Diogenes Laërtius on Plato

“He was the first author who wrote treatises in the form of dialogues … And as he argued against almost every one who had lived before his time, it is often asked why he has never mentioned Democritus.”

“Xenophon, too, does not appear to have been very friendlily disposed towards him: and accordingly they have, as if in rivalry of one another, both written books with the same title, the Banquet, the Defence of Socrates, Moral Reminiscences. Then, too, the one wrote the Cyropaedia and the other a book on Politics ; and Plato in his Laws says, that the Cyropaedia is a mere romance, for that Cyrus was not such a person as he is described in that book. And though they both speak so much of Socrates, neither of them ever mentions the other, except that Xenophon once speaks of Plato in the third book of his Reminiscences.”