The essays in this volume were written to celebrate the sixtieth birthday of G. E. L. Owen, who by his essays and seminars on ancient Greek philosophy has made a contribution to its study that is second to none. The authors, from both sides of the Atlantic, include not only scholars whose main research interests lie in Greek philosophy, but others best known for their work in general philosophy. All are pupils or younger colleagues of Professor Owen who are indebted to his practice of philosophical scholarship as a first-order philosophical activity. At the heart of G. E. L. Owen's work has been a preoccupation with the role of philosophical reflection on language in the metaphysics and epistemology of Plato, Aristotle and other ancient Greek thinkers. This is accordingly the general topic of the present volume, which includes five papers on Plato's critical dialogues and seven on Aristotle, prefaced by two on Heraclitus and followed by a study of the debate in Hellenistic philosophy on the sorites. This is a book for specialists in Greek philosophy and philosophers of language which will also be of interest to some linguists.