SOCRATES: Well, but if a man who is full of knowledge loses his knowledge, are there not pains of forgetting?
PROTARCHUS: Not necessarily, but there may be times of reflection, when he feels grief at the loss of his knowledge.
SOCRATES: Yes, my friend, but at present we are enumerating only the natural perceptions, and have nothing to do with reflection.
PROTARCHUS: In that case you are right in saying that the loss of knowledge is not attended with pain.
SOCRATES: These pleasures of knowledge, then, are unmixed with pain; and they are not the pleasures of the many but of a very few.
PROTARCHUS: Quite true.
SOCRATES: And now, having fairly separated the pure pleasures and those which may be rightly termed impure, let us further add to our description of them, that the pleasures which are in excess have no measure, but that those which are not in excess have measure; the great, the excessive, whether more or less frequent, we shall be right in referring to the class of the infinite, and of the more and less, which pours through body and soul alike; and the others we shall refer to the class which has measure.
PROTARCHUS: Quite right, Socrates.
SOCRATES: Still there is something more to be considered about pleasures.
PROTARCHUS: What is it?