EPICTETUS. DISCOURSES. Book iii. §2. ¶4.
IF anyone comes and tells you, that in a dispute which was the best of the philosophers, one of the company said that such a one was the only philosopher, that little soul of yours grows to the size of two cubits, instead of an inch; but if another should come and say, "You are mistaken, he is not worth hearing, for what doth he know? He hath the first rudiments, but nothing more," you are thunderstruck; you presently turn pale and cry out, "I will show him what a man, and how great a philosopher, I am." It is evident what you are by these very things; why do you aim to show it by others? Do not you know that Diogenes showed some sophist in this manner by extending his middle finger; and, when he was mad with rage, This, says Diogenes, is he; I have showed him to you. For a man is not shown in the same sense as a stone, or a piece of wood, by the finger; but whoever shows his principles, shows him as a man.