The vox Protagorus from Plato’s Theaetetus:
But I must beg you to put fair questions: for there is great inconsistency in saying that you have a zeal for virtue, and then always behaving unfairly in argument. The unfairness of which I complain is that you do not distinguish between mere disputation and dialectic: the disputer may trip up his opponent as often as he likes, and make fun; but the dialectician will be in earnest, and only correct his adversary when necessary, telling him the errors into which he has fallen through his own fault, or that of the company which he has previously kept. If you do so, your adversary will lay the blame of his own confusion and perplexity on himself, and not on you; will follow and love you, and will hate himself, and escape from himself into philosophy, in order that he may become different from what he was. But the other mode of arguing, which is practised by the many, will have just the opposite effect upon him; and as he grows older, instead of turning philosopher, he will come to hate philosophy. I would recommend you, therefore, as I said before, not to encourage yourself in this polemical and controversial temper, but to find out, in a friendly and congenial spirit, what we really mean when we say that all things are in motion, and that to every individual and state what appears, is.