In this collection, a stellar team of ancient philosophers from the UK, the USA, and Europe present a systematic, chapter-by-chapter study of one of Aristotle's key texts in his science and metaphysics Contributors include Keimpe Algra, Sarah Broadie, Jacques Brunschwig, M. F. Burnyeat, David Charles, Alan Code, John M. Cooper, Michael Crubellier, Dorothea Frede, Edward Hussey, Carlo Natali, David Sedley, and Christian Wildberg.