This is the first work to draw on the four hundred years of transition from ancient Greek philosophy to the medieval philosophy of Islam and the West. During this period, philosophy was often written in the form of commentaries on the works of Plato and Aristotle. Many ideas wrongly credited to the Middle Ages derive from these centuries, such as that of impetus in dynamics and intentional objects in philosophy of mind.

The later Neoplatonist commentators fought a losing battle with Christianity, but inadvertently made Aristotle acceptable to Christians by ascribing to him belief in a Creator God and human immortality. The commentators provide a panorama of up to a thousand years of Greek philosophy, much of which would otherwise be lost. They also serve as the missing link essential for understanding the subsequent history of Western philosophy.

This book covers three main subject areas. First, the metaphysics of Aristotle's logical works: the concepts of universal and particular underwent surprising transformations in this period, which gave rise to debates, still raging today, on personal survival after an interruption such as death. Second, logic in a more conventional sense: perhaps the most impressive debate was on the existence of the subject in singular and universal statements. There was also debate about the very different Aristotelian and Stoic conceptions of syllogism, of modal logic, of induction, of the nature of mathematics, and of philosophy of language. Third, the higher metaphysics of the Neoplatonists taught Augustine, and indirectly Descartes, to look for truth within themselves. The Neoplatonists struggled with the question whether our higher intellectual selves have distinct individuality, and thus they fed both sides in the great medieval debate between Aquinas and the followers of Averroes on individual human immortality.

All sources appear in English translation and are carefully linked and cross-referenced by editorial comment and explanation. Bibliographies are provided throughout.