Socrates: But how can a man who is empty for the first time, attain either by perception or memory to any apprehension of replenishment, of which he has no present or past experience?
Protarchus: Impossible.
Socrates: And yet he who desires, surely desires something?
Protarchus: Of course.
Socrates: He does not desire that which he experiences, for he experiences thirst, and thirst is emptiness; but he desires replenishment?
Protarchus: True.
Socrates: Then there must be something in the thirsty man which in some way apprehends replenishment?
Protarchus: There must.
Socrates: And that cannot be the body, for the body is supposed to be emptied?
Protarchus: Yes.
Socrates: The only remaining alternative is that the soul apprehends the replenishment by the help of memory; as is obvious, for what other way can there be?
Protarchus: I cannot imagine any other.
Socrates: But do you see the consequence?
Protarchus: What is it?
Socrates: That there is no such thing as desire of the body.
Protarchus: Why so?
Socrates: Why, because the argument shows that the endeavour of every animal is to the reverse of his bodily state.
Protarchus: Yes.
Socrates: And the impulse which leads him to the opposite of what he is experiencing proves that he has a memory of the opposite state.
Protarchus: True.
Socrates: And the argument, having proved that memory attracts us towards the objects of desire, proves also that the impulses and the desires and the moving principle in every living being have their origin in the soul.
Protarchus: Most true.
Socrates: The argument will not allow that our body either hungers or thirsts or has any similar experience.
Protarchus: Quite right.
Socrates: Let me make a further observation; the argument appears to me to imply that there is a kind of life which consists in these affections.