Theodorus THEO. So it seems.

Socrates 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.”

Theodorus THEO. You are right.

Socrates SOC. Except, Theodorus, that I said “thus,” and “not thus”; but we ought not even to say “thus”; 183b 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.

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

Socrates 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; 183c 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.

Theodorus 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.

Theaetetus THEAET. No, Theodorus, not until you and Socrates 183d have discussed those who say all things are at rest, as you proposed just now.

Theodorus 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.

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

Theodorus THEO. Calling Socrates to an argument is calling cavalry into an open plain. ¹ Just ask him a question and you shall hear.

Socrates SOC. Still I think, Theodorus, 183e I shall not comply with the request of Theaetetus.

Theodorus THEO. Why will you not comply with it?

Socrates SOC. Because I have a reverential fear of examining in a flippant manner Melissus and the others who teach that the universe is one and motionless, and because I reverence still more one man, Parmenides. Parmenides seems to me to be, in Homer’s words, one to be venerated and also awful. ² For I met him when I was very young and he was very old, and he appeared to me to possess an absolutely noble depth of mind. 184a So I am afraid we may not understand his words and may be still farther from understanding what he meant by them; but my chief fear is that the question with which we started, about the nature of knowledge, may fail to be investigated, because of the disorderly crowd of arguments which will burst in upon us if we let them in; especially as the argument we are now proposing is of vast extent, and would not receive its deserts if we treated it as a side issue, and if we treat it as it deserves, it will take so long as to do away with the discussion about knowledge. Neither of these things ought to happen, but we ought to try by the science of midwifery to deliver Theaetetus of the thoughts 184b about knowledge with which he is pregnant.

Theodorus THEO. Yes, if that is your opinion, we ought to do so.

Socrates SOC. Consider, then, Theaetetus, this further point about what has been said. Now you answered that perception is knowledge, did you not?

Theaetetus THEAET. Yes.

Socrates SOC. If, then, anyone should ask you, “By what does a man see white and black colors and by what does he hear high and low tones?” you would, I fancy, say, “By his eyes and ears.”

Theaetetus THEAET. Yes, I should.

Socrates SOC. The easy use of words and phrases and the avoidance of strict precision is in general a sign of good breeding; indeed, the opposite is hardly worthy of a gentleman, but sometimes it is necessary, as now it is necessary to object to your answer, in so far as it is incorrect. Just consider; which answer is more correct, that our eyes are that by which we see or that through which we see, and our ears that by which or that through which we hear?

Theaetetus THEAET. I think, Socrates, we perceive through, rather than by them, in each case.

Socrates SOC. Yes, for it would be strange indeed, my boy, if there are many senses ensconced within us, as if we were so many wooden horses of Troy, and they do not all unite in one power, whether we should call it soul or something else, by which we perceive through these as instruments the objects of perception.

Theaetetus THEAET. I think what you suggest is more likely than the other way.

Socrates SOC. Now the reason why I am so precise about the matter is this: I want to know whether there is some one and the same power within ourselves by which we perceive black and white through the eyes, and again other qualities 184e through the other organs, and whether you will be able, if asked, to refer all such activities to the body. But perhaps it is better that you make the statement in answer to a question than that I should take all the trouble for you. So tell me: do you not think that all the organs through which you perceive hot and hard and light and sweet are parts of the body? Or are they parts of something else?

Theaetetus THEAET. Of nothing else.

Socrates SOC. And will you also be ready to agree that it is impossible to perceive through one sense 185a what you perceive through another; for instance, to perceive through sight what you perceive through hearing, or through hearing what you perceive through sight?

Theaetetus THEAET. Of course I shall.

Socrates SOC. Then if you have any thought about both of these together, you would not have perception about both together either through one organ or through the other.

Theaetetus THEAET. No.

Socrates SOC. Now in regard to sound and color, you have, in the first place, this thought about both of them, that they both exist?

Theaetetus THEAET. Certainly.

Socrates SOC. And that each is different from the other and the same as itself?

Theaetetus THEAET. Of course.

Socrates SOC. And that both together are two and each separately is one?

Theaetetus THEAET. Yes, that also.

Socrates SOC. And are you able also to observe whether they are like or unlike each other?

Theaetetus THEAET. May be.

Socrates SOC. Now through what organ do you think all this about them? For it is impossible to grasp that which is common to them both either through hearing or through sight. Here is further evidence for the point I am trying to make: if it were possible to investigate the question whether the two, sound and color, are bitter or not, you know that you will be able to tell by what faculty you will investigate it, and that is clearly 185c neither hearing nor sight, but something else.

Theaetetus THEAET. Of course it is,—the faculty exerted through the tongue.

Socrates SOC. Very good. But through what organ is the faculty exerted which makes known to you that which is common to all things, as well as to these of which we are speaking—that which you call being and not-being, and the other attributes of things, about which we were asking just now? What organs will you assign for all these, through which that part of us which perceives gains perception of each and all of them?

Theaetetus THEAET. You mean being and not-being, and likeness and unlikeness, and identity and difference, 185d and also unity and plurality as applied to them. And you are evidently asking also through what bodily organs we perceive by our soul the odd and the even and everything else that is in the same category.

Socrates SOC. Bravo, Theaetetus! you follow me exactly; that is just what I mean by my question.

Theaetetus THEAET. By Zeus, Socrates, I cannot answer, except that I think there is no special organ at all for these notions, as there are for those others; but it appears to me that the soul views by itself directly 185e what all things have in common.

Socrates SOC. Why, you are beautiful, Theaetetus, and not, as Theodorus said, ugly; for he who speaks beautifully is beautiful and good. But besides being beautiful, you have done me a favor by relieving me from a long discussion, if you think that the soul views some things by itself directly and others through the bodily faculties; for that was my own opinion, and I wanted you to agree.