Republic (6.509)

But as for knowledge and truth, even as in our illustration it is right to deem light and vision sunlike, but never to think that they are the sun, so here it is right to consider these two their counterparts, as being like the good or boniform,[*] but to think that either of them is the good[*] is not right. Still higher honor belongs to the possession and habit[*] of the good.An inconceivable beauty you speak of, he said, if it is the source of knowledge and truth, and yet itself surpasses them in beauty. For you surely[*] cannot mean that it is pleasure. Hush, said I, but examine the similitude of it still further in this way.[*] How? The sun, I presume you will say, not only furnishes to visibles the power of visibility but it also provides for their generation and growth and nurture though it is not itself generation. Of course not. In like manner, then, you are to say that the objects of knowledge not only receive from the presence of the good their being known, but their very existence and essence is derived to them from it, though the good itself is not essence but still transcends essence[*] in dignity and surpassing power. And Glaucon very ludicrously[*] said, Heaven save us, hyperbole[*] can no further go. The fault is yours, I said, for compelling me to utter my thoughts about it. And don’t desist, he said, but at least[*] expound the similitude of the sun, if there is anything that you are omitting. Why, certainly, I said, I am omitting a great deal. Well, don’t omit the least bit, he said. I fancy, I said, that I shall have to pass over much, but nevertheless so far as it is at present practicable I shall not willingly leave anything out. Do not, he said. Conceive then, said I, as we were saying, that there are these two entities, and that one of them is sovereign over the intelligible order and region and the other over the world of the eye-ball, not to say the sky-ball,[*] but let that pass. You surely apprehend the two types, the visible and the intelligible. I do. Represent them then, as it were, by a line divided[*] into two unequal[*] sections and cut each section again in the same ratio (the section, that is, of the visible and that of the intelligible order), and then as an expression of the ratio of their comparative clearness and obscurity you will have, as one of the sections of the visible world, images.