This is a chapter from *Arabic Thought and Its Place in History* (1922) by De Lacy O'Leary, a scholarly history of Islamic intellectual and theological development. The text traces how the Mu'tazilite school of Islamic theology grappled with Greek philosophy — particularly Aristotle and Neoplatonism — as Arabic thinkers sought to reconcile rational philosophical inquiry with Quranic revelation in the 8th–9th centuries CE. The central preoccupations covered include the nature of God's attributes (whether they compromise divine unity), free will versus determinism, the eternity of the universe versus the Quranic account of creation, and the meaning of the beatific vision promised in paradise.
A distinctive feature of the text is its detailed, thinker-by-thinker account of how each major Mu'tazilite figure — al-Allaf, an-Nazzam, Bishr b. Mu'tamir, Ma'mar, Tumameh, al-Jahiz — developed or departed from predecessors, showing Islamic theology in active philosophical evolution rather than static doctrine. O'Leary highlights how imported Greek frameworks gradually pushed some thinkers toward positions orthodox Islam found heretical, including pantheism, the eternity of matter, and transmigration of souls. The work is written from the perspective of a Western historian synthesizing Arabic-language sources, presenting Islamic philosophy as a serious intellectual tradition with internal debates comparable to those of Christian scholasticism.