Charmides

Charmides blushed, and the blush heightened his beauty, for modesty is becoming in youth; he then said very ingenuously, that he really could not at once answer, either yes, or no, to the question which I had asked: For, said he, if I affirm that I am not temperate, that would be a strange thing for me to say of myself, and also I should give the lie to Critias, and many others who think as he tells you, that I am temperate: but, on the other hand, if I say that I am, I shall have to praise myself, which would be ill manners; and therefore I do not know how to answer you. - Taken from "Charmides" written by Plato