Michael Frede, who died in 2007, held positions successively in the departments of philosophy at the University of California, Berkeley, Princeton University, and Oxford University, where he held the Chair of the History of Philosophy. In 1997-1998, he was Sather Professor of Classical Literature at UC Berkeley, where he delivered the lectures that make up this volume. A. A. Long is Professor of Classics, Irving Stone Professor of Literature, and Affiliated Professor of Philosophy at the University of California, Berkeley. He is the author of Epictetus: A Stoic and Socratic Guide to Life and From Epicurus to Epictetus: Studies in Hellenistic and Roman Philosophy. David Sedley is Lawrence Professor of Ancient Philosophy at the University of Cambridge and the author of Creationism and Its Critics in Antiquity (UC Press).