The present monograph on Plato's Sophist developed from series of lectures given over a number of years to honours and graduate phi- losophy classes in the University of Waterloo. It is hoped that it will prove a useful guide to anyone trying to come to grips with, and gain a perspective of Plato's mature thought. At the same time my study is addressed to the specialist, and I have considered at the appropriate places a good deal of the scholarly literature that has appeared during the last thirty years. In this connection I regret that some of the pub- lications which came to my notice after...