Xenophon, "Memorabilia" (Against Paid "Professors" of Virtue aka "Sophists")

...Returning to the charge at another time, this same Antiphon engaged Socrates in conversation thus.

Ant. - "Socrates, for my part, I believe you to be a good and upright man; but for your wisdom I cannot say much. I fancy you would hardly dispute the verdict yourself, since, as I remark, you do not ask a money payment for your society; and yet if it were your cloak now, or your house, or any other of your possessions, you would set some value upon it, and never dream, I will not say of parting with it gratis, but of exchanging it for less than its worth. A plain proof, to my mind, that if you thought your society worth anything, you would ask for it not less than its equivalent in gold. Hence the conclusion to which I have come, as already stated: good and upright you may be, since you do not cheat people from pure selfishness; but wise you cannot be, since your knowledge is not worth a cent."

To this onslaught Socrates replied: "Antiphon, it is a tenet which we cling to that beauty and wisdom have this in common, that there is a fair way and a foul way in which to dispose of them. The vendor of beauty purchases an evil name, but supposing the same person have discerned a soul of beauty in his lover and makes that man his friend, we regard his choice as sensible. So is it with wisdom; he who sells it for money to the first bidder we name a sophist, as though one should say a man who prostitutes his wisdom; but if the same man, discerning the noble nature of another, shall teach that other every good thing, and make him his friend, of such a one we say he does that which it is the duty of every good citizen of gentle soul to do. In accordance with this theory, I too, Antiphon, having my tastes, even as another finds pleasure in his horse and his hounds, and another in his fighting cocks, so I too take my pleasure in good friends; and if I have any good thing myself I teach it them, or I commend them to others by whom I think they will be helped forwards on the path of virtue. The treasures also of the wise of old, written and bequeathed in their books, I unfold and peruse in common with my friends. If our eye light upon any good thing we cull it eagerly, and regard it as great gain if we may but grow in friendship with one another."

As I listened to this talk I could not but reflect that he, the master, was a person to be envied, and that we, his hearers, were being led by him to beauty and nobility of soul.

Again on some occasion the same Antiphon asked Socrates how he expected to make politicians of others when, even if he had the knowledge, he did not engage in politics himself.

Socrates replied: "I will put to you a question, Antiphon: Which were the more statesmanlike proceeding, to practise politics myself single- handed, or to devote myself to making as many others as possible fit to engage in that pursuit?"