SOCRATES: And yet they are very different; what common nature have we in view when we call them by a single name?
PROTARCHUS: By heavens, Socrates, that is a question which is not easily answered; but it must be answered.
SOCRATES: Then let us go back to our examples.
PROTARCHUS: Where shall we begin?
SOCRATES: Do we mean anything when we say 'a man thirsts'?
PROTARCHUS: Yes.
SOCRATES: We mean to say that he 'is empty'?
PROTARCHUS: Of course.
SOCRATES: And is not thirst desire?
PROTARCHUS: Yes, of drink.