"On the Soul" was the most widely read of all the Aristotle commentaries in the Renaissance. The best-known of Themistius's discussions is that concerned with Aristotle's active intellect, which leads to his wider musings on the nature of the self. The 15,000 pages of the ancient Greek commentators on Aristotle, written mainly between 200 and 500 AD, constitute the largest corpus of extant Greek philosophical writing not translated into English or other European languages. This new series of translations, planned in 60 volumes, fills an important gap in the history of European thought.