SOCRATES: A jest is sometimes refreshing, Protarchus, when it interrupts earnest. PROTARCHUS: Very true. SOCRATES: I think, friend, that we have now pretty clearly set forth the class to which mind belongs and what is the power of mind. PROTARCHUS: True. SOCRATES: And the class to which pleasure belongs has also been long ago discovered? PROTARCHUS: Yes. SOCRATES: And let us remember, too, of both of them, (1) that mind was akin to the cause and of this family; and (2) that pleasure is infinite and belongs to the class which neither has, nor ever will have in itself, a beginning, middle, or end of its own. PROTARCHUS: I shall be sure to remember. SOCRATES: We must next examine what is their place and under what conditions they are generated. And we will begin with pleasure, since her class was first examined; and yet pleasure cannot be rightly tested apart from pain. PROTARCHUS: If this is the road, let us take it. SOCRATES: I wonder whether you would agree with me about the origin of pleasure and pain. PROTARCHUS: What do you mean? SOCRATES: I mean to say that their natural seat is in the mixed class. PROTARCHUS: And would you tell me again, sweet Socrates, which of the aforesaid classes is the mixed one? SOCRATES: I will, my fine fellow, to the best of my ability. PROTARCHUS: Very good. SOCRATES: Let us then understand the mixed class to be that which we placed third in the list of four. PROTARCHUS: That which followed the infinite and the finite; and in which you ranked health, and, if I am not mistaken, harmony. SOCRATES: Capital; and now will you please to give me your best attention? PROTARCHUS: Proceed; I am attending. SOCRATES: I say that when the harmony in animals is dissolved, there is also a dissolution of nature and a generation of pain. PROTARCHUS: That is very probable. SOCRATES: And the restoration of harmony and return to nature is the source of pleasure, if I may be allowed to speak in the fewest and shortest words about matters of the greatest moment. PROTARCHUS: I believe that you are right, Socrates; but will you try to be a little plainer? SOCRATES: Do not obvious and every-day phenomena furnish the simplest illustration? PROTARCHUS: What phenomena do you mean? SOCRATES: Hunger, for example, is a dissolution and a pain. PROTARCHUS: True. SOCRATES: Whereas eating is a replenishment and a pleasure? PROTARCHUS: Yes. SOCRATES: Thirst again is a destruction and a pain, but the effect of moisture replenishing the dry place is a pleasure: once more, the unnatural separation and dissolution caused by heat is painful, and the natural restoration and refrigeration is pleasant. PROTARCHUS: Very true.