The Divided Line (The Republic , Book VI) You have to imagine, then, that there are two ruling powers, and that one of them is set over the intellectual world, the other over the visible. I do not say heaven, lest you should fancy that I am playing upon the name. May I suppose that you have this distinction of the visible and intelligible fixed in your mind? Glaucon I have. Socrates Now take a line which has been cut into two unequal parts and divide each of them again in the same proportion, and suppose the two main divisions to answer, one to the visible and the other to the intelligible, and then compare the subdivisions in respect of their clearness and want of clearness, and you will find that the first section in the sphere of the visible consists of images. And by images I mean, in the first place, shadows, and in the second place, reflections in water and in solid, smooth and polished bodies and the like: Do you understand? Glaucon Yes, I understand. Socrates Imagine, now, the other section, of which this is only the resemblance, to include the animals which we see, and everything that grows or is made. Glaucon Very good. Socrates Would you not admit that both the sections of this division have different degrees of truth, and that the copy is to the original as the sphere of opinion is to the sphere of knowledge? 1 Glaucon Most undoubtedly. Socrates Next proceed to consider the manner in which the sphere of the intellectual is to be divided. Glaucon In what manner? Socrates Thus: There are two subdivisions, in the lower of which the soul uses the figures given by thw former division as images; the enquiry can only be hypothetical, and instead of going upwards to a principle descends to the other end; in the higher of the two, the soul passes out of hypotheses, and goes up to a principle which is above hypotheses, making no use of images as in the former case, but proceeding only in and through the ideas ...
