"Is not a Sophist, Hippocrates, one who deals wholesale or retail in the food of the soul? To me that appears to be his nature. … Knowledge is the food of the soul; and we must take care, my friend, that the Sophist does not deceive us when he praises what he sells, like the dealers wholesale or retail who sell the food of the body; for they praise indiscriminately all their goods, without knowing what are really beneficial or hurtful. Neither do their customers know … unless he who buys of them happens to be a physician of the soul."