This is a sourcebook that draws upon the 400 years of transition from ancient Greek philosophy to the medieval philosophy of Islam and the West. Philosophy was then often written in the form of commentaries on the works of Plato and Aristotle. Many ideas wrongly credited to the Middle Ages derive from this period, e.g. 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. They also provided a panorama of up to 1000 years of preceding Greek philosophy, much of it otherwise lost. They serve as the missing link essential for understanding the history of Western philosophy. This volume covers three main areas of study. First, the metaphysics of Aristotle's logical works: the concepts of universal and particular underwent surprising transformations in this period, which explain later medieval views, and which gave rise to debates, still raging today, on personal survival after an interruption such as death.Secondly, logic in a more conventional sense: the most impressive debate was perhaps 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, on modal logic, on induction, on the nature of mathematics and on philosophy of language. Thirdly, the higher metaphysics of the Neoplatonists, who taught Augustine, and indirectly Descartes, to look for truth within ourselves. They struggled with the question whether our higher intellectual selves have distinct individuality, and thus gave food to 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.