Soc. Instead of saying that the soul forgets, when it is unaffected by the vibrations of the body,
 apply the term want of perception to that which you are now calling forgetfulness. Pro. I understand. Soc. And the union of soul and body in one common affection and one common motion you may properly call perception. Pro. Very true. Soc. Then do we now understand what we mean by perception? Pro. Certainly. Soc. I think, then, that memory may rightly be defined as the preservation of perception. Pro. Quite rightly. Soc. But do we not say that memory differs from recollection? Pro. Perhaps. Soc. And is this the difference? Pro. What? Soc. When the soul alone by itself, apart from the body, recalls completely any experience it has had in company with the body, we say that it recollects do we not? Pro. Certainly. Soc. And again when the soul has lost the memory of a perception or of something it has learned and then alone by itself regains this,
 we call everything of that kind recollection. Pro. You are right. Soc. Now my reason for saying all this is— Pro. What? Soc. That henceforth we may comprehend as completely and clearly as possible the pleasure of the soul, and likewise its desire, apart from the body; for both of these appear to be made plain by what has been said about memory and recollection. Pro. Let us, then, Socrates, discuss the next point. Soc. We must, it seems, consider many things in relation to the origin and general aspect of pleasure;
 but now I think our first task is to take up the nature and origin of desire. Pro. Then let us examine that; for we shall not lose anything. Soc. Oh yes, Protarchus, we shall lose a great deal! When we find what we are seeking we shall lose our perplexity about these very questions. Pro. That is a fair counter; but let us try to take up the next point. Soc. Did we not say just now that hunger, thirst,
 and the like were desires? Pro. They are, decidedly. Soc. What sort of identity have we in view when we call these, which are so different, by one name? Pro. By Zeus, Socrates, that question may not be easy to answer, yet it must be answered. Soc. Let us, then, begin again at that point with the same examples. Pro. At what point? Soc. We say of a thing on any particular occasion, it’s thirsty, do we not? Pro. Of course. Soc. And that means being empty? Pro. Certainly. Soc. And is thirst, then, a desire? Pro. Yes, of drink. Soc. Of drink, or of being filled with drink? Pro. Of being filled, I suppose. Soc. The man, then, who is empty desires, as it appears, the opposite of what he feels for, being empty, he longs to be filled. Pro. That is very plain. Soc. Well then, is there any source from which a man who is empty at first can gain a comprehension, whether by perception or by memory, of fulness, a thing which he does not feel at the time and has never felt before? Pro. It cannot be done. Soc. And yet he who desires, desires something, we say. Pro. Of course. Soc. And he does not desire that which he feels; for he is thirsty, and that is emptiness, but he desires fulness. Pro. Yes. Soc. Then somehow some part of him who is thirsty can apprehend fulness. Pro. Yes, obviously. Soc. But it cannot be the body, for that is empty. Pro. True. Soc. The only remaining possibility is that the soul apprehends it,
 which it must do by means of memory; for what other means could it employ? Pro. No other, I should say. Soc. And do we understand the consequences of this argument? Pro. What are the consequences? Soc. This argument declares that we have no bodily desire. Pro. How so? Soc. Because it shows that the endeavor of every living being is always towards the opposite of the actual conditions of the body. Pro. Yes, certainly. Soc. And the impulse which leads towards the opposite of those conditions shows that there is a memory of the opposite of the conditions. Pro. Certainly. Soc. And the argument, by showing that memory is that which leads us towards the objects of desire, has proved that all the impulse, the desire, and the ruling principle in every living being are of the soul. Pro. Quite right. Soc. So the argument denies utterly that the body hungers or thirsts or has any such affection. Pro. Very true. Soc. Let us consider a further point in connection with those very affections. For I think the purpose of the argument is to point out to us a state of life existing in them. Pro. Of what sort of life are you speaking, and in what affections does it exist? Soc. In the affections of fulness and emptiness and all which pertain to the preservation and destruction of living beings, and I am thinking that if we fall into one of these we feel pain, which is followed by joy when we change to the other. Pro. That is true. Soc. And what if a man is between the two? Pro. How between them?