In 1894 Edmund Pfleiderer observed that, since innumerable writers, many of them men of the highest reputation, had written about Socrates and Plato, anyone undertaking the task once more must surely, in tanta scriptorum turba, ask himself like Livy: Facturusne operae pretium sim? I should not like to have to count the number of books and articles about Socrates that have appeared in the seventy-odd years since Pfleiderer wrote, but I must hope that yet another presentation of him, in the context of the history of Greek philosophy and especially of the philosophic preoccupations of his own century, will prove worth while. The enormous bulk of the scholarly literature means that my own reading in it has been even more—much more—selective than for earlier periods of Greek thought. I have tried to make the selection representative of at least the more recent work, but it is probably inevitable that some of my readers will look in vain for their favourite items. I hope however that I have made myself sufficiently familiar with the ancient evidence to be entitled to views of my own, and it would not be safe to assume that the omission of a writer or a theory is necessarily due to ignorance. In putting Socrates into his setting in the history of Greek thought, it is impracticable to take note of every theory about him, including those which seem to me (though others may differ) to be highly improbable. I shall not, for instance, say much about what may be called the pan-Antisthenean school, who see Antisthenes lurking anonymously in many of Plato's dialogues and disguised as Socrates in Xenophon's Memorabilia.