Theaetetus

SO.What shall we do with all these people, my friend? For, advancing little by little, we have unwittingly fallen between the two parties, and, unless we protect ourselves and escape somehow, we shall pay the penalty, like those in the palaestra, who in playing on the line are caught by both sides and dragged in opposite directions. [*](In the game referred to (called διελκυστίνδα by Pollux, ix. 112) the players were divided into two parties, each of which tried to drag its opponents over a line drawn across the palaestra.) I think, then, we had better examine first the one party, those whom we originally set out to join, the flowing ones, and if we find their arguments sound, we will help them to pull us over, trying thus to escape the others; but if we find that the partisans of the whole seem to have truer doctrines, we will take refuge with them from those who would move what is motionless. But if we find that neither party has anything reasonable to say, we shall be ridiculous if we think that we, who are of no account, can say anything worth while after having rejected the doctrines of very ancient and very wise men. Therefore, Theodorus, see whether it is desirable to go forward into so great a danger.

THEO. Oh, it would be unendurable, Socrates, not to examine thoroughly the doctrines of both parties.

SOC. Then they must be examined, since you are so urgent. Now I think the starting-point of our examination of the doctrine of motion is this: Exactly what do they mean, after all, when they say that all things are in motion? What I wish to ask is this: Do they mean to say that there is only one kind of motion or, as I believe, two? But it must not be my belief alone; you must share it also, that if anything happens to us we may suffer it in common. Tell me, do you call it motion when a thing changes its place or turns round in the same place?

THEO. Yes.

SOC. Let this, then, be one kind of motion. Now when a thing remains in the same place, but grows old, or becomes black instead of white, or hard instead of soft, or undergoes any other kind of alteration, is it not proper to say that this is another kind of motion?

THEO. I think so.

SOC. Nay, it must be true. So I say that there are these two kinds of motion: alteration, and motion in space.

THEO. And you are right.

SOC. Now that we have made this distinction, let us at once converse with those who say that all things are in motion, and let us ask them, Do you mean that everything moves in both ways, moving in space and undergoing alteration, or one thing in both ways and another in one of the two ways only?

THEO. By Zeus, I cannot tell! But I think they would say that everything moves in both ways.

SOC. Yes; otherwise, my friend, they will find that things in motion are also things at rest, and it will be no more correct to say that all things are in motion than that all things are at rest.

THEO. What you say is very true.

SOC. Then since they must be in motion, and since absence of motion must be impossible for anything, all things are always in all kinds of motion.

THEO. Necessarily.

SOC. Then just examine this point of their doctrine. Did we not find that they say that heat or whiteness or anything you please arises in some such way as this, namely that each of these moves simultaneously with perception between the active and the passive element, and the passive becomes percipient, but not perception, and the active becomes, not a quality, but endowed with a quality? Now perhaps quality seems an extraordinary word, and you do not understand it when used with general application, so let me give particular examples. For the active element becomes neither heat nor whiteness, but hot or white, and other things in the same way; you probably remember that this was what we said earlier in our discourse, that nothing is in itself unvaryingly one, neither the active nor the passive, but from the union of the two with one another the perceptions and the perceived give birth and the latter become things endowed with some quality while the former become percipient.

THEO. I remember, of course.

SOC. Let us then pay no attention to other matters, whether they teach one thing or another; but let us attend strictly to this only, which is the object of our discussion. Let us ask them, Are all things, according to your doctrine, in motion and flux? Is that so?

THEO. Yes.

SOC. Have they then both kinds of motion which we distinguished? Are they moving in space and also undergoing alteration?

THEO. Of course; that is, if they are to be in perfect motion.

SOC. Then if they moved only in space, but did not undergo alteration, we could perhaps say what qualities belong to those moving things which are in flux, could we not?

THEO. That is right.

SOC. But since not even this remains fixed—that the thing in flux flows white, but changes, so that there is a flux of the very whiteness, and a change of color, that it may not in that way be convicted of remaining fixed, is it possible to give any name to a color, and yet to speak accurately?

THEO. How can it be possible, Socrates, or to give a name to anything else of this sort, if while we are speaking it always evades us, being, as it is, in flux?

SOC. But what shall we say of any of the perceptions, such as seeing or hearing? Does it perhaps remain fixed in the condition of seeing or hearing?

THEO. It must be impossible, if all things are in motion.

SOC. Then we must not speak of seeing more than not seeing, or of any other perception more than of non-perception, if all things are in all kinds of motion.

THEO. No, we must not.

SOC. And yet perception is knowledge, as Theaetetus and I said.

THEO. Yes, you did say that.

SOC. Then when we were asked what is knowledge? we answered no more what knowledge is than what not-knowledge is.

THEO. So it seems.

SOC. This would be a fine result of the correction of our answer, when we were so eager to show that all things are in motion, just for the purpose of making that answer prove to be correct. But this, I think, did prove to be true, that if all things are in motion, every answer to any question whatsoever is equally correct, and we may say it is thus or not thus—or, if you prefer, becomes thus, to avoid giving them fixity by using the word is.

THEO. You are right.

SOC. Except, Theodorus, that I said thus, and not thus; but we ought not even to say thus; for thus would no longer be in motion; nor, again, not thus. For there is no motion in this either; but some other expression must be supplied for those who maintain this doctrine, since now they have, according to their own hypothesis, no words, unless it be perhaps the word nohow. That might be most fitting for them, since it is indefinite.

THEO. At any rate that is the most appropriate form of speech for them.

SOC. So, Theodorus, we have got rid of your friend, and we do not yet concede to him that every man is a measure of all things, unless he be a sensible man; and we are not going to concede that knowledge is perception, at least not by the theory of universal motion, unless Theaetetus here has something different to say.

THEO. An excellent idea, Socrates; for now that this matter is settled, I too should be rid of the duty of answering your questions according to our agreement, since the argument about Protagoras is ended.

THEAET. No, Theodorus, not until you and Socrates have discussed those who say all things are at rest, as you proposed just now.

THEO. A young man like you, Theaetetus, teaching your elders to do wrong by breaking their agreements! No; prepare to answer Socrates yourself for the rest of the argument.

THEAET. I will if he wishes it. But I should have liked best to hear about the doctrine I mentioned.

THEO. Calling Socrates to an argument is calling cavalry into an open plain. [*](A proverbial expression. An open plain is just what cavalry desires.) Just ask him a question and you shall hear.

SOC. Still I think, Theodorus, I shall not comply with the request of Theaetetus.

THEO. Why will you not comply with it?