SOCRATES: And the cook will be a better judge than the guest, who is not a cook, of the pleasure to be derived from the dinner which is in preparation; for of present or past pleasure we are not as yet arguing; but can we say that every one will be to himself the best judge of the pleasure which will seem to be and will be to him in the future?—nay, would not you, Protagoras, better guess which arguments in a court would convince any one of us than the ordinary man?
THEODORUS: Certainly, Socrates, he used to profess in the strongest manner that he was the superior of all men in this respect.
SOCRATES: To be sure, friend: who would have paid a large sum for the privilege of talking to him, if he had really persuaded his visitors that neither a prophet nor any other man was better able to judge what will be and seem to be in the future than every one could for himself?
THEODORUS: Who indeed?
SOCRATES: And legislation and expediency are all concerned with the future; and every one will admit that states, in passing laws, must often fail of their highest interests?
THEODORUS: Quite true.
SOCRATES: Then we may fairly argue against your master, that he must admit one man to be wiser than another, and that the wiser is a measure: but I, who know nothing, am not at all obliged to accept the honour which the advocate of Protagoras was just now forcing upon me, whether I would or not, of being a measure of anything.
THEODORUS: That is the best refutation of him, Socrates; although he is also caught when he ascribes truth to the opinions of others, who give the lie direct to his own opinion.
SOCRATES: There are many ways, Theodorus, in which the doctrine that every opinion of every man is true may be refuted; but there is more difficulty in proving that states of feeling, which are present to a man, and out of which arise sensations and opinions in accordance with them, are also untrue. And very likely I have been talking nonsense about them; for they may be unassailable, and those who say that there is clear evidence of them, and that they are matters of knowledge, may probably be right; in which case our friend Theaetetus was not so far from the mark when he identified perception and knowledge. And therefore let us draw nearer, as the advocate of Protagoras desires; and give the truth of the universal flux a ring: is the theory sound or not? at any rate, no small war is raging about it, and there are combination not a few.
THEODORUS: No small, war, indeed, for in Ionia the sect makes rapid strides; the disciples of Heracleitus are most energetic upholders of the doctrine.