watery solution, in which its\nroots are plunged, contains nitrogen but no carbon; the air, to which\nthe leaves are exposed, contains carbon, but its nitrogen is in the\nstate of a free gas, in which condition the bean can make no use of\nit;[32] and the chlorophyll[33] is the apparatus by which the carbon is\nextracted from the atmospheric carbonic acid\u2014the leaves being the chief\nlaboratories in which this operation is effected.\n\nThe great majority of conspicuous plants are, as everybody knows,\ngreen; and this arises from the abundance of their chlorophyll.\nThe few which contain no chlorophyll and are colourless, are unable\nto extract the carbon which they require from atmospheric carbonic\nacid, and lead a parasitic existence upon other plants; but it by no\nmeans follows, often as the statement has been repeated, that the\nmanufacturing power of plants depends on their chlorophyll, and its\ninteraction with the rays of the sun. On the contrary, it is easily\ndemonstrated, as Pasteur first proved, that the lowest fungi, devoid\nof chlorophyll, or of any substitute for it, as they are, nevertheless\npossess the characteristic manufacturing powers of plants in a very\nhigh degree. Only it is necessary that they should be supplied with\na different kind of raw material; as they cannot extract carbon from\ncarbonic acid, they must be furnished with something else that contains\ncarbon. Tartaric acid is such a substance; and if a single spore of\nthe commonest and most troublesome of moulds\u2014_Penicillium_\u2014be sown\nin a saucerful of water, in which tartrate of ammonia, with a small\npercentage of phosphates and sulphates is contained, and kept warm,\nwhether in the dark or exposed to light, it will, in a short time, give\nrise to a thick crust of mould, which contains many million times the\nweight of the original spore, in protein compounds and cellulose. Thus\nwe have a very wide basis of fact for the generalisation that plants\nare essentially characterised by their manufacturing capacity\u2014by their\npower of working up mere mineral matters into complex organic compounds.\n\nContrariwise, there is a no less wide foundation for the\ngeneralisation that animals, as Cuvier puts it, depend directly or\nindirectly upon plants for the materials of their bodies; that is,\neither they are herbivorous, or they eat other animals which are\nherbivorous.\n\nBut for what constituents of their bodies are animals thus dependent\nupon plants? Certainly not for their horny matter; nor for chondrin,\nthe proximate chemical element of cartilage; nor for gelatine; nor for\nsyntonin, the constituent of muscle; nor for their nervous or biliary\nsubstances; nor for their amyloid matters; nor, necessarily, for their\nfats.\n\nIt can be experimentally demonstrated that animals can make these for\nthemselves. But that which they cannot make, but must, in all known\ncases, obtain directly or indirectly from plants, is the peculiar\nnitrogenous matter, protein. Thus the plant is the ideal _prol\u00e9taire_\nof the living world, the worker who produces; the animal, the ideal\naristocrat, who mostly occupies himself in consuming, after the manner\nof that noble representative of the line of Z\u00e4hdarm, whose epitaph is\nwritten in _Sartor Resartus_.\n\nHere is our last hope of finding a sharp line of demarcation between\nplants and animals; for, as I have already hinted, there is a border\nterritory between the two kingdoms, a sort of no-man\u2019s-land, the\ninhabitants of which certainly cannot be discriminated and brought to\ntheir proper allegiance in any other way.\n\nSome months ago, Professor Tyndall asked me to examine a drop of\ninfusion of hay, placed under an excellent and powerful microscope,\nand to tell him what I thought some organisms visible in it were.\nI looked and observed, in the first place, multitudes of _Bacteria_\nmoving about with their ordinary intermittent spasmodic wriggles. As\nto the vegetable nature of these there is now no doubt. Not only does\nthe close resemblance of the _Bacteria_ to unquestionable plants,\nsuch as the _Oscillatori\u00e6_, and lower forms of _Fungi_, justify this\nconclusion, but the manufacturing test settles the question at once. It\nis only needful to add a minute drop of fluid containing _Bacteria_,\nto water in which tartrate, phosphate, and sulphate of ammonia are\ndissolved; and, in a very short space of time, the clear fluid becomes\nmilky by reason of their prodigious multiplication, which, of course,\nimplies the manufacture of living Bacterium-stuff out of these merely\nsaline matters.\n\nBut other active organisms, very much larger than the _Bacteria_,\nattaining in fact the comparatively gigantic dimensions of 1/3000 of an\ninch or more, incessantly crossed the field of view. Each of these had\na body shaped like a pear, the small end being slightly incurved and\nproduced into a long curved filament, or _cilium_, of extreme tenuity.\nBehind this, from the concave side of the incurvation, proceeded\nanother long cilium, so delicate as to be discernible only by the use\nof the highest powers and careful management of the light. In the\ncentre of the pear-shaped body a clear round space could occasionally\nbe discerned, but not always; and careful watching showed that this\nclear vacuity appeared gradually, and then shut up and disappeared\nsuddenly, at regular intervals. Such a structure is of common\noccurrence among the lowest plants and animals, and is known as a\n_contractile vacuole_.\n\nThe little creature thus described sometimes propelled itself with\ngreat activity, with a curious rolling motion, by the lashing of the\nfront cilium, while the second cilium trailed behind; sometimes it\nanchored itself by the hinder cilium and was spun round by the working\nof the other, its motions resembling those of an anchor buoy in a heavy\nsea. Sometimes, when two were in full career towards one another, each\nwould appear dexterously to get out of the other\u2019s way; sometimes a\ncrowd would assemble and jostle one another, with as much semblance of\nindividual effort as a spectator on the Grands Mulets might observe\nwith a telescope among the specks representing men in the valley of\nChamounix.\n\nThe spectacle, though always surprising, was not new to me. So my\nreply to the question put to me was, that these organisms were what\nbiologists call _Monads_, and though they might be animals, it was\nalso possible that they might, like the _Bacteria_, be plants. My\nfriend received my verdict with an expression which showed a sad want\nof respect for authority. He would as soon believe that a sheep was\na plant. Naturally piqued by this want of faith, I have thought a\ngood deal over the matter; and as I still rest in the lame conclusion\nI originally expressed, and must even now confess that I cannot\ncertainly say whether this creature is an animal or a plant, I think\nit may be well to state the grounds of my hesitation at length. But,\nin the first place, in order that I may conveniently distinguish\nthis \u201cMonad\u201d from the multitude of other things which go by the same\ndesignation, I must give it a name of its own. I think (though, for\nreasons which need not be stated at present, I am not quite sure)\nthat it is identical with the species _Monas lens_, as defined by the\neminent French microscopist Dujardin, though his magnifying power was\nprobably insufficient to enable him to see that it is curiously like\na much larger form of monad which he has named _Heteromita_. I shall,\ntherefore, call it not _Monas_, but _Heteromita lens_.\n\nI have been unable to devote to my _Heteromita_ the prolonged study\nneedful to work out its whole history, which would involve weeks, or\nit may be months, of unremitting attention. But I the less regret this\ncircumstance, as some remarkable observations recently published by\nMessrs. Dallinger and Drysdale[34] on certain Monads, relate, in part,\nto a form so similar to my _Heteromita lens_, that the history of the\none may be used to illustrate that of the other. These most patient\nand painstaking observers, who employed the highest attainable powers\nof the microscope and, relieving one another, kept watch day and night\nover the same individual monads, have been enabled to trace out the\nwhole history of their _Heteromita_; which they found in infusions of\nthe heads of fishes of the Cod tribe.\n\nOf the four monads described and figured by these investigators,\none, as I have said, very closely resembles _Heteromita lens_ in\nevery particular, except that it has a separately distinguishable\ncentral particle or \u201cnucleus,\u201d which is not certainly to be made out\nin _Heteromita lens_; and that nothing is said by Messrs. Dallinger\nand Drysdale of the existence of a contractile vacuole in this monad,\nthough they describe it in another.\n\nTheir _Heteromita_, however, multiplied rapidly by fission. Sometimes\na transverse constriction appeared; the hinder half developed a new\ncilium, and the hinder cilium gradually split from its base to its\nfree end, until it was divided into two; a process which, considering\nthe fact that this fine filament cannot be much more than 1/100000\nof an inch in diameter, is wonderful enough. The constriction of the\nbody extended inwards until the two portions were united by a narrow\nisthmus; finally, they separated and each swam away by itself, a\ncomplete _Heteromita_, provided with its two cilia. Sometimes the\nconstriction took a longitudinal direction, with the same ultimate\nresult. In each case the process occupied not more than six or seven\nminutes. At this rate, a single _Heteromita_ would give rise to a\nthousand like itself in the course of an hour, to about a million in\ntwo hours, and to a number greater than the generally assumed number\nof human beings now living in the world in three hours; or, if we give\neach _Heteromita_ an hour\u2019s enjoyment of individual existence, the same\nresult will be obtained in about a day. The apparent suddenness of the\nappearance of multitudes of such organisms as these, in any nutritive\nfluid to which one obtains access, is thus easily explained.\n\nDuring these processes of multiplication by fission, the _Heteromita_\nremains active; but sometimes another mode of fission occurs. The body\nbecomes rounded and quiescent, or nearly so; and, while in this resting\nstate, divides into two portions, each of which is rapidly converted\ninto an active _Heteromita_.\n\nA still more remarkable phenomenon is that kind of multiplication\nwhich is preceded by the union of two monads, by a process which is\ntermed _conjugation_. Two active _Heteromit\u00e6_ become applied to one\nanother, and then slowly and gradually coalesce into one body. The\ntwo nuclei run into one; and the mass resulting from the conjugation\nof the two _Heteromit\u00e6_, thus fused together, has a triangular form.\nThe two pairs of cilia are to be seen, for some time, at two of the\nangles, which answer to the small ends of the conjoined monads; but\nthey ultimately vanish, and the twin organism, in which all visible\ntraces of organisation have disappeared, falls into a state of rest.\nSudden wave-like movements of its substance next occur; and, in a short\ntime, the apices of the triangular mass burst, and give exit to a dense\nyellowish, glairy fluid, filled with minute granules. This process,\nwhich, it will be observed, involves the actual confluence and mixture\nof the substance of two distinct organisms, is effected in the space of\nabout two hours.\n\nThe authors whom I quote say that they \u201ccannot express\u201d the excessive\nminuteness of the granules in question, and they estimate their\ndiameter at less than 1/200000 of an inch. Under the highest powers\nof the microscope at present applicable such specks are hardly\ndiscernible. Nevertheless, particles of this size are massive when\ncompared to physical molecules; whence there is no reason to doubt\nthat each, small as it is, may have a molecular structure sufficiently\ncomplex to give rise to the phenomena of life. And, as a matter of\nfact, by patient watching of the place at which these infinitesimal\nliving particles were discharged, our observers assured themselves\nof their growth and development into new monads. These, in about\nfour hours from their being set free, had attained a sixth of the\nlength of the parent, with the characteristic cilia, though at\nfirst they were quite motionless; and, in four hours more, they had\nattained the dimensions and exhibited all the activity of the adult.\nThese inconceivably minute particles are therefore the germs of the\n_Heteromita_; and from the dimensions of these germs it is easily\nshown that the body formed by conjugation may, at a low estimate,\nhave given exit to thirty thousand of them; a result of a matrimonial\nprocess whereby the contracting parties, without a metaphor, \u201cbecome\none flesh,\u201d enough to make a Malthusian despair of the future of the\nUniverse.\n\nI am not aware that the investigators from whom I have borrowed this\nhistory have endeavoured to ascertain whether their monads take solid\nnutriment or not; so that though they help us very much to fill up the\nblanks in the history of my _Heteromita_, their observations throw no\nlight on the problem we are trying to solve\u2014Is it an animal or is it a\nplant?\n\nUndoubtedly it is possible to bring forward very strong arguments in\nfavour of regarding _Heteromita_ as a plant.\n\nFor example, there is a Fungus, an obscure and almost microscopic\nmould, termed _Peronospora infestans_. Like many other Fungi, the\n_Peronospor\u00e6_ are parasitic upon other plants; and this particular\n_Peronospora_ happens to have attained much notoriety and political\nimportance, in a way not without a parallel in the career of notorious\npoliticians, namely, by reason of the frightful mischief it has\ndone to mankind. For it is this _Fungus_ which is the cause of the\npotato disease; and, therefore, _Peronospora infestans_ (doubtless of\nexclusively Saxon origin, though not accurately known to be so) brought\nabout the Irish famine. The plants afflicted with the malady are found\nto be infested by a mould, consisting of fine tubular filaments, termed\n_hyph\u00e6_, which burrow through the substance of the potato plant, and\nappropriate to themselves the substance of their host; while, at the\nsame time, directly or indirectly, they set up chemical changes by\nwhich even its woody framework becomes blackened, sodden, and withered.\n\nIn structure, however, the _Peronospora_ is as much a mould as the\ncommon _Penicillium_; and just as the _Penicillium_ multiplies by the\nbreaking up of its hyph\u00e6 into separate rounded bodies, the spores;\nso, in the _Peronospora_, certain of the hyph\u00e6 grow out into the air\nthrough the interstices of the superficial cells of the potato plant,\nand develop spores. Each of these hyph\u00e6 usually gives off several\nbranches. The ends of the branches dilate and become closed sacs, which\neventually drop off as spores. The spores falling on some part of the\nsame potato plant, or carried by the wind to another, may at once\ngerminate, throwing out tubular prolongations which become hyph\u00e6, and\nburrow into the substance of the plant attacked. But, more commonly,\nthe contents of the spore divide into six or eight separate portions.\nThe coat of the spore gives way, and each portion then emerges as an\nindependent organism, which has the shape of a bean, rather narrower at\none end than the other, convex on one side, and depressed or concave on\nthe opposite. From the depression, two long and delicate cilia proceed,\none shorter than the other, and directed forwards. Close to the origin\nof these cilia, in the substance of the body, is a regularly pulsating,\ncontractile vacuole. The shorter cilium vibrates actively, and effects\nthe locomotion of the organism, while the other trails behind; the\nwhole body rolling on its axis with its pointed end forwards.\n\nThe eminent botanist, De Bary, who was not thinking of our problem,\ntells us, in describing the movements of these \u201cZoospores,\u201d that, as\nthey swim about, \u201cForeign bodies are carefully avoided, and the whole\nmovement has a deceptive likeness to the voluntary changes of place\nwhich are observed in microscopic animals.\u201d\n\nAfter swarming about in this way in the moisture on the surface of\na leaf or stem (which, film though it may be, is an ocean to such a\nfish) for half an hour, more or less, the movement of the zoospore\nbecomes slower, and is limited to a slow turning upon its axis, without\nchange of place. It then becomes quite quiet, the cilia disappear, it\nassumes a spherical form, and surrounds itself with a distinct, though\ndelicate, membranous coat. A protuberance then grows out from one side\nof the sphere, and rapidly increasing in length, assumes the character\nof a hypha. The latter penetrates into the substance of the potato\nplant, either by entering a stomate, or by boring through the wall of\nan epidermic cell, and ramifies, as a mycelium, in the substance of\nthe plant, destroying the tissues with which it comes in contact. As\nthese processes of multiplication take place very rapidly, millions of\nspores are soon set free from a single infested plant; and, from their\nminuteness, they are readily transported by the gentlest breeze. Since,\nagain, the zoospores set free from each spore, in virtue of their\npowers of locomotion, swiftly disperse themselves over the surface, it\nis no wonder that the infection, once started, soon spreads from field\nto field, and extends its ravages over a whole country.\n\nHowever, it does not enter into my present plan to treat of the\npotato disease, instructively as its history bears upon that of other\nepidemics; and I have selected the case of the _Peronospora_ simply\nbecause it affords an example of an organism, which, in one stage of\nits existence, is truly a \u201cMonad,\u201d indistinguishable by any important\ncharacter from our _Heteromita_, and extraordinarily like it in some\nrespects. And yet this \u201cMonad\u201d can be traced, step by step, through the\nseries of metamorphoses which I have described, until it assumes the\nfeatures of an organism, which is as much a plant as is an oak or an\nelm.\n\nMoreover, it would be possible to pursue the analogy farther. Under\ncertain circumstances, a process of conjugation takes place in the\n_Peronospora_. Two separate portions of its protoplasm become fused\ntogether, surround themselves with a thick coat, and give rise to a\nsort of vegetable egg called an _oospore_. After a period of rest,\nthe contents of the oospore break up into a number of zoospores like\nthose already described, each of which, after a period of activity,\ngerminates in the ordinary way. This process obviously corresponds\nwith the conjugation and subsequent setting free of germs in the\n_Heteromita_.\n\nBut it may be said that the _Peronospora_ is, after all, a questionable\nsort of plant; that it seems to be wanting in the manufacturing power,\nselected as the main distinctive character of vegetable life; or, at\nany rate, that there is no proof that it does not get its protein\nmatter ready made from the potato plant.\n\nLet us, therefore, take a case which is not open to these objections.\n\nThere are some small plants known to botanists as members of the genus\n_Coleoch\u00e6te_, which, without being truly parasitic, grow upon certain\nwater-weeds, as lichens grow upon trees. The little plant has the form\nof an elegant green star, the branching arms of which are divided into\ncells. Its greenness is due to its chlorophyll, and it undoubtedly\nhas the manufacturing power in full degree, decomposing carbonic acid\nand setting oxygen free, under the influence of sunlight. But the\nprotoplasmic contents of some of the cells of which the plant is made\nup occasionally divide, by a method similar to that which effects the\ndivision of the contents of the _Peronospora_ spore; and the severed\nportions are then set free as active monad-like zoospores. Each is oval\nand is provided at one extremity with two long active cilia. Propelled\nby these, it swims about for a longer or shorter time, but at length\ncomes to a state of rest and gradually grows into a _Coleoch\u00e6te_.\nMoreover, as in the _Peronospora_, conjugation may take place and\nresult in an oospore; the contents of which divide and are set free as\nmonadiform germs.\n\nIf the whole history of the zoospores of _Peronospora_, and of\n_Coleoch\u00e6te_ were unknown, they would undoubtedly be classed among\n\u201cMonads\u201d with the same right as _Heteromita_; why then may not\n_Heteromita_ be a plant, even though the cycle of forms through\nwhich it passes shows no terms quite so complex as those which occur\nin _Peronospora_ and _Coleoch\u00e6te_? And, in fact, there are some\ngreen organisms, in every respect characteristically plants, such\nas _Chlamydomonas_, and the common _Volvox_, or so-called \u201cGlobe\nanimalcule,\u201d which run through a cycle of forms of just the same simple\ncharacter as those of _Heteromita_.\n\nThe name of _Chlamydomonas_ is applied to certain microscopic green\nbodies, each of which consists of a protoplasmic central substance\ninvested by a structureless sac. The latter contains cellulose, as\nin ordinary plants; and the chlorophyll which gives the green colour\nenables the _Chlamydomonas_ to decompose carbonic acid and fix carbon\nas they do. Two long cilia protrude through the cell-wall, and effect\nthe rapid locomotion of this \u201cmonad,\u201d which, in all respects except its\nmobility, is characteristically a plant. Under ordinary circumstances,\nthe _Chlamydomonas_ multiplies by simple fission, each splitting\ninto two or into four parts, which separate and become independent\norganisms. Sometimes, however, the _Chlamydomonas_ divides into eight\nparts, each of which is provided with four instead of two cilia. These\n\u201czoospores\u201d conjugate in pairs, and give rise to quiescent bodies,\nwhich multiply by division, and eventually pass into the active state.\n\nThus, so far as outward form and the general character of the cycle\nof modifications, through which the organism passes in the course of\nits life, are concerned, the resemblance between _Chlamydomonas_ and\n_Heteromita_ is of the closest description. And on the face of the\nmatter there is no ground for refusing to admit that _Heteromita_ may\nbe related to _Chlamydomonas_, as the colourless fungus is to the green\nalga. _Volvox_ may be compared to a hollow sphere, the wall of which\nis made up of coherent Chlamydomonads; and which progresses with a\nrotating motion effected by the paddling of the multitudinous pairs of\ncilia which project from its surface. Each _Volvox_monad, moreover,\npossesses a red pigment spot, like the simplest form of eye known among\nanimals. The methods of fissive multiplication and of conjugation\nobserved in the monads of this locomotive globe are essentially similar\nto those observed in _Chlamydomonas_; and, though a hard battle has\nbeen fought over it, _Volvox_ is now finally surrendered to the\nBotanists.\n\nThus there is really no reason why _Heteromita_ may not be a plant; and\nthis conclusion would be very satisfactory, if it were not equally easy\nto show that there is really no reason why it should not be an animal.\nFor there are numerous organisms presenting the closest resemblance to\n_Heteromita_, and, like it, grouped under the general name of \u201cMonads,\u201d\nwhich, nevertheless, can be observed to take in solid nutriment, and\nwhich, therefore, have a virtual, if not an actual, mouth and digestive\ncavity, and thus come under Cuvier\u2019s definition of an animal. Numerous\nforms of such animals have been described by Ehrenberg, Dujardin, H.\nJames Clark, and other writers on the _Infusoria_. Indeed, in another\ninfusion of hay in which my _Heteromita lens_ occurred, there were\ninnumerable infusorial animalcules belonging to the well-known species\n_Colpoda cucullus_.[35]\n\nFull-sized specimens of this animalcule attain a length of between\n1/300 or 1/400 of an inch, so that it may have ten times the length\nand a thousand times the mass of a _Heteromita_. In shape, it is\nnot altogether unlike _Heteromita_. The small end, however, is not\nproduced into one long cilium, but the general surface of the body is\ncovered with small actively vibrating ciliary organs, which are only\nlongest at the small end. At the point which answers to that from which\nthe two cilia arise in _Heteromita_, there is a conical depression, the\nmouth; and, in young specimens, a tapering filament, which reminds one\nof the posterior cilium of _Heteromita_, projects from this region.\n\nThe body consists of a soft granular protoplasmic substance, the middle\nof which is occupied by a large oval mass called the \u201cnucleus;\u201d while,\nat its hinder end, is a \u201ccontractile vacuole,\u201d conspicuous by its\nregular rhythmic appearances and disappearances. Obviously, although\nthe _Colpoda_ is not a monad, it differs from one only in subordinate\ndetails. Moreover, under certain conditions, it becomes quiescent,\nincloses itself in a delicate case or _cyst_, and then divides into\ntwo, four, or more portions, which are eventually set free and swim\nabout as active _Colpod\u00e6_.\n\nBut this creature is an unmistakable animal, and full-sized _Colpod\u00e6_\nmay be fed as easily as one feeds chickens. It is only needful to\ndiffuse very finely ground carmine through the water in which they\nlive, and, in a very short time, the bodies of the _Colpod\u00e6_ are\nstuffed with the deeply-coloured granules of the pigment.\n\nAnd if this were not sufficient evidence of the animality of _Colpoda_,\nthere comes the fact that it is even more similar to another well-known\nanimalcule, _Param\u00e6cium_, than it is to a monad. But _Param\u00e6cium_ is\nso huge a creature compared with those hitherto discussed\u2014it reaches\n1/120 of an inch or more in length\u2014that there is no difficulty in\nmaking out its organisation in detail; and in proving that it is not\nonly an animal, but that it is an animal which possesses a somewhat\ncomplicated organisation. For example, the surface layer of its body is\ndifferent in structure from the deeper parts. There are two contractile\nvacuoles, from each of which radiates a system of vessel-like canals;\nand not only is there a conical depression continuous with a tube,\nwhich serve as mouth and gullet, but the food ingested takes a definite\ncourse, and refuse is rejected from a definite region. Nothing is\neasier than to feed these animals, and to watch the particles of indigo\nor carmine accumulate at the lower end of the gullet. From this they\ngradually project, surrounded by a ball of water, which at length\npasses with a jerk, oddly simulating a gulp, into the pulpy central\nsubstance of the body, there to circulate up one side and down the\nother, until its contents are digested and assimilated. Nevertheless,\nthis complex animal multiplies by division, as the monad does, and,\nlike the monad, undergoes conjugation. It stands in the same relation\nto _Heteromita_ on the animal side, as _Coleoch\u00e6te_ does on the plant\nside. Start from either, and such an insensible series of gradations\nleads to the monad that it is impossible to say at any stage of the\nprogress\u2014here the line between the animal and the plant must be drawn.\n\nThere is reason to think that certain organisms which pass through a\nmonad stage of existence, such as the _Myxomycetes_, are, at one time\nof their lives, dependent upon external sources for their protein\nmatter, or are animals; and, at another period, manufacture it, or are\nplants. And seeing that the whole progress of modern investigation is\nin favour of the doctrine of continuity, it is a fair and probable\nspeculation\u2014though only a speculation\u2014that, as there are some plants\nwhich can manufacture protein out of such apparently intractable\nmineral matters as carbonic acid, water, nitrate of ammonia, metallic\nand earthy salts; while others need to be supplied with their carbon\nand nitrogen in the somewhat less raw form of tartrate of ammonia and\nallied compounds; so there may be yet others, as is possibly the case\nwith the true parasitic plants, which can only manage to put together\nmaterials still better prepared\u2014still more nearly approximated to\nprotein\u2014until we arrive at such organisms as the _Psorospermi\u00e6_ and the\n_Panhistophyton_, which are as much animal as vegetable in structure,\nbut are animal in their dependence on other organisms for their food.\n\nThe singular circumstance observed by Meyer, that the _Torula_ of\nyeast, though an indubitable plant, still flourishes most vigorously\nwhen supplied with the complex nitrogenous substance, pepsin; the\nprobability that the _Peronospora_ is nourished directly by the\nprotoplasm of the potato-plant; and the wonderful facts which have\nrecently been brought to light respecting insectivorous plants, all\nfavour this view; and tend to the conclusion that the difference\nbetween animal and plant is one of degree rather than of kind; and that\nthe problem whether, in a given case, an organism is an animal or a\nplant, may be essentially insoluble.\n\n\n\n\nVIII.\n\nON CERTAIN ERRORS RESPECTING THE STRUCTURE OF THE HEART\nATTRIBUTED TO ARISTOTLE.\n\n\nIn all the commentaries upon the \u201cHistoria Animalium\u201d which I have met\nwith, Aristotle\u2019s express and repeated statement, that the heart of\nman and the largest animals contains only three cavities, is noted as\na remarkable error. Even Cuvier, who had a great advantage over most\nof the commentators in his familiarity with the subject of Aristotle\u2019s\ndescription, and whose habitual caution and moderation seem to desert\nhim when the opportunity of panegyrising the philosopher presents\nitself, is betrayed into something like a sneer on this topic.\n\n  \u201cDu reste il n\u2019attribue \u00e0 cet organe que trois cavit\u00e9s,\n  erreur qui prouve au moins qu\u2019il en avait regard\u00e9 la\n  structure.\u201d[36]\n\nTo which remark, what follows will, I think, justify the reply, that it\n\u201cprouve au moins\u201d that Cuvier had not given ordinary attention, to say\nnothing of the careful study which they deserve, to sundry passages in\nthe first and the third books of the \u201cHistoria\u201d which I proceed to lay\nbefore the reader.\n\nFor convenience of reference these passages are marked _A_, _B_, _C_,\netc.[37]\n\n  Book i. 17.\u2014(_A_) \u201cThe heart has three cavities, it lies\n  above the lung on the division of the windpipe, and has\n  a fatty and thick membrane where it is united with the\n  great vein and the aorta. It lies upon the aorta, with\n  its point down the chest, in all animals that have a\n  chest. In all, alike in those that have a chest and in\n  those that have none, the foremost part of it is the\n  apex. This is often overlooked through the turning upside\n  down of the dissection. The rounded end of the heart is\n  uppermost, the pointed end of it is largely fleshy and\n  thick, and in its cavities there are tendons. In other\n  animals which have a chest the heart lies in the middle\n  of the chest; in men, more to the left side, between the\n  nipples, a little inclined to the left nipple in the\n  upper part of the chest. The heart is not large, and its\n  general form is not elongated but rounded, except that\n  the apex is produced into a point.\n\n  (_B_) \u201cIt has, as already stated, three cavities, the\n  largest of them is on the right, the smallest on the\n  left, the middle-sized one in the middle; they have all,\n  also the two small ones, passages (\u03c4\u03b5\u03c4\u03c1\u03b7\u03bc\u03ad\u03bd\u03b1\u03c2) towards\n  the lung, very evidently as respects one of the cavities.\n  In the region of the union [with the great vein and the\n  aorta] the largest cavity is connected with the largest\n  vein (near which is the mesentery); the middle cavity\n  with the aorta.\n\n  (_C_) \u201cCanals (\u03c0\u03cc\u03c1\u03bf\u03b9) from the heart pass to the lung and\n  divide in the same fashion as the windpipe does, closely\n  accompanying those from the windpipe through the whole\n  lung. The canals from the heart are uppermost.\n\n  (_D_) \u201cNo canal is common [to the branches of the\n  windpipe and those of the vein] (\u03bf\u1f50\u03b4\u03b5\u1f76\u03c2 \u03b4\u2019 \u1f10\u03c3\u03c4\u1f76 \u03ba\u03bf\u03b9\u03bd\u1f78\u03c2\n  \u03c0\u03cc\u03c1\u03bf\u03c2) but through those parts of them which are in\n  contact (\u03c4\u1f74\u03bd \u03c3\u03cd\u03bd\u03b1\u03c8\u03b9\u03bd) the air passes in and they [the\n  \u03c0\u03cc\u03c1\u03bf\u03b9] carry it to the heart.\n\n  (_E_) \u201cOne of the canals leads to the right cavity, the\n  other to the left.\n\n  (_F_) \u201cOf all the viscera, the heart alone contains blood\n  [in itself]. The lung contains blood, not in itself but\n  in the veins, the heart in itself; for in each of the\n  cavities there is blood; the thinnest is in the middle\n  cavity.\u201d\n\n  Book iii. 3.\u2014(_G_) \u201cTwo veins lie in the thorax alongside\n  the spine, on its inner face; the larger more forwards,\n  the smaller behind; the larger more to the right, the\n  smaller, which some call _aorta_ (on account of the\n  tendinous part of it seen in dead bodies), to the left.\n  These take their origin from the heart; they pass entire,\n  preserving the nature of veins, through the other viscera\n  that they reach; while the heart is rather a part of\n  them, and more especially of the anterior and larger one,\n  which is continued into veins above and below, while\n  between these is the heart.\n\n  (_H_) \u201cAll hearts contain cavities, but, in those of very\n  small animals, the largest [cavity] is hardly visible,\n  those of middling size have another, and the biggest all\n  three.\n\n  (_I_) \u201cThe point of the heart is directed forwards, as\n  was mentioned at first; the largest cavity to the right\n  and upper side of it, the smallest to the left, and the\n  middle-sized one between these; both of these are much\n  smaller than the largest.\n\n  (_K_) \u201cThey are all connected by passages (\u03c3\u03c5\u03bd\u03c4\u03ad\u03c4\u03c1\u03b7\u03bd\u03c4\u03b1\u03b9)\n  with the lung, but, on account of the smallness of the\n  canals, this is obscure except in one.\n\n  (_L_) \u201cThe great vein proceeds from the largest cavity\n  which lies upwards and to the right; next through the\n  hollow middle part (\u03b4\u03b9\u1f70 \u03c4\u03bf\u1fe6 \u03ba\u03bf\u03af\u03bb\u03bf\u03c5 \u03c4\u03bf\u1fe6 \u03bc\u03ad\u03c3\u03bf\u03c5) it becomes\n  vein again, this cavity being a part of the vein in which\n  the blood stagnates.\n\n  (_M_) \u201cThe aorta [proceeds from] the middle [cavity], but\n  not in the same way, for it is connected [with the middle\n  cavity] by a much more narrow tube (\u03c3\u03cd\u03c1\u03b9\u03b3\u03b3\u03b1).\n\n  (_N_) \u201cThe [great] vein extends through the heart,\n  towards the aorta from the heart.\n\n  (_O_) \u201cThe great vein is membranous like skin, the aorta\n  narrower than it and very tendinous, and as it extends\n  towards the head and the lower parts it becomes narrow\n  and altogether tendinous.\n\n  (_P_) \u201cIn the first place, a part of the great vein\n  extends upwards from the heart towards the lung and\n  the attachment of the aorta, the vein being large and\n  undivided. It divides into two parts, the one to the\n  lung, the other to the spine and the lowest vertebra of\n  the neck.\n\n  (_Q_) \u201cThe vein which extends to the lung first divides\n  into two parts for the two halves of it and then extends\n  alongside each tube (\u03c3\u03cd\u03c1\u03b9\u03b3\u03b3\u03b1) and each passage (\u03c4\u03c1\u1fc6\u03bc\u03b1),\n  the larger beside the larger and the smaller beside the\n  smaller, so that no part [of the lung] can be found\n  from which a passage (\u03c4\u03c1\u1fc6\u03bc\u03b1) and a vein are absent.\n  The terminations are invisible on account of their\n  minuteness, but the whole lung appears full of blood. The\n  canals from the vein lie above the tubes given off from\n  the windpipe.\u201d\n\nThe key to the whole of the foregoing description of the heart lies\nin the passages (_G_) and (_L_). They prove that Aristotle, like\nGalen, five hundred years afterwards, and like the great majority\nof the old Greek anatomists, did not reckon what we call the right\nauricle as a constituent of the heart at all, but as a hollow part, or\ndilatation, of the \u201cgreat vein.\u201d Aristotle is careful to state that his\nobservations were conducted on suffocated animals; and if any one will\nlay open the thorax of a dog or a rabbit, which has been killed with\nchloroform, in such a manner as to avoid wounding any important vessel,\nhe will at once see why Aristotle adopted this view.\n\nFor, as the subjoined figure (p. 185) shows, the vena cava inferior\n(_b_), the right auricle (_R.a._), and the vena cava superior and\ninnominate vein (_V.I._) distended with blood seem to form one\ncontinuous column, to which the heart is attached as a sort of\nappendage. This column is, as Aristotle says, vein above (_a_) and vein\nbelow (_b_), the upper and the lower divisions being connected \u03b4\u03b9\u1f70\n\u03c4\u03bf\u1fe6 \u03ba\u03bf\u03af\u03bb\u03bf\u03c5 \u03c4\u03bf\u1fe6 \u03bc\u03ad\u03c3\u03bf\u03c5\u2014or by means of the intervening cavity or chamber\n(_R.a._)\u2014which is that which we call the right auricle.\n\n[Illustration:\n\n  A dog having been killed by chloroform, enough of the\n  right wall of the thorax was removed, without any notable\n  bleeding, to expose the thoracic viscera. A carefully\n  measured outline sketch of the parts _in situ_ was then\n  made, and on dissection, twenty-four hours afterwards,\n  the necessary anatomical details were added. The woodcut\n  is a faithfully reduced copy of the drawing thus\n  constructed; and it represents the relations of the heart\n  and great vessels as Aristotle saw them in a suffocated\n  animal.\n\n  All but the inner lobe of the right lung has been\n  removed; as well as the right half of the pericardium and\n  the right walls of the right auricle and ventricle. It\n  must be remembered that the thin transparent pericardial\n  membrane appears nothing like so distinct in nature.\n\n  _a.b._, Aristotle\u2019s \u201cgreat vein\u201d; _V.I._, right vena\n  innominata and vena cava superior; _b_, the inferior\n  vena cava; _R.a._, the \u201chollow middle\u201d part of the great\n  vein or the right auricle; _R.v\u2032_, the prolongation of\n  the cavity of the right ventricle _R.v_ towards the\n  pulmonary artery; _tr_, one of the tricuspid valves;\n  _Pc_, the pericardium; _I.sv_, superior intercostal\n  vein; _Az_, vena azygos; _P.A._, right pulmonary artery;\n  _Br_, right bronchus; _L_, inner lobe of the right lung;\n  _\u0152_, \u0153sophagus; _Ao_, descending aorta; _H_, liver, in\n  section, with hepatic vein, vena port\u00e6, and gall-bladder,\n  _gb_, separated by the diaphragm, also seen in section,\n  from the thoracic cavity.]\n\nBut when, from the four cavities of the heart recognised by us moderns,\none is excluded, there remain three\u2014which is just what Aristotle says.\nThe solution of the difficulty is, in fact, as absurdly simple as that\npresented by the egg of Columbus; and any error there may be, is not\nto be put down to Aristotle, but to that inability to comprehend that\nthe same fact may be accurately described in different ways, which\nis the special characteristic of the commentatorial mind. That the\nthree cavities mentioned by Aristotle are just those which remain if\nthe right auricle is omitted, is plain enough from what is said in\n(_B_), (_C_), (_E_), (_I_), and (_L_). For, in a suffocated animal,\nthe \u201cright cavity\u201d which is directly connected with the great vein,\nand is obviously the right ventricle, being distended with blood, will\nlook much larger than the middle cavity, which, since it gives rise\nto the aorta, can only be the left ventricle. And this, again, will\nappear larger than the thin and collapsed left auricle, which must\nbe Aristotle\u2019s left cavity, inasmuch as this cavity is said to be\nconnected by \u03c0\u03cc\u03c1\u03bf\u03b9 with the lung. The reason why Aristotle considered\nthe left auricle to be a part of the heart, while he merged the right\nauricle in the great vein, is, obviously, the small relative size of\nthe venous trunks and their sharper demarcation from the auricle.\nGalen, however, perhaps more consistently, regarded the left auricle\nalso as a mere part of the \u201carteria venosa.\u201d The canal which leads\nfrom the right cavity of the heart to the lung (or, as Aristotle\nputs it (_E_), from the lung to the heart) is, without doubt, the\npulmonary artery. But it may be said that, in this case, Aristotle\ncontradicts himself, inasmuch as in (_P_) and (_Q_) a vessel, which\nis obviously the pulmonary artery, is described as a branch of the\ngreat vein. However, this difficulty also disappears, if we reflect\nthat, in Aristotle\u2019s way of looking at the matter, the line of\ndemarcation between the great vein and the heart coincides with the\nright auriculo-ventricular aperture; and that, inasmuch as the conical\nprolongation of the right ventricle which leads to the pulmonary\nartery (_R.v\u2032_ in the Figure), lies close in front of the auricle,\nits base may very easily (as the figure shows) be regarded as part of\nthe general opening of the great vein into the right ventricle. In\nfact, it is clear that Aristotle, having failed to notice the valves\nof the heart, did not distinguish the part of the right ventricle\nfrom which the pulmonary artery arises (_R.v\u2032_) from the proper trunk\nof the artery on the one hand, and from the right auricle (_R.a_) on\nthe other. Thus the root, as we may call it, of the pulmonary artery\nand the right auricle, taken together, are spoken of as the \u201cpart of\nthe great vein which extends upwards\u201d (_P_); and, as the vena azygos\n(_Az_) was one branch of this, so the \u201cvein to the lung\u201d was regarded\nas another branch of it. But the latter branch, being given off close\nto the connection of the great vein with the ventricle, was also\ncounted as one of the two \u03c0\u03cc\u03c1\u03bf\u03b9 by which the \u201cheart\u201d (that is to say\nthe right ventricle, the left ventricle, and the left auricle of our\nnomenclature) communicates with the lung.\n\nThe only other difficulty that I observe is connected with (_K_). If\nAristotle intended by this to affirm that the middle cavity (the left\nventricle), like the other two, is directly connected with the lung by\na \u03c0\u03cc\u03c1\u03bf\u03c2, he would be in error. But he has excluded this interpretation\nof his words by (_E_), in which the number and relations of the\ncanals, the existence of which he admits, are distinctly defined. I\ncan only imagine then, that, so far as this passage applies to the\nleft ventricle, it merely refers to the indirect communication of that\ncavity with the vessels of the lungs, through the left auricle.\n\nOn this evidence I submit that there is no escape from the conclusion\nthat, instead of having committed a gross blunder, Aristotle has given\na description of the heart which, so far as it goes, is remarkably\naccurate. He is in error only in regard to the differences which he\nimagines to exist between large and small hearts (_H_).\n\nCuvier (who has been followed by other commentators) ascribes another\nerror to Aristotle:\u2014\n\n  \u201cAristote suppose que la trach\u00e9e-art\u00e8re se prolonge\n  jusqu\u2019au c\u0153ur, et semble croire, en cons\u00e9quence, que\n  l\u2019air y p\u00e9n\u00e9tre (_l. c._ p. 152).\u201d\n\nUpon what foundation Cuvier rested the first of these two assertions,\nI am at a loss to divine. As a matter of fact, it will appear from the\nfollowing excerpts that Aristotle gives an account of the structure of\nthe lungs which is almost as good as that of the heart, and that it\ncontains nothing about any prolongation of the windpipe to the heart.\n\n  \u201cWithin the neck lie what is called the \u0153sophagus (so\n  named on account of its length and its narrowness) and\n  the windpipe (\u1f00\u03c1\u03c4\u03b7\u03c1\u03af\u03b1). The position of the windpipe in\n  all animals that have one, is in front of the \u0153sophagus.\n  All animals which possess a lung have a windpipe. The\n  windpipe is of a cartilaginous nature and is exsanguine,\n  but is surrounded by many little veins....\n\n  \u201cIt goes downwards towards the middle of the lung, and\n  then divides for each of the halves of the lung. In all\n  animals that possess one, the lung is divided into two\n  parts; but, in those which bring forth their young alive,\n  the separation is not equally well marked, least of all\n  in man.\n\n  \u201cIn oviparous animals, such as birds, and in quadrupeds\n  which are oviparous, the one half of the lung is widely\n  separated from the other; so that it appears as if they\n  had two lungs. And from being single, the windpipe\n  becomes (divided into) two, which extend to each half of\n  the lung. It is fastened to the great vein, and to what\n  is called the aorta. When the windpipe is blown up, the\n  air passes into the hollow parts of the lung. In these,\n  are cartilaginous tubes (\u03b4\u03b9\u03b1\u03c6\u03cd\u03c3\u03b5\u03b9\u03c2) which unite at an\n  angle; from the tubes passages (\u03c4\u03c1\u03ae\u03bc\u03b1\u03c4\u03b1) traverse the\n  whole of the lung; they are continually given off, the\n  smaller from the larger.\u201d (Book i. 16.)\n\nThat Aristotle should speak of the lung as a single organ divided into\ntwo halves, and should say that the division is least marked in man,\nis puzzling at first; but the statement becomes intelligible, if we\nreflect upon the close union of the bronchi, the pulmonary vessels and\nthe mediastinal walls of the pleur\u00e6, in mammals;[38] and it is quite\ntrue that the lungs are much more obviously distinct from one another\nin birds.\n\nAubert and Wimmer translate the last paragraph of the passage just\ncited as follows:\u2014\n\n  \u201cDiese haben aber knorpelige Scheidew\u00e4nde, welche unter\n  spitzen Winkeln zusammentreten, und aus ihnen f\u00fchren\n  Oeffnungen durch die ganze Lunge, indem sie sich in immer\n  kleineren verzweigen.\u201d\n\nBut I cannot think that by \u03b4\u03b9\u03b1\u03c6\u03cd\u03c3\u03b5\u03b9\u03c2 and \u03c4\u03c1\u03ae\u03bc\u03b1\u03c4\u03b1, in this passage,\nAristotle meant either \u201cpartitions\u201d or openings in the ordinary\nsense of the latter word. For, in Book iii. Cap. 3, in describing\nthe distribution of the \u201cvein which goes to the lung\u201d (the pulmonary\nartery), he says that it\n\n  \u201cextends alongside each tube (\u03c3\u03cd\u03c1\u03b9\u03b3\u03b3\u03b1) and each passage\n  (\u03c4\u03c1\u1fc6\u03bc\u03b1), the larger beside the larger, and the smaller\n  beside the smaller; so that no part (of the lung) can be\n  found from which a passage (\u03c4\u03c1\u1fc6\u03bc\u03b1) and a vein are absent.\u201d\n\nMoreover, in Book i. 17, he says\u2014\n\n  \u201cCanals (\u03c0\u03cc\u03c1\u03bf\u03b9) from the heart pass to the lung and\n  divide in the same fashion as the windpipe does, closely\n  accompanying those from the windpipe through the whole\n  lung.\u201d\n\nAnd again in Book i. 17\u2014\n\n  \u201cIt (the lung) is entirely spongy, and alongside of each\n  tube (\u03c3\u03cd\u03c1\u03b9\u03b3\u03b3\u03b1) run canals (\u03c0\u03cc\u03c1\u03bf\u03b9) from the great vein.\u201d\n\nOn comparing the last three statements with the facts of the case, it\nis plain that by \u03c3\u03cd\u03c1\u03b9\u03b3\u03b3\u03b5\u03c2, or tubes, Aristotle means the bronchi and so\nmany of their larger divisions as obviously contain cartilages; and\nthat by \u03b4\u03b9\u03b1\u03c6\u03cd\u03c3\u03b5\u03b9\u03c2 \u03c7\u03bf\u03bd\u03b4\u03c1\u03ce\u03b4\u03b5\u03b9\u03c2 he denotes the same things; and, if this\nbe so, then the \u03c4\u03c1\u03ae\u03bc\u03b1\u03c4\u03b1 must be the smaller bronchial canals, in which\nthe cartilages disappear.\n\nThis view of the structure of the lung is perfectly correct so far\nas it extends; and, bearing it in mind, we shall be in a position to\nunderstand what Aristotle thought about the passage of air from the\nlungs into the heart. In every part of the lung, he says, in effect,\nthere is an air tube which is derived from the trachea, and other tubes\nwhich are derived from the \u03c0\u03cc\u03c1\u03bf\u03b9 which connect the lung with the heart\n(_supr\u00e0_, _C_). Their applied walls constitute the thin \u201csynapses\u201d (\u03c4\u1f74\u03bd\n\u03c3\u03cd\u03bd\u03b1\u03c8\u03b9\u03bd) through which the air passes out of the air tubes into the\n\u03c0\u03cc\u03c1\u03bf\u03b9, or blood-vessels, by transudation or diffusion; for there is no\ncommunity between the cavities of the air tubes and cavities of the\ncanals; that is to say, no opening from one into the other (_supr\u00e0_,\n_D_).\n\nOn the words \u201c\u03ba\u03bf\u03b9\u03bd\u1f78\u03c2 \u03c0\u03cc\u03c1\u03bf\u03c2\u201d Aubert and Wimmer remark (_l. c._ p. 239),\n\u201cDa A. die Ansicht hat die Lungenluft w\u00fcrde dem Herzen zugef\u00fchrt,\nso postulirt er statt vieler kleiner Verbindungen einen grossen\nVerbindungsgang zwischen Lunge und Herz.\u201d\n\nBut does Aristotle make this assumption? The only evidence so far as\nI know in favour of the affirmative answer to this question is the\nfollowing passage:\u2014\n\n  \u201c\u03a3\u03c5\u03bd\u03ae\u03c1\u03c4\u03b5\u03c4\u03b1\u03b9 \u03b4\u1f72 \u03ba\u03b1\u1f76 \u1f21 \u03ba\u03b1\u03c1\u03b4\u03af\u03b1 \u03c4\u1fc7 \u1f00\u03c1\u03c4\u03b7\u03c1\u03b9\u1fb7 \u03c0\u03b9\u03bc\u03b5\u03bb\u03ce\u03b4\u03b5\u03c3\u03b9\n  \u03ba\u03b1\u1f76 \u03c7\u03bf\u03bd\u03b4\u03c1\u03ce\u03b4\u03b5\u03c3\u03b9 \u03ba\u03b1\u1f76 \u1f30\u03bd\u03ce\u03b4\u03b5\u03c3\u03b9 \u03b4\u03b5\u03c3\u03bc\u03bf\u1fd6\u03c2\u00b7 \u1f97 \u03b4\u1f72 \u03c3\u03c5\u03bd\u03ae\u03c1\u03c4\u03b5\u03c4\u03b1\u03b9,\n  \u03ba\u03bf\u1fd6\u03bb\u03cc\u03bd \u1f10\u03c3\u03c4\u03b9\u03bd. \u03c6\u03c5\u03c3\u03c9\u03bc\u03ad\u03bd\u03b7\u03c2 \u03b4\u1f72 \u03c4\u1fc6\u03c2 \u1f00\u03c1\u03c4\u03b7\u03c1\u03af\u03b1\u03c2 \u03bc\u1f72\u03bd \u1f10\u03bd\u03af\u03bf\u03b9\u03c2 \u1f10\u03bd \u03bf\u1f50\n  \u03ba\u03b1\u03c4\u03ac\u03b4\u03b7\u03bb\u03bf\u03bd \u03c0\u03bf\u03b9\u03b5\u1fd6, \u1f10\u03bd \u03b4\u1f72 \u03c4\u03bf\u1fd6\u03c2 \u03bc\u03b5\u03af\u03b6\u03bf\u03c3\u03b9 \u03c4\u1ff6\u03bd \u03b6\u1ff4\u03c9\u03bd \u03b4\u1fc6\u03bb\u03bf\u03bd \u1f45\u03c4\u03b9\n  \u03b5\u1f30\u03c3\u03ad\u03c1\u03c7\u03b5\u03c4\u03b1\u03b9 \u03c4\u1f78 \u03c0\u03bd\u03b5\u1fe6\u03bc\u03b1 \u03b5\u1f30\u03c2 \u03b1\u1f50\u03c4\u1f74\u03bd\u201d (i. cap. 16).\n\n  \u201cThe heart and the windpipe are connected by fatty and\n  cartilaginous and fibrous bands; where they are connected\n  it is hollow. Blowing into the windpipe does not show\n  clearly in some animals, but in the larger animals it is\n  clear that the air goes into it.\u201d\n\nAubert and Wimmer give a somewhat different rendering of this passage:\u2014\n\n  \u201cAuch das Herz h\u00e4ngt mit der Luftr\u00f6hre durch fettreiche,\n  knorpelige und faserige B\u00e4nder zusammen; und da, wo sie\n  zusammenh\u00e4ngen, ist eine H\u00f6hlung. Beim Aufblasen der\n  Lunge wird es bei manchen Thieren nicht wahrnehmbar, bei\n  den gr\u00f6sseren aber ist es offenbar, dass die Luft in das\n  Herz gelangt.\u201d\n\nThe sense here turns upon the signification which is to be ascribed to\n\u03b5\u1f30\u03c2 \u03b1\u1f50\u03c4\u1f74\u03bd. But if these words refer to the heart, then Aristotle has\ndistinctly pointed out the road which the air, in his opinion, takes,\nnamely, through the \u201csynapses\u201d (_D_); and there is no reason that I\ncan discover to believe that he \u201cpostulated\u201d any other and more direct\ncommunication.\n\nWith respect to the meaning of \u03ba\u03bf\u1fd6\u03bb\u03cc\u03bd \u1f10\u03c3\u03c4\u03b9\u03bd, Aubert and Wimmer observe:\u2014\n\n  \u201cDies scheint wohl die kurze Lungenvene zu sein.\n  Schneider bezieht dies auf die Vorkammern, allein diese\n  werden unten als H\u00f6hlen des Herzens beschrieben.\u201d\n\nI am disposed to think, on the contrary, that the words refer simply\nto the cavity of the pericardium. For a part of this cavity (_sinus\ntransversus pericardii_) lies between the aorta, on the one hand, and\nthe pulmonary vessels with the bifurcation of the trachea, on the other\nhand, and is much more conspicuous in some animals than in man. It is\nstrictly correct, therefore, in Aristotle\u2019s words, to say that where\nthe heart and the windpipe are connected \u201cit is hollow.\u201d If he had\nmeant to speak of one of the pulmonary veins, or of any of the cavities\nof the heart, he would have used the terms \u03c0\u03cc\u03c1\u03bf\u03b9 or \u03ba\u03bf\u03b9\u03bb\u03af\u03b1\u03c2 which he\nalways employs for these parts.\n\nAccording to Aristotle, then, the air taken into the lungs passes, from\nthe final ramifications of the bronchial tubes into the corresponding\nbranches of the pulmonary blood-vessels, not through openings, but by\ntransudation, or, as we should nowadays say, diffusion, through the\nthin partitions formed by the applied coats of the two sets of canals.\nBut the \u201cpneuma\u201d which thus reached the interior of the blood-vessels\nwas not, in Aristotle\u2019s opinion, exactly the same thing as the air.\nIt was \u201c\u1f00\u1f74\u03c1 \u03c0\u03bf\u03bb\u1f7a\u03c2 \u1fe5\u03ad\u03c9\u03bd \u03ba\u03b1\u1f76 \u1f00\u03b8\u03c1\u03cc\u03bf\u03c2\u201d (\u201cDe Mundo,\u201d iv. 9)\u2014subtilised and\ncondensed air; and it is hard to make out whether Aristotle considered\nit to possess the physical properties of an elastic fluid or those of\na liquid. As he affirms that all the cavities of the heart contain\nblood (_F_), it is clear that he did not hold the erroneous view\npropounded in the next generation by Erasistratus. On the other hand,\nthe fact that he supposes that the spermatic arteries do not contain\nblood but only an \u03b1\u1f31\u03bc\u03b1\u03c4\u1ff6\u03b4\u03b7\u03c2 \u1f51\u03b3\u03c1\u03cc\u03bd (\u201cHist. Animalium,\u201d iii. 1), shows\nthat his notions respecting the contents of the arteries were vague.\nNor does he seem to have known that the pulse is characteristic only\nof the arteries; and as he thought that the arteries end in solid\nfibrous bands, he naturally could not have entertained the faintest\nconception of the true motion of the blood. But, without attempting\nto read into Aristotle modern conceptions which never entered his\nmind, it is only just to observe that his view of what becomes of the\nair taken into the lungs is by no means worthy of contempt as a gross\nerror. On the contrary, here, as in the case of his anatomy of the\nheart, what Aristotle asserts is true as far as it goes. Something\ndoes actually pass from the air contained in the lungs through the\ncoats of the vessels into the blood, and thence to the heart; to wit,\noxygen. And I think that it speaks very well for ancient Greek science\nthat the investigator of so difficult a physiological problem as that\nof respiration, should have arrived at a conclusion, the statement of\nwhich, after the lapse of more than two thousand years, can be accepted\nas a thoroughly established scientific truth.\n\nI trust that the case in favour of removing the statements about\nthe heart, from the list of the \u201cerrors of Aristotle\u201d is now clear;\nand that the evidence proves, on the contrary, that they justify\nus in forming a very favourable estimate of the oldest anatomical\ninvestigations among the Greeks of which any sufficient record remains.\n\nBut is Aristotle to be credited with the merit of having ascertained so\nmuch of the truth? This question will not appear superfluous to those\nwho are acquainted with the extraordinary history of Aristotle\u2019s works,\nor who adopt the conclusion of Aubert and Wimmer, that, of the ten\nbooks of the \u201cHistoria Animalium\u201d which have come down to us, three\nare largely or entirely spurious, and that the others contain many\ninterpolations by later writers.\n\nIt so happens, however, that, apart from other reasons, there are\nsatisfactory internal grounds for ascribing the account of the heart\nto a writer of the time at which Aristotle lived. For, within thirty\nyears of his death, the anatomists of the Alexandrian school had\nthoroughly investigated the structure and the functions of the valves\nof the heart. During this time, the manuscripts of Aristotle were in\nthe possession of Theophrastus; and no interpolator of later date would\nhave shown that he was ignorant of the nature and significance of\nthese important structures, by the brief and obscure allusion\u2014\u201cin its\ncavities there are tendons\u201d (_A_). On the other hand, Polybus, whose\naccount of the vascular system is quoted in the \u201cHistoria Animalium\u201d\nwas an elder contemporary of Aristotle. Hence, if any part of the\nwork faithfully represents that which Aristotle taught, we may safely\nconclude that the description of the heart does so. Having granted\nthis much, however, it is another question, whether Aristotle is to\nbe regarded as the first discoverer of the facts which he has so well\nstated, or whether he, like other men, was the intellectual child of\nhis time and simply carried on a step or two the work which had been\ncommenced by others.\n\nOn the subject of Aristotle\u2019s significance as an original worker in\nbiology extraordinarily divergent views have been put forward. If we\nare to adopt Cuvier\u2019s estimate, Aristotle was simply a miracle:\u2014\n\n  \u201cAvant Aristote la philosophie, enti\u00e8rement sp\u00e9culative,\n  se perdait dans les abstractions d\u00e9pourvues de fondement;\n  la science n\u2019existait pas. Il semble qu\u2019elle soit\n  sortie toute faite du cerveau d\u2019Aristote comme Minerve,\n  toute arm\u00e9e, du cerveau de Jupiter. Seul, en effet,\n  sans ant\u00e9c\u00e9dents, sans rien emprunter aux si\u00e8cles qui\n  l\u2019avaient pr\u00e9c\u00e9d\u00e9, puisqu\u2019ils n\u2019avaient rien produit de\n  solide, le disciple de Platon d\u00e9couvrit et d\u00e9montra plus\n  de v\u00e9rit\u00e9s, executa plus de travaux scientifiques en un\n  vie de soixante-deux ans, qu\u2019apr\u00e8s lui vingt si\u00e8cles n\u2019en\n  ont pu faire,\u201d[39] etc. etc.\n\n  \u201cAristote est le premier qui ait introduit la m\u00e9thode\n  de l\u2019induction, de la comparaison des observations\n  pour en faire sortir des id\u00e9es g\u00e9n\u00e9rales, et celle de\n  l\u2019exp\u00e9rience pour multiplier les faits dont ces id\u00e9es\n  g\u00e9n\u00e9rales peuvent \u00eatre d\u00e9duites.\u201d\u2014ii. p. 515.\n\nThe late Mr. G. H. Lewes,[40] on the contrary, tells us \u201con a\nsuperficial examination, therefore, he [Aristotle] will seem to have\ngiven tolerable descriptions; especially if approached with that\ndisposition to discover marvels which unconsciously determines us\nin our study of eminent writers. But a more unbiassed and impartial\ncriticism will disclose that he has given no single anatomical\ndescription of the least value. All that he knew may have been known,\nand probably was known, without dissection.... I do not assert that\nhe never opened an animal; on the contrary it seems highly probable\nthat he had opened many.... He never followed the course of a vessel\nor a nerve; never laid bare the origin and insertion of a muscle;\nnever discriminated the component parts of organs; never made clear to\nhimself the connection of organs into systems.\u201d\u2014(pp. 156-7.)\n\nIn the face of the description of the heart and lungs, just quoted,\nI think we may venture to say that no one who has acquired even an\nelementary practical acquaintance with anatomy, and knows of his own\nknowledge that which Aristotle describes, will agree with the opinion\nexpressed by Mr. Lewes; and those who turn to the accounts of the\nstructure of the rock lobster and the common lobster, or to that of the\nCephalopods and other Mollusks, in the fourth book of the \u201cHistoria\nAnimalium\u201d will probably feel inclined to object to it still more\nstrongly.\n\nOn the other hand, Cuvier\u2019s exaggerated panegyric will as little bear\nthe test of cool discussion. In Greece, the century before Aristotle\u2019s\nbirth was a period of great intellectual activity, in the field of\nphysical science no less than elsewhere. The method of induction has\nnever been used to better effect than by Hippocrates; and the labours\nof such men as Alkmeon, Demokritus, and Polybus, among Aristotle\u2019s\npredecessors; Diokles, and Praxagoras, among his contemporaries, laid a\nsolid foundation for the scientific study of anatomy and development,\nindependently of his labours. Aristotle himself informs us that the\ndissection of animals was commonly practised; that the aorta had been\ndistinguished from the great vein; and that the connection of both with\nthe heart had been observed by his predecessors. What they thought\nabout the structure of the heart itself or that of the lungs, he does\nnot tell us, and we have no means of knowing. So far from arrogantly\nsuggesting that he owed nothing to his predecessors, Aristotle is\ncareful to refer to their observations, and to explain why, in his\njudgment, they fell into the errors which he corrects.\n\nAristotle\u2019s knowledge, in fact, appears to have stood in the same\nrelation to that of such men as Polybus and Diogenes of Apollonia, as\nthat of Herophilus and Erasistratus did to his own, so far as the heart\nis concerned. He carried science a step beyond the point at which he\nfound it; a meritorious, but not a miraculous, achievement. What he\ndid, required the possession of very good powers of observation; if\nthey had been powers of the highest class, he could hardly have left\nsuch conspicuous objects as the valves of the heart to be discovered by\nhis successors.\n\nAnd this leads me to make a final remark upon a singular feature of\nthe \u201cHistoria Animalium.\u201d As a whole, it is a most notable production,\nfull of accurate information, and of extremely acute generalisations of\nthe observations accumulated by naturalists up to that time. And yet,\nevery here and there, one stumbles upon assertions respecting matters\nwhich lie within the scope of the commonest inspection, which are not\nso much to be called errors, as stupidities. What is to be made of the\nstatement that the sutures of women\u2019s skulls are different from those\nof men; that men and sundry male animals have more teeth than their\nrespective females; that the back of the skull is empty; and so on? It\nis simply incredible to me, that the Aristotle who wrote the account of\nthe heart, also committed himself to absurdities which can be excused\nby no theoretical prepossession and which are contradicted by the\nplainest observation.\n\nWhat, after all, were the original manuscripts of the \u201cHistoria\nAnimalium\u201d? If they were notes of Aristotle\u2019s lectures taken by some of\nhis students, any lecturer who has chanced to look through such notes,\nwould find the interspersion of a foundation of general and sometimes\nminute accuracy, with patches of transcendent blundering, perfectly\nintelligible. Some competent Greek scholar may perhaps think it worth\nwhile to tell us what may be said for or against the hypothesis thus\nhinted. One obvious difficulty in the way of adopting it is the fact\nthat, in other works, Aristotle refers to the \u201cHistoria Animalium\u201d as\nif it had already been made public by himself.\n\n\n\n\nIX.\n\nON THE HYPOTHESIS THAT ANIMALS ARE AUTOMATA, AND ITS HISTORY.\n\n\nThe first half of the seventeenth century is one of the great epochs\nof biological science. For though suggestions and indications of the\nconceptions which took definite shape, at that time, are to be met\nwith in works of earlier date, they are little more than the shadows\nwhich coming truth casts forward; men\u2019s knowledge was neither extensive\nenough, nor exact enough, to show them the solid body of fact which\nthrew these shadows.\n\nBut, in the seventeenth century, the idea that the physical processes\nof life are capable of being explained in the same way as other\nphysical phenomena, and, therefore, that the living body is a\nmechanism, was proved to be true for certain classes of vital actions;\nand, having thus taken firm root in irrefragable fact, this conception\nhas not only successfully repelled every assault which has been made\nupon it, but has steadily grown in force and extent of application,\nuntil it is now the expressed or implied fundamental proposition of the\nwhole doctrine of scientific Physiology.\n\nIf we ask to whom mankind are indebted for this great service, the\ngeneral voice will name William Harvey. For, by his discovery of the\ncirculation of the blood in the higher animals, by his explanation of\nthe nature of the mechanism by which that circulation is effected,\nand by his no less remarkable, though less known, investigations of\nthe process of development, Harvey solidly laid the foundations of\nall those physical explanations of the functions of sustentation and\nreproduction which modern physiologists have achieved.\n\nBut the living body is not only sustained and reproduced: it adjusts\nitself to external and internal changes; it moves and feels. The\nattempt to reduce the endless complexities of animal motion and\nfeeling to law and order is, at least, as important a part of the task\nof the physiologist as the elucidation of what are sometimes called\nthe vegetative processes. Harvey did not make this attempt himself;\nbut the influence of his work upon the man who did make it is patent\nand unquestionable. This man was Ren\u00e9 Descartes, who, though by many\nyears Harvey\u2019s junior, died before him; and yet, in his short span\nof fifty-four years, took an undisputed place, not only among the\nchiefs of philosophy, but amongst the greatest and most original of\nmathematicians; while, in my belief, he is no less certainly entitled\nto the rank of a great and original physiologist; inasmuch as he did\nfor the physiology of motion and sensation that which Harvey had done\nfor the circulation of the blood, and opened up that road to the\nmechanical theory of these processes, which has been followed by all\nhis successors.\n\nDescartes was no mere speculator, as some would have us believe: but a\nman who knew of his own knowledge what was to be known of the facts of\nanatomy and physiology in his day. He was an unwearied dissector and\nobserver; and it is said, that, on a visitor once asking to see his\nlibrary, Descartes led him into a room set aside for dissections, and\nfull of specimens under examination. \u201cThere,\u201d said he, \u201cis my library.\u201d\n\nI anticipate a smile of incredulity when I thus champion Descartes\u2019\nclaim to be considered a physiologist of the first rank. I expect to\nbe told that I have read into his works what I find there, and to be\nasked, Why is it that we are left to discover Descartes\u2019 deserts at\nthis time of day, more than two centuries after his death? How is it\nthat Descartes is utterly ignored in some of the latest works which\ntreat expressly of the subject in which he is said to have been so\ngreat?\n\nIt is much easier to ask such questions than to answer them, especially\nif one desires to be on good terms with one\u2019s contemporaries; but, if I\nmust give an answer, it is this: The growth of physical science is now\nso prodigiously rapid, that those who are actively engaged in keeping\nup with the present, have much ado to find time to look at the past,\nand even grow into the habit of neglecting it. But, natural as this\nresult may be, it is none the less detrimental. The intellect loses,\nfor there is assuredly no more effectual method of clearing up one\u2019s\nown mind on any subject than by talking it over, so to speak, with\nmen of real power and grasp, who have considered it from a totally\ndifferent point of view. The parallax of time helps us to the true\nposition of a conception, as the parallax of space helps us to that of\na star. And the moral nature loses no less. It is well to turn aside\nfrom the fretful stir of the present and to dwell with gratitude and\nrespect upon the services of those \u201cmighty men of old who have gone\ndown to the grave with their weapons of war,\u201d but who, while they yet\nlived, won splendid victories over ignorance. It is well, again, to\nreflect that the fame of Descartes filled all Europe, and his authority\novershadowed it, for a century; while now, most of those who know his\nname think of him, either as a person who had some preposterous notions\nabout vortices and was deservedly annihilated by the great Sir Isaac\nNewton; or as the apostle of an essentially vicious method of deductive\nspeculation; and that, nevertheless, neither the chatter of shifting\nopinion, nor the silence of personal oblivion, has in the slightest\ndegree affected the growth of the great ideas of which he was the\ninstrument and the mouthpiece.\n\nIt is a matter of fact that the greatest physiologist of the eighteenth\ncentury, Haller, in treating of the functions of nerve, does little\nmore than reproduce and enlarge upon the ideas of Descartes. It is a\nmatter of fact that David Hartley, in his remarkable work the \u201cEssay\non Man,\u201d expressly, though still insufficiently, acknowledges the\nresemblance of his fundamental conceptions to those of Descartes; and\nI shall now endeavour to show that a series of propositions, which\nconstitute the foundation and essence of the modern physiology of the\nnervous system, are fully expressed and illustrated in the works of\nDescartes.\n\n  I. _The brain is the organ of sensation, thought, and\n  emotion; that is to say, some change in the condition of\n  the matter of this organ is the invariable antecedent of\n  the state of consciousness to which each of these terms\n  is applied._\n\nIn the \u201cPrincipes de la Philosophie\u201d (\u00a7 169), Descartes says:\u2014[41]\n\n  \u201cAlthough the soul is united to the whole body, its\n  principal functions are, nevertheless, performed in\n  the brain; it is here that it not only understands and\n  imagines, but also feels; and this is effected by the\n  intermediation of the nerves, which extend in the form\n  of delicate threads from the brain to all parts of the\n  body, to which they are attached in such a manner, that\n  we can hardly touch any part of the body without setting\n  the extremity of some nerve in motion. This motion passes\n  along the nerve to that part of the brain which is the\n  common sensorium, as I have sufficiently explained in\n  my Treatise on Dioptrics; and the movements which thus\n  travel along the nerves, as far as that part of the\n  brain with which the soul is closely joined and united,\n  cause it, by reason of their diverse characters, to have\n  different thoughts. And it is these different thoughts of\n  the soul, which arise immediately from the movements that\n  are excited by the nerves in the brain, which we properly\n  term our feelings, or the perceptions of our senses.\u201d\n\nElsewhere,[42] Descartes, in arguing that the seat of the passions is\nnot (as many suppose) the heart, but the brain, uses the following\nremarkable language:\u2014\n\n  \u201cThe opinion of those who think that the soul receives\n  its passions in the heart, is of no weight, for it is\n  based upon the fact that the passions cause a change to\n  be felt in that organ; and it is easy to see that this\n  change is felt, as if it were in the heart, only by the\n  intermediation of a little nerve which descends from the\n  brain to it; Just as pain is felt, as if it were in the\n  foot, by the intermediation of the nerves of the foot;\n  and the stars are perceived, as if they were in the\n  heavens, by the intermediation of their light and of the\n  optic nerves. So that it is no more necessary for the\n  soul to exert its functions immediately in the heart, to\n  feel its passions there, than it is necessary that it\n  should be in the heavens to see the stars there.\u201d\n\nThis definite allocation of all the phenomena of consciousness to the\nbrain as their organ, was a step the value of which it is difficult\nfor us to appraise, so completely has Descartes\u2019 view incorporated\nitself with every-day thought and common language. A lunatic is said\nto be \u201ccrack-brained\u201d or \u201ctouched in the head,\u201d a confused thinker\nis \u201cmuddle-headed,\u201d while a clever man is said to have \u201cplenty of\nbrains;\u201d but it must be remembered that at the end of the last century\na considerable, though much over-estimated, anatomist, Bichat, so far\nfrom having reached the level of Descartes, could gravely argue that\nthe apparatuses of organic life are the sole seat of the passions,\nwhich in no way affect the brain, except so far as it is the agent by\nwhich the influence of the passions is transmitted to the muscles.[43]\n\nModern physiology, aided by pathology, easily demonstrates that the\nbrain is the seat of all forms of consciousness, and fully bears out\nDescartes\u2019 explanation of the reference of those sensations in the\nviscera which accompany intense emotion, to these organs. It proves,\ndirectly, that those states of consciousness which we call sensations\nare the immediate consequent of a change in the brain excited by\nthe sensory nerves; and, on the well-known effects of injuries, of\nstimulants, and of narcotics, it bases the conclusion that thought and\nemotion are, in like manner, the consequents of physical antecedents.\n\n  II. _The movements of animals are due to the change of\n  form of muscles, which shorten and become thicker; and\n  this change of form in a muscle arises from a motion of\n  the substance contained within the nerves which go to the\n  muscle_.\n\nIn the \u201cPassions de l\u2019\u00c2me,\u201d Art. vii., Descartes writes:\u2014\n\n  \u201cMoreover, we know that all the movements of the limbs\n  depend on the muscles, and that these muscles are opposed\n  to one another in such a manner, that when one of them\n  shortens, it draws along the part of the body to which\n  it is attached, and so gives rise to a simultaneous\n  elongation of the muscle which is opposed to it. Then,\n  if it happens, afterwards, that the latter shortens, it\n  causes the former to elongate, and draws towards itself\n  the part to which it is attached. Lastly, we know that\n  all these movements of the muscles, as all the senses,\n  depend on the nerves, which are like little threads or\n  tubes, which all come from the brain, and, like it,\n  contain a certain very subtle air or wind, termed the\n  animal spirits.\u201d\n\nThe property of muscle mentioned by Descartes now goes by the general\nname of contractility, but his definition of it remains untouched. The\nlong-continued controversy whether contractile substance, speaking\ngenerally, has an inherent power of contraction, or whether it\ncontracts only in virtue of an influence exerted by nerve, is now\nsettled in Haller\u2019s favour; but Descartes\u2019 statement of the dependence\nof muscular contraction on nerve holds good for the higher forms of\nmuscle, under normal circumstances; so that, although the structure of\nthe various modifications of contractile matter has been worked out\nwith astonishing minuteness\u2014although the delicate physical and chemical\nchanges which accompany muscular contraction have been determined to\nan extent of which Descartes could not have dreamed, and have quite\nupset his hypothesis that the cause of the shortening and thickening of\nthe muscle is the flow of animal spirits into it from the nerves\u2014the\nimportant and fundamental part of his statement remains perfectly true.\n\nThe like may be affirmed of what he says about nerve. We know now that\nnerves are not exactly tubes, and that \u201canimal spirits\u201d are myths; but\nthe exquisitely refined methods of investigation of Dubois-Reymond and\nof Helmholz have no less clearly proved that the antecedent of ordinary\nmuscular contraction is a motion of the molecules of the nerve going to\nthe muscle; and that this motion is propagated with a measurable, and\nby no means great, velocity, through the substance of the nerve towards\nthe muscle.\n\nWith the progress of research, the term \u201canimal spirits\u201d gave way to\n\u201cnervous fluid,\u201d and \u201cnervous fluid\u201d has now given way to \u201cmolecular\nmotion of nerve-substance.\u201d Our conceptions of what takes place in\nnerve have altered in the same way as our conceptions of what takes\nplace in a conducting wire have altered, since electricity was shown to\nbe not a fluid, but a mode of molecular motion. The change is of vast\nimportance, but it does not affect Descartes\u2019 fundamental idea, that a\nchange in the substance of a motor nerve propagated towards a muscle is\nthe ordinary cause of muscular contraction.\n\n  III. _The sensations of animals are due to a motion of\n  the substance of the nerves which connect the sensory\n  organs with the brain._\n\nIn _La Dioptrique_ (Discours Quatri\u00e8me), Descartes explains, more fully\nthan in the passage cited above, his hypothesis of the mode of action\nof sensory nerves:\u2014\n\n  \u201cIt is the little threads of which the inner substance\n  of the nerves is composed which subserve sensation. You\n  must conceive that these little threads, being inclosed\n  in tubes, which are always distended and kept open by\n  the animal spirits which they contain, neither press\n  upon nor interfere with one another, and are extended\n  from the brain to the extremities of all the members\n  which are sensitive\u2014in such a manner, that the slightest\n  touch which excites the part of one of the members to\n  which a thread is attached, gives rise to a motion of\n  the part of the brain whence it arises, just as by\n  pulling one of the ends of a stretched cord, the other\n  end is instantaneously moved.... And we must take care\n  not to imagine that, in order to feel, the soul needs\n  to behold certain images sent by the objects of sense\n  to the brain, as our philosophers commonly suppose;\n  or, at least, we must conceive these images to be\n  something quite different from what they suppose them\n  to be. For, as all they suppose is that these images\n  ought to resemble the objects which they represent, it\n  is impossible for them to show how they can be formed by\n  the objects received by the organs of the external senses\n  and transmitted to the brain. And they have had no reason\n  for supposing the existence of these images except this;\n  seeing that the mind is readily excited by a picture to\n  conceive the object which is depicted, they have thought\n  that it must be excited in the same way to conceive those\n  objects which affect our senses by little pictures of\n  them formed in the head; instead of which we ought to\n  recollect that there are many things besides images which\n  may excite the mind, as, for example, signs and words,\n  which have not the least resemblance to the objects which\n  they signify.\u201d[44]\n\nModern physiology amends Descartes\u2019 conception of the mode of action of\nsensory nerves in detail, by showing that their structure is the same\nas that of motor nerves; and that the changes which take place in them,\nwhen the sensory organs with which they are connected are excited, are\nof just the same nature as those which occur in motor nerves, when the\nmuscles to which they are distributed are made to contract: there is a\nmolecular change which, in the case of the sensory nerve, is propagated\ntowards the brain. But the great fact insisted upon by Descartes, that\nno likeness of external things is, or can be, transmitted to the mind\nby the sensory organs; on the contrary, that, between the external\ncause of a sensation and the sensation, there is interposed a mode\nof motion of nervous matter, of which the state of consciousness is\nno likeness, but a mere symbol, is of the profoundest importance. It\nis the physiological foundation of the doctrine of the relativity\nof knowledge, and a more or less complete idealism is a necessary\nconsequence of it.\n\nFor of two alternatives one must be true. Either consciousness is\nthe function of a something distinct from the brain, which we call\nthe soul, and a sensation is the mode in which this soul is affected\nby the motion of a part of the brain; or there is no soul, and a\nsensation is something generated by the mode of motion of a part of\nthe brain. In the former case, the phenomena of the senses are purely\nspiritual affections; in the latter, they are something manufactured\nby the mechanism of the body, and as unlike the causes which set that\nmechanism in motion, as the sound of a repeater is unlike the pushing\nof the spring which gives rise to it.\n\nThe nervous system stands between consciousness and the assumed\nexternal world, as an interpreter who can talk with his fingers stands\nbetween a hidden speaker and a man who is stone deaf\u2014and Realism is\nequivalent to a belief on the part of the deaf man, that the speaker\nmust also be talking with his fingers. \u201cLes extr\u00eames se touchent;\u201d the\nshibboleth of materialists that \u201cthought is a secretion of the brain,\u201d\nis the Fichtean doctrine that \u201cthe phenomenal universe is the creation\nof the Ego,\u201d expressed in other language.\n\n  IV. _The motion of the matter of a sensory nerve may\n  be transmitted through the brain to motor nerves, and\n  thereby give rise to contraction of the muscles to which\n  these motor nerves are distributed; and this reflection\n  of motion from a sensory into a motor nerve may take\n  place without volition, or even contrary to it._\n\nIn stating these important truths, Descartes defined that which we now\nterm \u201creflex action.\u201d Indeed he almost uses the term itself, as he\ntalks of the \u201canimal spirits\u201d as \u201cr\u00e9fl\u00e9chis,\u201d[45] from the sensory into\nthe motor nerves. And that this use of the word \u201creflected\u201d was no mere\naccident, but that the importance and appropriateness of the idea it\nsuggests was fully understood by Descartes\u2019 contemporaries, is apparent\nfrom a passage in Willis\u2019s well-known essay, \u201cDe Anim\u00e2 Brutorum,\u201d\npublished in 1672, in which, in giving an account of Descartes\u2019 views,\nhe speaks of the animal spirits being diverted into motor channels,\n\u201cvelut undulatione reflex\u00e2.\u201d[46]\n\nNothing can be clearer in statement, or in illustration, than the view\nof reflex action which Descartes gives in the \u201cPassions de l\u2019\u00c2me,\u201d Art.\nxiii.\n\nAfter recapitulating the manner in which sensory impressions\ntransmitted by the sensory nerves to the brain give rise to sensation,\nhe proceeds:\u2014\n\n  \u201cAnd in addition to the different feelings excited in the\n  soul by these different motions of the brain, the animal\n  spirits, without the intervention of the soul, may take\n  their course towards certain muscles, rather than towards\n  others, and thus move the limbs, as I shall prove by\n  an example. If some one moves his hand rapidly towards\n  our eyes, as if he were going to strike us, although\n  we know that he is a friend, that he does it only in\n  jest, and that he will be very careful to do us no harm,\n  nevertheless it will be hard to keep from winking. And\n  this shows, that it is not by the agency of the soul\n  that the eyes shut, since this action is contrary to\n  that volition which is the only, or at least the chief,\n  function of the soul; but it is because the mechanism\n  of our body is so disposed, that the motion of the hand\n  towards our eyes excites another movement in our brain,\n  and this sends the animal spirits into those muscles\n  which cause the eyelids to close.\u201d\n\nSince Descartes\u2019 time, experiment has eminently enlarged our knowledge\nof the details of reflex action. The discovery of Bell has enabled us\nto follow the tracks of the sensory and motor impulses, along distinct\nbundles of nerve fibres; and the spinal cord, apart from the brain, has\nbeen proved to be a great centre of reflex action; but the fundamental\nconception remains as Descartes left it, and it is one of the pillars\nof nerve physiology at the present day.\n\n  V. _The motion of any given portion of the matter of the\n  brain excited by the motion of a sensory nerve, leaves\n  behind a readiness to be moved in the same way, in that\n  part. Anything which resuscitates the motion gives\n  rise to the appropriate feeling. This is the physical\n  mechanism of memory_.\n\nDescartes imagined that the pineal body (a curious appendage to the\nupper side of the brain, the function of which, if it have any, is\nwholly unknown) was the instrument through which the soul received\nimpressions from, and communicated them to, the brain. And he thus\nendeavours to explain what happens when one tries to recollect\nsomething:\u2014\n\n  \u201cThus when the soul wills to remember anything, this\n  volition, causing the [pineal] gland to incline itself\n  in different directions, drives the [animal] spirits\n  towards different regions of the brain, until they reach\n  that part in which are the traces, which the object\n  which it desires to remember has left. These traces are\n  produced thus: those pores of the brain through which the\n  [animal] spirits have previously been driven, by reason\n  of the presence of the object, have thereby acquired a\n  tendency to be opened by the animal spirits which return\n  towards them, more easily than other pores, so that the\n  animal spirits, impinging on these pores, enter them\n  more readily than others. By this means they excite a\n  particular movement in the pineal gland, which represents\n  the object to the soul, and causes it to know what it is\n  which it desired to recollect.\u201d[47]\n\nThat memory is dependent upon some condition of the brain is a fact\nestablished by many considerations\u2014among the most important of which\nare the remarkable phenomena of aphasia. And that the condition of the\nbrain on which memory depends, is largely determined by the repeated\noccurrence of that condition of its molecules, which gives rise to the\nidea of the thing remembered, is no less certain.\nEvery boy who learns his lesson by repeating it exemplifies the fact.\nDescartes, as we have seen, supposes that the pores of a given part\nof the brain are stretched by the animal spirits, on the occurrence\nof a sensation, and that the part of the brain thus stretched, being\nimperfectly elastic, does not return to exactly its previous condition,\nbut remains more distensible than it was before. Hartley supposes\nthat the vibrations, excited by a sensory, or other, impression,\ndo not die away, but are represented by smaller vibrations or\n\u201cvibratiuncules,\u201d the permanency and intensity of which are in relation\nwith the frequency of repetition of the primary vibrations. Haller has\nsubstantially the same idea, but contents himself with the general term\n\u201cmutationes,\u201d to express the cerebral change which is the cause of a\nstate of consciousness. These \u201cmutationes\u201d persist for a long time\nafter the cause which gives rise to them has ceased to operate, and\nare arranged in the brain according to the order of coexistence and\nsuccession of their causes. And he gives these persistent \u201cmutationes\u201d\nthe picturesque name of _vestigia rerum_, \u201cqu\u00e6 non in mente sed in ipso\ncorpore et in medulla quidem cerebri ineffabili modo incredibiliter\nminutis notis et copia infinita, inscript\u00e6 sunt.\u201d[48] I do not know\nthat any modern theory of the physical conditions of memory differs\nessentially from these, which are all children\u2014_mutatis mutandis_\u2014of\nthe Cartesian doctrine. Physiology is, at present, incompetent to\nsay anything positively about the matter, or to go farther than the\nexpression of the high probability, that every molecular change\nwhich gives rise to a state of consciousness, leaves a more or less\npersistent structural modification, through which the same molecular\nchange may be regenerated by other agencies than the cause which first\nproduced it.\n\nThus far, the propositions respecting the physiology of the nervous\nsystem which are stated by Descartes have simply been more clearly\ndefined, more fully illustrated, and, for the most part, demonstrated,\nby modern physiological research. But there remains a doctrine to which\nDescartes attached great weight, so that full acceptance of it became\na sort of note of a thorough-going Cartesian, but which, nevertheless,\nis so opposed to ordinary prepossessions that it attained more general\nnotoriety, and gave rise to more discussion, than almost any other\nCartesian hypothesis. It is the doctrine, that brute animals are mere\nmachines or automata, devoid not only of reason, but of any kind of\nconsciousness, which is stated briefly in the \u201cDiscours de la M\u00e9thode,\u201d\nand more fully in the \u201cR\u00e9ponses aux Quatri\u00e8mes Objections,\u201d and in the\ncorrespondence with Henry More.[49]\n\nThe process of reasoning by which Descartes arrived at this startling\nconclusion is well shown in the following passage of the \u201cR\u00e9ponses:\u201d\u2014\n\n  \u201cBut as regards the souls of beasts, although this is not\n  the place for considering them, and though, without a\n  general exposition of physics, I can say no more on this\n  subject than I have already said in the fifth part of my\n  Treatise on Method; yet, I will further state, here, that\n  it appears to me to be a very remarkable circumstance\n  that no movement can take place, either in the bodies of\n  beasts, or even in our own, if these bodies have not in\n  themselves all the organs and instruments by means of\n  which the very same movements would be accomplished in a\n  machine. So that, even in us, the spirit, or the soul,\n  does not directly move the limbs, but only determines\n  the course of that very subtle liquid which is called\n  the animal spirits, which, running continually from the\n  heart by the brain into the muscles, is the cause of all\n  the movements of our limbs, and often may cause many\n  different motions, one as easily as the other.\n\n  \u201cAnd it does not even always exert this determination;\n  for among the movements which take place in us, there\n  are many which do not depend on the mind at all, such\n  as the beating of the heart, the digestion of food, the\n  nutrition, the respiration, of those who sleep; and,\n  even in those who are awake, walking, singing, and other\n  similar actions, when they are performed without the\n  mind thinking about them. And, when one who falls from\n  a height throws his hands forwards to save his head, it\n  is in virtue of no ratiocination that he performs this\n  action; it does not depend upon his mind, but takes place\n  merely because his senses being affected by the present\n  danger, some change arises in his brain which determines\n  the animal spirits to pass thence into the nerves, in\n  such a manner as is required to produce this motion,\n  in the same way as in a machine, and without the mind\n  being able to hinder it. Now since we observe this in\n  ourselves, why should we be so much astonished if the\n  light reflected from the body of a wolf into the eye of\n  a sheep has the same force to excite in it the motion of\n  flight?\n\n  \u201cAfter having observed this, if we wish to learn by\n  reasoning, whether certain movements of beasts are\n  comparable to those which are effected in us by the\n  operation of the mind, or, on the contrary, to those\n  which depend only on the animal spirits and the\n  disposition of the organs, it is necessary to consider\n  the difference between the two, which I have explained\n  in the fifth part of the Discourse on Method (for I do\n  not think that any others are discoverable), and then\n  it will easily be seen, that all the actions of beasts\n  are similar only to those which we perform without the\n  help of our minds. For which reason we shall be forced\n  to conclude, that we know of the existence in them of no\n  other principle of motion than the disposition of their\n  organs and the continual affluence of animal spirits\n  produced by the heat of the heart, which attenuates and\n  subtilises the blood; and, at the same time, we shall\n  acknowledge that we have had no reason for assuming any\n  other principle, except that, not having distinguished\n  these two principles of motion, and seeing that the one,\n  which depends only on the animal spirits and the organs,\n  exists in beasts as well as in us, we have hastily\n  concluded that the other, which depends on mind and on\n  thought, was also possessed by them.\u201d\n\nDescartes\u2019 line of argument is perfectly clear. He starts from reflex\naction in man, from the unquestionable fact that, in ourselves,\nco-ordinate, purposive, actions may take place, without the\nintervention of consciousness or volition, or even contrary to the\nlatter. As actions of a certain degree of complexity are brought about\nby mere mechanism, why may not actions of still greater complexity\nbe the result of a more refined mechanism? What proof is there that\nbrutes are other than a superior race of marionettes, which eat without\npleasure, cry without pain, desire nothing, know nothing, and only\nsimulate intelligence as a bee simulates a mathematician?[50]\n\nThe Port Royalists adopted the hypothesis that brutes are machines,\nand are said to have carried its practical applications so far, as to\ntreat domestic animals with neglect, if not with actual cruelty. As\nlate as the middle of the eighteenth century, the problem was discussed\nvery fully and ably by Bouillier, in his \u201cEssai philosophique sur l\u2019\u00c2me\ndes B\u00eates,\u201d while Condillac deals with it in his \u201cTrait\u00e9 des Animaux;\u201d\nbut since then it has received little attention. Nevertheless, modern\nresearch has brought to light a great multitude of facts, which not\nonly show that Descartes\u2019 view is defensible, but render it far more\ndefensible than it was in his day.\n\nIt must be premised, that it is wholly impossible absolutely to prove\nthe presence or absence of consciousness in anything but one\u2019s own\nbrain, though, by analogy, we are justified in assuming its existence\nin other men. Now if, by some accident, a man\u2019s spinal cord is divided,\nhis limbs are paralysed, so far as his volition is concerned, below\nthe point of injury; and he is incapable of experiencing all those\nstates of consciousness, which, in his uninjured state, would be\nexcited by irritation of those nerves which come off below the injury.\nIf the spinal cord is divided in the middle of the back, for example,\nthe skin of the feet may be cut, or pinched, or burned, or wetted\nwith vitriol, without any sensation of touch, or of pain, arising in\nconsciousness. So far as the man is concerned, therefore, the part of\nthe central nervous system which lies beyond the injury is cut off\nfrom consciousness. It must indeed be admitted, that, if any one think\nfit to maintain that the spinal cord below the injury is conscious, but\nthat it is cut off from any means of making its consciousness known to\nthe other consciousness in the brain, there is no means of driving him\nfrom his position by logic. But assuredly there is no way of proving\nit, and in the matter of consciousness, if in anything, we may hold by\nthe rule, \u201cDe non apparentibus et de non existentibus eadem est ratio.\u201d\nHowever near the brain the spinal cord is injured, consciousness\nremains intact, except that the irritation of parts below the injury\nis no longer represented by sensation. On the other hand, pressure\nupon the anterior division of the brain, or extensive injuries to it,\nabolish consciousness. Hence, it is a highly probable conclusion,\nthat consciousness in man depends upon the integrity of the anterior\ndivision of the brain, while the middle and hinder divisions of the\nbrain, and the rest of the nervous centres, have nothing to do with it.\nAnd it is further highly probable, that what is true for man is true\nfor other vertebrated animals.\n\nWe may assume, then, that in a living vertebrated animal, any\nsegment of the cerebro-spinal axis (or spinal cord and brain)\nseparated from that anterior division of the brain which is the\norgan of consciousness, is as completely incapable of giving rise to\nconsciousness, as we know it to be incapable of carrying out volitions.\nNevertheless, this separated segment of the spinal cord is not passive\nand inert. On the contrary, it is the seat of extremely remarkable\npowers. In our imaginary case of injury, the man would, as we have\nseen, be devoid of sensation in his legs, and would have not the least\npower of moving them. But, if the soles of his feet were tickled, the\nlegs would be drawn up, just as vigorously as they would have been\nbefore the injury. We know exactly what happens when the soles of the\nfeet are tickled; a molecular change takes place in the sensory nerves\nof the skin, and is propagated along them and through the posterior\nroots of the spinal nerves, which are constituted by them, to the grey\nmatter of the spinal cord. Through that grey matter, the molecular\nmotion is reflected into the anterior roots of the same nerves,\nconstituted by the filaments which supply the muscles of the legs, and,\ntravelling along these motor filaments, reaches the muscles, which at\nonce contract, and cause the limbs to be drawn up.\n\nIn order to move the legs in this way, a definite co-ordination of\nmuscular contractions is necessary; the muscles must contract in a\ncertain order and with duly proportioned force; and moreover, as the\nfeet are drawn away from the source of irritation, it may be said that\nthe action has a final cause, or is purposive.\n\nThus it follows, that the grey matter of the segment of the man\u2019s\nspinal cord, though it is devoid of consciousness, nevertheless\nresponds to a simple stimulus by giving rise to a complex set of\nmuscular contractions, co-ordinated towards a definite end, and serving\nan obvious purpose.\n\nIf the spinal cord of a frog is cut across, so as to provide us with a\nsegment separated from the brain, we shall have a subject parallel to\nthe injured man, on which experiments can be made without remorse; as\nwe have a right to conclude that a frog\u2019s spinal cord is not likely to\nbe conscious, when a man\u2019s is not.\n\nNow the frog behaves just as the man did. The legs are utterly\nparalysed, so far as voluntary movement is concerned; but they are\nvigorously drawn up to the body when any irritant is applied to the\nfoot. But let us study our frog a little farther. Touch the skin of\nthe side of the body with a little acetic acid, which gives rise to\nall the signs of great pain in an uninjured frog. In this case, there\ncan be no pain, because the application is made to a part of the skin\nsupplied with nerves which come off from the cord below the point of\nsection; nevertheless, the frog lifts up the limb of the same side,\nand applies the foot to rub off the acetic acid; and, what is still\nmore remarkable, if the limb be held so that the frog cannot use it, it\nwill, by-and-by, move the limb of the other side, turn it across the\nbody, and use it for the same rubbing process. It is impossible that\nthe frog, if it were in its entirety and could reason, should perform\nactions more purposive than these: and yet we have most complete\nassurance that, in this case, the frog is not acting from purpose, has\nno consciousness, and is a mere insensible machine.\n\nBut now suppose that, instead of making a section of the cord in the\nmiddle of the body, it had been made in such a manner as to separate\nthe hindermost division of the brain from the rest of the organ, and\nsuppose the foremost two-thirds of the brain entirely taken away. The\nfrog is then absolutely devoid of any spontaneity; it sits upright in\nthe attitude which a frog habitually assumes; and it will not stir\nunless it is touched; but it differs from the frog which I have just\ndescribed in this, that, if it be thrown into the water, it begins to\nswim, and swims just as well as the perfect frog does. But swimming\nrequires the combination and successive co-ordination of a great number\nof muscular actions. And we are forced to conclude, that the impression\nmade upon the sensory nerves of the skin of the frog by the contact\nwith the water into which it is thrown, causes the transmission to the\ncentral nervous apparatus of an impulse, which sets going a certain\nmachinery by which all the muscles of swimming are brought into play\nin due co-ordination. If the frog be stimulated by some irritating\nbody, it jumps or walks as well as the complete frog can do. The simple\nsensory impression, acting through the machinery of the cord, gives\nrise to these complex combined movements.\n\nIt is possible to go a step farther. Suppose that only the anterior\ndivision of the brain\u2014so much of it as lies in front of the \u201coptic\nlobes\u201d\u2014is removed. If that operation is performed quickly and\nskilfully, the frog may be kept in a state of full bodily vigour for\nmonths, or it may be for years; but it will sit unmoved. It sees\nnothing; it hears nothing. It will starve sooner than feed itself,\nalthough food put into its mouth is swallowed. On irritation, it jumps\nor walks; if thrown into the water it swims. If it be put on the hand,\nit sits there, crouched, perfectly quiet, and would sit there for ever.\nIf the hand be inclined very gently and slowly, so that the frog would\nnaturally tend to slip off, the creature\u2019s fore paws are shifted on to\nthe edge of the hand, until he can just prevent himself from falling.\nIf the turning of the hand be slowly continued, he mounts up with great\ncare and deliberation, putting first one leg forward and then another,\nuntil he balances himself with perfect precision upon the edge; and, if\nthe turning of the hand is continued, over he goes through the needful\nset of muscular operations, until he comes to be seated in security,\nupon the back of the hand. The doing of all this requires a delicacy of\nco-ordination, and a precision of adjustment of the muscular apparatus\nof the body, which are only comparable to those of a rope-dancer. To\nthe ordinary influences of light, the frog, deprived of its cerebral\nhemispheres, appears to be blind. Nevertheless, if the animal be put\nupon a table, with a book at some little distance between it and the\nlight, and the skin of the hinder part of its body is then irritated,\nit will jump forward, avoiding the book by passing to the right or left\nof it. Therefore, although the frog appears to have no sensation of\nlight, visible objects act through its brain upon the motor mechanism\nof its body.[51]\n\nIt is obvious, that had Descartes been acquainted with these remarkable\nresults of modern research, they would have furnished him with far\nmore powerful arguments than he possessed in favour of his view of\nthe automatism of brutes. The habits of a frog, leading its natural\nlife, involve such simple adaptations to surrounding conditions,\nthat the machinery which is competent to do so much without the\nintervention of consciousness, might well do all. And this argument is\nvastly strengthened by what has been learned in recent times of the\nmarvellously complex operations which are performed mechanically, and\nto all appearance without consciousness, by men, when, in consequence\nof injury or disease, they are reduced to a condition more or less\ncomparable to that of a frog, in which the anterior part of the brain\nhas been removed. A case has recently been published by an eminent\nFrench physician, Dr. Mesnet, which illustrates this condition so\nremarkably, that I make no apology for dwelling upon it at considerable\nlength.[52]\n\nA sergeant of the French army, F\u2014\u2014, twenty-seven years of age, was\nwounded during the battle of Bazeilles, by a ball which fractured his\nleft parietal bone. He ran his bayonet through the Prussian soldier who\nwounded him, but almost immediately his right arm became paralysed;\nafter walking about two hundred yards, his right leg became similarly\naffected, and he lost his senses. When he recovered them, three weeks\nafterwards, in hospital at Mayence, the right half of the body was\ncompletely paralysed, and remained in this condition for a year. At\npresent, the only trace of the paralysis which remains is a slight\nweakness of the right half of the body. Three or four months after\nthe wound was inflicted, periodical disturbances of the functions of\nthe brain made their appearance, and have continued ever since. The\ndisturbances last from fifteen to thirty hours; the intervals at which\nthey occur being from fifteen to thirty days.\n\nFor four years, therefore, the life of this man has been divided into\nalternating phases\u2014short abnormal states intervening between long\nnormal states.\n\nIn the periods of normal life, the ex-sergeant\u2019s health is perfect; he\nis intelligent and kindly, and performs, satisfactorily, the duties of\na hospital attendant. The commencement of the abnormal state is ushered\nin by uneasiness and a sense of weight about the forehead, which the\npatient compares to the constriction of a circle of iron; and, after\nits termination, he complains, for some hours, of dulness and heaviness\nof the head. But the transition from the normal to the abnormal state\ntakes place in a few minutes, without convulsions or cries, and without\nanything to indicate the change to a bystander. His movements remain\nfree and his expression calm, except for a contraction of the brow, an\nincessant movement of the eyeballs, and a chewing motion of the jaws.\nThe eyes are wide open, and their pupils dilated. If the man happens to\nbe in a place to which he is accustomed, he walks about as usual; but,\nif he is in a new place, or if obstacles are intentionally placed in\nhis way, he stumbles gently against them, stops, and then, feeling over\nthe objects with his hands, passes on one side of them. He offers no\nresistance to any change of direction which may be impressed upon him,\nor to the forcible acceleration or retardation of his movements. He\neats, drinks, smokes, walks about, dresses and undresses himself, rises\nand goes to bed at the accustomed hours. Nevertheless, pins may be\nrun into his body, or strong electric shocks sent through it, without\ncausing the least indication of pain; no odorous substance, pleasant or\nunpleasant, makes the least impression; he eats and drinks with avidity\nwhatever is offered, and takes asaf\u0153tida, or vinegar, or quinine, as\nreadily as water; no noise affects him; and light influences him only\nunder certain conditions. Dr. Mesnet remarks, that the sense of touch\nalone seems to persist, and indeed to be more acute and delicate than\nin the normal state; and it is by means of the nerves of touch, almost\nexclusively, that his organism is brought into relation with the\nexternal world. Here a difficulty arises. It is clear from the facts\ndetailed, that the nervous apparatus by which, in the normal state,\nsensations of touch are excited, is that by which external influences\ndetermine the movements of the body, in the abnormal state. But does\nthe state of consciousness, which we term a tactile sensation,\naccompany the operation of this nervous apparatus in the abnormal\nstate? or is consciousness utterly absent, the man being reduced to an\ninsensible mechanism?\n\nIt is impossible to obtain direct evidence in favour of the one\nconclusion or the other; all that can be said is, that the case of the\nfrog shows that the man may be devoid of any kind of consciousness.\n\nA further difficult problem is this. The man is insensible to sensory\nimpressions made through the ear, the nose, the tongue, and, to a great\nextent, the eye; nor is he susceptible of pain from causes operating\nduring his abnormal state. Nevertheless, it is possible so to act upon\nhis tactile apparatus, as to give rise to those molecular changes in\nhis sensorium, which are ordinarily the causes of associated trains of\nideas. I give a striking example of this process in Dr. Mesnet\u2019s words:\u2014\n\n  \u201cIl se promenait dans le jardin, sous un massif d\u2019arbres,\n  on lui remet \u00e0 la main sa canne qu\u2019il avait laiss\u00e9\n  tomber quelques minutes avant. Il la palpe, prom\u00e8ne \u00e0\n  plusieurs reprises la main sur la poign\u00e9e coud\u00e9e de\n  sa canne\u2014devient attentif\u2014semble pr\u00eater l\u2019oreille\u2014et,\n  tout-\u00e0-coup, appelle \u2018Henri!\u2019 Puis, \u2018Les voil\u00e0! Ils sont\n  au moins une vingtaine! \u00e0 nous deux, nous en viendrons \u00e0\n  bout!\u2019 Et alors portant la main derri\u00e8re son dos comme\n  pour prendre une cartouche, il fait le mouvement de\n  charger son arme, se couche dans l\u2019herbe \u00e0 plat ventre,\n  la t\u00eate cach\u00e9e par un arbre, dans la position d\u2019un\n  tirailleur, et suit, l\u2019arme \u00e9paul\u00e9e, tous les mouvements\n  de l\u2019ennemi qu\u2019il croit voir \u00e0 courte distance.\u201d\n\nIn a subsequent abnormal period, Dr. Mesnet caused the patient to\nrepeat this scene by placing him in the same conditions. Now, in this\ncase, the question arises whether the series of actions constituting\nthis singular pantomime was accompanied by the ordinary states of\nconsciousness, the appropriate train of ideas, or not? Did the man\ndream that he was skirmishing? or was he in the condition of one of\nVaucauson\u2019s automata\u2014a senseless mechanism worked by molecular changes\nin his nervous system? The analogy of the frog shows that the latter\nassumption is perfectly justifiable.\n\nThe ex-sergeant has a good voice, and had, at one time, been employed\nas a singer at a caf\u00e9. In one of his abnormal states he was observed\nto begin humming a tune. He then went to his room, dressed himself\ncarefully, and took up some parts of a periodical novel, which lay on\nhis bed, as if he were trying to find something. Dr. Mesnet, suspecting\nthat he was seeking his music, made up one of these into a roll and\nput it into his hand. He appeared satisfied, took up his cane and went\ndown-stairs to the door. Here Dr. Mesnet turned him round, and he\nwalked quite contentedly, in the opposite direction, towards the room\nof the conci\u00e8rge. The light of the sun shining through a window now\nhappened to fall upon him, and seemed to suggest the footlights of the\nstage on which he was accustomed to make his appearance. He stopped,\nopened his roll of imaginary music, put himself into the attitude of a\nsinger, and sang, with perfect execution, three songs, one after the\nother. After which he wiped his face with his handkerchief and drank,\nwithout a grimace, a tumbler of strong vinegar and water which was put\ninto his hand.\n\nAn experiment which may be performed upon the frog deprived of the\nfore part of its brain, well known as G\u00f6ltz\u2019s \u201cQuak-versuch,\u201d affords\na parallel to this performance. If the skin of a certain part of the\nback of such a frog is gently stroked with the finger, it immediately\ncroaks. It never croaks unless it is so stroked, and the croak always\nfollows the stroke, just as the sound of a repeater follows the\ntouching of the spring. In the frog, this \u201csong\u201d is innate\u2014so to speak\n_\u00e0 priori_\u2014and depends upon a mechanism in the brain governing the\nvocal apparatus, which is set at work by the molecular change set up in\nthe sensory nerves of the skin of the back by the contact of a foreign\nbody.\n\nIn man there is also a vocal mechanism, and the cry of an infant is\nin the same sense innate and _\u00e0 priori_, inasmuch as it depends on an\norganic relation between its sensory nerves and the nervous mechanism\nwhich governs the vocal apparatus. Learning to speak, and learning to\nsing, are processes by which the vocal mechanism is set to new tunes.\nA song which has been learned has its molecular equivalent, which\npotentially represents it in the brain, just as a musical box wound up\npotentially represents an overture. Touch the stop and the overture\nbegins; send a molecular impulse along the proper afferent nerve and\nthe singer begins his song.\n\nAgain, the manner in which the frog, though apparently insensible to\nlight, is yet, under some circumstances, influenced by visual images,\nfinds a singular parallel in the case of the ex-sergeant.\n\nSitting at a table, in one of his abnormal states, he took up a\npen, felt for paper and ink, and began to write a letter to his\ngeneral, in which he recommended himself for a medal, on account of\nhis good conduct and courage. It occurred to Dr. Mesnet to ascertain\nexperimentally how far vision was concerned in this act of writing. He\ntherefore interposed a screen between the man\u2019s eyes and his hands;\nunder these circumstances he went on writing for a short time, but the\nwords became illegible, and he finally stopped, without manifesting\nany discontent. On the withdrawal of the screen he began to write\nagain where he had left off. The substitution of water for ink in the\ninkstand had a similar result. He stopped, looked at his pen, wiped it\non his coat, dipped it in the water, and began again, with the same\neffect.\n\nOn one occasion, he began to write upon the topmost of ten superimposed\nsheets of paper. After he had written a line or two, this sheet was\nsuddenly drawn away. There was a slight expression of surprise, but he\ncontinued his letter on the second sheet exactly as if it had been the\nfirst. This operation was repeated five times, so that the fifth sheet\ncontained nothing but the writer\u2019s signature at the bottom of the page.\nNevertheless, when the signature was finished, his eyes turned to the\ntop of the blank sheet, and he went through the form of reading over\nwhat he had written, a movement of the lips accompanying each word;\nmoreover, with his pen, he put in such corrections as were needed, in\nthat part of the blank page which corresponded with the position of the\nwords which required correction, in the sheets which had been taken\naway. If the five sheets had been transparent, therefore, they would,\nwhen superposed, have formed a properly written and corrected letter.\n\nImmediately after he had written his letter, F\u2014\u2014 got up, walked down\nto the garden, made himself a cigarette, lighted and smoked it. He was\nabout to prepare another, but sought in vain for his tobacco-pouch,\nwhich had been purposely taken away. The pouch was now thrust before\nhis eyes and put under his nose, but he neither saw nor smelt it; but,\nwhen it was placed in his hand, he at once seized it, made a fresh\ncigarette, and ignited a match to light the latter. The match was blown\nout, and another lighted match placed close before his eyes, but he\nmade no attempt to take it; and, if his cigarette was lighted for him,\nhe made no attempt to smoke. All this time the eyes were vacant, and\nneither winked, nor exhibited any contraction of the pupils. From these\nand other experiments, Dr. Mesnet draws the conclusion that his patient\nsees some things and not others; that the sense of sight is accessible\nto all things which are brought into relation with him by the sense of\ntouch, and, on the contrary, insensible to things which lie outside\nthis relation. He sees the match he holds, and does not see any other.\n\nJust so the frog \u201csees\u201d the book which is in the way of his jump, at\nthe same time that isolated visual impressions take no effect upon\nhim.[53]\n\nAs I have pointed out, it is impossible to prove that F\u2014\u2014 is absolutely\nunconscious in his abnormal state, but it is no less impossible to\nprove the contrary; and the case of the frog goes a long way to\njustify the assumption that, in the abnormal state, the man is a mere\ninsensible machine.\n\nIf such facts as these had come under the knowledge of Descartes, would\nthey not have formed an apt commentary upon that remarkable passage in\nthe \u201cTrait\u00e9 de l\u2019Homme,\u201d which I have quoted elsewhere,[54] but which\nis worth repetition?\u2014\n\n  \u201cAll the functions which I have attributed to this\n  machine (the body), as the digestion of food, the\n  pulsation of the heart and of the arteries; the nutrition\n  and the growth of the limbs; respiration, wakefulness,\n  and sleep; the reception of light, sounds, odours,\n  flavours, heat, and such like qualities, in the organs of\n  the external senses; the impression of the ideas of these\n  in the organ of common sensation and in the imagination;\n  the retention or the impression of these ideas on the\n  memory: the internal movements of the appetites and the\n  passions; and lastly the external movements of all the\n  limbs, which follow so aptly, as well the action of\n  the objects which are presented to the senses, as the\n  impressions which meet in the memory, that they imitate\n  as nearly as possible those of a real man; I desire, I\n  say, that you should consider that these functions in the\n  machine naturally proceed from the mere arrangement of\n  its organs, neither more nor less than do the movements\n  of a clock, or other automaton, from that of its weights\n  and its wheels; so that, so far as these are concerned,\n  it is not necessary to conceive any other vegetative or\n  sensitive soul, nor any other principle of motion or of\n  life, than the blood and the spirits agitated by the fire\n  which burns continually in the heart, and which is no\n  wise essentially different from all the fires which exist\n  in inanimate bodies.\u201d\n\nAnd would Descartes not have been justified in asking why we need deny\nthat animals are machines, when men, in a state of unconsciousness,\nperform, mechanically, actions as complicated and as seemingly rational\nas those of any animals?\n\nBut though I do not think that Descartes\u2019 hypothesis can be positively\nrefuted, I am not disposed to accept it. The doctrine of continuity\nis too well established for it to be permissible to me to suppose\nthat any complex natural phenomenon comes into existence suddenly,\nand without being preceded by simpler modifications; and very strong\narguments would be needed to prove that such complex phenomena, as\nthose of consciousness, first make their appearance in man. We know,\nthat, in the individual man, consciousness grows from a dim glimmer to\nits full light, whether we consider the infant advancing in years, or\nthe adult emerging from slumber and swoon. We know, further, that the\nlower animals possess, though less developed, that part of the brain\nwhich we have every reason to believe to be the organ of consciousness\nin man; and as, in other cases, function and organ are proportional, so\nwe have a right to conclude it is with the brain; and that the brutes,\nthough they may not possess our intensity of consciousness, and though,\nfrom the absence of language, they can have no trains of thoughts, but\nonly trains of feelings, yet have a consciousness which, more or less\ndistinctly, foreshadows our own.\n\nI confess that, in view of the struggle for existence which goes on\nin the animal world, and of the frightful quantity of pain with which\nit must be accompanied, I should be glad if the probabilities were in\nfavour of Descartes\u2019 hypothesis; but, on the other hand, considering\nthe terrible practical consequences to domestic animals which might\nensue from any error on our part, it is as well to err on the right\nside, if we err at all, and deal with them as weaker brethren, who are\nbound, like the rest of us, to pay their toll for living, and suffer\nwhat is needful for the general good. As Hartley finely says, \u201cWe\nseem to be in the place of God to them;\u201d and we may justly follow the\nprecedents He sets in nature in our dealings with them.\n\nBut though we may see reason to disagree with Descartes\u2019 hypothesis\nthat brutes are unconscious machines, it does not follow that he\nwas wrong in regarding them as automata. They may be more or less\nconscious, sensitive, automata; and the view that they are such\nconscious machines is that which is implicitly, or explicitly, adopted\nby most persons. When we speak of the actions of the lower animals\nbeing guided by instinct and not by reason, what we really mean is\nthat, though they feel as we do, yet their actions are the results\nof their physical organisation. We believe, in short, that they are\nmachines, one part of which (the nervous system) not only sets the rest\nin motion, and co-ordinates its movements in relation with changes\nin surrounding bodies, but is provided with special apparatus, the\nfunction of which is the calling into existence of those states of\nconsciousness which are termed sensations, emotions, and ideas. I\nbelieve that this generally accepted view is the best expression of the\nfacts at present known.\n\nIt is experimentally demonstrable\u2014any one who cares to run a pin into\nhimself may perform a sufficient demonstration of the fact\u2014that a mode\nof motion of the nervous system is the immediate antecedent of a state\nof consciousness. All but the adherents of \u201cOccasionalism,\u201d or of the\ndoctrine of \u201cPre-established Harmony\u201d (if any such now exist), must\nadmit that we have as much reason for regarding the mode of motion\nof the nervous system as the cause of the state of consciousness, as\nwe have for regarding any event as the cause of another. How the one\nphenomenon causes the other we know, as much or as little, as in any\nother case of causation; but we have as much right to believe that the\nsensation is an effect of the molecular change, as we have to believe\nthat motion is an effect of impact; and there is as much propriety in\nsaying that the brain evolves sensation, as there is in saying that an\niron rod, when hammered, evolves heat.\n\nAs I have endeavoured to show, we are justified in supposing that\nsomething analogous to what happens in ourselves takes place in the\nbrutes, and that the affections of their sensory nerves give rise to\nmolecular changes in the brain, which again give rise to, or evolve,\nthe corresponding states of consciousness. Nor can there be any\nreasonable doubt that the emotions of brutes, and such ideas as they\npossess, are similarly dependent upon molecular brain changes. Each\nsensory impression leaves behind a record in the structure of the\nbrain\u2014an \u201cideagenous\u201d molecule, so to speak, which is competent, under\ncertain conditions, to reproduce, in a fainter condition, the state of\nconsciousness which corresponds with that sensory impression; and it is\nthese \u201cideagenous molecules\u201d which are the physical basis of memory.\n\nIt may be assumed, then, that molecular changes in the brain are the\ncauses of all the states of consciousness of brutes. Is there any\nevidence that these states of consciousness may, conversely, cause\nthose molecular changes which give rise to muscular motion? I see\nno such evidence. The frog walks, hops, swims, and goes through his\ngymnastic performances quite as well without consciousness, and\nconsequently without volition, as with it; and, if a frog, in his\nnatural state, possesses anything corresponding with what we call\nvolition, there is no reason to think that it is anything but a\nconcomitant of the molecular changes in the brain which form part of\nthe series involved in the production of motion.\n\nThe consciousness of brutes would appear to be related to the mechanism\nof their body simply as a collateral product of its working, and to\nbe as completely without any power of modifying that working as the\nsteam-whistle which accompanies the work of a locomotive engine is\nwithout influence upon its machinery. Their volition, if they have\nany, is an emotion indicative of physical changes, not a cause of such\nchanges.\n\nThis conception of the relations of states of consciousness with\nmolecular changes in the brain\u2014of _psychoses_ with _neuroses_\u2014does not\nprevent us from ascribing free will to brutes. For an agent is free\nwhen there is nothing to prevent him from doing that which he desires\nto do. If a greyhound chases a hare, he is a free agent, because his\naction is in entire accordance with his strong desire to catch the\nhare; while so long as he is held back by the leash he is not free,\nbeing prevented by external force from following his inclination.\nAnd the ascription of freedom to the greyhound under the former\ncircumstances is by no means inconsistent with the other aspect of\nthe facts of the case\u2014that he is a machine impelled to the chase, and\ncaused, at the same time, to have the desire to catch the game by the\nimpression which the rays of light proceeding from the hare make upon\nhis eyes, and through them upon his brain.\n\nMuch ingenious argument has, at various times, been bestowed upon the\nquestion: How is it possible to imagine that volition, which is a state\nof consciousness, and, as such, has not the slightest community of\nnature with matter in motion, can act upon the moving matter of which\nthe body is composed, as it is assumed to do in voluntary acts? But\nif, as is here suggested, the voluntary acts of brutes\u2014or, in other\nwords, the acts which they desire to perform\u2014are as purely mechanical\nas the rest of their actions, and are simply accompanied by the state\nof consciousness called volition, the inquiry, so far as they are\nconcerned, becomes superfluous. Their volitions do not enter into the\nchain of causation of their actions at all.\n\nThe hypothesis that brutes are conscious automata is perfectly\nconsistent with any view that may be held respecting the often\ndiscussed and curious question whether they have souls or not; and,\nif they have souls, whether those souls are immortal or not. It is\nobviously harmonious with the most literal adherence to the text\nof Scripture concerning \u201cthe beast that perisheth;\u201d but it is not\ninconsistent with the amiable conviction ascribed by Pope to his\n\u201cuntutored savage,\u201d that when he passes to the happy hunting-grounds\nin the sky, \u201chis faithful dog shall bear him company.\u201d If the brutes\nhave consciousness and no souls, then it is clear that, in them,\nconsciousness is a direct function of material changes; while, if\nthey possess immaterial subjects of consciousness, or souls, then,\nas consciousness is brought into existence only as the consequence\nof molecular motion of the brain, it follows that it is an indirect\nproduct of material changes. The soul stands related to the body as the\nbell of a clock to the works, and consciousness answers to the sound\nwhich the bell gives out when it is struck.\n\nThus far I have strictly confined myself to the problem with which I\nproposed to deal at starting\u2014the automatism of brutes. The question\nis, I believe, a perfectly open one, and I feel happy in running\nno risk of either Papal or Presbyterian condemnation for the views\nwhich I have ventured to put forward. And there are so very few\ninteresting questions which one is, at present, allowed to think out\nscientifically\u2014to go as far as reason leads, and stop where evidence\ncomes to an end\u2014without speedily being deafened by the tattoo of \u201cthe\ndrum ecclesiastic\u201d\u2014that I have luxuriated in my rare freedom, and would\nnow willingly bring this disquisition to an end if I could hope that\nother people would go no farther. Unfortunately, past experience debars\nme from entertaining any such hope, even if\n\n          \u201c... that drum\u2019s discordant sound\n  Parading round and round and round,\u201d\n\nwere not, at present, as audible to me, as it was to the mild poet who\nventured to express his hatred of drums in general, in that well-known\ncouplet.\n\nIt will be said, that I mean that the conclusions deduced from the\nstudy of the brutes are applicable to man, and that the logical\nconsequences of such application are fatalism, materialism, and\natheism\u2014whereupon the drums will beat the _pas de charge_.\n\nOne does not do battle with drummers; but I venture to offer a few\nremarks for the calm consideration of thoughtful persons, untrammelled\nby foregone conclusions, unpledged to shore-up tottering dogmas, and\nanxious only to know the true bearings of the case.\n\nIt is quite true that, to the best of my judgment, the argumentation\nwhich applies to brutes holds equally good of men; and, therefore, that\nall states of consciousness in us, as in them, are immediately caused\nby molecular changes of the brain-substance. It seems to me that in\nmen, as in brutes, there is no proof that any state of consciousness\nis the cause of change in the motion of the matter of the organism. If\nthese positions are well based, it follows that our mental conditions\nare simply the symbols in consciousness of the changes which take\nplace automatically in the organism; and that, to take an extreme\nillustration, the feeling we call volition is not the cause of a\nvoluntary act, but the symbol of that state of the brain which is\nthe immediate cause of that act. We are conscious automata, endowed\nwith free will in the only intelligible sense of that much-abused\nterm\u2014inasmuch as in many respects we are able to do as we like\u2014but\nnone the less parts of the great series of causes and effects which, in\nunbroken continuity, composes that which is, and has been, and shall\nbe\u2014the sum of existence.\n\nAs to the logical consequences of this conviction of mine, I may be\npermitted to remark that logical consequences are the scarecrows of\nfools and the beacons of wise men. The only question which any wise man\ncan ask himself, and which any honest man will ask himself, is whether\na doctrine is true or false. Consequences will take care of themselves;\nat most their importance can only justify us in testing with extra care\nthe reasoning process from which they result.\n\nSo that if the view I have taken did really and logically lead to\nfatalism, materialism, and atheism, I should profess myself a fatalist,\nmaterialist, and atheist; and I should look upon those who, while they\nbelieved in my honesty of purpose and intellectual competency, should\nraise a hue and cry against me, as people who by their own admission\npreferred lying to truth, and whose opinions therefore were unworthy of\nthe smallest attention.\n\nBut, as I have endeavoured to explain on other occasions, I really have\nno claim to rank myself among fatalistic, materialistic, or atheistic\nphilosophers. Not among fatalists, for I take the conception of\nnecessity to have a logical, and not a physical foundation; not among\nmaterialists, for I am utterly incapable of conceiving the existence\nof matter if there is no mind in which to picture that existence; not\namong atheists, for the problem of the ultimate cause of existence is\none which seems to me to be hopelessly out of reach of my poor powers.\nOf all the senseless babble I have ever had occasion to read, the\ndemonstrations of these philosophers who undertake to tell us all about\nthe nature of God would be the worst, if they were not surpassed by the\nstill greater absurdities of the philosophers who try to prove that\nthere is no God.\n\nAnd if this personal disclaimer should not be enough, let me further\npoint out that a great many persons whose acuteness and learning will\nnot be contested, and whose Christian piety, and, in some cases, strict\northodoxy, are above suspicion, have held more or less definitely the\nview that man is a conscious automaton.\n\nIt is held, for example, in substance, by the whole school of\npredestinarian theologians, typified by St. Augustine, Calvin, and\nJonathan Edwards\u2014the great work of the latter on the will showing\nin this, as in other cases, that the growth of physical science has\nintroduced no new difficulties of principle into theological problems,\nbut has merely given visible body, as it were, to those which already\nexisted.\n\nAmong philosophers, the pious Geulincx and the whole school of\noccasionalist Cartesians held this view; the orthodox Leibnitz invented\nthe term \u201cautomate spirituel,\u201d and applied it to man; the fervent\nChristian, Hartley, was one of the chief advocates and best expositors\nof the doctrine; while another zealous apologist of Christianity in\na sceptical age, and a contemporary of Hartley, Charles Bonnet, the\nGenevese naturalist, has embodied the doctrine in language of such\nprecision and simplicity, that I will quote the little-known passage of\nhis \u201cEssai de Psychologie\u201d at length:\u2014\n\n\n\u201cANOTHER HYPOTHESIS CONCERNING THE MECHANISM OF IDEAS.[55]\n\n  \u201cPhilosophers accustomed to judge of things by that which\n  they are in themselves, and not by their relation to\n  received ideas, would not be shocked if they met with\n  the proposition that the soul is a mere spectator of\n  the movements of its body: that the latter performs of\n  itself all that series of actions which constitutes life:\n  that it moves of itself: that it is the body alone which\n  reproduces ideas, compares and arranges them; which forms\n  reasonings, imagines and executes plans of all kinds,\n  etc. This hypothesis, though perhaps of an excessive\n  boldness, nevertheless deserves some consideration.\n\n  \u201cIt is not to be denied that Supreme Power could create\n  an automaton which should exactly imitate all the\n  external and internal actions of man.\n\n  \u201cI understand by external actions, all those movements\n  which pass under our eyes; I term internal actions, all\n  the motions which in the natural state cannot be observed\n  because they take place in the interior of the body\u2014such\n  as the movements of digestion, circulation, sensation,\n  etc. Moreover, I include in this category the movements\n  which give rise to ideas, whatever be their nature.\n\n  \u201cIn the automaton which we are considering everything\n  would be precisely determined. Everything would occur\n  according to the rules of the most admirable mechanism:\n  one state would succeed another state, one operation\n  would lead to another operation, according to invariable\n  laws; motion would become alternately cause and effect,\n  effect and cause; reaction would answer to action, and\n  reproduction to production.\n\n  \u201cConstructed with definite relations to the activity\n  of the beings which compose the world, the automaton\n  would receive impressions from it, and, in faithful\n  correspondence thereto, it would execute a corresponding\n  series of motions.\n\n  \u201cIndifferent towards any determination, it would yield\n  equally to all, if the first impressions did not, so to\n  speak, wind up the machine and decide its operations and\n  its course.\n\n  \u201cThe series of movements which this automaton could\n  execute would distinguish it from all others formed on\n  the same model, but which, not having been placed in\n  similar circumstances, would not have experienced the\n  same impressions, or would not have experienced them in\n  the same order.\n\n  \u201cThe senses of the automaton, set in motion by the\n  objects presented to it, would communicate their motion\n  to the brain, the chief motor apparatus of the machine.\n  This would put in action the muscles of the hands and\n  feet, in virtue of their secret connection with the\n  senses. These muscles, alternately contracted and\n  dilated, would approximate or remove the automaton from\n  the objects, in the relation which they would bear to the\n  conservation or the destruction of the machine.\n\n  \u201cThe motions of perception and sensation which the\n  objects would have impressed on the brain, would be\n  preserved in it by the energy of its mechanism. They\n  would become more vivid according to the actual condition\n  of the automaton, considered in itself and relatively to\n  the objects.\n\n  \u201cWords being only the motions impressed on the organ\n  of hearing and that of voice, the diversity of these\n  movements, their combination, the order in which they\n  would succeed one another, would represent judgments,\n  reasoning, and all the operations of the mind.\n\n  \u201cA close correspondence between the organs of the senses,\n  either by the opening into one another of their nervous\n  ramifications, or by interposed springs (_ressorts_),\n  would establish such a connection in their working, that,\n  on the occasion of the movements impressed on one of\n  these organs, other movements would be excited, or would\n  become more vivid in some of the other senses.\n\n  \u201cGive the automaton a soul which contemplates its\n  movements, which believes itself to be the author of\n  them, which has different volitions on the occasion of\n  the different movements, and you will on this hypothesis\n  construct a man.\n\n  \u201cBut would this man be free? Can the feeling of our\n  liberty, this feeling which is so clear and so distinct\n  and so vivid as to persuade us that we are the authors of\n  our actions, be conciliated with this hypothesis? If it\n  removes the difficulty which attends the conception of\n  the action of the soul on the body, on the other hand it\n  leaves untouched that which meets us in endeavouring to\n  conceive the action of the body on the soul.\u201d\n\nBut if Leibnitz, Jonathan Edwards, and Hartley\u2014men who rank among\nthe giants of the world of thought\u2014could see no antagonism between\nthe doctrine under discussion and Christian orthodoxy, is it not\njust possible that smaller folk may be wrong in making such a coil\nabout \u201clogical consequences\u201d? And, seeing how large a share of this\nclamour is raised by the clergy of one denomination or another, may\nI say, in conclusion, that it really would be well if ecclesiastical\npersons would reflect that ordination, whatever deep-seated graces\nit may confer, has never been observed to be followed by any visible\nincrease in the learning or the logic of its subject. Making a man a\nBishop, or entrusting him with the office of ministering to even the\nlargest of Presbyterian congregations, or setting him up to lecture to\na Church congress, really does not in the smallest degree augment such\ntitle to respect as his opinions may intrinsically possess. And, when\nsuch a man presumes on an authority which was conferred upon him for\nother purposes, to sit in judgment upon matters his incompetence to\ndeal with which is patent, it is permissible to ignore his sacerdotal\npretensions, and to tell him, as one would tell a mere common,\nunconsecrated, layman: that it is not necessary for any man to occupy\nhimself with problems of this kind unless he so choose; life is filled\nfull enough by the performance of its ordinary and obvious duties. But\nthat, if a man elect to become a judge of these grave questions; still\nmore, if he assume the responsibility of attaching praise or blame\nto his fellow-men for the conclusions at which they arrive touching\nthem, he will commit a sin more grievous than most breaches of the\nDecalogue, unless he avoid a lazy reliance upon the information that\nis gathered by prejudice and filtered through passion, unless he go\nback to the prime sources of knowledge\u2014the facts of nature, and the\nthoughts of those wise men who for generations past have been her best\ninterpreters.\n\n\n\n\nX.\n\nON SENSATION AND THE UNITY OF STRUCTURE OF SENSIFEROUS ORGANS.\n\n\nThe maxim that metaphysical inquiries are barren of result, and that\nthe serious occupation of the mind with them is a mere waste of time\nand labour, finds much favour in the eyes of the many persons who\npride themselves on the possession of sound common sense; and we\nsometimes hear it enunciated by weighty authorities, as if its natural\nconsequence, the suppression of such studies, had the force of a moral\nobligation.\n\nIn this case, however, as in some others, those who lay down the law\nseem to forget that a wise legislator will consider, not merely whether\nhis proposed enactment is desirable, but whether obedience to it is\npossible. For, if the latter question is answered negatively, the\nformer is surely hardly worth debate.\n\nHere, in fact, lies the pith of the reply to those who would make\nmetaphysics contraband of intellect. Whether it is desirable to\nplace a prohibitory duty upon philosophical speculations or not, it\nis utterly impossible to prevent the importation of them into the\nmind. And it is not a little curious to observe that those who most\nloudly profess to abstain from such commodities are, all the while,\nunconscious consumers, on a great scale, of one or other of their\nmultitudinous disguises or adulterations. With mouths full of the\nparticular kind of heavily buttered toast which they affect, they\ninveigh against the eating of plain bread. In truth, the attempt to\nnourish the human intellect upon a diet which contains no metaphysics\nis about as hopeful as that of certain Eastern sages to nourish their\nbodies without destroying life. Everybody has heard the story of the\npitiless microscopist, who ruined the peace of mind of one of these\nmild enthusiasts by showing him the animals moving in a drop of the\nwater with which, in the innocency of his heart, he slaked his thirst;\nand the unsuspecting devotee of plain common sense may look for as\nunexpected a shock when the magnifier of severe logic reveals the\ngerms, if not the full-grown shapes, of lively metaphysical postulates\nrampant amidst his most positive and matter-of-fact notions.\n\nBy way of escape from the metaphysical Will-o\u2019-the-wisps generated\nin the marshes of literature and theology, the serious student is\nsometimes bidden to betake himself to the solid ground of physical\nscience. But the fish of immortal memory, who threw himself out of the\nfrying-pan into the fire, was not more ill advised than the man who\nseeks sanctuary from philosophical persecution within the walls of\nthe observatory or of the laboratory. It is said that \u201cmetaphysics\u201d\nowe their name to the fact that, in Aristotle\u2019s works, questions of\npure philosophy are dealt with immediately after those of physics. If\nso, the accident is happily symbolical of the essential relations of\nthings; for metaphysical speculation follows as closely upon physical\ntheory as black care upon the horseman.\n\nOne need but mention such fundamental, and indeed indispensable,\nconceptions of the natural philosopher as those of atoms and forces:\nor that of attraction considered as action at a distance; or that of\npotential energy; or the antinomies of a vacuum and a plenum; to call\nto mind the metaphysical background of physics and chemistry; while, in\nthe biological sciences, the case is still worse. What is an individual\namong the lower plants and animals? Are genera and species realities or\nabstractions? Is there such a thing as Vital Force? or does the name\ndenote a mere relic of metaphysical fetichism? Is the doctrine of final\ncauses legitimate or illegitimate? These are a few of the metaphysical\ntopics which are suggested by the most elementary study of biological\nfacts. But, more than this, it may be truly said that the roots of\nevery system of philosophy lie deep among the facts of physiology. No\none can doubt that the organs and the functions of sensation are as\nmuch a part of the province of the physiologist, as are the organs and\nfunctions of motion, or those of digestion; and yet it is impossible\nto gain an acquaintance with even the rudiments of the physiology of\nsensation without being led straight to one of the most fundamental of\nall metaphysical problems. In fact, the sensory operations have been,\nfrom time immemorial, the battle-ground of philosophers.\n\nI have more than once taken occasion to point out that we are\nindebted to Descartes, who happened to be a physiologist as well as\na philosopher, for the first distinct enunciation of the essential\nelements of the true theory of sensation. In later times, it is not to\nthe works of the philosophers, if Hartley and James Mill are excepted,\nbut to those of the physiologists, that we must turn for an adequate\naccount of the sensory process. Haller\u2019s luminous, though summary,\naccount of sensation in his admirable \u201cPrim\u00e6 Line\u00e6,\u201d the first edition\nof which was printed in 1747, offers a striking contrast to the\nprolixity and confusion of thought which pervade Reid\u2019s \u201cInquiry,\u201d of\nseventeen years\u2019 later date.[56] Even Sir William Hamilton, learned\nhistorian and acute critic as he was, not only failed to apprehend the\nphilosophical bearing of long-established physiological truths; but,\nwhen he affirmed that there is no reason to deny that the mind feels at\nthe finger points, and none to assert that the brain is the sole organ\nof thought,[57] he showed that he had not apprehended the significance\nof the revolution commenced, two hundred years before his time, by\nDescartes, and effectively followed up by Haller, Hartley, and Bonnet,\nin the middle of the last century.\n\nIn truth, the theory of sensation, except in one point, is, at the\npresent moment, very much where Hartley, led by a hint of Sir Isaac\nNewton\u2019s, left it, when, a hundred and twenty years since, the\n\u201cObservations on Man: his Frame, his Duty, and his Expectations,\u201d was\nlaid before the world. The whole matter is put in a nutshell in the\nfollowing passages of this notable book.\n\n  \u201cExternal objects impressed upon the senses occasion,\n  first on the nerves on which they are impressed, and then\n  on the brain, vibrations of the small and, as we may say,\n  infinitesimal medullary particles.\n\n  \u201cThese vibrations are motions backwards and forwards\n  of the small particles; of the same kind with the\n  oscillations of pendulums and the tremblings of the\n  particles of sounding bodies. They must be conceived to\n  be exceedingly short and small, so as not to have the\n  least efficacy to disturb or move the whole bodies of the\n  nerves or brain.\u201d[58]\n\n  \u201cThe white medullary substance of the brain is also the\n  immediate instrument by which ideas are presented to\n  the mind; or, in other words, whatever changes are made\n  in this substance, corresponding changes are made in our\n  ideas; and _vice versa_.\u201d[59]\n\nHartley, like Haller, had no conception of the nature and functions of\nthe grey matter of the brain. But, if for \u201cwhite medullary substance,\u201d\nin the latter paragraph, we substitute \u201cgrey cellular substance,\u201d\nHartley\u2019s propositions embody the most probable conclusions which are\nto be drawn from the latest investigations of physiologists. In order\nto judge how completely this is the case, it will be well to study some\nsimple case of sensation, and, following the example of Reid and of\nJames Mill, we may begin with the sense of smell. Suppose that I become\naware of a musky scent, to which the name of \u201cmuskiness\u201d may be given.\nI call this an odour, and I class it along with the feelings of light,\ncolours, sounds, tastes, and the like, among those phenomena which are\nknown as sensations. To say that I am aware of this phenomenon, or that\nI have it, or that it exists, are simply different modes of affirming\nthe same facts. If I am asked how I know that it exists, I can only\nreply that its existence and my knowledge of it are one and the same\nthing; in short, that my knowledge is immediate or intuitive, and, as\nsuch, is possessed of the highest conceivable degree of certainty.\n\nThe pure sensation of muskiness is almost sure to be followed by\na mental state which is not a sensation, but a belief, that there\nis somewhere close at hand a something on which the existence of\nthe sensation depends. It may be a musk-deer, or a musk-rat, or a\nmusk-plant, or a grain of dry musk, or simply a scented handkerchief;\nbut former experience leads us to believe that the sensation is due to\nthe presence of one or other of these objects, and that it will vanish\nif the object is removed. In other words, there arises a belief in an\nexternal cause of the muskiness, which, in common language, is termed\nan odorous body.\n\nBut the manner in which this belief is usually put into words is\nstrangely misleading. If we are dealing with a musk-plant, for example,\nwe do not confine ourselves to a simple statement of that which we\nbelieve, and say that the musk-plant is the cause of the sensation\ncalled muskiness; but we say that the plant has a musky smell, and\nwe speak of the odour as a quality, or property, inherent in the\nplant. And the inevitable reaction of words upon thought has in this\ncase become so complete, and has penetrated so deeply, that when an\naccurate statement of the case\u2014namely, that muskiness, inasmuch as\nthe term denotes nothing but a sensation, is a mental state, and has\nno existence except as a mental phenomenon\u2014is first brought under the\nnotice of common-sense folks, it is usually regarded by them as what\nthey are pleased to call a mere metaphysical paradox and a patent\nexample of useless subtlety. Yet the slightest reflection must suffice\nto convince any one possessed of sound reasoning faculties, that it is\nas absurd to suppose that muskiness is a quality inherent in one plant,\nas it would be to imagine that pain is a quality inherent in another,\nbecause we feel pain when a thorn pricks the finger.\n\nEven the common-sense philosopher, _par excellence_, says of smell: \u201cIt\nappears to be a simple and original affection or feeling of the mind,\naltogether inexplicable and unaccountable. It is indeed impossible that\nit can be in any body: it is a sensation, and a sensation can only be\nin a sentient thing.\u201d[60]\n\nThat which is true of muskiness is true of every other odour.\nLavender-smell, clove-smell, garlic-smell, are, like \u201cmuskiness,\u201d names\nof states of consciousness, and have no existence except as such.\nBut, in ordinary language, we speak of all these odours as if they\nwere independent entities residing in lavender, cloves, and garlic;\nand it is not without a certain struggle that the false metaphysic of\nso-called common sense, thus ingrained in us, is expelled.\n\nFor the present purpose, it is unnecessary to inquire into the origin\nof our belief in external bodies, or into that of the notion of\ncausation. Assuming the existence of an external world, there is no\ndifficulty in obtaining experimental proof that, as a general rule,\nolfactory sensations are caused by odorous bodies; and we may pass on\nto the next step of the inquiry\u2014namely, how the odorous body produces\nthe effect attributed to it.\n\nThe first point to be noted here is another fact revealed by\nexperience; that the appearance of the sensation is governed, not only\nby the presence of the odorous substance, but by the condition of a\ncertain part of our corporeal structure, the nose. If the nostrils are\nclosed, the presence of the odorous substance does not give rise to\nthe sensation; while, when they are open, the sensation is intensified\nby the approximation of the odorous substance to them, and by snuffing\nup the adjacent air in such a manner as to draw it into the nose. On\nthe other hand, looking at an odorous substance, or rubbing it on the\nskin, or holding it to the ear, does not awaken the sensation. Thus,\nit can be readily established by experiment that the perviousness of\nthe nasal passages is, in some way, essential to the sensory function;\nin fact, that the organ of that function is lodged somewhere in the\nnasal passages. And, since odorous bodies give rise to their effects at\nconsiderable distances, the suggestion is obvious that something must\npass from them into the sense organ. What is this \u201csomething,\u201d which\nplays the part of an intermediary between the odorous body and the\nsensory organ?\n\nThe oldest speculation about the matter dates back to Democritus and\nthe Epicurean School, and it is to be found fully stated in the fourth\nbook of Lucretius. It comes to this: that the surfaces of bodies\nare constantly throwing off excessively attenuated films of their\nown substance: and that these films, reaching the mind, excite the\nappropriate sensations in it.\n\nAristotle did not admit the existence of any such material films, but\nconceived that it was the form of the substance, and not its matter,\nwhich affected sense, as a seal impresses wax, without losing anything\nin the process. While many, if not the majority, of the Schoolmen took\nup an intermediate position and supposed that a something, which was\nnot exactly either material or immaterial, and which they called an\n\u201cintentional species,\u201d effected the needful communication between the\nbodily cause of sensation and the mind.\n\nBut all these notions, whatever may be said for or against them in\ngeneral, are fundamentally defective, by reason of an oversight\nwhich was inevitable, in the state of knowledge at the time in which\nthey were promulgated. What the older philosophers did not know, and\ncould not know, before the anatomist and the physiologist had done\ntheir work, is that, between the external object and that mind in\nwhich they supposed the sensation to inhere, there lies a physical\nobstacle. The sense organ is not a mere passage by which the \u201ctenuia\nsimulacra rerum,\u201d or the \u201cintentional species\u201d cast off by objects,\nor the \u201cforms\u201d of sensible things, pass straight to the mind; on the\ncontrary, it stands as a firm and impervious barrier, through which no\nmaterial particle of the world without can make its way to the world\nwithin.\n\nLet us consider the olfactory sense organ more nearly. Each of the\nnostrils leads into a passage completely separated from the other\nby a partition, and these two passages place the nostrils in free\ncommunication with the back of the throat, so that they freely transmit\nthe air passing to the lungs when the mouth is shut, as in ordinary\nbreathing. The floor of each passage is flat, but its roof is a high\narch, the crown of which is seated between the orbital cavities of the\nskull, which serve for the lodgment and protection of the eyes; and\nit therefore lies behind the apparent limits of that feature which,\nin ordinary language, is called the nose. From the side walls of the\nupper and back part of these arched chambers, certain delicate plates\nof bone project, and these, as well as a considerable part of the\npartition between the two chambers, are covered by a fine, soft, moist\nmembrane. It is to this \u201cSchneiderian,\u201d or olfactory, membrane that\nodorous bodies must obtain direct access, if they are to give rise\nto their appropriate sensations; and it is upon the relatively large\nsurface, which the olfactory membrane offers, that we must seek for\nthe seat of the organ of the olfactory sense. The only essential part\nof that organ consists of a multitude of minute rod-like bodies, set\nperpendicularly to the surface of the membrane, and forming a part of\nthe cellular coat, or epithelium, which covers the olfactory membrane,\nas the epidermis covers the skin. In the case of the olfactory sense,\nthere can be no doubt that the Democritic hypothesis, at any rate for\nsuch odorous substances as musk, has a good foundation. Infinitesimal\nparticles of musk fly off from the surface of the odorous body, and,\nbecoming diffused through the air, are carried into the nasal passages,\nand thence into the olfactory chambers, where they come into contact\nwith the filamentous extremities of the delicate olfactory epithelium.\n\nBut this is not all. The \u201cmind\u201d is not, so to speak, upon the other\nside of the epithelium. On the contrary, the inner ends of the\nolfactory cells are connected with nerve fibres, and these nerve\nfibres, passing into the cavity of the skull, at length end in a\npart of the brain, the olfactory sensorium. It is certain that the\nintegrity of each, and the physical inter-connection of all these three\nstructures, the epithelium of the sensory organ, the nerve fibres,\nand the sensorium, are essential conditions of ordinary sensation.\nThat is to say, the air in the olfactory chambers may be charged with\nparticles of musk; but, if either the epithelium, or the nerve fibres,\nor the sensorium is injured, or if they are physically disconnected\nfrom one another, sensation will not arise. Moreover, the epithelium\nmay be said to be receptive, the nerve fibres transmissive, and the\nsensorium sensifacient. For, in the act of smelling, the particles of\nthe odorous substance produce a molecular change (which Hartley was in\nall probability right in terming a vibration) in the epithelium, and\nthis change being transmitted to the nerve fibres, passes along them\nwith a measurable velocity, and, finally reaching the sensorium, is\nimmediately followed by the sensation.\n\nThus, modern investigation supplies a representative of the Epicurean\nsimulacra in the volatile particles of the musk; but it also gives us\nthe stamp of the particles on the olfactory epithelium, without any\ntransmission of matter, as the equivalent of the Aristotelian \u201cform;\u201d\nwhile, finally, the modes of motion of the molecules of the olfactory\ncells, of the nerve, and of the cerebral sensorium, which are Hartley\u2019s\nvibrations, may stand very well for a double of the \u201cintentional\nspecies\u201d of the Schoolmen. And this last remark is not intended merely\nto suggest a fanciful parallel; for, if the cause of the sensation is,\nas analogy suggests, to be sought in the mode of motion of the object\nof sense, then it is quite possible that the particular mode of motion\nof the object is reproduced in the sensorium; exactly as the diaphragm\nof a telephone reproduces the mode of motion taken up at its receiving\nend. In other words, the secondary \u201cintentional species\u201d may be, as the\nSchoolmen thought the primary one was, the last link between matter and\nmind.\n\nNone the less, however, does it remain true that no similarity exists,\nnor indeed is conceivable, between the cause of the sensation and the\nsensation. Attend as closely to the sensations of muskiness, or any\nother odour, as we will, no trace of extension, resistance, or motion\nis discernible in them. They have no attribute in common with those\nwhich we ascribe to matter; they are, in the strictest sense of the\nwords, immaterial entities.\n\nThus, the most elementary study of sensation justifies Descartes\u2019\nposition, that we know more of mind than we do of body; that the\nimmaterial world is a firmer reality than the material. For the\nsensation \u201cmuskiness\u201d is known immediately. So long as it persists,\nit is a part of what we call our thinking selves, and its existence\nlies beyond the possibility of doubt. The knowledge of an objective or\nmaterial cause of the sensation, on the other hand, is mediate; it is\na belief as contradistinguished from an intuition; and it is a belief\nwhich, in any given instance of sensation, may, by possibility, be\ndevoid of foundation. For odours, like other sensations, may arise from\nthe occurrence of the appropriate molecular changes in the nerve or in\nthe sensorium, by the operation of a cause distinct from the affection\nof the sense organ by an odorous body. Such \u201csubjective\u201d sensations\nare as real existences as any others, and as distinctly suggest an\nexternal odorous object as their cause; but the belief thus generated\nis a delusion. And, if beliefs are properly termed \u201ctestimonies of\nconsciousness,\u201d then undoubtedly the testimony of consciousness may be,\nand often is, untrustworthy.\n\nAnother very important consideration arises out of the facts as they\nare now known. That which, in the absence of a knowledge of the\nphysiology of sensation, we call the cause of the smell, and term the\nodorous object, is only such, mediately, by reason of its emitting\nparticles which give rise to a mode of motion in the sense organ. The\nsense organ, again, is only a mediate cause by reason of its producing\na molecular change in the nerve fibre; while this last change is also\nonly a mediate cause of sensation, depending, as it does, upon the\nchange which it excites in the sensorium.\n\nThe sense organ, the nerve, and the sensorium, taken together,\nconstitute the sensiferous apparatus. They make up the thickness of the\nwall between the mind, as represented by the sensation \u201cmuskiness,\u201d and\nthe object, as represented by the particle of musk in contact with the\nolfactory epithelium.\n\nIt will be observed that the sensiferous wall and the external world\nare of the same nature; whatever it is that constitutes them both is\nexpressible in terms of matter and motion. Whatever changes take place\nin the sensiferous apparatus are continuous with, and similar to, those\nwhich take place in the external world.[61] But, with the sensorium,\nmatter and motion come to an end; while phenomena of another order,\nor immaterial states of consciousness, make their appearance. How is\nthe relation between the material and the immaterial phenomena to\nbe conceived? This is the metaphysical problem of problems, and the\nsolutions which have been suggested have been made the corner-stones of\nsystems of philosophy. Three mutually irreconcilable readings of the\nriddle have been offered.\n\nThe first is, that an immaterial substance of mind exists; and that it\nis affected by the mode of motion of the sensorium in such a way as to\ngive rise to the sensation.\n\nThe second is, that the sensation is a direct effect of the mode of\nmotion of the sensorium, brought about without the intervention of any\nsubstance of mind.\n\nThe third is, that the sensation is neither directly nor indirectly\nan effect of the mode of motion of the sensorium, but that it has an\nindependent cause. Properly speaking, therefore, it is not an effect of\nthe motion of the sensorium, but a concomitant of it.\n\nAs none of these hypotheses is capable of even an approximation to\ndemonstration, it is almost needless to remark that they have been\nseverally held with tenacity and advocated with passion. I do not\nthink it can be said of any of the three that it is inconceivable, or\nthat it can be assumed on _\u00e0 priori_ grounds to be impossible.\n\nConsider the first, for example; an immaterial substance is perfectly\nconceivable. In fact, it is obvious that, if we possessed no sensations\nbut those of smell and hearing, we should be unable to conceive a\nmaterial substance. We might have a conception of time, but could\nhave none of extension, or of resistance, or of motion. And without\nthe three latter conceptions no idea of matter could be formed. Our\nwhole knowledge would be limited to that of a shifting succession\nof immaterial phenomena. But, if an immaterial substance may exist,\nit may have any conceivable properties; and sensation may be one of\nthem. All these propositions may be affirmed with complete dialectic\nsafety, inasmuch as they cannot possibly be disproved; but neither\ncan a particle of demonstrative evidence be offered in favour of the\nexistence of an immaterial substance.\n\nAs regards the second hypothesis, it certainly is not inconceivable,\nand therefore it may be true, that sensation is the direct effect of\ncertain kinds of bodily motion. It is just as easy to suppose this as\nto suppose, on the former hypothesis, that bodily motion affects an\nimmaterial substance. But neither is it susceptible of proof.\n\nAnd, as to the third hypothesis, since the logic of induction is in no\ncase competent to prove that events apparently standing in the relation\nof cause and effect may not both be effects of a common cause\u2014that\nalso is as safe from refutation, if as incapable of demonstration, as\nthe other two.\n\nIn my own opinion, neither of these speculations can be regarded\nseriously as anything but a more or less convenient working hypothesis.\nBut, if I must choose among them, I take the \u201claw of parsimony\u201d for my\nguide, and select the simplest\u2014namely, that the sensation is the direct\neffect of the mode of motion of the sensorium. It may justly be said\nthat this is not the slightest explanation of sensation; but then am\nI really any the wiser, if I say that a sensation is an activity (of\nwhich I know nothing) of a substance of mind (of which also I know\nnothing)? Or, if I say that the Deity causes the sensation to arise in\nmy mind immediately after He has caused the particles of the sensorium\nto move in a certain way, is anything gained? In truth, a sensation, as\nwe have already seen, is an intuition\u2014a part of immediate knowledge.\nAs such, it is an ultimate fact and inexplicable; and all that we\ncan hope to find out about it, and that indeed is worth finding out,\nis its relation to other natural facts. That relation appears to me\nto be sufficiently expressed, for all practical purposes, by saying\nthat sensation is the invariable consequent of certain changes in the\nsensorium\u2014or, in other words, that, so far as we know, the change in\nthe sensorium is the cause of the sensation.\n\nI permit myself to imagine that the untutored, if noble, savage of\n\u201ccommon sense\u201d who has been misled into reading thus far by the hope\nof getting positive solid information about sensation, giving way to\nnot unnatural irritation, may here interpellate: \u201cThe upshot of all\nthis long disquisition is that we are profoundly ignorant. We knew\nthat to begin with, and you have merely furnished another example of\nthe emptiness and uselessness of metaphysics.\u201d But I venture to reply,\nPardon me, you were ignorant, but you did not know it. On the contrary,\nyou thought you knew a great deal, and were quite satisfied with the\nparticularly absurd metaphysical notions which you were pleased to\ncall the teachings of common sense. You thought that your sensations\nwere properties of external things, and had an existence outside of\nyourself. You thought that you knew more about material than you do\nabout immaterial existences. And if, as a wise man has assured us,\nthe knowledge of what we don\u2019t know is the next best thing to the\nknowledge of what we do know, this brief excursion into the province of\nphilosophy has been highly profitable.\n\nOf all the dangerous mental habits, that which schoolboys call\n\u201ccocksureness\u201d is probably the most perilous; and the inestimable\nvalue of metaphysical discipline is that it furnishes an effectual\ncounterpoise to this evil proclivity. Whoso has mastered the elements\nof philosophy knows that the attribute of unquestionable certainty\nappertains only to the existence of a state of consciousness so long\nas it exists; all other beliefs are mere probabilities of a higher or\nlower order. Sound metaphysic is an amulet which renders its possessor\nproof alike against the poison of superstition and the counter-poison\nof nihilism; by showing that the affirmations of the former and the\ndenials of the latter alike deal with matters about which, for lack of\nevidence, nothing can be either affirmed or denied.\n\n\nI have dwelt at length upon the nature and origin of our sensations of\nsmell, on account of the comparative freedom of the olfactory sense\nfrom the complications which are met with in most of the other senses.\n\nSensations of taste, however, are generated in almost as simple a\nfashion as those of smell. In this case, the sense organ is the\nepithelium which covers the tongue and the palate: and which sometimes,\nbecoming modified, gives rise to peculiar organs termed \u201cgustatory\nbulbs,\u201d in which the epithelial cells elongate and assume a somewhat\nrod-like form. Nerve fibres connect the sensory organ with the\nsensorium, and tastes or flavours are states of consciousness caused\nby the change of molecular state of the latter. In the case of the\nsense of touch there is often no sense organ distinct from the general\nepidermis. But many fishes and amphibia exhibit local modifications\nof the epidermic cells which are sometimes extraordinarily like the\ngustatory bulbs; more commonly, both in lower and higher animals,\nthe effect of the contact of external bodies is intensified by the\ndevelopment of hair-like filaments, or of true hairs, the bases of\nwhich are in immediate relation with the ends of the sensory nerves.\nEvery one must have noticed the extreme delicacy of the sensations\nproduced by the contact of bodies with the ends of the hairs of the\nhead; and the \u201cwhiskers\u201d of cats owe their functional importance to\nthe abundant supply of nerves to the follicles in which their bases\nare lodged. What part, if any, the so-called \u201ctactile corpuscles,\u201d\n\u201cend bulbs,\u201d and \u201cPacinian bodies,\u201d play in the mechanism of touch is\nunknown. If they are sense organs, they are exceptional in character,\nin so far as they do not appear to be modifications of the epidermis.\nNothing is known respecting the organs of those sensations of\nresistance which are grouped under the head of the muscular sense;\nnor of the sensations of warmth and cold; nor of that very singular\nsensation which we call tickling.\n\nIn the case of heat and cold, the organism not only becomes affected\nby external bodies, far more remote than those which affect the\nsense of smell; but the Democritic hypothesis is obviously no longer\npermissible. When the direct rays of the sun fall upon the skin,\nthe sensation of heat is certainly not caused by \u201cattenuated films\u201d\nthrown off from that luminary, but is due to a mode of motion which is\ntransmitted to us. In Aristotelian phrase, it is the form without the\nmatter of the sun which stamps the sense organ; and this, translated\ninto modern language, means nearly the same thing as Hartley\u2019s\nvibrations. Thus we are prepared for what happens in the case of\nthe auditory and the visual senses. For neither the ear, nor the\neye, receives anything but the impulses or vibrations originated by\nsonorous or luminous bodies. Nevertheless, the receptive apparatus\nstill consists of nothing but specially modified epithelial cells.\nIn the labyrinth of the ear of the higher animals, the free ends of\nthese cells terminate in excessively delicate hair-like filaments;\nwhile, in the lower forms of auditory organ, its free surface is\nbeset with delicate hairs like those of the surface of the body, and\nthe transmissive nerves are connected with the bases of these hairs.\nThus there is an insensible gradation in the forms of the receptive\napparatus, from the organ of touch, on the one hand, to those of taste\nand smell; and, on the other hand, to that of hearing. Even in the\ncase of the most refined of all the sense organs, that of vision, the\nreceptive apparatus departs but little from the general type. The\nonly essential constituent of the visual sense organ is the retina,\nwhich forms so small a part of the eyes of the higher animals; and the\nsimplest eyes are nothing but portions of the integument, in which\nthe cells of the epidermis have become converted into glassy rod-like\nretinal corpuscles. The outer ends of these are turned towards the\nlight; their sides are more or less extensively coated with a dark\npigment, and their inner ends are connected with the transmissive nerve\nfibres. The light, impinging on these visual rods, produces a change in\nthem which is communicated to the nerve fibres, and, being transmitted\nto the sensorium, gives rise to the sensation\u2014if indeed all animals\nwhich possess eyes are endowed with what we understand as sensation.\n\nIn the higher animals, a complicated apparatus of lenses, arranged\non the principle of a camera obscura, serves at once to concentrate\nand to individualise the pencils of light proceeding from external\nbodies. But the essential part of the organ of vision is still a layer\nof cells, which have the form of rods with truncated or conical ends.\nBy what seems a strange anomaly, however, the glassy ends of these are\nturned not towards, but away from, the light; and the latter has to\ntraverse the layer of nervous tissues with which their outer ends are\nconnected, before it can affect them. Moreover, the rods and cones of\nthe vertebrate retina are so deeply seated, and in many respects so\npeculiar in character, that it appears impossible, at first sight, that\nthey can have anything to do with that epidermis of which gustatory and\ntactile, and at any rate the lower forms of auditory and visual, organs\nare obvious modifications.\n\nWhatever be the apparent diversities among the sensiferous apparatuses,\nhowever, they share certain common characters. Each consists of a\nreceptive, a transmissive, and a sensificatory portion. The essential\npart of the first is an epithelium, of the second, nerve fibres, of the\nthird, a part of the brain; the sensation is always the consequence\nof the mode of motion excited in the receptive, and sent along the\ntransmissive, to the sensificatory part of the sensiferous apparatus.\nAnd, in all the senses, there is no likeness whatever between the\nobject of sense, which is matter in motion, and the sensation, which is\nan immaterial phenomenon.\n\nOn the hypothesis which appears to me to be the most convenient,\nsensation is a product of the sensiferous apparatus caused by certain\nmodes of motion which are set up in it by impulses from without. The\nsensiferous apparatuses are, as it were, factories, all of which at\nthe one end receive raw materials of a similar kind\u2014namely, modes of\nmotion\u2014while, at the other, each turns out a special product, the\nfeeling which constitutes the kind of sensation characteristic of it.\n\nOr, to make use of a closer comparison, each sensiferous apparatus is\ncomparable to a musical-box wound up; with as many tunes as there are\nseparate sensations. The object of a simple sensation is the agent\nwhich presses down the stop of one of these tunes, and the more feeble\nthe agent, the more delicate must be the mobility of the stop.[62]\n\nBut, if this be true, if the recipient part of the sensiferous\napparatus is, in all cases, merely a mechanism affected by coarser or\nfiner kinds of material motion, we might expect to find that all sense\norgans are fundamentally alike, and result from the modification of the\nsame morphological elements. And this is exactly what does result from\nall recent histological and embryological investigations.\n\nIt has been seen that the receptive part of the olfactory apparatus is\na slightly modified epithelium, which lines an olfactory chamber deeply\nseated between the orbits in adult human beings. But, if we trace back\nthe nasal chambers to their origin in the embryo, we find, that, to\nbegin with, they are mere depressions of the skin of the fore part\nof the head, lined by a continuation of the general epidermis. These\ndepressions become pits, and the pits, by the growth of the adjacent\nparts, gradually acquire the position which they finally occupy. The\nolfactory organ, therefore, is a specially modified part of the general\nintegument.\n\nThe human ear would seem to present greater difficulties. For the\nessential part of the sense organ, in this case, is the membranous\nlabyrinth, a bag of complicated form, which lies buried in the depths\nof the floor of the skull, and is surrounded by dense and solid bone.\nHere, however, recourse to the study of development readily unravels\nthe mystery. Shortly after the time when the olfactory organ appears,\nas a depression of the skin on the side of the fore part of the head,\nthe auditory organ appears as a similar depression on the side of its\nback part. The depression, rapidly deepening, becomes a small pouch;\nand then, the communication with the exterior becoming shut off, the\npouch is converted into a closed bag, the epithelial lining of which is\na part of the general epidermis segregated from the rest. The adjacent\ntissues, changing first into cartilage and then into bone, enclose\nthe auditory sac in a strong case, in which it undergoes its further\nmetamorphoses; while the drum, the ear bones, and the external ear,\nare superadded by no less extraordinary modifications of the adjacent\nparts. Still more marvellous is the history of the development of the\norgan of vision. In the place of the eye, as in that of the nose and\nthat of the ear, the young embryo presents a depression of the general\nintegument; but, in man and the higher animals, this does not give\nrise to the proper sensory organ, but only to part of the accessory\nstructures concerned in vision. In fact, this depression, deepening\nand becoming converted into a shut sac, produces only the cornea, the\naqueous humour, and the crystalline lens of the perfect eye.\n\nThe retina is added to this by the outgrowth of the wall of a portion\nof the brain into a sort of bag, or sac, with a narrow neck, the convex\nbottom of which is turned outwards, or towards the crystalline lens.\nAs the development of the eye proceeds, the convex bottom of the bag\nbecomes pushed in, so that it gradually obliterates the cavity of the\nsac, the previously convex wall of which becomes deeply concave. The\nsac of the brain is now like a double nightcap ready for the head, but\nthe place which the head would occupy is taken by the vitreous humour,\nwhile the layer of nightcap next it becomes the retina. The cells of\nthis layer which lie farthest from the vitreous humour, or, in other\nwords, bound the original cavity of the sac, are metamorphosed into\nthe rods and cones. Suppose now that the sac of the brain could be\nbrought back to its original form; then the rods and cones would form\npart of the lining of a side pouch of the brain. But one of the most\nwonderful revelations of embryology is the proof of the fact that the\nbrain itself is, at its first beginning, merely an infolding of the\nepidermic layer of the general integument. Hence it follows that the\nrods and cones of the vertebrate eye are modified epidermic cells, as\nmuch as the crystalline cones of the insect or crustacean eye are; and\nthat the inversion of the position of the former in relation to light\narises simply from the roundabout way in which the vertebrate retina is\ndeveloped.\n\nThus all the higher sense organs start from one foundation, and the\nreceptive epithelium of the eye, or of the ear, is as much modified\nepidermis as is that of the nose. The structural unity of the sense\norgans is the morphological parallel to their identity of physiological\nfunction, which, as we have seen, is to be impressed by certain modes\nof motion; and they are fine or coarse, in proportion to the delicacy\nor the strength of the impulses by which they are to be affected.\n\n\nIn ultimate analysis, then, it appears that a sensation is the\nequivalent in terms of consciousness for a mode of motion of the matter\nof the sensorium. But, if inquiry is pushed a stage farther, and the\nquestion is asked, What then do we know about matter and motion? there\nis but one reply possible. All that we know about motion is that it is\na name for certain changes in the relations of our visual, tactile, and\nmuscular sensations; and all that we know about matter is that it is\nthe hypothetical substance of physical phenomena\u2014the assumption of the\nexistence of which is as pure a piece of metaphysical speculation as is\nthat of the existence of the substance of mind.\n\nOur sensations, our pleasures, our pains, and the relations of these,\nmake up the sum total of the elements of positive, unquestionable\nknowledge. We call a large section of these sensations and their\nrelations matter and motion; the rest we term mind and thinking; and\nexperience shows that there is a certain constant order of succession\nbetween some of the former and some of the latter.\n\nThis is all that just metaphysical criticism leaves of the idols\nset up by the spurious metaphysics of vulgar common sense. It is\nconsistent either with pure Materialism, or with pure Idealism, but\nit is neither. For the Idealist, not content with declaring the truth\nthat our knowledge is limited to facts of consciousness, affirms the\nwholly unprovable proposition that nothing exists beyond these and the\nsubstance of mind. And, on the other hand, the Materialist, holding by\nthe truth that, for anything that appears to the contrary, material\nphenomena are the causes of mental phenomena, asserts his unprovable\ndogma, that material phenomena and the substance of matter are the sole\nprimary existences.\n\nStrike out the propositions about which neither controversialist does\nor can know anything, and there is nothing left for them to quarrel\nabout. Make a desert of the Unknowable, and the divine Astr\u00e6a of\nphilosophic peace will commence her blessed reign.\n\n\n\n\nXI.\n\nEVOLUTION IN BIOLOGY.\n\n\nIn the former half of the eighteenth century, the term \u201cevolution\u201d was\nintroduced into biological writings, in order to denote the mode in\nwhich some of the most eminent physiologists of that time conceived\nthat the generation of living things took place; in opposition to the\nhypothesis advocated, in the preceding century, by Harvey in that\nremarkable work[63] which would give him a claim to rank among the\nfounders of biological science, even had he not been the discoverer of\nthe circulation of the blood.\n\nOne of Harvey\u2019s prime objects is to defend and establish, on the\nbasis of direct observation, the opinion already held by Aristotle;\nthat, in the higher animals at any rate, the formation of the new\norganism by the process of generation takes place, not suddenly, by\nsimultaneous accretion of rudiments of all, or of the most important,\nof the organs of the adult; nor by sudden metamorphosis of a formative\nsubstance into a miniature of the whole, which subsequently grows;\nbut by _epigenesis_, or successive differentiation of a relatively\nhomogeneous rudiment into the parts and structures which are\ncharacteristic of the adult.\n\n  \u201cEt prim\u00f2, quidem, quoniam per _epigenesin_ sive\n  partium superexorientium additamentum pullum fabricari\n  certum est: qu\u00e6nam pars ante alias omnes exstruatur,\n  et quid de illa ejusque generandi modo observandum\n  veniat, dispiciemus. Ratum sane est et in ovo manifest\u00e8\n  apparet quod _Aristoteles_ de perfectorum animalium\n  generatione enuntiat: nimirum, non omnes partes\n  simul fieri, sed ordine aliam post aliam; prim\u00f9mque\n  existere particulam genitalem, cujus virtute postea\n  (tanquam ex principio quodam) reliqu\u00e6 omnes partes\n  prosiliant. Qualem in plantarum seminibus (fabis,\n  put\u00e0, aut glandibus) gemmam sive apicem protuberantem\n  cernimus, totius futur\u00e6 arboris principium. _Estque\n  h\u00e6c particula velut filius emancipatus seorsumque\n  collocatus, et principium per se vivens; unde postea\n  membrorum ordo describitur; et qu\u00e6cunque ad absolvendum\n  animal pertinent, disponuntur._[64] Quoniam enim _nulla\n  pars se ipsam generat; sed postquam generata est, se\n  ipsam jam auget; ideo eam prim\u00f9m oriri necesse est, qu\u00e6\n  principium augendi contineat (sive enim planta, sive\n  animal est, \u00e6que omnibus inest quod vim habeat vegetandi,\n  sive nutriendi)_,[65] simulque reliquas omnes partes\n  suo quamque ordine distinguat et formet; proindeque\n  in eadem primogenita particula anima primario inest,\n  sensus, motusque, et totius vit\u00e6 auctor et principium.\u201d\n  (Exercitatio 51.)\n\nHarvey proceeds to contrast this view with that of the \u201cMedici,\u201d or\nfollowers of Hippocrates and Galen, who, \u201cbadly philosophising,\u201d\nimagined that the brain, the heart, and the liver were simultaneously\nfirst generated in the form of vesicles; and, at the same time, while\nexpressing his agreement with Aristotle in the principle of epigenesis,\nhe maintains that it is the blood which is the primal generative part,\nand not, as Aristotle thought, the heart.\n\nIn the latter part of the seventeenth century, the doctrine of\nepigenesis, thus advocated by Harvey, was controverted, on the ground\nof direct observation, by Malpighi, who affirmed that the body of\nthe chick is to be seen in the egg, before the _punctum sanguineum_\nmakes its appearance. But, from this perfectly correct observation\na conclusion which is by no means warranted was drawn; namely, that\nthe chick, as a whole, really exists in the egg antecedently to\nincubation; and that what happens in the course of the latter process\nis no addition of new parts, \u201calias post alias natas,\u201d as Harvey puts\nit, but a simple expansion, or unfolding, of the organs which already\nexist, though they are too small and inconspicuous to be discovered.\nThe weight of Malpighi\u2019s observations therefore fell into the scale of\nthat doctrine which Harvey terms _metamorphosis_, in contradistinction\nto epigenesis.\n\nThe views of Malpighi were warmly welcomed, on philosophical grounds,\nby Leibnitz,[66] who found in them a support to his hypothesis\nof monads, and by Malebranche;[67] while, in the middle of the\neighteenth century, not only speculative considerations, but a\ngreat number of new and interesting observations on the phenomena\nof generation, led the ingenious Bonnet, and Haller,[68] the first\nphysiologist of the age, to adopt, advocate, and extend them.\n\nBonnet affirms that, before fecundation, the hen\u2019s egg contains an\nexcessively minute but complete chick; and that fecundation and\nincubation simply cause this germ to absorb nutritious matters, which\nare deposited in the interstices of the elementary structures of which\nthe miniature chick, or germ, is made up. The consequence of this\nintussusceptive growth is the \u201cdevelopment\u201d or \u201cevolution\u201d of the germ\ninto the visible bird. Thus an organised individual (_tout organis\u00e9_)\n\u201cis a composite body consisting of the original, or _elementary_,\nparts and of the matters which have been associated with them by the\naid of nutrition;\u201d so that, if these matters could be extracted from\nthe individual (_tout_), it would, so to speak, become concentrated\nin a point, and would thus be restored to its primitive condition of\na _germ_; \u201cjust as by extracting from a bone the calcareous substance\nwhich is the source of its hardness, it is reduced to its primitive\nstate of gristle or membrane.\u201d[69]\n\n\u201cEvolution\u201d and \u201cdevelopment\u201d are, for Bonnet, synonymous terms; and\nsince by \u201cevolution\u201d he means simply the expansion of that which was\ninvisible into visibility, he was naturally led to the conclusion,\nat which Leibnitz had arrived by a different line of reasoning, that\nno such thing as generation, in the proper sense of the word, exists\nin nature. The growth of an organic being is simply a process of\nenlargement, as a particle of dry gelatine may be swelled up by the\nintussusception of water; its death is a shrinkage, such as the swelled\njelly might undergo on desiccation. Nothing really new is produced\nin the living world, but the germs which develop have existed since\nthe beginning of things; and nothing really dies, but, when what we\ncall death takes place, the living thing shrinks back into its germ\nstate.[70]\n\nThe two parts of Bonnet\u2019s hypothesis, namely, the doctrine that all\nliving things proceed from pre-existing germs, and that these contain,\none inclosed within the other, the germs of all future living things,\nwhich is the hypothesis of \u201c_embo\u00eetement_;\u201d and the doctrine that every\ngerm contains in miniature all the organs of the adult, which is the\nhypothesis of evolution or development, in the primary senses of these\nwords, must be carefully distinguished. In fact, while holding firmly\nby the former, Bonnet more or less modified the latter in his later\nwritings, and, at length, he admits that a \u201cgerm\u201d need not be an actual\nminiature of the organism; but that it may be merely an \u201coriginal\npreformation\u201d capable of producing the latter.[71]\n\nBut, thus defined, the germ is neither more nor less than the\n\u201cparticula genitalis\u201d of Aristotle, or the \u201cprimordium vegetale\u201d or\n\u201covum\u201d of Harvey; and the \u201cevolution\u201d of such a germ would not be\ndistinguishable from \u201cepigenesis.\u201d\n\nSupported by the great authority of Haller, the doctrine of evolution,\nor development, prevailed throughout the whole of the eighteenth\ncentury, and Cuvier appears to have substantially adopted Bonnet\u2019s\nlater views, though probably he would not have gone all lengths in\nthe direction of \u201cembo\u00eetement.\u201d In a well-known note to Laurillards\u2019\n\u201c\u00c9loge,\u201d prefixed to the last edition of the \u201cOssemens fossiles,\u201d the\n\u201cradical de l\u2019\u00eatre\u201d is much the same thing as Aristotle\u2019s \u201cparticula\ngenitalis\u201d and Harvey\u2019s \u201covum.\u201d[72]\n\nBonnet\u2019s eminent contemporary, Buffon, held nearly the same views\nwith respect to the nature of the germ, and expresses them even more\nconfidently.[73]\n\n  \u201cCeux qui ont cru que le c\u0153ur \u00e9toit le premier form\u00e9,\n  se sont tromp\u00e9s; ceux qui disent que c\u2019est le sang se\n  trompent aussi: tout est form\u00e9 en m\u00eame temps. Si l\u2019on ne\n  consulte que l\u2019observation, le poulet se voit dans l\u2019\u0153uf\n  avant qui\u2019il ait \u00e9t\u00e9 couv\u00e9.\u201d\n\n  \u201cJ\u2019ai ouvert une grande quantit\u00e9 d\u2019\u0153ufs \u00e0 differens temps\n  avant et apr\u00e8s l\u2019incubation, et je me suis convaincu par\n  mes yeux que le poulet existe en entier dans le milieu\n  de la cicatricule au moment qu\u2019il sort du corps de la\n  poule.\u201d[74]\n\nThe \u201cmoule int\u00e9rieur\u201d of Buffon is the aggregate of elementary\nparts which constitute the individual, and is thus the equivalent\nof Bonnet\u2019s germ,[75] as defined in the passage cited above. But\nBuffon further imagined that innumerable \u201cmolecules organiques\u201d are\ndispersed throughout the world, and that alimentation consists in the\nappropriation by the parts of an organism of those molecules which\nare analogous to them. Growth, therefore, was, on this hypothesis, a\nprocess partly of simple evolution, and partly of what has been termed\n\u201csyngenesis.\u201d Buffon\u2019s opinion is, in fact, a sort of combination of\nviews, essentially similar to those of Bonnet, with others, somewhat\nsimilar to those of the \u201cMedici\u201d whom Harvey condemns. The \u201cmolecules\norganiques\u201d are physical equivalents of Leibnitz\u2019s \u201cmonads.\u201d\n\nIt is a striking example of the difficulty of getting people to use\ntheir own powers of investigation accurately, that this form of the\ndoctrine of evolution should have held its ground so long; for it was\nthoroughly and completely exploded, not long after its enunciation, by\nCaspar Friederich Wolff, who in his \u201cTheoria Generationis,\u201d published\nin 1759, placed the opposite theory of epigenesis upon the secure\nfoundation of fact, from which it has never been displaced. But Wolff\nhad no immediate successors. The school of Cuvier was lamentably\ndeficient in embryologists; and it was only in the course of the\nfirst thirty years of the present century, that Pr\u00e9vost and Dumas in\nFrance, and, later on, D\u00f6llinger, Pander, Von B\u00e4r, Rathke, and Remak\nin Germany, founded modern embryology; while, at the same time, they\nproved the utter incompatibility of the hypothesis of evolution, as\nformulated by Bonnet and Haller, with easily demonstrable facts.\n\nNevertheless, though the conceptions originally denoted by \u201cevolution\u201d\nand \u201cdevelopment\u201d were shown to be untenable, the words retained\ntheir application to the process by which the embryos of living\nbeings gradually make their appearance; and the terms \u201cDevelopment,\u201d\n\u201cEntwickelung,\u201d and \u201cEvolutio,\u201d are now indiscriminately used for\nthe series of genetic changes exhibited by living beings, by writers\nwho would emphatically deny that \u201cDevelopment\u201d or \u201cEntwickelung\u201d or\n\u201cEvolutio,\u201d in the sense in which these words were usually employed by\nBonnet or by Haller, ever occurs.\n\nEvolution, or development, is, in fact, at present employed in biology\nas a general name for the history of the steps by which any living\nbeing has acquired the morphological and the physiological characters\nwhich distinguish it. As civil history may be divided into biography,\nwhich is the history of individuals, and universal history, which is\nthe history of the human race, so evolution falls naturally into two\ncategories,\u2014the evolution of the individual, and the evolution of the\nsum of living beings. It will be convenient to deal with the modern\ndoctrine of evolution under these two heads.\n\n\nI. _The Evolution of the Individual._\n\nNo exception is, at this time, known to the general law, established\nupon an immense multitude of direct observations, that every living\nthing is evolved from a particle of matter in which no trace of the\ndistinctive characters of the adult form of that living thing is\ndiscernible. This particle is termed a _germ_. Harvey[76] says\u2014\n\n  \u201cOmnibus viventibus primordium insit, ex quo et a quo\n  proveniant. Liceat hoc nobis _primordium vegetale_\n  nominare; nempe substantiam quandam corpoream vitam\n  habentem potenti\u00e2; vel quoddam per se existens, quod\n  aptum sit, in vegetativam formam, ab interno principio\n  operante, mutari. Quale nempe primordium, ovum est et\n  plantarum semen; tale etiam viviparorum conceptus,\n  et insectorum _vermis_ ab Aristotele dictus: diversa\n  scilicet diversorum viventium primordia.\u201d\n\nThe definition of a germ as \u201cmatter potentially alive, and having\nwithin itself the tendency to assume a definite living form,\u201d appears\nto meet all the requirements of modern science. For, notwithstanding it\nmight be justly questioned whether a germ is not merely potentially,\nbut rather actually, alive, though its vital manifestations are reduced\nto a minimum, the term \u201cpotential\u201d may fairly be used in a sense broad\nenough to escape the objection. And the qualification of \u201cpotential\u201d\nhas the advantage of reminding us that the great characteristic of\nthe germ is not so much what it is, but what it may, under suitable\nconditions, become. Harvey shared the belief of Aristotle\u2014whose\nwritings he so often quotes, and of whom he speaks as his precursor and\nmodel, with the generous respect with which one genuine worker should\nregard another\u2014that such germs may arise by a process of \u201cequivocal\ngeneration\u201d out of not-living matter; and the aphorism so commonly\nascribed to him, \u201c_omne vivum ex ovo_,\u201d and which is indeed a fair\nsummary of his reiterated assertions, though incessantly employed\nagainst the modern advocates of spontaneous generation, can be honestly\nso used only by those who have never read a score of pages of the\n\u201cExercitationes.\u201d Harvey, in fact, believed as implicitly as Aristotle\ndid in the equivocal generation of the lower animals. But, while the\ncourse of modern investigation has only brought out into greater\nprominence the accuracy of Harvey\u2019s conception of the nature and mode\nof development of germs, it has as distinctly tended to disprove the\noccurrence of equivocal generation, or abiogenesis, in the present\ncourse of nature. In the immense majority of both plants and animals,\nit is certain that the germ is not merely a body in which life is\ndormant or potential, but that it is itself simply a detached portion\nof the substance of a pre-existing living body; and the evidence has\nyet to be adduced which will satisfy any cautious reasoner that \u201comne\nvivum ex vivo\u201d is not as well-established a law of the existing course\nof nature as \u201comne vivum ex ovo.\u201d\n\nIn all instances which have yet been investigated, the substance of\nthis germ has a peculiar chemical composition, consisting of at fewest\nfour elementary bodies, viz. carbon, hydrogen, oxygen, and nitrogen,\nunited into the ill-defined compound known as protein, and associated\nwith much water, and very generally, if not always, with sulphur and\nphosphorus in minute proportions. Moreover, up to the present time,\nprotein is known only as a product and constituent of living matter.\nAgain, a true germ is either devoid of any structure discernible by\noptical means, or, at most, it is a simple nucleated cell.[77]\n\nIn all cases, the process of evolution consists in a succession of\nchanges of the form, structure, and functions of the germ, by which\nit passes, step by step, from an extreme simplicity, or relative\nhomogeneity, of visible structure, to a greater or less degree\nof complexity or heterogeneity; and the course of progressive\ndifferentiation is usually accompanied by growth, which is effected by\nintussusception. This intussusception, however, is a very different\nprocess from that imagined either by Buffon, or by Bonnet. The\nsubstance by the addition of which the germ is enlarged is, in no\ncase, simply absorbed ready-made from the not-living world and packed\nbetween the elementary constituents of the germ, as Bonnet imagined;\nstill less does it consist of the \u201cmolecules organiques\u201d of Buffon. The\nnew material is, in great measure, not only absorbed but assimilated,\nso that it becomes part and parcel of the molecular structure of\nthe living body into which it enters. And, so far from the fully\ndeveloped organism being simply the germ _plus_ the nutriment which\nit has absorbed, it is probable that the adult contains neither in\nform, nor in substance, more than an inappreciable fraction of the\nconstituents of the germ, and that it is almost, if not wholly, made\nup of assimilated and metamorphosed nutriment. In the great majority of\ncases, at any rate, the full-grown organism becomes what it is by the\nabsorption of not-living matter, and its conversion into living matter\nof a specific type. As Harvey says (Ex. 45), all parts of the body are\nnourished \u201cab eodem succo alibili, aliter aliterque cambiato,\u201d \u201cut\nplant\u00e6 omnes ex eodem communi nutrimento (sive rore seu terr\u00e6 humore).\u201d\n\nIn all animals and plants, above the lowest, the germ is a nucleated\ncell, using that term in its broadest sense; and the first step in the\nprocess of the evolution of the individual is the division of this\ncell into two or more portions. The process of division is repeated,\nuntil the organism, from being unicellular, becomes multicellular.\nThe single cell becomes a cell-aggregate; and it is to the growth and\nmetamorphosis of the cells of the cell-aggregate thus produced, that\nall the organs and tissues of the adult owe their origin.\n\nIn certain animals belonging to every one of the chief groups into\nwhich the _Metazoa_ are divisible, the cells of the cell-aggregate\nwhich results from the process of yelk-division, and which is termed\na _morula_, diverge from one another in such a manner as to give rise\nto a central space, around which they dispose themselves as a coat or\nenvelope; and thus the morula becomes a vesicle filled with fluid,\nthe _planula_. The wall of the planula is next pushed in on one side,\nor invaginated, whereby it is converted into a double-walled sac\nwith an opening, the _blastopore_, which leads into the cavity lined\nby the inner wall. This cavity is the primitive alimentary cavity or\n_archenteron_; the inner, or invaginated, layer is the _hypoblast_,\nthe outer the _epiblast_; and the embryo, in this stage, is termed\na _gastrula_. In all the higher animals, a layer of cells makes its\nappearance between the hypoblast and the epiblast, and is termed the\n_mesoblast_. In the further course of development, the epiblast becomes\nthe ectoderm or epidermic layer of the body; the hypoblast becomes\nthe epithelium of the middle portion of the alimentary canal; and the\nmesoblast gives rise to all the other tissues, except the central\nnervous system, which originates from an ingrowth of the epiblast.\n\nWith more or less modification in detail, the embryo has been observed\nto pass through these successive evolutional stages in sundry Sponges,\nC\u0153lenterates, Worms, Echinoderms, Tunicates, Arthropods, Mollusks,\nand Vertebrates; and there are valid reasons for the belief, that\nall animals of higher organisation than the _Protozoa_ agree in the\ngeneral character of the early stages of their individual evolution.\nEach, starting from the condition of a simple nucleated cell, becomes\na cell-aggregate; and this passes through a condition which represents\nthe gastrula stage, before taking on the features distinctive of the\ngroup to which it belongs. Stated in this form, the \u201cgastr\u00e6a theory\u201d of\nHaeckel appears to the present writer to be one of the most important\nand best founded of recent generalisations. So far as individual\nplants and animals are concerned, therefore, evolution is not a\nspeculation but a fact; and it takes place by epigenesis.\n\n  \u201cAnimal ... per _epigenesin_ procreatur, materiam simul\n  attrahit, parat, concoquit, et e\u00e2dem utitur; formatur\n  simul et augetur ... primum futuri corporis concrementum\n  ... prout augetur, dividitur sensim et distinguitur in\n  partes, non simul omnes, sed alias post alias natas, et\n  ordine quasque suo emergentes.\u201d[78]\n\nIn these words, by the divination of genius, Harvey, in the seventeenth\ncentury, summed up the outcome of the work of all those who, with\nappliances he could not dream of, are continuing his labours in the\nnineteenth century.\n\nNevertheless, though the doctrine of epigenesis, as understood by\nHarvey, has definitively triumphed over the doctrine of evolution,\nas understood by his opponents of the eighteenth century, it is not\nimpossible that, when the analysis of the process of development is\ncarried still farther, and the origin of the molecular components of\nthe physically gross, though sensibly minute, bodies which we term\ngerms is traced, the theory of development will approach more nearly\nto metamorphosis than to epigenesis. Harvey thought that impregnation\ninfluenced the female organism as a contagion; and that the blood,\nwhich he conceived to be the first rudiment of the germ, arose in\nthe clear fluid of the \u201ccolliquamentum\u201d of the ovum by a process of\nconcrescence, as a sort of living precipitate. We now know, on the\ncontrary, that the female germ or ovum, in all the higher animals\nand plants, is a body which possesses the structure of a nucleated\ncell; that impregnation consists in the fusion of the substance[79]\nof another more or less modified nucleated cell, the male germ, with\nthe ovum; and that the structural components of the body of the\nembryo are all derived, by a process of division, from the coalesced\nmale and female germs. Hence it is conceivable, and indeed probable,\nthat every part of the adult contains molecules, derived both from\nthe male and from the female parent; and that, regarded as a mass\nof molecules, the entire organism may be compared to a web of which\nthe warp is derived from the female and the woof from the male. And\neach of these may constitute one individuality, in the same sense\nas the whole organism is one individual, although the matter of the\norganism has been constantly changing. The primitive male and female\nmolecules may play the part of Buffon\u2019s \u201cmoules organiques,\u201d and\nmould the assimilated nutriment, each according to its own type, into\ninnumerable new molecules. From this point of view the process, which,\nin its superficial aspect, is epigenesis, appears in essence, to be\nevolution, in the modified sense adopted in Bonnet\u2019s later writings;\nand development is merely the expansion of a potential organism or\n\u201coriginal preformation\u201d according to fixed laws.\n\n\nII. _The Evolution of the Sum of Living Beings._\n\nThe notion that all the kinds of animals and plants may have come into\nexistence by the growth and modification of primordial germs is as old\nas speculative thought; but the modern scientific form of the doctrine\ncan be traced historically to the influence of several converging lines\nof philosophical speculation and of physical observation, none of which\ngo farther back than the seventeenth century. These are:\u2014\n\n1. The enunciation by Descartes of the conception that the physical\nuniverse, whether living or not living, is a mechanism, and that, as\nsuch, it is explicable on physical principles.\n\n2. The observation of the gradations of structure, from extreme\nsimplicity to very great complexity, presented by living things, and of\nthe relation of these graduated forms to one another.\n\n3. The observation of the existence of an analogy between the series\nof gradations presented by the species which compose any great group\nof animals or plants, and the series of embryonic conditions of the\nhighest members of that group.\n\n4. The observation that large groups of species of widely different\nhabits present the same fundamental plan of structure; and that parts\nof the same animal or plant, the functions of which are very different,\nlikewise exhibit modifications of a common plan.\n\n5. The observation of the existence of structures, in a rudimentary\nand apparently useless condition, in one species of a group, which are\nfully developed and have definite functions in other species of the\nsame group.\n\n6. The observation of the effects of varying conditions in modifying\nliving organisms.\n\n7. The observation of the facts of geographical distribution.\n\n8. The observation of the facts of the geological succession of the\nforms of life.\n\n\n1. Notwithstanding the elaborate disguise which fear of the powers that\nwere led Descartes to throw over his real opinions, it is impossible to\nread the \u201cPrincipes de la Philosophie\u201d without acquiring the conviction\nthat this great philosopher held that the physical world and all things\nin it, whether living or not living, have originated by a process of\nevolution, due to the continuous operation of purely physical causes,\nout of a primitive relatively formless matter.[80]\n\nThe following passage is especially instructive:\u2014\n\n  \u201cEt tant s\u2019en faut que je veuille que l\u2019on croie toutes\n  les choses que j\u2019\u00e9crirai, que m\u00eame je pretends en\n  proposer ici quelques unes que je crois absolument \u00eatre\n  fausses; \u00e0 savoir, je ne doute point que le monde n\u2019ait\n  \u00e9t\u00e9 cr\u00e9\u00e9 au commencement avec autant de perfection qu\u2019il\n  en a; en sorte que le soleil, la terre, la lune, et\n  les \u00e9toiles ont \u00e9t\u00e9 d\u00e8s lors; et que la terre n\u2019a pas\n  eu seulement en soi les semences des plantes, mais que\n  les plantes m\u00eame en ont couvert une partie; et qu\u2019Adam\n  et Eve n\u2019ont pas \u00e9t\u00e9 cr\u00e9\u00e9s enfans mais en \u00e2ge d\u2019hommes\n  parfaits. La religion chr\u00e9tienne veut que nous le croyons\n  ainsi, et la raison naturelle nous persuade enti\u00e8rement\n  cette v\u00e9rit\u00e9; car si nous consid\u00e9rons la toute puissance\n  de Dieu, nous devons juger que tout ce qu\u2019il a fait a\n  eu d\u00e8s le commencement toute la perfection qu\u2019il devoit\n  avoir. Mais n\u00e9anmoins, comme on conn\u00f4itroit beaucoup\n  mieux quelle a \u00e9t\u00e9 la nature d\u2019Adam et celle des arbres\n  de Paradis si on avoit examin\u00e9 comment les enfants se\n  forment peu \u00e0 peu dans le ventre de leurs m\u00e8res et\n  comment les plantes sortent de leurs semences, que si on\n  avoit seulement consid\u00e9r\u00e9 quels ils ont \u00e9t\u00e9 quand Dieu\n  les a cr\u00e9\u00e9s: tout de m\u00eame, nous ferons mieux entendre\n  quelle est g\u00e9n\u00e9ralement la nature de toutes les choses\n  qui sont au monde si nous pouvons imaginer quelques\n  principes qui soient fort intelligibles et fort simples,\n  desquels nous puissions voir clairement que les astres et\n  la terre et enfin tout ce monde visible auroit pu \u00eatre\n  produit ainsi que de quelques semences (bien que nous\n  sachions qu\u2019il n\u2019a pas \u00e9t\u00e9 produit en cette fa\u00e7on) que si\n  nous la decrivions seulement comme il est, ou bien comme\n  nous croyons qu\u2019il a \u00e9t\u00e9 cr\u00e9\u00e9. Et parceque je pense avoir\n  trouv\u00e9 des principes qui sont tels, je tacherai ici de\n  les expliquer.\u201d[81]\n\nIf we read between the lines of this singular exhibition of force of\none kind and weakness of another, it is clear that Descartes believed\nthat he had divined the mode in which the physical universe had been\nevolved; and the \u201cTrait\u00e9 de l\u2019homme,\u201d and the essay \u201cSur les Passions\u201d\nafford abundant additional evidence that he sought for, and thought\nhe had found, an explanation of the phenomena of physical life by\ndeduction from purely physical laws.\n\nSpinoza abounds in the same sense, and is as usual perfectly candid\u2014\n\n  \u201cNatur\u00e6 leges et regul\u00e6, secundum quas omnia fiunt et\n  ex unis formis in alias mutantur, sunt ubique et semper\n  eadem.\u201d[82]\n\nLeibnitz\u2019s doctrine of continuity necessarily led him in the same\ndirection; and, of the infinite multitude of monads with which he\npeopled the world, each is supposed to be the focus of an endless\nprocess of evolution and involution. In the \u201cProtog\u00e6a,\u201d xxvi., Leibnitz\ndistinctly suggests the mutability of species\u2014\n\n  \u201cAlii mirantur in saxis passim species videri quas vel\n  in orbe cognito, vel saltem in vicinis locis frustra\n  qu\u00e6ras. Ita \u201cCornua Ammonis,\u201d qu\u00e6 ex nautilorum numero\n  habeantur, passim et forma et magnitudine (nam et pedali\n  diametro aliquando reperiuntur) ab omnibus illis naturis\n  discrepare dicunt, quas pr\u00e6bet mare. Sed quis absconditos\n  ejus recessus aut subterraneas abyssos pervestigavit?\n  quam multa nobis animalia antea ignota offert novus\n  orbis? Et credibile est per magnas illas conversiones\n  etiam animalium species plurimum immutatas.\u201d\n\nThus, in the end of the seventeenth century, the seed was sown which\nhas, at intervals, brought forth recurrent crops of evolutional\nhypotheses, based, more or less completely, on general reasonings.\n\nAmong the earliest of these speculations is that put forward by Benoit\nde Maillet in his \u201cTelliamed,\u201d which, though printed in 1735, was\nnot published until twenty-three years later. Considering that this\nbook was written before the time of Haller, or Bonnet, or Linn\u00e6us,\nor Hutton, it surely deserves more respectful consideration than it\nusually receives. For De Maillet not only has a definite conception\nof the plasticity of living things, and of the production of existing\nspecies by the modification of their predecessors; but he clearly\napprehends the cardinal maxim of modern geological science, that the\nexplanation of the structure of the globe is to be sought in the\ndeductive application to geological phenomena of the principles\nestablished inductively by the study of the present course of nature.\nSomewhat later, Maupertuis[83] suggested a curious hypothesis as to\nthe causes of variation, which he thinks may be sufficient to account\nfor the origin of all animals from a single pair. Robinet[84] followed\nout much the same line of thought as De Maillet, but less soberly; and\nBonnet\u2019s speculations in the \u201cPaling\u00e9n\u00e9sie,\u201d which appeared in 1769,\nhave already been mentioned. Buffon (1753-1778), at first a partisan\nof the absolute immutability of species, subsequently appears to have\nbelieved that larger or smaller groups of species have been produced by\nthe modification of a primitive stock; but he contributed nothing to\nthe general doctrine of evolution.\n\nErasmus Darwin (\u201cZoonomia,\u201d 1794), though a zealous evolutionist, can\nhardly be said to have made any real advance on his predecessors;\nand, notwithstanding that Goethe (1791-4) had the advantage of a\nwide knowledge of morphological facts, and a true insight into their\nsignification, while he threw all the power of a great poet into\nthe expression of his conceptions, it may be questioned whether he\nsupplied the doctrine of evolution with a firmer scientific basis\nthan it already possessed. Moreover, whatever the value of Goethe\u2019s\nlabours in that field, they were not published before 1820, long after\nevolutionism had taken a new departure from the works of Treviranus\nand Lamarck\u2014the first of its advocates who were equipped for their\ntask with the needful large and accurate knowledge of the phenomena of\nlife, as a whole. It is remarkable that each of these writers seems\nto have been led, independently and contemporaneously, to invent the\nsame name of \u201cBiology\u201d for the science of the phenomena of life; and\nthus, following Buffon, to have recognised the essential unity of these\nphenomena, and their contradistinction from those of inanimate nature.\nAnd it is hard to say whether Lamarck or Treviranus has the priority in\npropounding the main thesis of the doctrine of evolution; for though\nthe first volume of Treviranus\u2019s \u201cBiologie\u201d appeared only in 1802, he\nsays, in the preface to his later work, the \u201cErscheinungen und Gesetze\ndes organischen Lebens,\u201d dated 1831, that he wrote the first volume of\nthe \u201cBiologie\u201d \u201cnearly five-and-thirty years ago,\u201d or about 1796.\n\nNow, in 1794, there is evidence that Lamarck held doctrines which\npresent a striking contrast to those which are to be found in the\n\u201cPhilosophic Zoologique,\u201d as the following passages show:\u2014\n\n  \u201c685. Quoique mon unique objet dans cet article n\u2019ait \u00e9t\u00e9\n  que de traiter de la cause physique de l\u2019entretien de la\n  vie des \u00eatres organiques, malgr\u00e9 cela j\u2019ai os\u00e9 avancer\n  en d\u00e9butant, que l\u2019existence de ces \u00eatres \u00e9tonnants\n  n\u2019appartiennent nullement \u00e0 la nature; que tout ce qu\u2019on\n  peut entendre par le mot _nature_, ne pouvoit donner la\n  vie, c\u2019est-\u00e0-dire, que toutes les qualit\u00e9s de la mati\u00e8re,\n  jointes \u00e0 toutes les circonstances possibles, et m\u00eame \u00e0\n  l\u2019activit\u00e9 r\u00e9pandue dans l\u2019univers, ne pouvaient point\n  produire un \u00eatre muni du mouvement organique, capable de\n  reproduire son semblable, et sujet \u00e0 la mort.\n\n  \u201c686. Tous les individus de cette nature, qui existent,\n  proviennent d\u2019individus semblables qui tous ensemble\n  constituent l\u2019esp\u00e8ce enti\u00e8re. Or, je crois qu\u2019il est\n  aussi impossible \u00e0 l\u2019homme de conn\u00f4itre la cause physique\n  du premier individu de chaque esp\u00e8ce, que d\u2019assigner\n  aussi physiquement la cause de l\u2019existence de la\n  mati\u00e8re ou de l\u2019univers entier. C\u2019est au moins ce que\n  le r\u00e9sultat de mes connaissances et de mes r\u00e9flexions\n  me portent \u00e0 penser. S\u2019il existe beaucoup de vari\u00e9t\u00e9s\n  produites par l\u2019effet des circonstances, ces vari\u00e9t\u00e9s ne\n  d\u00e9naturent point les esp\u00e8ces; mais on se trompe, sans\n  doute souvent, en indiquant comme esp\u00e8ce, ce qui n\u2019est\n  que vari\u00e9t\u00e9; et alors je sens que cette erreur peut tirer\n  \u00e0 cons\u00e9quence dans les raisonnements que l\u2019on fait sur\n  cette mati\u00e8re.\u201d[85]\n\nThe first three volumes of Treviranus\u2019s \u201cBiologie,\u201d which contain\nhis general views of evolution, appeared between 1802 and 1805. The\n\u201cRecherches sur l\u2019organisation des corps vivants,\u201d in which the\noutlines of Lamarck\u2019s doctrines are given, was published in 1802; but\nthe full development of his views, in the \u201cPhilosophie Zoologique,\u201d did\nnot take place until 1809.\n\nThe \u201cBiologie\u201d and the \u201cPhilosophie Zoologique\u201d are both very\nremarkable productions, and are still worthy of attentive study, but\nthey fell upon evil times. The vast authority of Cuvier was employed\nin support of the traditionally respectable hypotheses of special\ncreation and of catastrophism; and the wild speculations of the\n\u201cDiscours sur les R\u00e9volutions de la Surface du Globe\u201d were held to be\nmodels of sound scientific thinking, while the really much more sober\nand philosophical hypotheses of the \u201cHydrogeologie\u201d were scouted. For\nmany years it was the fashion to speak of Lamarck with ridicule, while\nTreviranus was altogether ignored.\n\nNevertheless, the work had been done. The conception of evolution\nwas henceforward irrepressible, and it incessantly reappears, in one\nshape or another,[86] up to the year 1858, when Mr. Darwin and Mr.\nWallace published their \u201cTheory of Natural Selection.\u201d The \u201cOrigin of\nSpecies\u201d appeared in 1859; and it is within the knowledge of all whose\nmemories go back to that time, that, henceforward, the doctrine of\nevolution has assumed a position and acquired an importance which it\nnever before possessed. In the \u201cOrigin of Species,\u201d and in his other\nnumerous and important contributions to the solution of the problem of\nbiological evolution, Mr. Darwin confines himself to the discussion of\nthe causes which have brought about the present condition of living\nmatter, assuming such matter to have once come into existence. On the\nother hand, Mr. Spencer[87] and Professor Haeckel[88] have dealt with\nthe whole problem of evolution. The profound and vigorous writings of\nMr. Spencer embody the spirit of Descartes in the knowledge of our own\nday, and may be regarded as the \u201cPrincipes de la Philosophie\u201d of the\nnineteenth century; while, whatever hesitation may not unfrequently\nbe felt by less daring minds, in following Haeckel in many of his\nspeculations, his attempt to systematise the doctrine of evolution and\nto exhibit its influence as the central thought of modern biology,\ncannot fail to have a far-reaching influence on the progress of science.\n\nIf we seek for the reason of the difference between the scientific\nposition of the doctrine of evolution a century ago, and that which it\noccupies now, we shall find it in the great accumulation of facts, the\nseveral classes of which have been enumerated above, under the second\nto the eighth heads. For those which are grouped under the second to\nthe seventh of these classes, respectively, have a clear significance\non the hypothesis of evolution, while they are unintelligible if that\nhypothesis be denied. And those of the eighth group are not only\nunintelligible without the assumption of evolution, but can be proved\nnever to be discordant with that hypothesis, while, in some cases,\nthey are exactly such as the hypothesis requires. The demonstration of\nthese assertions would require a volume, but the general nature of the\nevidence on which they rest may be briefly indicated.\n\n2. The accurate investigation of the lowest forms of animal life,\ncommenced by Leeuwenhoek and Swammerdam, and continued by the\nremarkable labours of Reaumur, Trembley, Bonnet, and a host of other\nobservers, in the latter part of the seventeenth and the first half\nof the eighteenth centuries, drew the attention of biologists to the\ngradation in the complexity of organisation which is presented by\nliving beings, and culminated in the doctrine of the \u201c\u00e9chelle des\n\u00eatres,\u201d so powerfully and clearly stated by Bonnet; and, before him,\nadumbrated by Locke and by Leibnitz. In the then state of knowledge, it\nappeared that all the species of animals and plants could be arranged\nin one series; in such a manner that, by insensible gradations, the\nmineral passed into the plant, the plant into the polype, the polype\ninto the worm, and so, through gradually higher forms of life, to man,\nat the summit of the animated world.\n\nBut, as knowledge advanced, this conception ceased to be tenable in\nthe crude form in which it was first put forward. Taking into account\nexisting animals and plants alone, it became obvious that they fell\ninto groups which were more or less sharply separated from one another;\nand, moreover, that even the species of a genus can hardly ever be\narranged in linear series. Their natural resemblances and differences\nare only to be expressed by disposing them as if they were branches\nspringing from a common hypothetical centre.\n\nLamarck, while affirming the verbal proposition that animals form a\nsingle series, was forced by his vast acquaintance with the details\nof zoology to limit the assertion to such a series as may be formed\nout of the abstractions constituted by the common characters of each\ngroup.[89]\n\nCuvier on anatomical, and Von Baer on embryological grounds, made the\nfurther step of proving that, even in this limited sense, animals\ncannot be arranged in a single series, but that there are several\ndistinct plans of organisation to be observed among them, no one of\nwhich, in its highest and most complicated modification, leads to any\nof the others.\n\nThe conclusions enunciated by Cuvier and Von Baer have been confirmed,\nin principle, by all subsequent research into the structure of animals\nand plants. But the effect of the adoption of these conclusions has\nbeen rather to substitute a new metaphor for that of Bonnet than to\nabolish the conception expressed by it. Instead of regarding living\nthings as capable of arrangement in one series like the steps of a\nladder, the results of modern investigation compel us to dispose them\nas if they were the twigs and branches of a tree. The ends of the twigs\nrepresent individuals, the smallest groups of twigs species, larger\ngroups genera, and so on, until we arrive at the source of all these\nramifications of the main branch, which is represented by a common\nplan of structure. At the present moment, it is impossible to draw up\nany definition, based on broad anatomical or developmental characters,\nby which any one of Cuvier\u2019s great groups shall be separated from all\nthe rest. On the contrary, the lower members of each tend to converge\ntowards the lower members of all the others. The same may be said of\nthe vegetable world. The apparently clear distinction between flowering\nand flowerless plants has been broken down by the series of gradations\nbetween the two exhibited by the _Lycopodiace\u00e6_, _Rhizocarpe\u00e6_, and\n_Gymnosperme\u00e6_. The groups of _Fungi_, _Lichenes_, and _Alg\u00e6_ have\ncompletely run into one another, and, when the lowest forms of each are\nalone considered, even the animal and vegetable kingdoms cease to have\na definite frontier.\n\nIf it is permissible to speak of the relations of living forms to one\nanother metaphorically, the similitude chosen must undoubtedly be\nthat of a common root, whence two main trunks, one representing the\nvegetable and one the animal world, spring; and, each dividing into a\nfew main branches, these subdivide into multitudes of branchlets and\nthese into smaller groups of twigs.\n\nAs Lamarck has well said\u2014[90]\n\n  \u201cIl n\u2019y a que ceux qui se sont longtemps et fortement\n  occup\u00e9s de la d\u00e9termination des esp\u00e8ces, et qui ont\n  consult\u00e9 de riches collections, qui peuvent savoir\n  jusqu\u2019\u00e0 quel point les _esp\u00e8ces_, parmi les corps vivants\n  se fondent les unes dans les autres, et qui ont pu se\n  convaincre que, dans les parties o\u00f9 nous voyons des\n  _esp\u00e8ces_ isol\u00e8s, cela n\u2019est ainsi que parcequ\u2019il nous\n  en manque d\u2019autres qui en sont plus voisines et que nous\n  n\u2019avons pas encore recueillies.\n\n  \u201cJe ne veux pas dire pour cela que les animaux qui\n  existent forment une s\u00e9rie tr\u00e8s-simple et partout\n  \u00e9galement nuanc\u00e9e; mais je dis qu\u2019ils forment une s\u00e9rie\n  rameuse, irr\u00e9guli\u00e9rement gradu\u00e9e et qui n\u2019a point de\n  discontinuit\u00e9 dans ses parties, ou qui, du moins, n\u2019en\n  a toujours pas eu, s\u2019il est vrai que, par suite de\n  quelques esp\u00e8ces perdues, il s\u2019en trouve quelque part.\n  Il en resulte que les _esp\u00e8ces_ qui terminent chaque\n  rameau de la s\u00e9rie g\u00e9n\u00e9rale tiennent, au moins d\u2019un\n  c\u00f4t\u00e9, \u00e0 d\u2019autres esp\u00e8ces voisines qui se nuancent avec\n  elles. Voil\u00e0 ce que l\u2019\u00e9tat bien connu des choses me\n  met maintenant \u00e0 port\u00e9e de demontrer. Je n\u2019ai besoin\n  d\u2019aucune hypoth\u00e8se ni d\u2019aucune supposition pour cela:\n  j\u2019en atteste tous les naturalistes observateurs.\u201d\n\n3. In a remarkable essay[91] Meckel remarks\u2014\n\n  \u201cThere is no good physiologist who has not been struck by\n  the observation that the original form of all organisms\n  is one and the same, and that out of this one form, all,\n  the lowest as well as the highest, are developed in such\n  a manner that the latter pass through the permanent forms\n  of the former as transitory stages. Aristotle, Haller,\n  Harvey, Kielmeyer, Autenrieth, and many others, have\n  either made this observation incidentally, or, especially\n  the latter, have drawn particular attention to it, and\n  drawn therefrom results of permanent importance for\n  physiology.\u201d\n\nMeckel proceeds to exemplify the thesis, that the lower forms of\nanimals represent stages in the course of the development of the\nhigher, with a large series of illustrations.\n\nAfter comparing the Salamanders and the perenni-branchiate _Urodela_\nwith the Tadpoles and the Frogs, and enunciating the law that the more\nhighly any animal is organised the more quickly does it pass through\nthe lower stages, Meckel goes on to say\u2014\n\n  \u201cFrom these lowest Vertebrata to the highest, and to\n  the highest forms among these, the comparison between\n  the embryonic conditions of the higher animals and the\n  adult states of the lower can be more completely and\n  thoroughly instituted than if the survey is extended to\n  the Invertebrata, inasmuch as the latter are in many\n  respects constructed upon an altogether too dissimilar\n  type; indeed they often differ from one another far more\n  than the lowest vertebrate does from the highest mammal;\n  yet the following pages will show that the comparison\n  may also be extended to them with interest. In fact,\n  there is a period when, as Aristotle long ago said, the\n  embryo of the highest animal has the form of a mere worm;\n  and, devoid of internal and external organisation, is\n  merely an almost structureless lump of polype-substance.\n  Notwithstanding the origin of organs, it still for a\n  certain time, by reason of its want of an internal bony\n  skeleton, remains worm and mollusk, and only later enters\n  into the series of the Vertebrata, although traces of the\n  vertebral column even in the earliest periods testify its\n  claim to a place in that series.\u201d\u2014_Op. cit._ pp. 4, 5.\n\nIf Meckel\u2019s proposition is so far qualified, that the comparison of\nadult with embryonic forms is restricted within the limits of one type\nof organisation; and, if it is further recollected that the resemblance\nbetween the permanent lower form and the embryonic stage of a higher\nform is not special but general, it is in entire accordance with modern\nembryology; although there is no branch of biology which has grown so\nlargely, and improved its methods so much, since Meckel\u2019s time, as\nthis. In its original form, the doctrine of \u201carrest of development,\u201d\nas advocated by Geoffroy Saint-Hilaire and Serres, was no doubt an\nover-statement of the case. It is not true, for example, that a fish\nis a reptile arrested in its development, or that a reptile was ever\na fish: but it is true that the reptile embryo, at one stage of its\ndevelopment, is an organism which, if it had an independent existence,\nmust be classified among fishes; and all the organs of the reptile\npass, in the course of their development, through conditions which are\nclosely analogous to those which are permanent in some fishes.\n\n4. That branch of biology which is termed Morphology is a commentary\nupon, and expansion of, the proposition that widely different animals\nor plants, and widely different parts of animals or plants, are\nconstructed upon the same plan. From the rough comparison of the\nskeleton of a bird with that of a man by Belon, in the sixteenth\ncentury (to go no farther back), down to the theory of the limbs\nand the theory of the skull at the present day; or, from the first\ndemonstration of the homologies of the parts of a flower by C. F.\nWolff, to the present elaborate analysis of the floral organs,\nmorphology exhibits a continual advance towards the demonstration of a\nfundamental unity among the seeming diversities of living structures.\nAnd this demonstration has been completed by the final establishment\nof the cell theory, which involves the admission of a primitive\nconformity, not only of all the elementary structures in animals and\nplants respectively, but of those in the one of these great divisions\nof living things with those in the other. No _\u00e0 priori_ difficulty can\nbe said to stand in the way of evolution, when it can be shown that\nall animals and all plants proceed by modes of development, which are\nsimilar in principle, from a fundamental protoplasmic material.\n\n5. The innumerable cases of structures, which are rudimentary and\napparently useless, in species, the close allies of which possess\nwell developed and functionally important homologous structures, are\nreadily intelligible on the theory of evolution, while it is hard to\nconceive their _raison d\u2019\u00eatre_ on any other hypothesis. However, a\ncautious reasoner will probably rather explain such cases deductively\nfrom the doctrine of evolution than endeavour to support the doctrine\nof evolution by them. For it is almost impossible to prove that any\nstructure, however rudimentary, is useless\u2014that is to say, that it\nplays no part whatever in the economy; and, if it is in the slightest\ndegree useful, there is no reason why, on the hypothesis of direct\ncreation, it should not have been created. Nevertheless, double-edged\nas is the argument from rudimentary organs, there is probably none\nwhich has produced a greater effect in promoting the general acceptance\nof the theory of evolution.\n\n6. The older advocates of evolution sought for the causes of the\nprocess exclusively in the influence of varying conditions, such\nas climate and station, or hybridisation, upon living forms. Even\nTreviranus has got no farther than this point. Lamarck introduced\nthe conception of the action of an animal on itself as a factor in\nproducing modification. Starting from the well-known fact that the\nhabitual use of a limb tends to develop the muscles of the limb, and to\nproduce a greater and greater facility in using it, he made the general\nassumption that the effort of an animal to exert an organ in a given\ndirection tends to develop the organ in that direction. But a little\nconsideration showed that, though Lamarck had seized what, as far as\nit goes, is a true cause of modification, it is a cause the actual\neffects of which are wholly inadequate to account for any considerable\nmodification in animals, and which can have no influence at all in the\nvegetable world; and probably nothing contributed so much to discredit\nevolution, in the early part of this century, as the floods of easy\nridicule which were poured upon this part of Lamarck\u2019s speculation.\nThe theory of natural selection, or survival of the fittest, was\nsuggested by Wells in 1813, and further elaborated by Matthew in 1831.\nBut the pregnant suggestions of these writers remained practically\nunnoticed and forgotten, until the theory was independently devised\nand promulgated by Darwin and Wallace in 1858, and the effect of its\npublication was immediate and profound.\n\nThose who were unwilling to accept evolution, without better grounds\nthan such as are offered by Lamarck, or the author of that particularly\nunsatisfactory book, the \u201cVestiges of the Natural History of the\nCreation,\u201d and who therefore preferred to suspend their judgment on the\nquestion, found, in the principle of selective breeding, pursued in all\nits applications with marvellous knowledge and skill by Mr. Darwin,\na valid explanation of the occurrence of varieties and races; and\nthey saw clearly that, if the explanation would apply to species, it\nwould not only solve the problem of their evolution, but that it would\naccount for the facts of teleology, as well as for those of morphology;\nand for the persistence of some forms of life unchanged through long\nepochs of time, while others undergo comparatively rapid metamorphosis.\n\nHow far \u201cnatural selection\u201d suffices for the production of species\nremains to be seen. Few can doubt that, if not the whole cause, it is a\nvery important factor in that operation; and that it must play a great\npart in the sorting out of varieties into those which are transitory\nand those which are permanent.\n\nBut the causes and conditions of variation have yet to be thoroughly\nexplored; and the importance of natural selection will not be impaired,\neven if further inquiries should prove that variability is definite,\nand is determined in certain directions rather than in others, by\nconditions inherent in that which varies. It is quite conceivable that\nevery species tends to produce varieties of a limited number and kind,\nand that the effect of natural selection is to favour the development\nof some of these, while it opposes the development of others along\ntheir predetermined lines of modification.\n\n7. No truths brought to light by biological investigation were better\ncalculated to inspire distrust of the dogmas intruded upon science\nin the name of theology, than those which relate to the distribution\nof animals and plants on the surface of the earth. Very skilful\naccommodation was needful, if the limitation of sloths to South\nAmerica, and of the ornithorhynchus to Australia, was to be reconciled\nwith the literal interpretation of the history of the deluge; and,\nwith the establishment of the existence of distinct provinces of\ndistribution, any serious belief in the peopling of the world by\nmigration from Mount Ararat came to an end.\n\nUnder these circumstances, only one alternative was left for those\nwho denied the occurrence of evolution\u2014namely, the supposition that\nthe characteristic animals and plants of each great province were\ncreated, as such, within the limits in which we find them. And as the\nhypothesis of \u201cspecific centres,\u201d thus formulated, was heterodox from\nthe theological point of view, and unintelligible under its scientific\naspect, it may be passed over without further notice, as a phase of\ntransition from the creational to the evolutional hypothesis.\n\n8. In fact, the strongest and most conclusive arguments in favour of\nevolution are those which are based upon the facts of geographical,\ntaken in conjunction with those of geological, distribution.\n\nBoth Mr. Darwin and Mr. Wallace lay great stress on the close relation\nwhich obtains between the existing fauna of any region and that of\nthe immediately antecedent geological epoch in the same region; and\nrightly, for it is in truth inconceivable that there should be no\ngenetic connection between the two. It is possible to put into words\nthe proposition that all the animals and plants of each geological\nepoch were annihilated, and that a new set of very similar forms was\ncreated for the next epoch; but it may be doubted if any one who ever\ntried to form a distinct mental image of this process of spontaneous\ngeneration on the grandest scale, ever really succeeded in realising it.\n\nWithin the last twenty years, the attention of the best pal\u00e6ontologists\nhas been withdrawn from the hodman\u2019s work of making \u201cnew species\u201d\nof fossils, to the scientific task of completing our knowledge of\nindividual species, and tracing out the succession of the forms\npresented by any given type in time.\n\nThose who desire to inform themselves of the nature and extent of\nthe evidence bearing on these questions may consult the works of\nR\u00fctimeyer, Gaudry, Kowalewsky, Marsh, and the writer of the present\narticle. It must suffice, in this place, to say that the successive\nforms of the Equine type have been fully worked out; while those of\nnearly all the other existing types of Ungulate mammals and of the\n_Carnivora_ have been almost as closely followed through the Tertiary\ndeposits; the gradations between birds and reptiles have been traced;\nand the modifications undergone by the _Crocodilia_, from the Triassic\nepoch to the present day, have been demonstrated. On the evidence of\npal\u00e6ontology, the evolution of many existing forms of animal life\nfrom their predecessors is no longer an hypothesis, but an historical\nfact; it is only the nature of the physiological factors to which that\nevolution is due which is still open to discussion.\n\n\n\n\nXII.\n\nTHE COMING OF AGE OF \u201cTHE ORIGIN OF SPECIES.\u201d\n\n\nMany of you will be familiar with the aspect of this small\ngreen-covered book. It is a copy of the first edition of the \u201cOrigin of\nSpecies,\u201d and bears the date of its production\u2014the 1st of October 1859.\nOnly a few months, therefore, are needed to complete the full tale of\ntwenty-one years since its birthday.\n\nThose whose memories carry them back to this time will remember that\nthe infant was remarkably lively, and that a great number of excellent\npersons mistook its manifestations of a vigorous individuality for\nmere naughtiness; in fact there was a very pretty turmoil about its\ncradle. My recollections of the period are particularly vivid; for,\nhaving conceived a tender affection for a child of what appeared to me\nto be such remarkable promise, I acted for some time in the capacity\nof a sort of under-nurse, and thus came in for my share of the storms\nwhich threatened the very life of the young creature. For some years it\nwas undoubtedly warm work; but considering how exceedingly unpleasant\nthe apparition of the new-comer must have been to those who did not\nfall in love with him at first sight, I think it is to the credit of\nour age that the war was not fiercer, and that the more bitter and\nunscrupulous forms of opposition died away as soon as they did.\n\nI speak of this period as of something past and gone, possessing\nmerely an historical, I had almost said an antiquarian interest. For,\nduring the second decade of the existence of the \u201cOrigin of Species,\u201d\nopposition, though by no means dead, assumed a different aspect. On the\npart of all those who had any reason to respect themselves, it assumed\na thoroughly respectful character. By this time, the dullest began to\nperceive that the child was not likely to perish of any congenital\nweakness or infantile disorder, but was growing into a stalwart\npersonage, upon whom mere goody scoldings and threatenings with the\nbirch-rod were quite thrown away.\n\nIn fact, those who have watched the progress of science within the last\nten years will bear me out to the full, when I assert that there is no\nfield of biological inquiry in which the influence of the \u201cOrigin of\nSpecies\u201d is not traceable; the foremost men of science in every country\nare either avowed champions of its leading doctrines, or at any rate\nabstain from opposing them; a host of young and ardent investigators\nseek for and find inspiration and guidance in Mr. Darwin\u2019s great work;\nand the general doctrine of evolution, to one side of which it gives\nexpression, obtains, in the phenomena of biology, a firm base of\noperations whence it may conduct its conquest of the whole realm of\nnature.\n\nHistory warns us, however, that it is the customary fate of new truths\nto begin as heresies and to end as superstitions; and, as matters now\nstand, it is hardly rash to anticipate that, in another twenty years,\nthe new generation, educated under the influences of the present day,\nwill be in danger of accepting the main doctrines of the \u201cOrigin of\nSpecies,\u201d with as little reflection, and it may be with as little\njustification, as so many of our contemporaries, twenty years ago,\nrejected them.\n\nAgainst any such a consummation let us all devoutly pray; for the\nscientific spirit is of more value than its products, and irrationally\nheld truths may be more harmful than reasoned errors. Now the essence\nof the scientific spirit is criticism. It tells us that whenever a\ndoctrine claims our assent we should reply, Take it if you can compel\nit. The struggle for existence holds as much in the intellectual as in\nthe physical world. A theory is a species of thinking, and its right\nto exist is coextensive with its power of resisting extinction by its\nrivals.\n\nFrom this point of view, it appears to me that it would be but a poor\nway of celebrating the Coming of Age of the \u201cOrigin of Species,\u201d were I\nmerely to dwell upon the facts, undoubted and remarkable as they are,\nof its far-reaching influence and of the great following of ardent\ndisciples who are occupied in spreading and developing its doctrines.\nMere insanities and inanities have before now swollen to portentous\nsize in the course of twenty years. Let us rather ask this prodigious\nchange in opinion to justify itself; let us inquire whether anything\nhas happened since 1859, which will explain, on rational grounds, why\nso many are worshipping that which they burned, and burning that which\nthey worshipped. It is only in this way that we shall acquire the means\nof judging whether the movement we have witnessed is a mere eddy of\nfashion, or truly one with the irreversible current of intellectual\nprogress, and, like it, safe from retrogressive reaction.\n\nEvery belief is the product of two factors: the first is the state of\nthe mind to which the evidence in favour of that belief is presented;\nand the second is the logical cogency of the evidence itself. In both\nthese respects, the history of biological science during the last\ntwenty years appears to me to afford an ample explanation of the change\nwhich has taken place; and a brief consideration of the salient events\nof that history will enable us to understand why, if the \u201cOrigin of\nSpecies\u201d appeared now, it would meet with a very different reception\nfrom that which greeted it in 1859.\n\nOne-and-twenty years ago, in spite of the work commenced by Hutton and\ncontinued with rare skill and patience by Lyell, the dominant view\nof the past history of the earth was catastrophic. Great and sudden\nphysical revolutions, wholesale creations and extinctions of living\nbeings, were the ordinary machinery of the geological epic brought into\nfashion by the misapplied genius of Cuvier. It was gravely maintained\nand taught that the end of every geological epoch was signalised by a\ncataclysm, by which every living being on the globe was swept away,\nto be replaced by a brand-new creation when the world returned to\nquiescence. A scheme of nature which appeared to be modelled on the\nlikeness of a succession of rubbers of whist, at the end of each of\nwhich the players upset the table and called for a new pack, did not\nseem to shock anybody.\n\nI may be wrong, but I doubt if, at the present time, there is a single\nresponsible representative of these opinions left. The progress\nof scientific geology has elevated the fundamental principle of\nuniformitarianism, that the explanation of the past is to be sought\nin the study of the present, into the position of an axiom; and the\nwild speculations of the catastrophists, to which we all listened with\nrespect a quarter of a century ago, would hardly find a single patient\nhearer at the present day. No physical geologist now dreams of seeking,\noutside the range of known natural causes, for the explanation of\nanything that happened millions of years ago, any more than he would be\nguilty of the like absurdity in regard to current events.\n\nThe effect of this change of opinion upon biological speculation\nis obvious. For, if there have been no periodical general physical\ncatastrophes, what brought about the assumed general extinctions\nand re-creations of life which are the corresponding biological\ncatastrophes? And, if no such interruptions of the ordinary course of\nnature have taken place in the organic, any more than in the inorganic,\nworld, what alternative is there to the admission of evolution?\n\nThe doctrine of evolution in biology is the necessary result of the\nlogical application of the principles of uniformitarianism to the\nphenomena of life. Darwin is the natural successor of Hutton and Lyell,\nand the \u201cOrigin of Species\u201d the logical sequence of the \u201cPrinciples of\nGeology.\u201d\n\nThe fundamental doctrine of the \u201cOrigin of Species,\u201d as of all forms of\nthe theory of evolution applied to biology, is \u201cthat the innumerable\nspecies, genera, and families of organic beings with which the world\nis peopled have all descended, each within its own class or group,\nfrom common parents, and have all been modified in the course of\ndescent.\u201d[92]\n\nAnd, in view of the facts of geology, it follows that all living\nanimals and plants \u201care the lineal descendants of those which lived\nlong before the Silurian epoch.\u201d[93]\n\nIt is an obvious consequence of this theory of descent with\nmodification, as it is sometimes called, that all plants and animals,\nhowever different they may now be, must, at one time or other, have\nbeen connected by direct or indirect intermediate gradations, and that\nthe appearance of isolation presented by various groups of organic\nbeings must be unreal.\n\nNo part of Mr. Darwin\u2019s work ran more directly counter to the\nprepossessions of naturalists twenty years ago than this. And such\nprepossessions were very excusable, for there was undoubtedly a great\ndeal to be said, at that time, in favour of the fixity of species\nand of the existence of great breaks, which there was no obvious or\nprobable means of filling up, between various groups of organic beings.\n\nFor various reasons, scientific and unscientific, much had been made of\nthe hiatus between man and the rest of the higher mammalia, and it is\nno wonder that issue was first joined on this part of the controversy.\nI have no wish to revive past and happily forgotten controversies; but\nI must state the simple fact that the distinctions in the cerebral and\nother characters, which were so hotly affirmed to separate man from all\nother animals in 1860, have all been demonstrated to be non-existent,\nand that the contrary doctrine is now universally accepted and taught.\n\nBut there were other cases in which the wide structural gaps asserted\nto exist between one group of animals and another, were by no means\nfictitious; and, when such structural breaks were real, Mr. Darwin\ncould account for them only by supposing that the intermediate forms\nwhich once existed had become extinct. In a remarkable passage he says\u2014\n\n\u201cWe may thus account even for the distinctness of whole classes from\neach other\u2014for instance, of birds from all other vertebrate animals\u2014by\nthe belief that many animal forms of life have been utterly lost,\nthrough which the early progenitors of birds were formerly connected\nwith the early progenitors of the other vertebrate classes.\u201d[94]\n\nAdverse criticism made merry over such suggestions as these. Of course\nit was easy to get out of the difficulty by supposing extinction; but\nwhere was the slightest evidence that such intermediate forms between\nbirds and reptiles as the hypothesis required ever existed? And then\nprobably followed a tirade upon this terrible forsaking of the paths of\n\u201cBaconian induction.\u201d\n\nBut the progress of knowledge has justified Mr. Darwin to an extent\nwhich could hardly have been anticipated. In 1862, the specimen of\n_Arch\u00e6opteryx_, which, until the last two or three years, has remained\nunique, was discovered; and it is an animal which, in its feathers and\nthe greater part of its organisation, is a veritable bird, while, in\nother parts, it is as distinctly reptilian.\n\nIn 1868, I had the honour of bringing under your notice, in this\ntheatre, the results of investigations made, up to that time, into\nthe anatomical characters of certain ancient reptiles, which showed\nthe nature of the modifications in virtue of which the type of the\nquadrupedal reptile passed into that of a bipedal bird; and abundant\nconfirmatory evidence of the justice of the conclusions which I then\nlaid before you has since come to light.\n\nIn 1875, the discovery of the toothed birds of the cretaceous\nformation in North America by Professor Marsh completed the series of\ntransitional forms between birds and reptiles, and removed Mr. Darwin\u2019s\nproposition that \u201cmany animal forms of life have been utterly lost,\nthrough which the early progenitors of birds were formerly connected\nwith the early progenitors of the other vertebrate classes,\u201d from the\nregion of hypothesis to that of demonstrable fact.\n\nIn 1859, there appeared to be a very sharp and clear hiatus between\nvertebrated and invertebrated animals, not only in their structure,\nbut, what was more important, in their development. I do not think\nthat we even yet know the precise links of connection between the two;\nbut the investigations of Kowalewsky and others upon the development\nof _Amphioxus_ and of the _Tunicata_ prove, beyond a doubt, that the\ndifferences which were supposed to constitute a barrier between the two\nare non-existent. There is no longer any difficulty in understanding\nhow the vertebrate type may have arisen from the invertebrate, though\nthe full proof of the manner in which the transition was actually\neffected may still be lacking.\n\nAgain, in 1859, there appeared to be a no less sharp separation\nbetween the two great groups of flowering and flowerless plants. It\nis only subsequently that the series of remarkable investigations\ninaugurated by Hofmeister has brought to light the extraordinary and\naltogether unexpected modifications of the reproductive apparatus in\nthe _Lycopodiace\u00e6_, the _Rhizocarpe\u00e6_, and the _Gymnosperme\u00e6_, by which\nthe ferns and the mosses are gradually connected with the Phanerogamic\ndivision of the vegetable world.\n\nSo, again, it is only since 1859 that we have acquired that wealth of\nknowledge of the lowest forms of life which demonstrates the futility\nof any attempt to separate the lowest plants from the lowest animals,\nand shows that the two kingdoms of living nature have a common\nborderland which belongs to both or to neither.\n\nThus it will be observed that the whole tendency of biological\ninvestigation, since 1859, has been in the direction of removing the\ndifficulties which the apparent breaks in the series created at that\ntime; and the recognition of gradation is the first step towards the\nacceptance of evolution.\n\nAs another great factor in bringing about the change of opinion which\nhas taken place among naturalists, I count the astonishing progress\nwhich has been made in the study of embryology. Twenty years ago,\nnot only were we devoid of any accurate knowledge of the mode of\ndevelopment of many groups of animals and plants, but the methods of\ninvestigation were rude and imperfect. At the present time, there is\nno important group of organic beings the development of which has\nnot been carefully studied; and the modern methods of hardening and\nsection-making enable the embryologist to determine the nature of the\nprocess, in each case, with a degree of minuteness and accuracy which\nis truly astonishing to those whose memories carry them back to the\nbeginnings of modern histology. And the results of these embryological\ninvestigations are in complete harmony with the requirements of the\ndoctrine of evolution. The first beginnings of all the higher forms of\nanimal life are similar, and however diverse their adult conditions,\nthey start from a common foundation. Moreover, the process of\ndevelopment of the animal or the plant from its primary egg or germ is\na true process of evolution\u2014a progress from almost formless to more or\nless highly organised matter, in virtue of the properties inherent in\nthat matter.\n\nTo those who are familiar with the process of development, all _\u00e0\npriori_ objections to the doctrine of biological evolution appear\nchildish. Any one who has watched the gradual formation of a\ncomplicated animal from the protoplasmic mass, which constitutes the\nessential element of a frog\u2019s or a hen\u2019s egg, has had under his eyes\nsufficient evidence that a similar evolution of the whole animal world\nfrom the like foundation is, at any rate, possible.\n\nYet another product of investigation has largely contributed to the\nremoval of the objections to the doctrine of evolution current in 1859.\nIt is the proof afforded by successive discoveries that Mr. Darwin\ndid not over-estimate the imperfection of the geological record. No\nmore striking illustration of this is needed than a comparison of our\nknowledge of the mammalian fauna of the Tertiary epoch in 1859 with its\npresent condition. M. Gaudry\u2019s researches on the fossils of Pikermi\nwere published in 1868, those of Messrs. Leidy, Marsh, and Cope, on\nthe fossils of the Western Territories of America, have appeared\nalmost wholly since 1870, those of M. Filhol on the phosphorites of\nQuercy in 1878. The general effect of these investigations has been\nto introduce to us a multitude of extinct animals, the existence of\nwhich was previously hardly suspected; just as if zoologists were to\nbecome acquainted with a country, hitherto unknown, as rich in novel\nforms of life as Brazil or South Africa once were to Europeans. Indeed,\nthe fossil fauna of the Western Territories of America bids fair to\nexceed in interest and importance all other known Tertiary deposits\nput together; and yet, with the exception of the case of the American\ntertiaries, these investigations have extended over very limited areas;\nand, at Pikermi, were confined to an extremely small space.\n\n\nSuch appear to me to be the chief events in the history of the progress\nof knowledge during the last twenty years, which account for the\nchanged feeling with which the doctrine of evolution is at present\nregarded by those who have followed the advance of biological science,\nin respect of those problems which bear indirectly upon that doctrine.\n\nBut all this remains mere secondary evidence. It may remove dissent,\nbut it does not compel assent. Primary and direct evidence in favour of\nevolution can be furnished only by pal\u00e6ontology. The geological record,\nso soon as it approaches completeness, must, when properly questioned,\nyield either an affirmative or a negative answer: if evolution has\ntaken place, there will its mark be left; if it has not taken place,\nthere will lie its refutation.\n\nWhat was the state of matters in 1859? Let us hear Mr. Darwin, who may\nbe trusted always to state the case against himself as strongly as\npossible.\n\n\u201cOn this doctrine of the extermination of an infinitude of connecting\nlinks between the living and extinct inhabitants of the world, and at\neach successive period between the extinct and still older species,\nwhy is not every geological formation charged with such links? Why\ndoes not every collection of fossil remains afford plain evidence\nof the gradation and mutation of the forms of life? We meet with no\nsuch evidence, and this is the most obvious and plausible of the many\nobjections which may be urged against my theory.\u201d[95]\n\nNothing could have been more useful to the opposition than this\ncharacteristically candid avowal, twisted as it immediately was into\nan admission that the writer\u2019s views were contradicted by the facts of\npal\u00e6ontology. But, in fact, Mr. Darwin made no such admission. What he\nsays in effect is, not that pal\u00e6ontological evidence is against him,\nbut that it is not distinctly in his favour; and, without attempting\nto attenuate the fact, he accounts for it by the scantiness and the\nimperfection of that evidence.\n\nWhat is the state of the case now, when, as we have seen, the amount\nof our knowledge respecting the mammalia of the Tertiary epoch\nis increased fifty-fold, and in some directions even approaches\ncompleteness?\n\nSimply this, that, if the doctrine of evolution had not existed,\npal\u00e6ontologists must have invented it, so irresistibly is it forced\nupon the mind by the study of the remains of the Tertiary mammalia\nwhich have been brought to light since 1859.\n\nAmong the fossils of Pikermi, Gaudry found the successive stages\nby which the ancient civets passed into the more modern hy\u00e6nas;\nthrough the Tertiary deposits of Western America, Marsh tracked the\nsuccessive forms by which the ancient stock of the horse has passed\ninto its present form; and innumerable less complete indications of\nthe mode of evolution of other groups of the higher mammalia have been\nobtained. In the remarkable memoir on the phosphorites of Quercy, to\nwhich I have referred, M. Filhol describes no fewer than seventeen\nvarieties of the genus _Cynodictis_, which fill up all the interval\nbetween the viverine animals and the bear-like dog _Amphicyon_; nor\ndo I know any solid ground of objection to the supposition that, in\nthis _Cynodictis-Amphicyon_ group, we have the stock whence all the\nViverid\u00e6, Felid\u00e6, Hy\u00e6nid\u00e6, Canid\u00e6, and perhaps the Procyonid\u00e6 and\nUrsid\u00e6, of the present fauna have been evolved. On the contrary, there\nis a great deal to be said in favour.\n\nIn the course of summing up his results, M. Filhol observes:\u2014\n\n  \u201cDuring the epoch of the phosphorites, great changes took\n  place in animal forms, and almost the same types as those\n  which now exist became defined from one another.\n\n  \u201cUnder the influence of natural conditions of which\n  we have no exact knowledge, though traces of them are\n  discoverable, species have been modified in a thousand\n  ways: races have arisen which, becoming fixed, have thus\n  produced a corresponding number of secondary species.\u201d\n\nIn 1859, language of which this is an unintentional paraphrase,\noccurring in the \u201cOrigin of Species,\u201d was scouted as wild speculation;\nat present, it is a sober statement of the conclusions to which an\nacute and critically-minded investigator is led by large and patient\nstudy of the facts of pal\u00e6ontology. I venture to repeat what I have\nsaid before, that, so far as the animal world is concerned, evolution\nis no longer a speculation, but a statement of historical fact. It\ntakes its place alongside of those accepted truths which must be\nreckoned with by philosophers of all schools.\n\nThus when, on the first day of October next, the \u201cOrigin of Species\u201d\ncomes of age, the promise of its youth will be amply fulfilled; and we\nshall be prepared to congratulate the venerated author of the book, not\nonly that the greatness of his achievement and its enduring influence\nupon the progress of knowledge have won him a place beside our Harvey;\nbut, still more, that, like Harvey, he has lived long enough to outlast\ndetraction and opposition, and to see the stone that the builders\nrejected become the head-stone of the corner.\n\n\n\n\nXIII.\n\nTHE CONNECTION OF THE BIOLOGICAL SCIENCES WITH MEDICINE.\n\n\nThe great body of theoretical and practical knowledge which has been\naccumulated by the labours of some eighty generations, since the dawn\nof scientific thought in Europe, has no collective English name to\nwhich an objection may not be raised; and I use the term \u201cmedicine\u201d as\nthat which is least likely to be misunderstood; though, as every one\nknows, the name is commonly applied, in a narrower sense, to one of the\nchief divisions of the totality of medical science.\n\nTaken in this broad sense, \u201cmedicine\u201d not merely denotes a kind\nof knowledge, but it comprehends the various applications of that\nknowledge to the alleviation of the sufferings, the repair of the\ninjuries, and the conservation of the health, of living beings. In\nfact, the practical aspect of medicine so far dominates over every\nother, that the \u201cHealing Art\u201d is one of its most widely-received\nsynonyms. It is so difficult to think of medicine otherwise than as\nsomething which is necessarily connected with curative treatment, that\nwe are apt to forget that there must be, and is, such a thing as a\npure science of medicine\u2014a \u201cpathology\u201d which has no more necessary\nsubservience to practical ends than has zoology or botany.\n\nThe logical connection between this purely scientific doctrine of\ndisease, or pathology, and ordinary biology, is easily traced.\nLiving matter is characterised by its innate tendency to exhibit a\ndefinite series of the morphological and physiological phenomena which\nconstitute organisation and life. Given a certain range of conditions,\nand these phenomena remain the same, within narrow limits, for each\nkind of living thing. They furnish the normal and typical character\nof the species, and, as such, they are the subject-matter of ordinary\nbiology.\n\nOutside the range of these conditions, the normal course of the\ncycle of vital phenomena is disturbed; abnormal structure makes its\nappearance, or the proper character and mutual adjustment of the\nfunctions cease to be preserved. The extent and the importance of these\ndeviations from the typical life may vary indefinitely. They may have\nno noticeable influence on the general well-being of the economy, or\nthey may favour it. On the other hand, they may be of such a nature\nas to impede the activities of the organism, or even to involve its\ndestruction.\n\nIn the first case, these perturbations are ranged under the wide and\nsomewhat vague category of \u201cvariations;\u201d in the second, they are called\nlesions, states of poisoning, or diseases; and, as morbid states, they\nlie within the province of pathology. No sharp line of demarcation can\nbe drawn between the two classes of phenomena. No one can say where\nanatomical variations end and tumours begin, nor where modification\nof function, which may at first promote health, passes into disease.\nAll that can be said is, that whatever change of structure or function\nis hurtful belongs to pathology. Hence it is obvious that pathology\nis a branch of biology; it is the morphology, the physiology, the\ndistribution, the \u00e6tiology of abnormal life.\n\nHowever obvious this conclusion may be now, it was nowise apparent\nin the infancy of medicine. For it is a peculiarity of the physical\nsciences, that they are independent in proportion as they are\nimperfect; and it is only as they advance that the bonds which really\nunite them all become apparent. Astronomy had no manifest connection\nwith terrestrial physics before the publication of the \u201cPrincipia;\u201d\nthat of chemistry with physics is of still more modern revelation;\nthat of physics and chemistry with physiology, has been stoutly denied\nwithin the recollection of most of us, and perhaps still may be.\n\nOr, to take a case which affords a closer parallel with that of\nmedicine. Agriculture has been cultivated from the earliest times,\nand, from a remote antiquity, men have attained considerable practical\nskill in the cultivation of the useful plants, and have empirically\nestablished many scientific truths concerning the conditions under\nwhich they flourish. But, it is within the memory of many of us, that\nchemistry on the one hand, and vegetable physiology on the other,\nattained a stage of development such that they were able to furnish\na sound basis for scientific agriculture. Similarly, medicine took\nits rise in the practical needs of mankind. At first, studied without\nreference to any other branch of knowledge, it long maintained, indeed\nstill to some extent maintains, that independence. Historically, its\nconnection with the biological sciences has been slowly established,\nand the full extent and intimacy of that connection are only now\nbeginning to be apparent. I trust I have not been mistaken in supposing\nthat an attempt to give a brief sketch of the steps by which a\nphilosophical necessity has become an historical reality, may not be\ndevoid of interest, possibly of instruction, to the members of this\ngreat Congress, profoundly interested as all are in the scientific\ndevelopment of medicine.\n\nThe history of medicine is more complete and fuller than that of any\nother science, except, perhaps, astronomy; and, if we follow back the\nlong record as far as clear evidence lights us, we find ourselves taken\nto the early stages of the civilisation of Greece. The oldest hospitals\nwere the temples of \u00c6sculapius; to these Asclepeia, always erected on\nhealthy sites, hard by fresh springs and surrounded by shady groves,\nthe sick and the maimed resorted to seek the aid of the god of health.\nVotive tablets or inscriptions recorded the symptoms, no less than the\ngratitude, of those who were healed; and, from these primitive clinical\nrecords, the half-priestly, half-philosophic caste of the Asclepiads\ncompiled the data upon which the earliest generalisations of medicine,\nas an inductive science, were based.\n\nIn this state, pathology, like all the inductive sciences at their\norigin, was merely natural history; it registered the phenomena of\ndisease, classified them, and ventured upon a prognosis, wherever\nthe observation of constant co-existences and sequences suggested a\nrational expectation of the like recurrence under similar circumstances.\n\nFurther than this it hardly went. In fact, in the then state of\nknowledge, and in the condition of philosophical speculation at that\ntime, neither the causes of the morbid state, nor the _rationale_ of\ntreatment, were likely to be sought for as we seek for them now. The\nanger of a god was a sufficient reason for the existence of a malady,\nand a dream ample warranty for therapeutic measures; that a physical\nphenomenon must needs have a physical cause was not the implied or\nexpressed axiom that it is to us moderns.\n\nThe great man whose name is inseparately connected with the foundation\nof medicine, Hippocrates, certainly knew very little, indeed\npractically nothing, of anatomy or physiology; and he would, probably,\nhave been perplexed, even to imagine the possibility of a connection\nbetween the zoological studies of his contemporary Democritus and\nmedicine. Nevertheless, in so far as he, and those who worked before\nand after him, in the same spirit, ascertained, as matters of\nexperience, that a wound, or a luxation, or a fever, presented such\nand such symptoms, and that the return of the patient to health was\nfacilitated by such and such measures, they established laws of\nnature, and began the construction of the science of pathology. All\ntrue science begins with empiricism\u2014though all true science is such\nexactly, in so far as it strives to pass out of the empirical stage\ninto that of the deduction of empirical from more general truths.\nThus, it is not wonderful, that the early physicians had little or\nnothing to do with the development of biological science; and, on the\nother hand, that the early biologists did not much concern themselves\nwith medicine. There is nothing to show that the Asclepiads took any\nprominent share in the work of founding anatomy, physiology, zoology,\nand botany. Rather do these seem to have sprung from the early\nphilosophers, who were essentially natural philosophers, animated by\nthe characteristically Greek thirst for knowledge as such. Pythagoras,\nAlcmeon, Democritus, Diogenes of Apollonia, are all credited with\nanatomical and physiological investigations; and, though Aristotle is\nsaid to have belonged to an Asclepiad family, and not improbably owed\nhis taste for anatomical and zoological inquiries to the teachings of\nhis father, the physician Nicomachus, the \u201cHistoria Animalium,\u201d and\nthe treatise \u201cDe Partibus Animalium,\u201d are as free from any allusion to\nmedicine as if they had issued from a modern biological laboratory.\n\nIt may be added, that it is not easy to see in what way it could have\nbenefited a physician of Alexander\u2019s time to know all that Aristotle\nknew on these subjects. His human anatomy was too rough to avail\nmuch in diagnosis; his physiology was too erroneous to supply data\nfor pathological reasoning. But when the Alexandrian school, with\nErasistratus and Herophilus at their head, turned to account the\nopportunities of studying human structure, afforded to them by the\nPtolemies, the value of the large amount of accurate knowledge thus\nobtained to the surgeon for his operations, and to the physician for\nhis diagnosis of internal disorders, became obvious, and a connection\nwas established between anatomy and medicine, which has ever become\ncloser and closer. Since the revival of learning, surgery, medical\ndiagnosis, and anatomy have gone hand in hand. Morgagni called his\ngreat work, \u201cDe sedibus et causis morborum per anatomen indagatis,\u201d and\nnot only showed the way to search out the localities and the causes\nof disease by anatomy, but himself travelled wonderfully far upon the\nroad. Bichat, discriminating the grosser constituents of the organs and\nparts of the body, one from another, pointed out the direction which\nmodern research must take; until, at length, histology, a science of\nyesterday, as it seems to many of us, has carried the work of Morgagni\nas far as the microscope can take us, and has extended the realm of\npathological anatomy to the limits of the invisible world.\n\nThanks to the intimate alliance of morphology with medicine, the\nnatural history of disease has, at the present day, attained a\nhigh degree of perfection. Accurate regional anatomy has rendered\npracticable the exploration of the most hidden parts of the organism,\nand the determination, during life, of morbid changes in them;\nanatomical and histological postmortem investigations have supplied\nphysicians with a clear basis upon which to rest the classification\nof diseases, and with unerring tests of the accuracy or inaccuracy of\ntheir diagnoses.\n\nIf men could be satisfied with pure knowledge, the extreme precision\nwith which, in these days, a sufferer may be told what is happening,\nand what is likely to happen, even in the most recondite parts of\nhis bodily frame, should be as satisfactory to the patient as it is\nto the scientific pathologist who gives him the information. But I\nam afraid it is not; and even the practising physician, while nowise\nunderestimating the regulative value of accurate diagnosis, must often\nlament that so much of his knowledge rather prevents him from doing\nwrong than helps him to do right.\n\nA scorner of physic once said that nature and disease may be compared\nto two men fighting, the doctor to a blind man with a club, who strikes\ninto the _mel\u00e9e_, sometimes hitting the disease, and sometimes hitting\nnature. The matter is not mended if you suppose the blind man\u2019s hearing\nto be so acute that he can register every stage of the struggle, and\npretty clearly predict how it will end. He had better not meddle at\nall, until his eyes are opened\u2014until he can see the exact position of\nthe antagonists, and make sure of the effect of his blows. But that\nwhich it behoves the physician to see, not, indeed, with his bodily\neye, but with clear, intellectual vision, is a process, and the chain\nof causation involved in that process. Disease, as we have seen, is\na perturbation of the normal activities of a living body, and it is,\nand must remain, unintelligible, so long as we are ignorant of the\nnature of these normal activities. In other words, there could be no\nreal science of pathology until the science of physiology had reached a\ndegree of perfection unattained, and indeed unattainable, until quite\nrecent times.\n\nSo far as medicine is concerned, I am not sure that physiology, such\nas it was down to the time of Harvey, might as well not have existed.\nNay, it is perhaps no exaggeration to say that, within the memory of\nliving men, justly renowned practitioners of medicine and surgery knew\nless physiology than is now to be learned from the most elementary\ntext-book; and, beyond a few broad facts, regarded what they did know\nas of extremely little practical importance. Nor am I disposed to\nblame them for this conclusion; physiology must be useless, or worse\nthan useless, to pathology, so long as its fundamental conceptions are\nerroneous.\n\nHarvey is often said to be the founder of modern physiology; and there\ncan be no question that the elucidations of the function of the heart,\nof the nature of the pulse, and of the course of the blood, put forth\nin the ever-memorable little essay, \u201cDe motu cordis,\u201d directly worked\na revolution in men\u2019s views of the nature and of the concatenation of\nsome of the most important physiological processes among the higher\nanimals; while, indirectly, their influence was perhaps even more\nremarkable.\n\nBut, though Harvey made this signal and perennially important\ncontribution to the physiology of the moderns, his general conception\nof vital processes was essentially identical with that of the ancients;\nand, in the \u201cExercitationes de generatione,\u201d and notably in the\nsingular chapter \u201cDe calido innato,\u201d he shows himself a true son of\nGalen and of Aristotle.\n\nFor Harvey, the blood possesses powers superior to those of the\nelements; it is the seat of a soul which is not only vegetative, but\nalso sensitive and motor. The blood maintains and fashions all parts of\nthe body, \u201cidque summ\u00e2 cum providenti\u00e2 et intellectu in finem certum\nagens, quasi ratiocinio quodam uteretur.\u201d\n\nHere is the doctrine of the \u201cpneuma,\u201d the product of the philosophical\nmould into which the animism of primitive men ran in Greece, in full\nforce. Nor did its strength abate for long after Harvey\u2019s time. The\nsame ingrained tendency of the human mind to suppose that a process\nis explained when it is ascribed to a power of which nothing is known\nexcept that it is the hypothetical agent of the process, gave rise, in\nthe next century, to the animism of Stahl; and, later, to the doctrine\nof a vital principle, that \u201casylum ignoranti\u00e6\u201d of physiologists, which\nhas so easily accounted for everything and explained nothing, down to\nour own times.\n\nNow the essence of modern, as contrasted with ancient, physiological\nscience appears to me to lie in its antagonism to animistic hypotheses\nand animistic phraseology. It offers physical explanations of vital\nphenomena, or frankly confesses that it has none to offer. And, so far\nas I know, the first person who gave expression to this modern view\nof physiology, who was bold enough to enunciate the proposition that\nvital phenomena, like all the other phenomena of the physical world,\nare, in ultimate analysis, resolvable into matter and motion, was Ren\u00e9\nDescartes.\n\nThe fifty-four years of life of this most original and powerful thinker\nare widely overlapped, on both sides, by the eighty of Harvey, who\nsurvived his younger contemporary by seven years, and takes pleasure\nin acknowledging the French philosopher\u2019s appreciation of his great\ndiscovery.\n\nIn fact, Descartes accepted the doctrine of the circulation as\npropounded by \u201cHarv\u00e6us m\u00e9decin d\u2019Angleterre,\u201d and gave a full account\nof it in his first work, the famous \u201cDiscours de la M\u00e9thode,\u201d which\nwas published in 1637, only nine years after the exercitation \u201cDe motu\ncordis;\u201d and, though differing from Harvey on some important points\n(in which it may be noted, in passing, Descartes was wrong and Harvey\nright), he always speaks of him with great respect. And so important\ndoes the subject seem to Descartes, that he returns to it in the\n\u201cTrait\u00e9 des Passions,\u201d and in the \u201cTrait\u00e9 de l\u2019Homme.\u201d\n\nIt is easy to see that Harvey\u2019s work must have had a peculiar\nsignificance for the subtle thinker, to whom we owe both the\nspiritualistic and the materialistic philosophies of modern times. It\nwas in the very year of its publication, 1628, that Descartes withdrew\ninto that life of solitary investigation and meditation of which his\nphilosophy was the fruit. And, as the course of his speculations\nled him to establish an absolute distinction of nature between the\nmaterial and the mental worlds, he was logically compelled to seek\nfor the explanation of the phenomena of the material world within\nitself; and having allotted the realm of thought to the soul, to see\nnothing but extension and motion in the rest of nature. Descartes uses\n\u201cthought\u201d as the equivalent of our modern term \u201cconsciousness.\u201d Thought\nis the function of the soul, and its only function. Our natural heat\nand all the movements of the body, says he, do not depend on the soul.\nDeath does not take place from any fault of the soul, but only because\nsome of the principal parts of the body become corrupted. The body of a\nliving man differs from that of a dead man in the same way as a watch\nor other automaton (that is to say, a machine which moves of itself)\nwhen it is wound up and has, in itself, the physical principle of the\nmovements which the mechanism is adapted to perform, differs from the\nsame watch, or other machine, when it is broken, and the physical\nprinciple of its movement no longer exists. All the actions which are\ncommon to us and the lower animals depend only on the conformation of\nour organs, and the course which the animal spirits take in the brain,\nthe nerves, and the muscles; in the same way as the movement of a watch\nis produced by nothing but the force of its spring and the figure of\nits wheels and other parts.\n\nDescartes\u2019 \u201cTreatise on Man\u201d is a sketch of human physiology, in which\na bold attempt is made to explain all the phenomena of life, except\nthose of consciousness, by physical reasonings. To a mind turned in\nthis direction, Harvey\u2019s exposition of the heart and vessels as a\nhydraulic mechanism must have been supremely welcome.\n\nDescartes was not a mere philosophical theorist, but a hardworking\ndissector and experimenter, and he held the strongest opinion\nrespecting the practical value of the new conception which he was\nintroducing. He speaks of the importance of preserving health, and of\nthe dependence of the mind on the body being so close that, perhaps,\nthe only way of making men wiser and better than they are, is to be\nsought in medical science. \u201cIt is true,\u201d says he, \u201cthat as medicine\nis now practised, it contains little that is very useful; but without\nany desire to depreciate, I am sure that there is no one, even among\nprofessional men, who will not declare that all we know is very little\nas compared with that which remains to be known; and that we might\nescape an infinity of diseases of the mind, no less than of the body,\nand even perhaps from the weakness of old age, if we had sufficient\nknowledge of their causes, and of all the remedies with which nature\nhas provided us.\u201d[96] So strongly impressed was Descartes with this,\nthat he resolved to spend the rest of his life in trying to acquire\nsuch a knowledge of nature as would lead to the construction of a\nbetter medical doctrine.[97] The anti-Cartesians found material for\ncheap ridicule in these aspirations of the philosopher; and it is\nalmost needless to say that, in the thirteen years which elapsed\nbetween the publication of the \u201cDiscours\u201d and the death of Descartes,\nhe did not contribute much to their realisation. But, for the next\ncentury, all progress in physiology took place along the lines which\nDescartes laid down.\n\nThe greatest physiological and pathological work of the seventeenth\ncentury, Borelli\u2019s treatise \u201cDe Motu Animalium,\u201d is, to all intents\nand purposes, a development of Descartes\u2019 fundamental conception; and\nthe same may be said of the physiology and pathology of Boerhaave,\nwhose authority dominated in the medical world of the first half of the\neighteenth century.\n\nWith the origin of modern chemistry, and of electrical science, in the\nlatter half of the eighteenth century, aids in the analysis of the\nphenomena of life, of which Descartes could not have dreamed, were\noffered to the physiologist. And the greater part of the gigantic\nprogress which has been made in the present century is a justification\nof the prevision of Descartes. For it consists, essentially, in a more\nand more complete resolution of the grosser organs of the living body\ninto physico-chemical mechanisms.\n\n\u201cI shall try to explain our whole bodily machinery in such a way, that\nit will be no more necessary for us to suppose that the soul produces\nsuch movements as are not voluntary, than it is to think that there is\nin a clock a soul which causes it to show the hours.\u201d[98] These words\nof Descartes might be appropriately taken as a motto by the author of\nany modern treatise on physiology.\n\nBut though, as I think, there is no doubt that Descartes was the\nfirst to propound the fundamental conception of the living body as\na physical mechanism, which is the distinctive feature of modern,\nas contrasted with ancient physiology, he was misled by the natural\ntemptation to carry out, in all its details, a parallel between the\nmachines with which he was familiar, such as clocks and pieces of\nhydraulic apparatus, and the living machine. In all such machines there\nis a central source of power, and the parts of the machine are merely\npassive distributors of that power. The Cartesian school conceived\nof the living body as a machine of this kind; and herein they might\nhave learned from Galen, who, whatever ill use he may have made of the\ndoctrine of \u201cnatural faculties,\u201d nevertheless had the great merit of\nperceiving that local forces play a great part in physiology.\n\nThe same truth was recognised by Glisson, but it was first prominently\nbrought forward in the Hallerian doctrine of the \u201cvis insita\u201d of\nmuscles. If muscle can contract without nerve, there is an end of the\nCartesian mechanical explanation of its contraction by the influx of\nanimal spirits.\n\nThe discoveries of Trembley tended in the same direction. In the\nfreshwater _Hydra_, no trace was to be found of that complicated\nmachinery upon which the performance of the functions in the higher\nanimals was supposed to depend. And yet the hydra moved, fed, grew,\nmultiplied, and its fragments exhibited all the powers of the whole.\nAnd, finally, the work of Caspar F. Wolff,[99] by demonstrating the\nfact that the growth and development of both plants and animals take\nplace antecedently to the existence of their grosser organs, and are,\nin fact, the causes and not the consequences of organisation (as then\nunderstood), sapped the foundations of the Cartesian physiology as a\ncomplete expression of vital phenomena.\n\nFor Wolff, the physical basis of life is a fluid, possessed of a \u201cvis\nessentialis\u201d and a \u201csolidescibilitas,\u201d in virtue of which it gives rise\nto organisation; and, as he points out, this conclusion strikes at the\nroot of the whole iatro-mechanical system.\n\nIn this country, the great authority of John Hunter exerted a similar\ninfluence; though it must be admitted that the too sibylline utterances\nwhich are the outcome of Hunter\u2019s struggles to define his conceptions\nare often susceptible of more than one interpretation. Nevertheless,\non some points Hunter is clear enough. For example, he is of opinion\nthat \u201cSpirit is only a property of matter\u201d (\u201cIntroduction to Natural\nHistory,\u201d p. 6), he is prepared to renounce animism (_l.c._ p. 8),\nand his conception of life is so completely physical that he thinks\nof it as something which can exist in a state of combination in the\nfood. \u201cThe aliment we take in has in it, in a fixed state, the real\nlife; and this does not become active until it has got into the lungs;\nfor there it is freed from its prison\u201d (\u201cObservations on Physiology,\u201d\np. 113). He also thinks that \u201cIt is more in accord with the general\nprinciples of the animal machine to suppose that none of its effects\nare produced from any mechanical principle whatever; and that every\neffect is produced from an action in the part; which action is produced\nby a stimulus upon the part which acts, or upon some other part with\nwhich this part sympathises so as to take up the whole action\u201d (_l.c._\np. 152).\n\nAnd Hunter is as clear as Wolff, with whose work he was probably\nunacquainted, that \u201cwhatever life is, it most certainly does not depend\nupon structure or organisation\u201d (_l.c._ p. 114).\n\nOf course it is impossible that Hunter could have intended to deny\nthe existence of purely mechanical operations in the animal body.\nBut while, with Borelli and Boerhaave, he looked upon absorption,\nnutrition, and secretion as operations effected by means of the small\nvessels, he differed from the mechanical physiologists, who regarded\nthese operations as the result of the mechanical properties of the\nsmall vessels, such as the size, form, and disposition of their canals\nand apertures. Hunter, on the contrary, considers them to be the effect\nof properties of these vessels which are not mechanical but vital. \u201cThe\nvessels,\u201d says he, \u201chave more of the polypus in them than any other\npart of the body,\u201d and he talks of the \u201cliving and sensitive principles\nof the arteries,\u201d and even of the \u201cdispositions or feelings of the\narteries.\u201d \u201cWhen the blood is good and genuine the sensations of the\narteries, or the dispositions for sensation, are agreeable.... It is\nthen they dispose of the blood to the best advantage, increasing the\ngrowth of the whole, supplying any losses, keeping up a due succession,\netc.\u201d (_l.c._ p. 133).\n\nIf we follow Hunter\u2019s conceptions to their logical issue, the life of\none of the higher animals is essentially the sum of the lives of all\nthe vessels, each of which is a sort of physiological unit, answering\nto a polype; and, as health is the result of the normal \u201caction of the\nvessels,\u201d so is disease an effect of their abnormal action. Hunter thus\nstands in thought, as in time, midway between Borelli on the one hand,\nand Bichat on the other.\n\nThe acute founder of general anatomy, in fact, outdoes Hunter in his\ndesire to exclude physical reasonings from the realm of life. Except in\nthe interpretation of the action of the sense organs, he will not allow\nphysics to have anything to do with physiology.\n\n\u201cTo apply the physical sciences to physiology is to explain the\nphenomena of living bodies by the laws of inert bodies. Now this\nis a false principle, hence all its consequences are marked with\nthe same stamp. Let us leave to chemistry its affinity; to physics,\nits elasticity and its gravity. Let us invoke for physiology only\nsensibility and contractility.\u201d[100]\n\nOf all the unfortunate dicta of men of eminent ability this seems\none of the most unhappy, when we think of what the application of\nthe methods and the data of physics and chemistry has done towards\nbringing physiology into its present state. It is not too much to say\nthat one half of a modern text-book of physiology consists of applied\nphysics and chemistry; and that it is exactly in the exploration of the\nphenomena of sensibility and contractility that physics and chemistry\nhave exerted the most potent influence.\n\nNevertheless, Bichat rendered a solid service to physiological progress\nby insisting upon the fact that what we call life, in one of the higher\nanimals, is not an indivisible unitary arch\u00e6us dominating, from its\ncentral seat, the parts of the organism, but a compound result of the\nsynthesis of the separate lives of those parts.\n\n\u201cAll animals,\u201d says he, \u201care assemblages of different organs, each of\nwhich performs its function and concurs, after its fashion, in the\npreservation of the whole. They are so many special machines in the\ngeneral machine which constitutes the individual. But each of these\nspecial machines is itself compounded of many tissues of very different\nnatures, which in truth constitute the elements of those organs\u201d\n(_l.c._ lxxix.) \u201cThe conception of a proper vitality is applicable only\nto these simple tissues, and not to the organs themselves\u201d (_l.c._\nlxxxiv.)\n\nAnd Bichat proceeds to make the obvious application of this doctrine of\nsynthetic life, if I may so call it, to pathology. Since diseases are\nonly alterations of vital properties, and the properties of each tissue\nare distinct from those of the rest, it is evident that the diseases of\neach tissue must be different from those of the rest. Therefore, in any\norgan composed of different tissues, one may be diseased and the other\nremain healthy; and this is what happens in most cases (_l.c._ lxxxv.)\n\nIn a spirit of true prophecy, Bichat says, \u201cWe have arrived at an\nepoch, in which pathological anatomy should start afresh.\u201d For, as the\nanalysis of the organs had led him to the tissues, as the physiological\nunits of the organism; so, in a succeeding generation, the analysis\nof the tissues led to the cell as the physiological element of the\ntissues. The contemporaneous study of development brought out the same\nresult; and the zoologists and botanists, exploring the simplest and\nthe lowest forms of animated beings, confirmed the great induction of\nthe cell theory. Thus the apparently opposed views, which have been\nbattling with one another ever since the middle of the last century,\nhave proved to be each half the truth.\n\nThe proposition of Descartes that the body of a living man is a\nmachine, the actions of which are explicable by the known laws of\nmatter and motion, is unquestionably largely true. But it is also\ntrue, that the living body is a synthesis of innumerable physiological\nelements, each of which may nearly be described, in Wolff\u2019s words, as a\nfluid possessed of a \u201cvis essentialis,\u201d and a \u201csolidescibilitas\u201d; or,\nin modern phrase, as protoplasm susceptible of structural metamorphosis\nand functional metabolism: and that the only machinery, in the precise\nsense in which the Cartesian school understood mechanism, is, that\nwhich co-ordinates and regulates these physiological units into an\norganic whole.\n\nIn fact, the body is a machine of the nature of an army, not of that\nof a watch or of a hydraulic apparatus. Of this army each cell is a\nsoldier, an organ a brigade, the central nervous system headquarters\nand field telegraph, the alimentary and circulatory system the\ncommissariat. Losses are made good by recruits born in camp, and the\nlife of the individual is a campaign, conducted successfully for a\nnumber of years, but with certain defeat in the long run.\n\nThe efficacy of an army, at any given moment, depends on the health of\nthe individual soldier, and on the perfection of the machinery by which\nhe is led and brought into action at the proper time; and, therefore,\nif the analogy holds good, there can be only two kinds of diseases, the\none dependent on abnormal states of the physiological units, the other\non perturbations of their co-ordinating and alimentative machinery.\n\nHence, the establishment of the cell theory, in normal biology, was\nswiftly followed by a \u201ccellular pathology,\u201d as its logical counterpart.\nI need not remind you how great an instrument of investigation this\ndoctrine has proved in the hands of the man of genius to whom its\ndevelopment is due, and who would probably be the last to forget that\nabnormal conditions of the co-ordinative and distributive machinery of\nthe body are no less important factors of disease.\n\nHenceforward, as it appears to me, the connection of medicine with the\nbiological sciences is clearly defined. Pure pathology is that branch\nof biology which defines the particular perturbation of cell-life, or\nof the co-ordinating machinery, or of both, on which the phenomena of\ndisease depend.\n\nThose who are conversant with the present state of biology will hardly\nhesitate to admit that the conception of the life of one of the higher\nanimals as the summation of the lives of a cell aggregate, brought into\nharmonious action by a co-ordinative machinery formed by some of these\ncells, constitutes a permanent acquisition of physiological science.\nBut the last form of the battle between the animistic and the physical\nviews of life is seen in the contention whether the physical analysis\nof vital phenomena can be carried beyond this point or not.\n\nThere are some to whom living protoplasm is a substance, even such as\nHarvey conceived the blood to be, \u201csumm\u00e2 cum providenti\u00e2 et intellectu\nin finem certum agens, quasi ratiocinio quodam;\u201d and who look with as\nlittle favour as Bichat did, upon any attempt to apply the principles\nand the methods of physics and chemistry to the investigation of the\nvital processes of growth, metabolism, and contractility. They stand\nupon the ancient ways; only, in accordance with that progress towards\ndemocracy, which a great political writer has declared to be the fatal\ncharacteristic of modern times, they substitute a republic formed by a\nfew billion of \u201canimul\u00e6\u201d for the monarchy of the all-pervading \u201canima.\u201d\n\nOthers, on the contrary, supported by a robust faith in the universal\napplicability of the principles laid down by Descartes, and seeing\nthat the actions called \u201cvital\u201d are, so far as we have any means of\nknowing, nothing but changes of place of particles of matter, look to\nmolecular physics to achieve the analysis of the living protoplasm\nitself into a molecular mechanism. If there is any truth in the\nreceived doctrines of physics, that contrast between living and inert\nmatter, on which Bichat lays so much stress, does not exist. In nature,\nnothing is at rest, nothing is amorphous; the simplest particle of\nthat which men in their blindness are pleased to call \u201cbrute matter\u201d\nis a vast aggregate of molecular mechanisms performing complicated\nmovements of immense rapidity, and sensitively adjusting themselves\nto every change in the surrounding world. Living matter differs from\nother matter in degree and not in kind; the microcosm repeats the\nmacrocosm; and one chain of causation connects the nebulous original of\nsuns and planetary systems with the protoplasmic foundation of life and\norganisation.\n\nFrom this point of view, pathology is the analogue of the theory of\nperturbations in astronomy; and therapeutics resolves itself into\nthe discovery of the means by which a system of forces competent to\neliminate any given perturbation may be introduced into the economy.\nAnd, as pathology bases itself upon normal physiology, so therapeutics\nrests upon pharmacology; which is, strictly speaking, a part of the\ngreat biological topic of the influence of conditions on the living\norganism, and has no scientific foundation apart from physiology.\n\nIt appears to me that there is no more hopeful indication of the\nprogress of medicine towards the ideal of Descartes than is to\nbe derived from a comparison of the state of pharmacology, at the\npresent day, with that which existed forty years ago. If we consider\nthe knowledge positively acquired, in this short time, of the _modus\noperandi_ of urari, of atropia, of physostigmin, of veratria, of casca,\nof strychnia, of bromide of potassium, of phosphorus, there can surely\nbe no ground for doubting that, sooner or later, the pharmacologist\nwill supply the physician with the means of affecting, in any desired\nsense, the functions of any physiological element of the body. It will,\nin short, become possible to introduce into the economy a molecular\nmechanism which, like a very cunningly-contrived torpedo, shall find\nits way to some particular group of living elements, and cause an\nexplosion among them, leaving the rest untouched.\n\nThe search for the explanation of diseased states in modified\ncell-life; the discovery of the important part played by parasitic\norganisms in the \u00e6tiology of disease; the elucidation of the action of\nmedicaments by the methods and the data of experimental physiology;\nappear to me to be the greatest steps which have ever been made towards\nthe establishment of medicine on a scientific basis. I need hardly say\nthey could not have been made except for the advance of normal biology.\n\nThere can be no question, then, as to the nature or the value of the\nconnection between medicine and the biological sciences. There can\nbe no doubt that the future of pathology and of therapeutics, and,\ntherefore, that of practical medicine, depends upon the extent to\nwhich those who occupy themselves with these subjects are trained in\nthe methods and impregnated with the fundamental truths of biology.\n\nAnd, in conclusion, I venture to suggest that the collective sagacity\nof this Congress could occupy itself with no more important question\nthan with this: How is medical education to be arranged, so that,\nwithout entangling the student in those details of the systematist\nwhich are valueless to him, he may be enabled to obtain a firm grasp of\nthe great truths respecting animal and vegetable life, without which,\nnotwithstanding all the progress of scientific medicine, he will still\nfind himself an empiric?\n\n\n\n\nFOOTNOTES:\n\n[1] See _Joseph Priestley_, p. 94, _infra_.\n\n[2] The advocacy of the introduction of physical science into general\neducation by George Combe and others commenced a good deal earlier; but\nthe movement had acquired hardly any practical force before the time to\nwhich I refer.\n\n[3] _Essays in Criticism_, p. 37.\n\n[4] \u201cQuamvis enim melius sit bene facere quam nosse, prius tamen est\nnosse quam facere.\u201d\u2014\u201cKaroli Magni Regis Constitutio de Scholis per\nsingula Episcopia et Monasteria instituendis,\u201d addressed to the Abbot\nof Fulda. Baluzius, \u201cCapitularia Regum Francorum,\u201d T. i., p. 202.\n\n[5] Inaugural Address delivered to the University of St. Andrew\nFebruary 1, 1867, by J. S. Mill, Rector of the University (pp. 32, 33).\n\n[6] \u201cSuggestions for Academical Organisation, with Especial Reference\nto Oxford.\u201d By the Rector of Lincoln.\n\n[7] Goethe, _Zahme Xenien, Vierte Abtheilung_. I should be glad to take\ncredit for the close and vigorous English version; but it is my wife\u2019s,\nand not mine.\n\n[8] See the \u201cProgramme\u201d for 1878, issued by the Society of Arts, p. 14.\n\n[9] It is perhaps advisable to remark that the important question of\nthe professional education of managers of industrial works is not\ntouched in the foregoing remarks.\n\n[10] \u201cQuasi cursores, vita\u00ef lampada tradunt.\u201d\u2014LUCR. _De Rerum Nat._ ii.\n78.\n\n[11] \u201cLife and Correspondence of Dr. Priestley,\u201d by J. T. Rutt. Vol. i.\np. 50.\n\n[12] \u201cAutobiography,\u201d \u00a7\u00a7 100, 101.\n\n[13] See \u201cThe Life of Mary Anne Schimmelpenninck.\u201d Mrs.\nSchimmelpenninck (_n\u00e9e_ Galton) remembered Priestley very well, and her\ndescription of him is worth quotation:\u2014\u201cA man of admirable simplicity,\ngentleness and kindness of heart, united with great acuteness of\nintellect. I can never forget the impression produced on me by the\nserene expression of his countenance. He, indeed, seemed present with\nGod by recollection, and with man by cheerfulness. I remember that,\nin the assembly of these distinguished men, amongst whom Mr. Boulton,\nby his noble manner, his fine countenance (which much resembled that\nof Louis XIV.), and princely munificence, stood pre-eminently as the\ngreat Mec\u00e6nas; even as a child, I used to feel, when Dr. Priestley\nentered after him, that the glory of the one was terrestrial, that of\nthe other celestial; and utterly far as I am removed from a belief in\nthe sufficiency of Dr. Priestley\u2019s theological creed, I cannot but here\nrecord this evidence of the eternal power of any portion of the truth\nheld in its vitality.\u201d\n\n[14] Even Mrs. Priestley, who might be forgiven for regarding the\ndestroyers of her household gods with some asperity, contents herself,\nin writing to Mrs. Barbauld, with the sarcasm that the Birmingham\npeople \u201cwill scarcely find so many respectable characters, a second\ntime, to make a bonfire of.\u201d\n\n[15] \u201cExperiments and Observations on Different Kinds of Air,\u201d vol. ii.\np. 31.\n\n[16] _Ibid._ pp. 34, 35.\n\n[17] \u201cExperiments and Observations on Different Kinds of Air,\u201d vol. ii.\np. 40.\n\n[18] _Ibid._ p. 48.\n\n[19] _Ibid._ p. 55.\n\n[20] \u201cExperiments and Observations on Different Kinds of Air,\u201d vol. ii.\np. 60. The italics are Priestley\u2019s own.\n\n[21] \u201cIn all the newspapers and most of the periodical publications\nI was represented as an unbeliever in Revelation, and no better than\nan atheist.\u201d\u2014\u201cAutobiography,\u201d Rutt. vol. i. p. 124. \u201cOn the walls of\nhouses, etc., and especially where I usually went, were to be seen, in\nlarge characters, \u2018MADAN FOR EVER; DAMN PRIESTLEY; NO PRESBYTERIANISM;\nDAMN THE PRESBYTERIANS,\u2019 etc. etc.; and, at one time, I was followed by\na number of boys, who left their play, repeating what they had seen on\nthe walls, and shouting out, \u2018_Damn Priestley; damn him, damn him, for\never, for ever_,\u2019 etc. etc. This was no doubt a lesson which they had\nbeen taught by their parents, and what they, I fear, had learned from\ntheir superiors.\u201d\u2014\u201cAppeal to the Public on the Subject of the Riots at\nBirmingham.\u201d\n\n[22] First Series. \u201cOn Some of the Peculiarities of the Christian\nReligion.\u201d Essay I. Revelation of a Future State.\n\n[23] Not only is Priestley at one with Bishop Courtenay in this\nmatter, but with Hartley and Bonnet, both of them stout champions of\nChristianity. Moreover, Archbishop Whately\u2019s essay is little better\nthan an expansion of the first paragraph of Hume\u2019s famous essay on\nthe Immortality of the Soul:\u2014\u201cBy the mere light of reason it seems\ndifficult to prove the immortality of the soul; the arguments for it\nare commonly derived either from metaphysical topics, or moral, or\nphysical. But it is in reality the Gospel, and the Gospel alone, that\nhas brought _life and immortality to light_.\u201d It is impossible to\nimagine that a man of Whately\u2019s tastes and acquirements had not read\nHume or Hartley, though he refers to neither.\n\n[24] \u201cEssay on the First Principles of Government.\u201d Second edition,\n1771, p. 13.\n\n[25] \u201cUtility of Establishments,\u201d in \u201cEssay on First Principles of\nGovernment,\u201d p. 198, 1771.\n\n[26] In 1732 Doddridge was cited for teaching without the Bishop\u2019s\nleave, at Northampton.\n\n[27] The recent proceedings of the House of Commons throw a doubt,\nwhich it is to be hoped may speedily be removed, on the accuracy of\nthis statement. (September 1881.)\n\n[28] \u201cDiscours sur les r\u00e9volutions de la surface du globe,\u201d _Recherches\nsur les ossemens fossiles_, Ed. iv. t. i. p. 185.\n\n[29] \u201cOn the Eclipses of Agathocles, Thales, and Xerxes,\u201d\n_Philosophical Transactions_, vol. cxliii.\n\n[30] There is every reason to believe that living plants, like living\nanimals, always respire, and, in respiring, absorb oxygen and give off\ncarbonic acid; but, that in green plants exposed to daylight or to\nthe electric light, the quantity of oxygen evolved in consequence of\nthe decomposition of carbonic acid by a special apparatus which green\nplants possess exceeds that absorbed in the concurrent respiratory\nprocess.\n\n[31] Darwin, \u201cInsectivorous Plants,\u201d p. 289.\n\n[32] I purposely assume that the air with which the bean is supplied in\nthe case stated contains no ammoniacal salts.\n\n[33] The recent researches of Pringsheim have raised a host of\nquestions as to the exact share taken by chlorophyll in the chemical\noperations which are effected by the green parts of plants. It may\nbe that the chlorophyll is only a constant concomitant of the actual\ndeoxidising apparatus.\n\n[34] \u201cResearches in the Life-history of a Cercomonad: a Lesson in\nBiogenesis;\u201d and \u201cFurther Researches in the Life-history of the\nMonads.\u201d\u2014\u201cMonthly Microscopical Journal,\u201d 1873.\n\n[35] Excellently described by Stein, almost all of whose statements I\nhave verified.\n\n[36] \u201cHistoire des Sciences Naturelles,\u201d i. p. 152.\n\n[37] The text I have followed is that given by Aubert and Wimmer,\n\u201cAristoteles Thierkunde; kritisch berichtigter Text mit deutschen\nUebersetzung;\u201d but I have tried here and there to bring the English\nversion rather closer to the original than the German translation,\nexcellent as it is, seems to me to be.\n\n[38] In modern works on Veterinary Anatomy the lungs are sometimes\ndescribed as two lobes of a single organ.\n\n[39] \u201cHistoire des Sciences Naturelles.\u201d\u2014t. i. p. 130.\n\n[40] \u201cAristotle, a Chapter from the History of Science.\u201d\n\n[41] I quote, here and always, Cousin\u2019s edition of the works of\nDescartes, as most convenient for reference. It is entitled \u201c\u0152uvres\ncompl\u00e8tes de Descartes,\u201d publi\u00e9es par Victor Cousin. 1824.\n\n[42] \u201cLes Passions de l\u2019\u00c2me,\u201d Article xxxiii.\n\n[43] \u201cRecherches physiologiques sur la Vie et la Mort.\u201d Par Xav.\nBichat. Art. Sixi\u00e8me.\n\n[44] Locke (_Human Understanding_, Book II., chap. viii. 37) uses\nDescartes\u2019 illustration for the same purpose, and warns us that \u201cmost\nof the ideas of sensation are no more the likeness of something\nexisting without us than the names that stand for them are the likeness\nof our ideas, which yet, upon hearing, they are apt to excite in us,\u201d a\ndeclaration which paved the way for Berkeley.\n\n[45] \u201cPassions de l\u2019\u00c2me,\u201d Art. xxxvi.\n\n[46] \u201cQuamcumque Bruti actionem, velut automati mechanici motum\nartificialem, in eo consistere quod se prim\u00f2 sensibile aliquod spiritus\nanimales afficiens, eosque introrsum convertens, _sensionem_ excitat,\n\u00e0 qua mox iidem spiritus, velut undulatione reflex\u00e2 denuo retrorsum\ncommoti atque pro concinno ipsius fabric\u00e6 organorum, et partium ordine,\nin certos nervos musculosque determinati, respectivos _membrorum motus_\nperficiunt.\u201d\u2014WILLIS: \u201cDe Anim\u00e2 Brutorum,\u201d p. 5, ed. 1763.\n\n[47] \u201cLes Passions de l\u2019\u00c2me,\u201d xlii.\n\n[48] Haller, \u201cPrim\u00e6 Line\u00e6,\u201d ed. iii. \u201cSensus Interni,\u201d dlviii.\n\n[49] \u201cR\u00e9ponse de M. Descartes \u00e0 M. Morus.\u201d 1649. \u201c\u0152uvres,\u201d tome x. p.\n204. \u201cMais le plus grand de tous les pr\u00e9jug\u00e9s que nous ayons retenus de\nnotre enfance, est celui de croire que les b\u00eates pensent,\u201d etc.\n\n[50] Malebranche states the view taken by orthodox Cartesians in\n1689 very forcibly: \u201cAinsi dans les chiens, les chats, et les autres\nanimaux, il n\u2019y a ny intelligence, ny \u00e2me spirituelle comme on l\u2019entend\nordinairement. Ils mangent sans plaisir; ils crient sans douleur; ils\ncroissent sans le s\u00e7avoir; ils ne d\u00e9sirent rien; ils ne connoissent\nrien; et s\u2019ils agissent avec adresse et d\u2019une mani\u00e8re qui marque\nl\u2019intelligence, c\u2019est que Dieu les faisant pour les conserver, il a\nconform\u00e9 leurs corps de telle mani\u00e8re, qu\u2019ils \u00e9vitent organiquement,\nsans le s\u00e7avoir, tout ce qui peut les d\u00e9truire et qu\u2019ils semblent\ncraindre.\u201d (\u201cFeuillet de Conches. M\u00e9ditations M\u00e9taphysiques et\nCorrespondance de N. Malebranche. Neuvi\u00e8me M\u00e9ditation.\u201d 1841.)\n\n[51] See the remarkable essay of G\u00f6ltz, \u201cBeitr\u00e4ge zur Lehre von den\nFunctionen der Nervencentren des Frosches,\u201d published in 1869. I have\nrepeated G\u00f6ltz\u2019s experiments, and obtained the same results.\n\n[52] \u201cDe l\u2019Automatisme de la M\u00e9moire et du Souvenir, dans le\nSomnambulisme pathologique.\u201d Par le Dr. E. Mesnet, M\u00e9decin de l\u2019H\u00f4pital\nSaint-Antoine. \u201cL\u2019Union M\u00e9dicale,\u201d Juillet 21 et 23, 1874. My attention\nwas first called to a summary of this remarkable case, which appeared\nin the \u201cJournal des D\u00e9bats\u201d for the 7th of August 1874, by my friend\nGeneral Strachey, F.R.S.\n\n[53] Those who have had occasion to become acquainted with the\nphenomena of somnambulism and of mesmerism, will be struck with the\nclose parallel which they present to the proceedings of F. in his\nabnormal state. But the great value of Dr. Mesnet\u2019s observations lies\nin the fact that the abnormal condition is traceable to a definite\ninjury to the brain, and that the circumstances are such as to keep\nus clear of the cloud of voluntary and involuntary fictions in which\nthe truth is too often smothered in such cases. In the unfortunate\nsubjects of such abnormal conditions of the brain, the disturbance of\nthe sensory and intellectual faculties is not unfrequently accompanied\nby a perturbation of the moral nature, which may manifest itself in a\nmost astonishing love of lying for its own sake. And, in this respect,\nalso, F.\u2019s case is singularly instructive, for though, in his normal\nstate, he is a perfectly honest man, in his abnormal condition he is\nan inveterate thief, stealing and hiding away whatever he can lay\nhands on, with much dexterity, and with an absurd indifference as to\nwhether the property is his own or not. Hoffman\u2019s terrible conception\nof the \u201cDoppelt-g\u00e4nger\u201d is realised by men in this state\u2014who live two\nlives, in the one of which they may be guilty of the most criminal\nacts, while, in the other, they are eminently virtuous and respectable.\nNeither life knows anything of the other. Dr. Mesnet states that he\nhas watched a man in his abnormal state elaborately prepare to hang\nhimself, and has let him go on until asphyxia set in, when he cut him\ndown. But on passing into the normal state the would-be suicide was\nwholly ignorant of what had happened. The problem of responsibility is\nhere as complicated as that of the prince-bishop, who swore as a prince\nand not as a bishop. \u201cBut, highness, if the prince is damned, what will\nbecome of the bishop?\u201d said the peasant.\n\n[54] \u201cLay Sermons, Essays and Reviews,\u201d p. 355.\n\n[55] \u201cEssai de Psychologie,\u201d chap. xxvii.\n\n[56] In justice to Reid, however, it should be stated that the chapters\non sensation in the \u201cEssays on the Intellectual Powers\u201d (1785) exhibit\na great improvement. He is, in fact, in advance of his commentator, as\nthe note to Essay II. chap. ii. p. 248 of Hamilton\u2019s edition shows.\n\n[57] Haller, amplifying Descartes, writes in the \u201cPrim\u00e6 Line\u00e6,\u201d\nCCCLXVI.\u2014\u201cNon est adeo obscurum sensum omnem oriri ab objecti\nsensibilis impressione in nervum quemcumque corporis humani, et eamdem\nper eum nervum ad cerebrum pervenientem tunc demum representari anim\u00e6,\nquando cerebrum adtigit. Ut etiam hoc falsum sit animam inproximo per\nsensoria nervorumque ramos sentire.\u201d... DLVII.\u2014\u201cDum ergo sentimus\nquinque diversissima entia conjunguntur: corpus quod sentimus:\norgani sensorii adfectio ab eo corpore: cerebri adfectio a sensorii\npercussione nata: in anima nata mutatio: anim\u00e6 denique conscientia et\nsensationis adperceptio.\u201d Nevertheless, Sir William Hamilton gravely\ninforms his hearers:\u2014\u201cWe have no more right to deny that the mind feels\nat the finger points, as consciousness assures us, than to assert\nthat it thinks exclusively in the brain.\u201d\u2014\u201cLecture on Metaphysics and\nLogic,\u201d ii. p. 128. \u201cWe have no reason whatever to doubt the report\nof consciousness, that we actually perceive at the external point of\nsensation, and that we perceive the material reality.\u201d\u2014_Ibid._ p. 129.\n\n[58] \u201cObservations on Man,\u201d vol. i. p. 11.\n\n[59] _Ibid._ p. 8. The speculations of Bonnet are remarkably similar\nto those of Hartley; and they appear to have originated independently,\nthough the \u201cEssai de Psychologie\u201d (1754) is of five years\u2019 later date\nthan the \u201cObservations on Man\u201d (1749).\n\n[60] \u201cAn Inquiry into the Human Mind on the Principles of Common\nSense,\u201d chap. ii. \u00a7 2. Reid affirms that \u201cit is genius, and not the\nwant of it, that adulterates philosophy, and fills it with error and\nfalse theory;\u201d and no doubt his own lucubrations are free from the\nsmallest taint of the impurity to which he objects. But, for want of\nsomething more than that sort of \u201ccommon sense,\u201d which is very common\nand a little dull, the contemner of genius did not notice that the\nadmission here made knocks so big a hole in the bottom of \u201ccommon sense\nphilosophy,\u201d that nothing can save it from foundering in the dreaded\nabyss of Idealism.\n\n[61] The following diagrammatic scheme may help to elucidate the theory\nof sensation:\u2014\n\n                        Mediate Knowledge\n  \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510     Immediate\n                               Sensiferous Apparatus                Knowledge\n                    \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510 \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\n  Objects of sense \u2502 Receptive    Transmissive  Sensificatory   \u2502 Sensations  and\n                   \u2502(Sense Organ)   (Nerve)      (Sensorium)    \u2502 other States of\n                   \u2502                                            \u2502  Consciousness\n                   \u2502                                            \u2502\n    Hypothetical   \u2502                                            \u2502   Hypothetical\n    Substance of   \u2502                                            \u2502   Substance of\n       Matter      \u2502                                            \u2502      Mind\n\n  \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518\n                               Physical World                     Mental World\n  \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518\n       Not Self                                Self\n  \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518 \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518\n                          Non-Ego or Object                      Ego or Subject\n\nImmediate knowledge is confined to states of consciousness, or, in\nother words, to the phenomena of mind. Knowledge of the physical\nworld, or of one\u2019s own body and of objects external to it, is a system\nof beliefs or judgments based on the sensations. The term \u201cself\u201d is\napplied not only to the series of mental phenomena which constitute the\nego, but to the fragment of the physical world which is their constant\nconcomitant. The corporeal self, therefore, is part of the non-ego;\nand is objective in relation to the ego as subject.\n\n[62] \u201cChaque fibre est une esp\u00e8ce de touche ou de marteau destin\u00e9 \u00e0\nrendre un certain ton.\u201d\u2014Bonnet, \u201cEssai de Psychologie,\u201d chap. iv.\n\n[63] The \u201cExercitationes de Generatione Animalium,\u201d which Dr. George\nEnt extracted from him and published in 1651.\n\n[64] \u201cDe Generatione Animalium,\u201d lib ii. cap. x.\n\n[65] \u201cDe Generatione,\u201d lib. ii. cap. iv.\n\n[66] \u201cCependant, pour revenir aux formes ordinaires ou aux \u00e2mes\nmat\u00e9rielles, cette dur\u00e9e qu\u2019il leur faut attribuer \u00e0 la place de celle\nqu\u2019on avoit attribut\u00e9e aux atomes pourroit faire douter si elles ne\nvont pas de corps en corps; ce qui seroit la m\u00e9tempsychose, \u00e0 peu\npr\u00e8s comme quelques philosophes ont cru la transmission du mouvement\net celle des esp\u00e8ces. Mais cette imagination est bien \u00e9loign\u00e9e de la\nnature des choses. Il n\u2019y a point de tel passage; et c\u2019est ici o\u00f9 les\ntransformations de Messieurs Swammerdam, Malpighi, et Leewenhoek, qui\nsont des plus excellens observateurs de notre tems, sont venues \u00e0 mon\nsecours, et m\u2019ont fait admettre plus ais\u00e9ment, que l\u2019animal, et toute\nautre substance organis\u00e9e ne commence point lorsque nous le croyons, et\nque sa generation apparente n\u2019est qu\u2019une d\u00e9veloppement et une esp\u00e8ce\nd\u2019augmentation. Aussi ai je remarqu\u00e9 que l\u2019auteur de la \u201cRecherche de\nla Verit\u00e9,\u201d M. Regis, M. Hartsocker, et d\u2019autres habiles hommes n\u2019ont\npas \u00e9t\u00e9 fort \u00e9loign\u00e9s de ce sentiment.\u201d Leibnitz, \u201cSyst\u00e8me nouveau\nde la Nature,\u201d 1695. The doctrine of \u201cEmbo\u00eetement\u201d is contained in\nthe \u201cConsid\u00e9rations sur le principe de vie,\u201d 1705; the preface to the\n\u201cTheodic\u00e9e,\u201d 1710; and the \u201cPrincipes de la Nature et de la Grace\u201d (\u00a7\n6), 1718.\n\n[67] \u201cIl est vrai que la pens\u00e9e la plus raisonnable et la plus conforme\n\u00e0 l\u2019experience sur cette question tr\u00e8s difficile de la formation du\nf\u0153tus; c\u2019est que les enfans sont d\u00e9ja presque tout form\u00e9s avant m\u00eame\nl\u2019action par laquelle ils sont con\u00e7us; et que leurs m\u00e8res ne font que\nleur donner l\u2019accroissement ordinaire dans le temps de la grossesse.\u201d\n\u201cDe la Recherche de la Verit\u00e9,\u201d livre ii. chap. vii. p. 334, 7th ed.,\n1721.\n\n[68] The writer is indebted to Dr. Allen Thomson for reference to\nthe evidence contained in a note to Haller\u2019s edition of Boerhaave\u2019s\n\u201cPr\u00e6lectiones Academic\u00e6,\u201d vol. v. pt ii. p. 497, published in 1744,\nthat Haller originally advocated epigenesis.\n\n[69] \u201cConsid\u00e9rations sur les Corps organis\u00e9s,\u201d chap. x.\n\n[70] Bonnet had the courage of his opinions, and in the \u201cPaling\u00e9n\u00e9sie\nPhilosophique,\u201d part vi. chap, iv., he develops a hypothesis which\nhe terms \u201c\u00e9volution naturelle;\u201d and which, making allowance for his\npeculiar views of the nature of generation, bears no small resemblance\nto what is understood by \u201cevolution\u201d at the present day:\u2014\n\n\u201cSi la volont\u00e9 divine a cr\u00e9\u00e9 par un seul Acte l\u2019Universalit\u00e9 des \u00eatres,\nd\u2019o\u00f9 venoient ces plantes et ces animaux dont Moyse nous decrit la\nProduction au troisieme et au cinquieme jour du renouvellement de notre\nmonde?\n\n\u201cAbuserois-je de la libert\u00e9 de conjectures si je disois, que les\nPlantes et les Animaux qui existent aujourd\u2019hui sont parvenus par une\nsorte d\u2019evolution naturelle des Etres organis\u00e9s qui peuplaient ce\npremier Monde, sorti imm\u00e9diatement des MAINS du CREATEUR?...\n\n\u201cNe supposons que trois r\u00e9volutions. La Terre vient de sortir des MAINS\ndu CREATEUR. Des causes prepar\u00e9es par sa SAGESSE font d\u00e9velopper de\ntoutes parts les Germes. Les Etres organis\u00e9s commencent \u00e0 jouir de\nl\u2019existence. Ils \u00e9toient probablement alors bien diff\u00e9rens de ce qu\u2019ils\nsont aujourd\u2019hui. Ils l\u2019etoient autant que ce premier Monde diff\u00e9roit\nde celui que nous habitons. Nous manquons de moyens pour juger de ces\ndissemblances, et peut-\u00eatre que le plus habile Naturaliste qui auroit\n\u00e9t\u00e9 plac\u00e9 dans ce premier Monde y auroit enti\u00e8rement m\u00e9connu nos\nPlantes et nos Animaux.\u201d\n\n[71] \u201cCe mot (germe) ne d\u00e9signera pas seulement un corps organis\u00e9\n_r\u00e9duit en petit_; il d\u00e9signera encore toute esp\u00e8ce de _pr\u00e9formation\noriginelle dont un Tout organique pent r\u00e9sulter comme de son principe\nimm\u00e9diat_.\u201d\u2014\u201cPaling\u00e9n\u00e9sie Philosophique,\u201d part x. chap. ii.\n\n[72] \u201cM. Cuvier consid\u00e9rant que tous les \u00eatres organis\u00e9s sont d\u00e9riv\u00e9s\nde parens, et ne voyant dans la nature aucune force capable de produire\nl\u2019organisation, croyait \u00e0 la pr\u00e9-existence des germes; non pas \u00e0 la\npr\u00e9-existence d\u2019un \u00eatre tout form\u00e9, puisqu\u2019il est bien \u00e9vident que\nce n\u2019est que par des d\u00e9veloppemens successifs que l\u2019\u00eatre acquiert\nsa forme; mais, si l\u2019on peut s\u2019exprimer ainsi, \u00e0 la pr\u00e9-existence\ndu _radical de l\u2019\u00eatre_, radical qui existe avant que la s\u00e9rie des\n\u00e9volutions ne commence, et qui remonte certainement, suivant la belle\nobservation de Bonnet, \u00e0 plusieurs generations.\u201d\u2014Laurillard, \u201c\u00c9loge de\nCuvier,\u201d note 12.\n\n[73] \u201cHistoire Naturelle,\u201d tom. ii. ed. ii. 1750, p. 350.\n\n[74] _Ibid._ p. 351.\n\n[75] See particularly Buffon, _l.c._ p. 41.\n\n[76] \u201cExercitationes de Generatione.\u201d Ex. 62, \u201cOvum esse primordium\ncommune omnibus animalibus.\u201d\n\n[77] In some cases of sexless multiplication the germ is a\ncell-aggregate\u2014if we call germ only that which is already detached from\nthe parent organism.\n\n[78] Harvey, \u201cExercitationes de Generatione.\u201d Ex. 45, \u201cQu\u00e6nam sit pulli\nmateria et quomodo fiat in Ovo.\u201d\n\n[79] Not yet actually demonstrated in the case of ph\u00e6nogamous plants.\n\n[80] As Buffon has well said:\u2014\u201cL\u2019id\u00e9e de ramener l\u2019explication de tous\nles ph\u00e9nom\u00e8nes \u00e0 des principes mecaniques est assurement grande et\nbelle, ce pas est le plus hardi qu\u2019on peut faire en philosophie, et\nc\u2019est Descartes qui l\u2019a fait.\u201d\u2014_l.c._ p. 50.\n\n[81] \u201cPrincipes de la Philosophie,\u201d Troisi\u00e8me partie, \u00a7 45.\n\n[82] \u201cEthices,\u201d Pars tertia, Pr\u00e6fatio.\n\n[83] \u201cSyst\u00e8me de la Nature.\u201d \u201cEssai sur la Formation des Corps\nOrganis\u00e9s,\u201d 1751, xiv.\n\n[84] \u201cConsid\u00e9rations Philosophiques sur la gradation naturelle des\nformes de l\u2019\u00eatre; ou les essais de la nature qui apprend \u00e0 faire\nl\u2019homme,\u201d 1768.\n\n[85] \u201cRecherches sur les causes des principaux faits physiques,\u201d par\nJ. B. Lamarck. Paris. Seconde ann\u00e9e de la R\u00e9publique. In the preface,\nLamarck says that the work was written in 1776, and presented to the\nAcademy in 1780; but it was not published before 1794, and, at that\ntime, it presumably expressed Lamarck\u2019s mature views. It would be\ninteresting to know what brought about the change of opinion manifested\nin the \u201cRecherches sur l\u2019organisation des corps vivants,\u201d published\nonly seven years later.\n\n[86] See the \u201cHistorical Sketch\u201d prefixed to the last edition of the\n\u201cOrigin of Species.\u201d\n\n[87] \u201cFirst Principles\u201d and \u201cPrinciples of Biology,\u201d 1860-1864.\n\n[88] \u201cGenerelle Morphologie,\u201d 1866.\n\n[89] \u201cIl s\u2019agit donc de prouver que la s\u00e9rie qui constitute l\u2019\u00e9chelle\nanimale r\u00e9side essentiellement dans la distribution des masses\nprincipales qui la composent et non dans celle des esp\u00e8ces ni m\u00eame\ntoujours dans celle des genres.\u201d\u2014\u201cPhil. Zoologique,\u201d chap. v.\n\n[90] Philosophie Zoologique, premi\u00e8re partie, chap. iii.\n\n[91] \u201cEntwurf einer Darstellung der zwischen dem Embryozustande\nder h\u00f6heren Thiere und dem permanenten der niederen stattfindenden\nParallele,\u201d \u201cBeytr\u00e4ge zur Vergleichenden Anatomie,\u201d Bd. ii. 1811.\n\n[92] \u201cOrigin of Species,\u201d ed. 1, p. 457.\n\n[93] _Ibid._ p. 458.\n\n[94] \u201cOrigin of the Species,\u201d p. 431.\n\n[95] \u201cOrigin of Species,\u201d ed. 1, p. 463.\n\n[96] \u201cDiscours de la M\u00e9thode,\u201d 6^e partie, Ed. Cousin, p. 193.\n\n[97] _Ibid._ pp. 193 and 211.\n\n[98] \u201cDe la Formation du F\u0153tus.\u201d\n\n[99] \u201cTheoria Generationis,\u201d 1759.\n\n[100] \u201cAnatomie g\u00e9n\u00e9rale,\u201d i. p. liv.\n\n\nTHE END.\n\n\n_Printed by_ R. & R. CLARK, _Edinburgh_.\n\n\n\n\nMESSRS. MACMILLAN & CO.\u2019S PUBLICATIONS.\n\n\nBY THE SAME AUTHOR.\n\nLay Sermons, Addresses, and Reviews. Eighth Edition. 8vo.\n7s. 6d.\n\n  CONTENTS:\u2014The Advisableness of improving Natural\n  Knowledge\u2014Emancipation, Black and White\u2014A Liberal\n  Education, and where to find it\u2014Scientific Education\u2014On\n  the Study of Zoology\u2014On the Physical Basis of Life\u2014The\n  Scientific Aspects of Positivism\u2014On a Piece of Chalk, the\n  Origin of Species, etc.\n\nEssays selected from Lay Sermons, Addresses, and Reviews. Third\nEdition. Crown 8vo. 1s.\n\nCritiques and Addresses. 8vo. 10s. 6d.\n\n  CONTENTS:\u2014Administrative Nihilism\u2014The School Boards:\n  what they can do, and what they may do\u2014On Medical\n  Education\u2014Yeast\u2014On the Formation of Coal\u2014On Coral and\n  Coral Reefs\u2014On the Methods and Results of Ethnology\u2014On\n  some Fixed Points in British Ethnology\u2014Pal\u00e6ontology and\n  the Doctrine of Evolution\u2014Biogenesis and Abiogenesis\u2014Mr.\n  Darwin\u2019s Critics\u2014The Genealogy of Animals\u2014Bishop Berkeley\n  on the Metaphysics of Sensation, etc.\n\nAmerican Addresses, with a Lecture on the Study of Biology. 8vo. 6s. 6d.\n\n  CONTENTS:\u2014Three Lectures on Evolution: I. The Three\n  Hypotheses respecting the History of Nature; II. The\n  Hypothesis of Evolution, the Neutral and the Favourable\n  Evidence; III. The Demonstrative Evidence of Evolution\u2014An\n  Address on the occasion of the Opening of the Johns\n  Hopkins University\u2014On the Study of Biology, etc.\n\nPhysiography. An Introduction to the Study of Nature. With Coloured\nPlates and Woodcuts. New and Cheaper Edition. Crown 8vo. 6s.\n(Thirty-third Thousand.)\n\n  \u201cIt would hardly be possible to place a more useful or\n  suggestive book in the hands of learners and teachers,\n  or one that is better calculated to make physiography a\n  favourite subject in the Science Schools.\u201d\u2014_Academy._\n\n  \u201cIt is not too much to say that any one who will read\n  through this little volume will have a clearer and more\n  connected idea of the physical phenomena of the earth\n  than could be obtained by the perusal of many elaborate\n  treatises.\u201d\u2014_The Guardian._\n\nLessons in Elementary Physiology. With numerous Illustrations. New\nEdition. Fcap. 8vo. 4s. 6d.\n\nIntroductory Primer. 18mo. 1s. (Macmillan\u2019s _Science Primers_.)\n\nHume. Crown 8vo. Paper Covers, 1s.; Cloth, 1s. 6d. (_English Men of\nLetters._)\n\n  \u201cIt may fairly be said that no one now living could\n  have expounded Hume with more sympathy or with equal\n  perspicuity.\u201d\u2014_Athen\u00e6um._\n\n\nA Course of Practical Instruction in Elementary Biology. By T. H.\nHUXLEY, F.R.S., LL.D., assisted by H. N. MARTIN, M.A., M.B., D.Sc.,\nF.R.S., Fellow of Christ\u2019s College, Cambridge. New Edition, revised and\nextended by G. B. HOWES, Assistant Professor of Zoology, Normal School\nof Science, and Royal School of Mines; and D. H. SCOTT, M.A., Ph.D.,\nAssistant Professor of Botany, Normal School of Science, and Royal\nSchool of Mines. New Edition, thoroughly revised. With a Preface by T.\nH. HUXLEY, F.R.S. Crown 8vo. 10s. 6d.\n\n\nBY PROFESSOR CLIFFORD, F.R.S., ETC.\n\n  Lectures and Essays. By the late Professor W. K.\n  CLIFFORD, F.R.S. Edited by LESLIE STEPHEN and FREDERICK\n  POLLOCK, with Introduction by F. POLLOCK. With Portraits.\n  Two vols. 8vo. 25s. Popular Edition. Crown 8vo. 8s. 6d.\n\n  Mathematical Papers. Edited by ROBERT TUCKER. With an\n  Introduction by H. J. STEPHEN SMITH, M.A., LL.D., F.R.S.,\n  etc. Demy 8vo. 30s.\n\n  Seeing and Thinking. With Diagrams. Crown 8vo. 3s. 6d.\n  (_Nature Series._)\n\n\nBY PROFESSOR P. G. TAIT.\n\n  Lectures on some Recent Advances in Physical Science.\n  With Illustrations. Second Edition. Revised and enlarged,\n  with the Lecture on Force, delivered before the British\n  Association. Crown 8vo. 9s.\n\n\nBY ALFRED RUSSEL WALLACE.\n\n  The Malay Archipelago: The Land of the Orang Utan and the\n  Bird of Paradise. A Narrative of Travel. With Studies\n  of Man and Nature. With Maps and Illustrations. Ninth\n  Edition. Crown 8vo. 7s. 6d.\n\n  Contributions to the Theory of Natural Selection. A\n  Series of Essays. New Edition. Crown 8vo. 8s. 6d.\n\n  The Geographical Distribution of Animals, with a Study of\n  the Relations of Living and Extinct Faunas as elucidating\n  the past changes of the Earth\u2019s Surface. With numerous\n  Illustrations by ZWECKER, and Maps. Two vols. Medium 8vo.\n  42s.\n\n  Tropical Nature; and other Essays. 8vo. 12s.\n\n  Island Life; or, The Phenomena and Causes of Insular\n  Faunas and Floras, including a revision and attempted\n  solution of the Problem of Geological Climates. With\n  Illustrations and Maps. Demy 8vo. 18s.\n\n\nBY SIR JOHN LUBBOCK, BART., M.P., F.R.S., D.C.L.\n\n  Fifty Years of Science. Being the Presidential Address\n  delivered at York to the British Association, 1881. 8vo.\n  2s. 6d.\n\n  The Origin and Metamorphoses of Insects. With\n  Illustrations. New Edition. Crown 8vo. 3s. 6d. (_Nature\n  Series._)\n\n  On British Wild Flowers considered in their Relation to\n  Insects. With Illustrations. New Edition. Cr. 8vo. 4s.\n  6d. (_Nature Series._)\n\n  Flowers, Fruits, and Leaves. With Illustrations. Crown\n  8vo. 4s. 6d. (_Nature Series._)\n\n  Scientific Lectures. With Illustrations. 8vo. 8s. 6d.\n\n  Political and Educational Addresses. 8vo. 8s. 6d.\n\n\nBY PROFESSOR BOYD DAWKINS, F.R.S., ETC.\n\n  Cave-Hunting: Researches on the Evidence of Caves\n  respecting the Early Inhabitants of Europe. With Coloured\n  Plate and Woodcuts. 8vo. 21s.\n\n  Early Man in Britain, and his Place in the Tertiary\n  Period. With Illustrations. 8vo. 25s.\n\n\nMACMILLAN & CO., LONDON, W.C.","title":"Science and Culture, and Other Essays","tradition":"philosophy-ethics","translated_text":null,"word_count":93765}