Diogenes Laertius Vitae philosophorum 2.5.20

[20] And Aristophanes attacks him in his plays for making the worse appear the better reason. For Favorinus in his Miscellaneous History says Socrates and his pupil Aeschines were the first to teach rhetoric; and this is confirmed by Idomeneus in his work on the Socratic circle. ¹ Again, he was the first who discoursed on the conduct of life, and the first philosopher who was tried and put to death. Aristoxenus, the son of Spintharus, says of him that he made money; he would at all events invest sums, collect the interest accruing, and then, when this was expended, put out the principal again.

Demetrius of Byzantium relates that Crito removed him from his workshop and educated him, being struck by his beauty of soul;