In the twelfth century, the princess and scholar Anna Comnena sought to reinvigorate Aristotelian philosophy in Byzantium. She commissioned the scholar and theologian Eustratius of Nicaea to contribute to this ambitious project. The present volume translates Eustratius' commentary on several chapters from the second book of Aristotle's Posterior Analytics (2.7-10).

It is valuable to historians of philosophy, in part, for its crucial preservation of lost material from earlier commentators, including Alexander of Aphrodisias. Eustratius' comments carry independent interest, as they bear on long-standing issues in Aristotelian philosophy: whether a definition can be demonstrated or 'proven', how science relates to its objects in the world, and how to develop explanatory deductions.

This translation is accompanied by explanatory notes, an introduction, and scholarly apparatus, including indices, glossaries and bibliography. The volume will be of interest to historians of philosophy and the philosophy of science, and to the legacy of Aristotelian thought in Byzantium and beyond.