Socrates: You are a beauty, Theaetetus, and not ugly, as Theodorus was saying; for he who utters the beautiful is himself beautiful and good. And besides being beautiful, you have done me a kindness in releasing me from a very long discussion, if you are clear that the soul views some things by herself and others through the bodily organs. For that was my own opinion, and I wanted you to agree with me.
Theaetetus: I am quite clear.
Socrates: And to which class would you refer being or essence; for this, of all our notions, is the most universal?
Theaetetus: I should say, to that class which the soul aspires to know of herself.
Socrates: And would you say this also of like and unlike, same and other?
Theaetetus: Yes.
Socrates: And would you say the same of the noble and base, and of good and evil?
Theaetetus: These I conceive to be notions which are essentially relative, and which the soul also perceives by comparing in herself things past and present with the future.
Socrates: And does she not perceive the hardness of that which is hard by the touch, and the softness of that which is soft equally by the touch?
Theaetetus: Yes.
Socrates: But their essence and what they are, and their opposition to one another, and the essential nature of this opposition, the soul herself endeavours to decide for us by the review and comparison of them?
Theaetetus: Certainly.
Socrates: The simple sensations which reach the soul through the body are given at birth to men and animals by nature, but their reflections on the being and use of them are slowly and hardly gained, if they are ever gained, by education and long experience.
Theaetetus: Assuredly.
Socrates: And can a man attain truth who fails of attaining being?
Theaetetus: Impossible.
Socrates: And can he who misses the truth of anything, have a knowledge of that thing?
Theaetetus: He cannot.
Socrates: Then knowledge does not consist in impressions of sense, but in reasoning about them; in that only, and not in the mere impression, truth and being can be attained?
Theaetetus: Clearly.
Socrates: And would you call the two processes by the same name, when there is so great a difference between them?
Theaetetus: That would certainly not be right.
Socrates: And what name would you give to seeing, hearing, smelling, being cold and being hot?
Theaetetus: I should call all of them perceiving—what other name could be given to them?
Socrates: Perception would be the collective name of them?