Recent accounts of the life of Protagoras differ widely from one another in their treatment of the ancient sources, and in the conclusions which they draw from them. A re-examination of the evidence, undertaken in 1949–50 as part of a study of the Prometheus trilogy, has convinced me that a new discussion is urgently needed if we are to place the earlier stages of the sophistic movement in the right context historically; and the purpose of this paper is to lay (...) at least a part of the foundation for such a discussion. Since the evidence for the life of Protagoras includes some allusions to his relations with Democritus, and there are some obvious affinities between the careers of Protagoras and Anaxagoras, I have added a short account of the relevant points in the biography of Democritus and a more detailed study of the evidence for the life of Anaxagoras. (shrink)