The volumes of the have become essential reference works for the study of Aristotle. In this twentieth volume, ten renowned scholars of ancient philosophy offer a running commentary on Aristotle's . It is in this text, one of his most intriguing works, that Aristotle sets out the general principles of animal locomotion. A philological and a philosophical introduction sketch the current state of research on this treatise, situating current thought in the context of three decades of scholarly debates. The nine contributed essays together comment on each chapter of the Aristotelian text, discussing in detail the philosophical issues that are raised across the different sections of the text. Comprehensive analyses of Aristotle's doctrines and arguments, as well as critical discussion of rival interpretations, make this volume a valuable resource for scholars of Aristotle. The present volume also includes a newly reconstructed Greek text with a facing English translation by Benjamin Morison.