Soc. Then now, Theaetetus, take another view of the subject : you answered that knowledge is perception ?
Theaet. I did.
Soc. And if any one were to ask you : With what does a man see black and white colours ? and with what does he hear high and low sounds ? — you would say, if I am not mistaken, “With the eyes and with the ears.”
Theaet. I should.
Soc. The free use of words and phrases, rather than minute precision, is generally characteristic of a liberal education, and the opposite is pedantic ; but sometimes precision. is necessary, and I believe that the answer which you have just given is open to the charge of incorrectness ; for which is more correct, to say that we see or hear with the eyes and with the ears, or through the eyes and through the ears.
Theaet. I should say “through,” Socrates, rather than “with.”
Soc. Yes, my boy, for no one can suppose that in each of us, as in a sort of Trojan horse, there are perched a number of unconnected senses, which do not all meet in some one nature, the mind, or whatever we please to call it, of which they are the instruments, and with which through them we perceive objects of sense.
Theaet. I agree with you in that opinion.
Soc. The reason why I am thus precise is, because I want to know whether, when we perceive black and white through the eyes, and again, other qualities through other organs, we do not perceive them with one and the same part of ourselves, and, if you were asked, you might refer all such perceptions to the body. Perhaps, however, I had better allow you to answer for yourself and not interfere ; Tell me, then, are not the organs through which you perceive warm and hard and light and sweet, organs of the body ?
Theaet. Of the body, certainly.
Soc. And you would admit that what you perceive through one faculty you cannot perceive through another ; the objects of hearing, for example, cannot be perceived through sight, or the objects of sight through hearing ?
Theaet. Of course not.
Soc. If you have any thought about both of them, this common perception cannot come to you, either through the one or the other organ ?
Theaet. It cannot.
Soc. How about sounds and colours : in the first place you would admit that they both exist ?
Theaet. Yes.
Soc. And that either of them is different from the other, and the same with itself ?
Theaet. Certainly.
Soc. And that both are two and each of them one ?
Theaet. Yes.
Soc. You can further observe whether they are like or unlike one another ?
Theaet. I dare say.
Soc. But through what do you perceive all this about them ? for neither through hearing nor yet through seeing can you apprehend that which they have in common. Let me give you an illustration of the point at issue : — If there were any meaning in asking whether sounds and colours are saline or not, you would be able to tell me what faculty would consider the question. It would not be sight or hearing, but some other.
Theaet. Certainly ; the faculty of taste.
Soc. Very good ; and now tell me what is the power which discerns, not only in sensible objects, but in all things, universal notions, such as those which are called being and not-being, and those others about which we were just asking — what organs will you assign for the perception of these notions ?
Theaet. You are thinking of being and not being, likeness and unlikeness, sameness and difference, and also of unity and other numbers which are applied to objects of sense ; and you mean to ask, through what bodily organ the soul perceives odd and even numbers and other arithmetical conceptions.
Soc. You follow me excellently, Theaetetus ; that is precisely what I am asking.
Theaet. Indeed, Socrates, I cannot answer ; my only notion is, that these, unlike objects of sense, have no separate organ, but that the mind, by a power of her own, contemplates the universals in all things.
Soc. 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.
Theaet. I am quite clear.
Soc. And to which class would you refer being or essence ; for this, of all our notions, is the most universal ?
Theaet. I should say, to that class which the soul aspires to know of herself.
Soc. And would you say this also of like and unlike, same and other ?
Theaet. Yes.
Soc. And would you say the same of the noble and base, and of good and evil ?
Theaet. 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.
Soc. 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 ?
Theaet. Yes.
Soc. 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 ?
Theaet. Certainly.
Soc. 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.
Theaet. Assuredly.
Soc. And can a man attain truth who fails of attaining being ?
Theaet. Impossible.
Soc. And can he who misses the truth of anything, have a knowledge of that thing ?
Theaet. He cannot.
Soc. 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 ?
Theaet. Clearly.
Soc. And would you call the two processes by the same name, when there is so great difference between them ?
Theaet. That would certainly not be right.
Soc. And what name would you give to seeing, hearing, smelling, being cold and being hot ?
Theaet. I should call all of them perceiving — what other name could be given to them ?
Soc. Perception would be the collective name of them ?
Theaet. Certainly.
Soc. Which, as we say, has no part in the attainment of truth any more of being ?
Theaet. Certainly not.
Soc. And therefore not in. science or knowledge ?
Theaet. No.
Soc. Then perception, Theaetetus, can never be the same as knowledge or science ?
Theaet. Clearly not, Socrates ; and knowledge has now been most distinctly proved to be different from perception.