18 That Phaedo the Socratic was a slave; and that several others also were of that condition.
Phaedo of Elis belonged to that famous Socratic band and was on terms of close intimacy with Socrates and Plato. His name was given by Plato to that inspired dialogue of his on the immortality of the soul. This Phaedo, though a slave, was of noble person and intellect, and according to some writers, in his boyhood was driven to prostitution by his master, who was a pander. We are told that Cebes the Socratic, at Socrates' earnest request, bought Phaedo and gave him the opportunity of studying philosophy. And he afterwards became a distinguished philosopher, whose very tasteful discourses on Socrates are in circulation.
There were not a few other slaves too afterwards who became famous philosophers, among them that Menippus whose works Marcus Varro emulated in those satires which others call “Cynic,” but he himself, “Menippean.”
Besides these, Pompylus, the slave of the Peripatetic Theophrastus, and the slave of the Stoic Zeno who was called Persaeus, and the slave of Epicurus whose name was Mys, were philosophers of repute.
Diogenes the Cynic also served as a slave, but he was a freeborn man, who was sold into slavery. When Xeniades of Corinth wished to buy him and asked whether he knew any trade, Diogenes replied: “I know how to govern free men.” Then Xeniades, in admiration of his answer, bought him, set him free, and entrusting to him his own children, said: “Take my children to govern.”
But as to the well-known philosopher Epictetus, the fact that he too was a slave is too fresh in our memory to need to be committed to writing, as if it had been forgotten.