Theaetetus (178)

THEO. Certainly not.

SOC. And does it always hit the mark, or does every state often miss it?

THEO. I should say they do often miss it!

SOC. Continuing, then, and proceeding from this point, every one would more readily agree to this assertion, if the question were asked concerning the whole class to which the advantageous belongs; and that whole class, it would seem, pertains to the future. For when we make laws, we make them with the idea that they will be advantageous in after time; and this is rightly called the future.

THEO. Certainly.

SOC. Come then, on this assumption, let us question Protagoras or someone of those who agree with him. Man is the measure of all things, as your school says, Protagoras, of the white, the heavy, the light, everything of that sort without exception; for he possesses within himself the standard by which to judge them, and when his thoughts about them coincide with his sensations, he thinks what to him is true and really is. Is not that what they say?

THEO. Yes.

SOC. Does he, then, also, Protagoras, we shall say, possess within himself the standard by which to judge of the things which are yet to be, and do those things which he thinks will be actually come to pass for him who thought them? Take, for instance, heat; if some ordinary man thinks he is going to take a fever, that is to say, that this particular heat will be, and some other man, who is a physician, thinks the contrary, whose opinion shall we expect the future to prove right? Or perhaps the opinion of both, and the man will become, not hot or feverish to the physician, but to himself both?

THEO. No, that would be ridiculous.

SOC. But, I imagine, in regard to the sweetness or dryness which will be in a wine, the opinion of the husbandman, not that of the lyre-player, will be valid.

THEO. Of course.

SOC. And again, in a matter of discord or tunefulness in music that has never been played, a gymnastic teacher could not judge better than a musician what will, when performed, seem tuneful even to a gymnastic teacher himself.

THEO. Certainly not.

SOC. Then, too, when a banquet is in preparation the opinion of him who is to be a guest, unless he has training in cookery, is of less value concerning the pleasure that will be derived from the viands than that of the cook. For we need not yet argue about that which already is or has been pleasant to each one but concerning that which will in the future seem and be pleasant to each one, is he himself the best judge for himself, or would you, Protagoras—at least as regards the arguments which will be persuasive in court to each of us—be able to give an opinion beforehand better than anyone whatsoever who has no especial training?

THEO. Certainly, Socrates, in this, at any rate, he used to declare emphatically that he himself excelled everyone.