Plato, Protagoras, 348c-349a
Protagoras, do not presume that I am conversing with you from any other motive than to investigate those issues that constantly perplex me. For I believe that a line from Homer says it all:
When two go together, one observes before the other.
For in this way we shall all be more resourceful people in every action, word and thought. But if someone has an insight on his own, he immediately goes about, searching until he meets someone to whom he can present it, and with whom he can confirm it. So for this very reason, I would gladly converse with you, more so than anyone else, because I believe that you will best inquire into the wide range of issues that a reasonable person is likely to consider, and especially into excellence. Indeed who else could I choose but you? You not only believe yourself to be noble and good, just like others who are reasonable but unable to make other people reasonable, but you, by contrast, are good, and are also able to make others good. What’s more, you have such belief in yourself that while others conceal this skill, you have proclaimed yourself openly throughout the entire Greek world, giving yourself the title of a sophist, a self-declared teacher of culture and excellence, the first person who thought it right to demand payment for this. So what could I do but call you into this enquiry; question you and consult with you? There is no other option.