Abstract

Plato, and a wide variety of ancient, Arabic, and medieval Platonisms had a significant influence on Aquinas. The Corpus, with its quasi-Apostolic origin for Aquinas, was his most authoritative and influential source of Neoplatonism. His most influential early sources of Platonism came from Aristotle and Augustine, that is besides the Dionysian Corpus and the Liber. Aquinas greatly acknowledged the Neoplatonic, and the Peripatetic, commentaries and paraphrases he gradually acquired, because they enabled getting to the Hellenic sources. A great part of Aquinas's last writing was devoted to explicating Aristotle's works including the Liber de causis, which was attributed to him. Aquinas wished to understand the philosophical schools such as their characters, the differences between and within them, their memberships, influences, histories, and the extent to which they are complementary. Aquinas gave an extended treatment of the history of philosophy, including lists of differences and agreements between Plato and Aristotle, beginning with ‘the opinions of the ancients and of Plato’ in his On Separate Substances. When Aquinas treated Aristotle in On Separate Substances, he did not leave his Neoplatonic framework behind. There is much more in On Separate Substances concerning the numbers, including an elaborate reasoning that saves the verbally opposed positions of both Proclus and Dionysius.