The Memorabilia by Xenophon
Again I may cite, as known to myself, the following discussion; the arguments were addressed to Diodorus, one of his companions. The master said:
Tell me, Diodorus, if one of your slaves runs away, are you at pains to recover him?
More than that (Diodorus answered), I summon others to my aid and I have a reward cried for his recovery.
Socrates. Well, if one of your domestics is sick, do you tend him and call in the doctors to save his life?
Diodorus. Decidedly I do.
Socrates. And if an intimate acquaintance who is far more precious to you than any of your household slaves is about to perish of want, you would think it incumbent on you to take pains to save his life? Well! now you know without my telling you that Hermogenes is not made of wood or stone. If you helped him he would be ashamed not to pay you in kind. And yet--the opportunity of possessing a willing, kindly, and trusty assistant well fitted to do your bidding, and not merely that, but capable of originating useful ideas himself, with a certain forecast of mind and judgment--I say such a man is worth dozens of slaves. Good economists tell us that when a precious article may be got at a low price we ought to buy. And nowadays when times are so bad it is possible to get good friends exceedingly cheap.
Diodorus answered: You are quite right, Socrates; bid Hermogenes come to me.
Socrates. Bid Hermogenes come to you!--not I indeed! since for aught I can understand you are no better entitled to summon him that to go to him yourself, nor is the advantage more on his side than your own.
Thus Diodorus went off in a trice to seek Hermogenes, and at no great outlay won to himself a friend--a friend whose one concern it now was to discover how, by word or deed, he might help and gladden Diodorus.
 Or, "for which I can personally vouch."
 Hermogenes, presumably the son of Hipponicus. See I. ii. 48.