SOCRATES: I mean, O my Protarchus, to ask whether you would tell me that ship-building is for the sake of ships, or ships for the sake of ship-building? and in all similar cases I should ask the same question.
PROTARCHUS: Why do you not answer yourself, Socrates?
SOCRATES: I have no objection, but you must take your part.
PROTARCHUS: Certainly.
SOCRATES: My answer is, that all things instrumental, remedial, material, are given to us with a view to generation, and that each generation is relative to, or for the sake of, some being or essence, and that the whole of generation is relative to the whole of essence.
PROTARCHUS: Assuredly.
SOCRATES: Then pleasure, being a generation, must surely be for the sake of some essence?
PROTARCHUS: True.
SOCRATES: And that for the sake of which something else is done must be placed in the class of good, and that which is done for the sake of something else, in some other class, my good friend.
PROTARCHUS: Most certainly.