Soc. Then we must not speak of seeing any more than of not-seeing,
nor of any other perception more than of any non-perception, if all
things partake of every kind of motion?
Theod. Certainly not.
Soc. Yet perception is knowledge: so at least Theaetetus and I
Theod. Very true.
Soc. Then when we were asked what is knowledge, we no more
answered what is knowledge than what is not knowledge?
Theod. I suppose not.
Soc. Here, then, is a fine result: we corrected our first answer
in our eagerness to prove that nothing is at rest. But if nothing is
at rest, every answer upon whatever subject is equally right: you
may say that a thing is or is not thus; or, if you prefer, "becomes"
thus; and if we say "becomes," we shall not then hamper them with
words expressive of rest.
Theod. Quite true.
Soc. Yes, Theodorus, except in saying "thus" and "not thus." But you
ought not to use the word "thus," for there is no motion in "thus"
or in "not thus." The maintainers of the doctrine have as yet no words
in which to express themselves, and must get a new language. I know of
no word that will suit them, except perhaps "no how," which is
Theod. Yes, that is a manner of speaking in which they will be quite
Soc. And so, Theodorus, we have got rid of your friend without
assenting to his doctrine, that every man is the measure of all
things-a wise man only is a measure; neither can we allow that
knowledge is perception, certainly not on the hypothesis of a
perpetual flux, unless perchance our friend Theaetetus is able to
convince us that it is.
Theod. Very good, Socrates; and now that the argument about the
doctrine of Protagoras has been completed, I am absolved from
answering; for this was the agreement.
Theaet. Not, Theodorus, until you and Socrates have discussed the
doctrine of those who say that all things are at rest, as you were
Theod. You, Theaetetus, who are a young rogue, must not instigate
your elders to a breach of faith, but should prepare to answer
Socrates in the remainder of the argument.
Theaet. Yes, if he wishes; but I would rather have heard about the
doctrine of rest.
Theod. Invite Socrates to an argument-invite horsemen to the open
plain; do but ask him, and he will answer.
Soc. Nevertheless, Theodorus, I am afraid that I shall not be able
to comply with the request of Theaetetus.
Theod. Not comply! for what reason?
Soc. My reason is that I have a kind of reverence; not so much for
Melissus and the others, who say that "All is one and at rest," as for
the great leader himself, Parmenides, venerable and awful, as in
Homeric language he may be called;-him I should be ashamed to approach
in a spirit unworthy of him. I met him when he was an old man, and I
was a mere youth, and he appeared to me to have a glorious depth of
mind. And I am afraid that we may not understand his words, and may be
still further from understanding his meaning; above all I fear that
the nature of knowledge, which is the main subject of our
discussion, may be thrust out of sight by the unbidden guests who will
come pouring in upon our feast of discourse, if we let them
in-besides, the question which is now stirring is of immense extent,
and will be treated unfairly if only considered by the way; or if
treated adequately and at length, will put into the shade the other
question of knowledge. Neither the one nor the other can be allowed;
but I must try by my art of midwifery to deliver Theaetetus of his
conceptions about knowledge.