And therefore, I said, as we might expect, there is nothing here which invites or excites intelligence. There is not, he said. But is this equally true of the greatness and smallness of the fingers? Can sight adequately perceive them? and is no difference made by the circumstance that one of the fingers is in the middle and another at the extremity? And in like manner does the touch adequately perceive the qualities of thickness or thinness, or softness or hardness? And so of the other senses; do they give perfect intimations of such matters? Is not their mode of operation on this wise--the sense which is concerned with the quality of hardness is necessarily concerned also with the quality of softness, and only intimates to the soul that the same thing is felt to be both hard and soft? You are quite right, he said. And must not the soul be perplexed at this intimation which the sense gives of a hard which is also soft? What, again, is the meaning of light and heavy, if that which is light is also heavy, and that which is heavy, light? Yes, he said, these intimations which the soul receives are very curious and require to be explained. Yes, I said, and in these perplexities the soul naturally summons to her aid calculation and intelligence, that she may see whether the several objects announced to her are one or two. True. And if they turn out to be two, is not each of them one and different? Certainly. And if each is one, and both are two, she will conceive the two as in a state of division, for if there were undivided they could only be conceived of as one? True. The eye certainly did see both small and great, but only in a confused manner; they were not distinguished. Yes. Whereas the thinking mind, intending to light up the chaos, was compelled to reverse the process, and look at small and great as separate and not confused. Very true. Was not this the beginning of the enquiry 'What is great?' and 'What is small?' Exactly so. And thus arose the distinction of the visible and the intelligible. Most true. This was what I meant when I spoke of impressions which invited the intellect, or the reverse--those which are simultaneous with opposite impressions, invite thought; those which are not simultaneous do not. I understand, he said, and agree with you. And to which class do unity and number belong? I do not know, he replied.