"When I was young, Cebes, I had a prodigious desire to know the department of philosophy which is called Natural Science; this appeared to me to have lofty aims, as being the science which has to do with the causes of things, and which teaches why a thing is, and is created and destroyed; and I always agitated myself with the consideration of such questions as these... I went on to examine the decay of them, and then to the study of the heaven and earth, and at last I concluded that I was wholly incapable of these inquiries... There was a time when I thought that I understood the meaning of greater and less pretty well... that ten is more than eight, and that two cubits are more than one, because two is twice one. I should be far from imagining... that I knew the cause of any of them, indeed I should, for I cannot satisfy myself that when one is added to one, the one to which the addition is made becomes two... nor can I understand how the division of one is the way to make two; for then a different cause would produce the same effect."