Book excerpt: This volume completes, starting from chapter 6, the commentary by the young Philoponus on Aristotle's Categories, of which chapters 1–5 were previously published in this series (Philoponus: On Aristotle Categories 1–5 with Philoponus: A Treatise Concerning the Whole and the Parts). This ancient commentary was the first work in the Aristotelian syllabus after a general introduction to Aristotle by the same author. It is influenced by an extant short anonymous record of Philoponus' teacher Ammonius' lectures on the same work, but Philoponus' commentary is two and a half times as long as that anonymous record, and includes special contributions of Philoponus' own, for example in philology, Christian theology and in disagreements with Aristotle. This English translation of Philoponus' work is the latest volume in the Ancient Commentators on Aristotle series and makes this philosophical work accessible to a modern readership. The translation is accompanied by an introduction, comprehensive commentary notes, bibliography, glossary of translated terms and a subject index.