Part 25

THEODORUS: Most true.

SOCRATES: Consider a further point: did we not understand them to explain the generation of heat, whiteness, or anything else, in some such manner as the following:--were they not saying that each of them is moving between the agent and the patient, together with a perception, and that the patient ceases to be a perceiving power and becomes a percipient, and the agent a quale instead of a quality? I suspect that quality may appear a strange and uncouth term to you, and that you do not understand the abstract expression. Then I will take concrete instances: I mean to say that the producing power or agent becomes neither heat nor whiteness but hot and white, and the like of other things. For I must repeat what I said before, that neither the agent nor patient have any absolute existence, but when they come together and generate sensations and their objects, the one becomes a thing of a certain quality, and the other a percipient. You remember?

THEODORUS: Of course.

SOCRATES: We may leave the details of their theory unexamined, but we must not forget to ask them the only question with which we are concerned: Are all things in motion and flux?

THEODORUS: Yes, they will reply.

SOCRATES: And they are moved in both those ways which we distinguished, that is to say, they move in place and are also changed?

THEODORUS: Of course, if the motion is to be perfect.

SOCRATES: If they only moved in place and were not changed, we should be able to say what is the nature of the things which are in motion and flux?

THEODORUS: Exactly.

SOCRATES: But now, since not even white continues to flow white, and whiteness itself is a flux or change which is passing into another colour, and is never to be caught standing still, can the name of any colour be rightly used at all?

THEODORUS: How is that possible, Socrates, either in the case of this or of any other quality--if while we are using the word the object is escaping in the flux?

SOCRATES: And what would you say of perceptions, such as sight and hearing, or any other kind of perception? Is there any stopping in the act of seeing and hearing?

THEODORUS: Certainly not, if all things are in motion.

SOCRATES: 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?

THEODORUS: Certainly not.

SOCRATES: Yet perception is knowledge: so at least Theaetetus and I were saying.

THEODORUS: Very true.

SOCRATES: Then when we were asked what is knowledge, we no more answered what is knowledge than what is not knowledge?

THEODORUS: I suppose not.

SOCRATES: 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.

THEODORUS: Quite true.

SOCRATES: 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 perfectly indefinite.

THEODORUS: Yes, that is a manner of speaking in which they will be quite at home.

SOCRATES: 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.

THEODORUS: 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.

THEAETETUS: Not, Theodorus, until you and Socrates have discussed the doctrine of those who say that all things are at rest, as you were proposing.

THEODORUS: 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.

THEAETETUS: Yes, if he wishes; but I would rather have heard about the doctrine of rest.