Читать книгу Plato: The Complete Works онлайн

81 страница из 571

Yes, he said.

Now then, I said, making an offering of the third or last argument to Zeus the Saviour, let us begin again, and ask, in the first place, whether it is or is not possible for a person to know that he knows and does not know what he knows and does not know; and in the second place, whether, if perfectly possible, such knowledge is of any use.

That is what we have to consider, he said.

And here, Critias, I said, I hope that you will find a way out of a difficulty into which I have got myself. Shall I tell you the nature of the difficulty?

By all means, he replied.

Does not what you have been saying, if true, amount to this: that there must be a single science which is wholly a science of itself and of other sciences, and that the same is also the science of the absence of science?

Yes.

But consider how monstrous this proposition is, my friend: in any parallel case, the impossibility will be transparent to you.

How is that? and in what cases do you mean?

In such cases as this: Suppose that there is a kind of vision which is not like ordinary vision, but a vision of itself and of other sorts of vision, and of the defect of them, which in seeing sees no colour, but only itself and other sorts of vision: Do you think that there is such a kind of vision?