J. L. Ackrill's work on Plato and Aristotle has had a considerable influence upon ancient philosophical studies in the late twentieth century. In his writings the rigour and clarity of contemporary analytical philosophy are brought to bear upon ancient thought; in many cases he has provided the first analytic treatment of a key issue. Gathered now in this volume are the best of Ackrill's essays on the two greatest philosophers of antiquity. Here he examines a wide range of texts and topics -- from ethics and logic to epistemology and metaphysics -- which continue to be the focus of debate today.