In a previous article, I have attempted to summarize the evidence of Aristotle about the relations of Socrates and Plato in the development of the theory of Ideas. It may be of interest now to carry the enquiry further, and to see whether writers later than Aristotle have anything of importance to say about the whole question of the general intellectual relationship between the two men. In particular we must enquire whether or how far they regard or say anything to lead us to regard the Dialogues of Plato as a record of Plato's own thought or as a biographical account of the thought of Socrates or—a third possibility—as both at the same time. And, in addition to this, we shall have to attempt some estimate of the value, if any, which we can put upon such statements—an estimate which would depend in its turn on our answer to the question how far they had access to original sources of information no longer extant.