Str. The venerable method of our fathers, which they generally employed towards their sons, and which many still employ, of sometimes showing anger at their errors
 and sometimes more gently exhorting them—that would most properly be called as a whole admonition. Theaet. That is true. Str. On the other hand, some appear to have convinced themselves that all ignorance is involuntary, and that he who thinks himself wise would never be willing to learn any of those things in which he believes he is clever, and that the admonitory kind of education takes a deal of trouble and accomplishes little. Theaet. They are quite right. Str. So they set themselves to cast out the conceit of cleverness in another way. Theaet. In what way? Str. They question a man about the things about which he thinks he is talking sense when he is talking nonsense; then they easily discover that his opinions are like those of men who wander, and in their discussions they collect those opinions and compare them with one another, and by the comparison they show that they contradict one another about the same things, in relation to the same things and in respect to the same things. But those who see this grow angry with themselves and gentle towards others, and this is the way in which
 they are freed from their high and obstinate opinions about themselves. The process of freeing them, moreover, affords the greatest pleasure to the listeners and the most lasting benefit to him who is subjected to it. For just as physicians who care for the body believe that the body cannot get benefit from any food offered to it until all obstructions are removed, so, my boy, those who purge the soul believe that the soul can receive no benefit from any teachings offered to it
 until someone by cross-questioning reduces him who is cross-questioned to an attitude of modesty, by removing the opinions that obstruct the teachings, and thus purges him and makes him think that he knows only what he knows, and no more. Theaet. That is surely the best and most reasonable state of mind. Str. For all these reasons, Theaetetus, we must assert that cross-questioning is the greatest and most efficacious of all purifications, and that he who is not cross-questioned, even though he be the Great King,
 has not been purified of the greatest taints, and is therefore uneducated and deformed in those things in which he who is to be truly happy ought to be most pure and beautiful. Theaet. Perfectly true. Str. Well then, who are those who practise this art? 
 I am afraid to say the sophists. Theaet. Why so? Str. Lest we grant them too high a meed of honor. Theaet. But the description you have just given is very like someone of that sort. Str. Yes, and a wolf is very like a dog, the wildest like the tamest of animals. But the cautious man must be especially on his guard in the matter of resemblances, for they are very slippery things. However, let us agree that they are the sophists; for I think the strife will not be about petty discriminations
 when people are sufficiently on their guard. Theaet. No, probably not. Str. Then let it be agreed that part of the discriminating art is purification, and as part of purification let that which is concerned with the soul be separated off, and as part of this, instruction, and as part of instruction, education; and let us agree that the cross-questioning of empty conceit of wisdom, which has come to light in our present discussion, is nothing else than the true-born art of sophistry. Theaet. Let us agree to all that; but the sophist has by this time appeared to be so many things that I am at a loss
 to know what in the world to say he really is, with any assurance that I am speaking the truth. Str. No wonder you are at a loss. But it is fair to suppose that by this time he is still more at a loss to know how he can any longer elude our argument; for the proverb is right which says it is not easy to escape all the wrestler’s grips. So now we must attack him with redoubled vigor. Theaet. You are right. Str. First, then, let us stop to take breath and while we are resting let us count up
 the number of forms in which the sophist has appeared to us. First, I believe, he was found to be a paid hunter after the young and wealthy. Theaet. Yes. Str. And secondly a kind of merchant in articles of knowledge for the soul. Theaet. Certainly. Str. And thirdly did he not turn up as a retailer of these same articles of knowledge? Theaet. Yes, and fourthly we found he was a seller of his own productions of knowledge. Str. Your memory is good; but I will try to recall the fifth case myself. He was an athlete
 in contests of words, who had taken for his own the art of disputation. Theaet. Yes, he was. Str. The sixth case was doubtful, but nevertheless we agreed to consider him a purger of souls, who removes opinions that obstruct learning. Theaet. Very true. Str. Then do you see that when a man appears to know many things, but is called by the name of a single art, there is something wrong about this impression, and that, in fact, the person who labors under this impression in connexion with any art is clearly unable to see the common principle of the art, to which all these kinds of knowledge pertain, so that he calls him who possesses them by many names instead of one? Theaet. Something like that is very likely to be the case. Str. We must not let that happen to us in our search through lack of diligence. So let us first take up again one of our statements about the sophist. For there is one of them which seemed to me to designate him most plainly. Theaet. Which was it? Str. I think we said he was a disputer. Theaet. Yes. Str. And did we not also say that he taught this same art of disputing to others? Theaet. Certainly. Str. Now let us examine and see what the subjects are about which such men say they make their pupils able to dispute. Let us begin our examination
 at the beginning with this question: Is it about divine things which are invisible to others that they make people able to dispute? Theaet. That is their reputation, at any rate. Str. And how about the visible things of earth and heaven and the like? Theaet. Those are included, of course. Str. And furthermore in private conversations, when the talk is about generation and being in general, we know (do we not?) that they are clever disputants themselves and impart equal ability to others. Theaet. Certainly. Str. And how about laws and public affairs in general? Do they not promise to make men able to argue about those? Theaet. Yes, for nobody, to speak broadly, would attend their classes if they did not make that promise. Str. However in all arts jointly and severally what the professional ought to answer to every opponent is written down somewhere and published that he who will may learn. Theaet. You seem to refer to the text-books of Protagoras
 on wrestling and the other arts. Str. Yes, my friend, and to those of many other authors. But is not the art of disputation, in a word, a trained ability for arguing about all things? Theaet. Well, at any rate, it does not seem to leave much out. Str. For heaven’s sake, my boy, do you think that is possible? For perhaps you young people may look at the matter with sharper vision than our duller sight.