sight, and what is perceived by sight cannot be perceived by hearing; yet we can form a notion of them both together, and observe what properties they have in common, and how they differ: this, however, is not done by the senses, but by the soul itself, for children as soon as they are born are able to perceive by the bodily organs, but only arrive, with much labour and difficulty, at the power of comparing things with each other, and so obtain a knowledge of them, whence again it follows that perception and science are not the same[1].
The first definition of science attempted by Theætetus being thus overthrown, Socrates again asks him. What science is. To which he answers that it appears to be true judgment. Socrates however thinks proper first to enquire whether there is such a thing as false judgment. People, he says, must either know or not know things about which they form judgments. Now false judgments are formed, when a person thinks that things which he does not know are certain other things that he does not know, or when he thinks that things which he does know are other things that he does know, or that things which he does not know are things that he does know. But none of these things can happen, therefore it is not possible to form false judgments. Again if existence is put for knowledge a similar train of reasoning leads to the same conclusion. A third method of forming false judgments may be when any one says that any real object is another real object, changing one for the other in his thoughts. But in that case he must think of both of them or one only; if the former he would contradict himself; if the latter he cannot judge that the one is the other, for he thinks of one only, so that neither in this way can false judgment be formed. There still remains another mode in which false judgments may be formed. Suppose that we have in our souls a waxen tablet of various qualities in different persons: on this tablet are impressed the images of our perceptions and thoughts, and whatever is so impressed we remember and know so long as the image remains. But by ex-
- ↑ § 101–107.
