that he taught me something more than is taught by all masters alike; that he roused my better feelings by his encouragement, and that at one time he would raise my spirits by praise, and at another warn me to shake off slothfulness: that he laid his hand, as it were, upon my latent and torpid powers of intellect and drew them out into the light of day; that he did not stingily dole out to me what he knew, in order that he might be wanted for a longer time, but was eager, if possible, to pour all his learning into me; then I am ungrateful, if I do not love him as much as I love my nearest relatives and my dearest friends. XVII. We give something additional even to those who teach the meanest trades, if their efforts appear to be extraordinary; we bestow a gratuity upon pilots, upon workmen who deal with the commonest materials and hire themselves out by the day. In the noblest arts, however, those which either preserve or beautify our lives, a man would be ungrateful who thinks he owes the artist no more than he bargained for. Besides this, the teaching of such learning as we have spoken of blends mind with mind; now when this takes place, both in the case of the physician and of the teacher the price of his work is paid, but that of his mind remains owing. XVIII. Plato once crossed a river, and as the ferryman did not ask him for anything, he supposed that he had let him pass free out of respect, and said that the ferryman had laid Plato under an obligation. Shortly afterwards, seeing the ferryman take one person after another across the river with the same pains, and without charging anything, Plato declared that the ferryman had not laid him under an obligation. If you wish me to be grateful for what you give, you must not merely give it to me, but show that you mean it specially for me; you cannot make any claim upon one for having given him what you fling away broad-cast among the crowd. What then? shall I owe you nothing for it? Nothing, as an individual; I will pay, when the rest of mankind do, what I owe no more than they.