And have you ever observed any fear which fears itself and the other fears, but has no fear of a single dreadful thing?

 No, I have not, he replied.

 Or an opinion which is an opinion of opinions and of itself, but without any opinion such as the other opinions have?

 By no means.

 But it is apparently a science of this kind that we are assuming—one that is a science of no branch of study, but a science of itself and of the other sciences.

 So we are.

 And it is a strange thing, if it really exists? For we should not affirm as yet that it does not exist, but should still consider whether it does exist. You are right.

 Well now, this science is a science of something, that is, it has a certain faculty whereby it can be a science of something, has it not?

 Certainly.

 For, you know, we say the greater has a certain faculty whereby it can be greater than something? At this point Socrates adduces the relation of greater to smaller ( τινὸς εἶναι μεῖζον ) to suggest a difficulty in conceiving a science to be a science of itself: in so doing he draws a false analogy between two quite different uses of the genitive in Greek, represented in English by the comparative than and the objective of. 

 Quite so.

 That is, than something smaller, if it is to be greater.

 Necessarily.

 So if we could find a greater which is greater than other greater things, and than itself, but not greater than the things beside which the others are greater, I take it there can be no doubt that it would be in the situation of being, if greater than itself, at the same time smaller than itself, would it not?

 Most inevitably, Socrates, he said.

 Or again, if there is a double of other doubles and of itself, both it and the others must of course be halves, if it is to be their double; for, you know, a double cannot be of anything else than its half.

 True.

 And what is more than itself will also be less, and the heavier will be lighter, and the older younger, and so on with everything else: whatever has its own faculty applied to itself will have also the natural quality to which its faculty was applicable, will it not? For instance, hearing is, as we say, just a hearing of sound, is it not? Yes.

 So if it is to hear itself, it will hear a sound of its own; for it would not hear otherwise.

 Most inevitably.

 And sight, I suppose, my excellent friend, if it is to see itself, must needs have a color; for sight can never see what is colorless.

 No more it can.

 Then do you perceive, Critias, in the various cases we have propounded, how some of them strike us as absolutely impossible, while others raise serious doubts as to the faculty of the thing being ever applicable to itself? For with magnitudes, numbers, and the like it is absolutely impossible, is it not?

 Certainly. But again, with hearing and sight, or in the further bases of motion moving itself and heat burning itself, and all other actions of the sort, the fact must appear incredible to some, but perhaps not to others. So what we want, my friend, is some great man who will determine to our satisfaction in every respect whether there is nothing in nature so constituted as to have its own faculty applicable to itself, and not only some other object, or whether there are some such, and others not such; and whether, again, if there are things that have such relation to themselves, they include a science which we assert to be temperance. For my part, I distrust my own competence to determine these questions, and hence I am neither able to affirm whether it is possible that there should be a science of science, nor willing, let it be ever so true, to acknowledge this to be temperance until I have made out whether such a thing as this would benefit us or not. For, you see, I have a presentiment that temperance is something beneficial and good; and you, therefore, son of Callaeschrus—since you lay it down that temperance is this very science of science, and moreover of the lack of science—shall first indicate the possibility, as I put it just now, and then the benefit added to the possibility, of such a thing; and perhaps you will then satisfy me that your definition of temperance is correct.

 Now when Critias heard this and saw me in a difficulty, he seemed to me—just as the sight of someone yawning opposite causes people to be affected in the same way—to be compelled by the sense of my difficulty to be caught in a difficulty himself. And so, since he usually contrived to distinguish himself, he was too ashamed to bring himself to admit to me before the company that he was unable to determine the questions with which I challenged him, and he made a very indistinct reply in order to conceal his difficulty. Then I, to forward the discussion, remarked: Well, if you prefer, Critias, let us concede for the moment that there may possibly be a science of science : some other time we shall consider whether such is the fact or not. Come then; suppose it is perfectly possible: how is one helped thereby to know what one knows and does not know? For this, you are aware, we said Plat. Charm. 167a . was the meaning of self-knowledge and temperance, did we not?

 Certainly, he said; and it must surely follow, Socrates; for if a man has a science which knows itself, he will be similar himself to that which he has. For instance, he who has swiftness will be swift, he who has beauty will be beautiful, and he who has knowledge will know; and when he has knowledge that is of itself, he will then, surely, be in the position of knowing himself.

 I do not dispute, I said, that when a man has that which knows itself he will know himself; but having that, how is he bound to know what he knows and what he does not know? Because, Socrates, the two things are the same.

 I daresay, I said; but I am afraid I am still my old self: I still do not see how knowing what one knows and does not know is the same as the other. How do you mean? he asked.

 In this way, I replied: will a science of science, if such exists, be able to do more than determine that one of two things is science, and the other is not science?

 No, only that. Now, is science or lack of science of health the same as science or lack of science of justice?

 By no means.

 For the one, I suppose, is medicine, and the other politics, while the thing in question is merely science.

 Yes, to be sure.

 And if a man has no added knowledge of health and justice, but knows only science, as having science of that alone, he will probably know that he has a certain piece of scientific knowledge about himself and about other people, will he not?

 Yes. But how will this science help him to know what he knows? For of course he knows health by means of medicine, not temperance, and harmony by means of music, not temperance, and building by means of the builder’s art, not temperance; and so it will be in every case, will it not?

 Apparently.

 And how will temperance, supposing it is only a science of sciences, help him to know that he knows health, or that he knows building?

 By no means.

 Then he who is ignorant of all this will not know what he knows, but only that he knows.

 So it seems. Then being temperate, or temperance, will not be this knowledge of what one knows or does not know, but, it would seem, merely knowing that one knows or does not know.

 It looks like it.

 Then such a person will also be unable to examine another man’s claim to some knowledge, and make out whether he knows or does not know what he says he knows: he will merely know, it would seem, that he has a certain knowledge; but of what it is, temperance will not cause him to know. Apparently not. So he will be able to distinguish neither the man who pretends to be a doctor, but is none, from the man who really is one, nor any other man who has knowledge from him who has none. But let us consider it another way: if the temperate man or anybody else would discriminate between the true doctor and the false, he will go to work thus, will he not? He will surely not talk to him about medicine; for, as we were saying, the doctor understands nothing else but health and disease. Is not that so?

 Yes, it is.

 But about science he knows nothing, for that, you know, we assigned to temperance alone.

 Yes. So the medical man knows nothing about medicine either, since medicine is, of course, a science.

 True.

 Then the temperate man will know, indeed, that the doctor has a certain science; but when he has to put its nature to the proof, must he not consider what its subjects are? Is not each science marked out, not merely as a science, but as a particular one, by the particular subjects it has?

 It is, to be sure.

 And medicine is marked out as different from the other sciences by being a science of health and disease.

 Yes.

 And so anyone who wishes to inquire into medicine must make those things, whatever they may be, with which it is concerned, the matter of his inquiry; not those foreign things, I presume, with which it is not?

 No, indeed.

 Then he who conducts his inquiry aright will consider the doctor, as a medical man, in connection with cases of health and disease.

 So it seems.

 And will inquire whether, in what is said or done in such cases, his words are truly spoken, and his acts rightly done?

 He must.

 Well now, could anyone follow up either of these points without the medical art?

 No, indeed. Nobody at all, it would seem, but a doctor; and so not the temperate man either: for he would have to be a doctor, in addition to his temperance. That is so.

 Then inevitably, if temperance is only a science of science and of lack of science, it will be equally unable to distinguish a doctor who knows the business of his art from one who does not know but pretends or thinks he does, and any other person who has knowledge of anything at all: one will only distinguish one’s fellow-artist, as craftsmen usually can.

 Apparently, he said. Then what benefit, I asked, Critias, can we still look for from temperance, if it is like that? For if, as we began by assuming, the temperate man knew what he knew and what he did not know, and that he knows the one and does not know the other, and if he were able to observe this same condition in bother man, it would be vastly to our benefit, we agree, to be temperate; since we should pass all our lives, both we who had temperance and all the rest who were governed by us, without error. For neither should we ourselves attempt to do what we did not know, instead of finding out those who knew and placing the matter in their hands, nor should we permit others under our governance to do anything but what they were likely to do aright; and they would do that when they had knowledge of it; and so it would be that a house which was ordered, or a state which was administered, as temperance bade, and everything else that was ruled by temperance, could not but be well ordered; for with error abolished, and rightness leading, in their every action men would be bound to do honorably and well under such conditions, and those who did well would be happy. Did we not so speak of temperance, I said, Critias, when we remarked how great a boon it was to know what one knows and what one does not know?

 To be sure we did, he replied.

 Whereas now, I went on, you see that nowhere can any such science be found.

 I see, he said. Then may we say, I asked, that there is this good point in the knowledge of knowledge and of lack of knowledge, which we now find to be what temperance is, that he who has it will not only learn more easily whatever he learns, but will perceive everything more plainly, since besides the particular things that he learns he will behold the science; and hence he will probe more surely the state of other men respecting the things which he has learnt himself, while those who probe without such knowledge will do it more feebly and poorly? Are these, my friend, the kind of advantages that we shall gain from temperance? But are we really looking at something greater, and requiring it to be something greater than it really is?

 Probably, he replied, that is so.

 I daresay, I said; and I daresay also our inquiry has been worthless. And this I conclude, because I observe certain strange facts about temperance, if it is anything like that. For suppose, if you please, we concede that there may possibly be a science of science, and let us grant, and not withdraw, our original proposition that temperance is the knowledge of what one knows and does not know; granting all this, let us still more thoroughly inquire whether on these terms it will be of any profit to us. For our suggestion just now, that temperance of that sort, as our guide in ordering house or state, must be a great boon, was not, to my thinking, Critias, a proper admission. How so? he asked.

 Because, I replied, we too tightly admitted that it would be a great boon to mankind if each of us should do what he knows, but should place what he did not know in the hands of others who had the knowledge. Well, was that, he asked, not a proper admission? Not to my mind, I answered.

 In very truth, your words are strange! he said, Socrates.

 Yes, by the Dog, I said, and they strike me too in the same way; and it was in view of this, just now, that I spoke of strange results that I noticed, and said I feared we were not inquiring rightly.