My meaning was, that if one term of a relation is taken alone, the other is taken alone; if one term is qualified, the other is also qualified.

I do not mean to say that relatives may not be disparate, or that the science of health is healthy, or of disease necessarily diseased, or that the sciences of good and evil are therefore good and evil; but only that, when the term science is no longer used absolutely, but has a qualified object which in this case is the nature of health and disease, it becomes defined, and is hence called not merely science, but the science of medicine.
I quite understand, and I think as you do.
Would you not say that thirst is one of these essentially relative terms, having clearly a relation-- Yes, thirst is relative to drink.
And a certain kind of thirst is relative to a certain kind of drink; but thirst taken alone is neither of much nor little, nor of good nor bad, nor of any particular kind of drink, but of drink only?
Certainly.
Then the soul of the thirsty one, in so far as he is thirsty, desires only drink; for this he yearns and tries to obtain it?
That is plain.
And if you suppose something which pulls a thirsty soul away from drink, that must be different from the thirsty principle which draws him like a beast to drink; for, as we were saying, the same thing cannot at the same time with the same part of itself act in contrary ways about the same.
Impossible.
No more than you can say that the hands of the archer push and pull the bow at the same time, but what you say is that one hand pushes and the other pulls.
Exactly so, he replied.
And might a man be thirsty, and yet unwilling to drink?
Yes, he said, it constantly happens.
And in such a case what is one to say?
Would you not say that there was something in the soul bidding a man to drink, and something else forbidding him, which is other and stronger than the principle which bids him?
I should say so.
And the forbidding principle is derived from reason, and that which bids and attracts proceeds from passion and disease?
Clearly.
Then we may fairly assume that they are two, and that they differ from one another; the one with which a man reasons, we may call the rational principle of the soul, the other, with which he loves and hungers and thirsts and feels the flutterings of any other desire, may be termed the irrational or appetitive, the ally of sundry pleasures and satisfactions?
Yes, he said, we may fairly assume them to be different.
Then let us finally determine that there are two principles existing in the soul.

And what of passion, or spirit?
Is it a third, or akin to one of the preceding?
I should be inclined to say--akin to desire.
Well, I said, there is a story which I remember to have heard, and in which I put faith.

The story is, that Leontius, the son of Aglaion, coming up one day from the Piraeus, under the north wall on the outside, observed some dead bodies lying on the ground at the place of execution.
He felt a desire to see them, and also a dread and abhorrence of them; for a time he struggled and covered his eyes, but at length the desire got the better of him; and forcing them open, he ran up to the dead bodies, saying, Look, ye wretches, take your fill of the fair sight.
I have heard the story myself, he said.
The moral of the tale is, that anger at times goes to war with desire, as though they were two distinct things.
Yes; that is the meaning, he said.
And are there not many other cases in which we observe that when a man's desires violently prevail over his reason, he reviles himself, and is angry at the violence within him, and that in this struggle, which is like the struggle of factions in a State, his spirit is on the side of his reason;--but for the passionate or spirited element to take part with the desires when reason decides that she should not be opposed, is a sort of thing which I believe that you never observed occurring in yourself, nor, as I should imagine, in any one else?
Certainly not.
Suppose that a man thinks he has done a wrong to another, the nobler he is the less able is he to feel indignant at any suffering, such as hunger, or cold, or any other pain which the injured person may inflict upon him--these he deems to be just, and, as I say, his anger refuses to be excited by them.
True, he said.
But when he thinks that he is the sufferer of the wrong, then he boils and chafes, and is on the side of what he believes to be justice; and because he suffers hunger or cold or other pain he is only the more determined to persevere and conquer.

His noble spirit will not be quelled until he either slays or is slain; or until he hears the voice of the shepherd, that is, reason, bidding his dog bark no more.
The illustration is perfect, he replied; and in our State, as we were saying, the auxiliaries were to be dogs, and to hear the voice of the rulers, who are their shepherds.
I perceive, I said, that you quite understand me; there is, however, a further point which I wish you to consider.
What point?
You remember that passion or spirit appeared at first sight to be a kind of desire, but now we should say quite the contrary; for in the conflict of the soul spirit is arrayed on the side of the rational principle.
Most assuredly.
But a further question arises: Is passion different from reason also, or only a kind of reason; in which latter case, instead of three principles in the soul, there will only be two, the rational and the concupiscent; or rather, as the State was composed of three classes, traders, auxiliaries, counsellors, so may there not be in the individual soul a third element which is passion or spirit, and when not corrupted by bad education is the natural auxiliary of reason?
Yes, he said, there must be a third.
Yes, I replied, if passion, which has already been shown to be different from desire, turn out also to be different from reason.
But that is easily proved:--We may observe even in young children that they are full of spirit almost as soon as they are born, whereas some of them never seem to attain to the use of reason, and most of them late enough.
Excellent, I said, and you may see passion equally in brute animals, which is a further proof of the truth of what you are saying.