Str. Observe, then, that we have now been just in time in carrying our point against the supporters of such doctrine, and in forcing them to admit that one thing mingles with another. Theaet. What was our object? Str. Our object was to establish discourse as one of our classes of being. For if we were deprived of this, we should be deprived of philosophy, which would be the greatest calamity; moreover, we must at the present moment come to an agreement about the nature of discourse, and if we were robbed of it by its absolute non-existence, we could no longer discourse; and we should be robbed of it
 if we agreed that there is no mixture of anything with anything. Theaet. That is true enough; but I do not understand why we must come to an agreement about discourse just now. Str. Perhaps the easiest way for you to understand is by following this line of argument. Theaet. What line? Str. We found that not-being was one of the classes of being, permeating all being. Theaet. Yes. Str. So the next thing is to inquire whether it mingles with opinion and speech. Theaet. Why? Str. If it does not mingle with them, the necessary result
 is that all things are true, but if it does, then false opinion and false discourse come into being; for to think or say what is not—that is, I suppose, falsehood arising in mind or in words. Theaet. So it is. Str. But if falsehood exists, deceit exists. Theaet. Yes. Str. And if deceit exists, all things must be henceforth full of images and likenesses and fancies. Theaet. Of course. Str. But we said that the sophist had
 taken refuge in this region and had absolutely denied the existence of falsehood: for he said that not-being could be neither conceived nor uttered, since not-being did not in any way participate in being. Theaet. Yes, so it was. Str. But now not-being has been found to partake of being, and so, perhaps, he would no longer keep up the fight in this direction; but he might say that some ideas partake of not-being and some do not, and that speech and opinion are among those which do not; and he would therefore again contend that the image-making and fantastic art,
 in which we placed him, has absolutely no existence, since opinion and speech have no participation in not-being; for falsehood cannot possibly exist unless such participation takes place. Str. For this reason we must first inquire into the nature of speech and opinion and fancy, The English word fancy, though etymologically identical with the Greek φαντασία , has lost the close connection with seeming ( φαίνεσθαι ) which the Greek retains. The Greek word is therefore more comprehensive than the English, denoting that which appears to be, whether as the result of imagination or of sensation. Cf. 235 D ff. in order that when they are made clear we may perceive that they participate in not-being,
 and when we have perceived that, may prove the existence of falsehood, and after proving that, may imprison the sophist therein, if he can be held on that charge, and if not, may set him free and seek him in another class. Theaet. It certainly seems, Stranger, that what you said at first about the sophist—that he was a hard kind of creature to catch—is true; for he seems to have no end of defences, Perhaps a sort of pun is intended, for πρόβλημα was already beginning to have the meaning of problem. and when he throws one of them up, his opponent has first to fight through it before he can reach the man himself; for now, you see, we have barely passed through
 the non-existence of being, which was his first prepared line of defence, when we find another line ready; and so we must prove that falsehood exists in relation to opinion and to speech; and after this, perhaps, there will be another line, and still another after that; and it seems no end will ever appear. Str. No one should be discouraged, Theaetetus, who can make constant progress, even though it be slow. For if a man is discouraged under these conditions, what would he do under others—if he did not get ahead at all or were even pressed back? It would be a long time, as the saying is,
 before such a man would ever take a city. But now, my friend, since we have passed the line you speak of, the main defences would surely be in our hands, and the rest will now be smaller and easier to take. Theaet. Good. Str. First, then, let us take up speech and opinion, as I said just now, in order to come to a clearer understanding whether not-being touches them, or they are both entirely true, and neither is ever false. Theaet. Very well. Str. Then let us now investigate names, just a we spoke a while ago about ideas and letters; for in that direction the object of our present search is coming in sight. Theaet. What do we need to understand about names? Str. Whether they all unite with one another, or none of them, or some will and some will not. Theaet. Evidently the last; some will and some will not. Str. This, perhaps, is what you mean, that those which are spoken in order
 and mean something do unite, but those that mean nothing in their sequence do not unite. Theaet. How so, and what do you mean by that? Str. What I supposed you had in mind when you assented; for we have two kinds of vocal indications of being. Theaet. How so? Str. One called nouns, the other verbs. The science of language, in all its branches, was young in the time of Plato. Words of general meaning were necessarily used in a technical sense. So here ὄνομα and ῥῆμα are used as parts of grammatical terminology in the sense of verb and noun, though Plato elsewhere employs them with their ordinary meanings. Similarly the distinction between vowels and consonants ( Plat. Theaet. 203 ; cf. Plat. Soph. 253 ) was at least relatively new, as was that between the active and the passive voice. How important Plato’s part was in the development of linguistic study can no longer be accurately determined. Theaet. Define each of them. Str. The indication which relates to action we may call a verb. Theaet. Yes. Str. And the vocal sign applied to those who perform the actions in question we call a noun. Theaet. Exactly. Str. Hence discourse is never composed of nouns alone spoken in succession, nor of verbs spoken without nouns. Theaet. I do not understand that. Str. I see; you evidently had something else in mind when you assented just now; for what I wished to say was just this, that verbs and nouns do not make discourse if spoken successively in this way. Theaet. In what way? Str. For instance, walks, runs, sleeps and the other verbs which denote actions, even if you utter all there are of them in succession, do not make discourse for all that. Theaet. No, of course not. Str. And again, when lion, stag, horse, and all other names of those who perform these actions are uttered,
 such a succession of words does not yet make discourse; for in neither case do the words uttered indicate action or inaction or existence of anything that exists or does not exist, until the verbs are mingled with the nouns; then the words fit, and their first combination is a sentence, about the first and shortest form of discourse. Theaet. What do you mean by that? Str. When one says a man learns, you agree that this is the least and first of sentences, do you not? Theaet. Yes. Str. For when he says that, he makes a statement about that which is or is becoming or has become or is to be; he does not merely give names, but he reaches a conclusion by combining verbs with nouns. That is why we said that he discourses and does not merely give names, and therefore we gave to this combination the name of discourse. Theaet. That was right. Str. So, then, just as of things some fit each other and some do not, so too some vocal signs do not fit,
 but some of them do fit and form discourse. Theaet. Certainly. Str. Now there is another little point. Theaet. What is it? Str. A sentence, if it is to be a sentence, must have a subject; without a subject it is impossible. Theaet. True. Str. And it must also be of some quality, must it not? Theaet. Of course. Str. Now let us pay attention to each other. Theaet. Yes, at any rate we ought to do so. Str. Now, then, I will speak a sentence to you in which a action and the result of action are combined by means of a noun and a verb, and whatever the subject of the sentence is do you tell me.