--He said, as I returned it to him, You have heard military men say that such a person had an eye for country, have n't you? One man will note all the landmarks, keep the points of compass in his head, observe how the streams run, in short, carry a map in his brain of any region that he has marched or galloped through. Another man takes no note of any of these things; always follows somebody else's lead when he can, and gets lost if he is left to himself; a mere owl in daylight. Just so some men have an eye for an equation, and would read at sight the one that you puzzled over. It is told of Sir Isaac Newton that he required no demonstration of the propositions in Euclid's Geometry, but as soon as he had read the enunciation the solution or answer was plain at once. The power may be cultivated, but I think it is to a great degree a natural gift, as is the eye for color, as is the ear for music. --I think I could read equations readily enough,--I said,--if I could only keep my attention fixed on them; and I think I could keep my attention on them if I were imprisoned in a thinking-cell, such as the Creative Intelligence shapes for its studio when at its divinest work. The young man's lustrous eyes opened very widely as he asked me to explain what I meant. --What is the Creator's divinest work?--I asked. --Is there anything more divine than the sun; than a sun with its planets revolving about it, warming them, lighting them, and giving conscious life to the beings that move on them? --You agree, then, that conscious life is the grand aim and end of all this vast mechanism. Without life that could feel and enjoy, the splendors and creative energy would all be thrown away. You know Harvey's saying, omnia animalia ex ovo,--all animals come from an egg. You ought to know it, for the great controversy going on about spontaneous generation has brought it into special prominence lately. Well, then, the ovum, the egg, is, to speak in human phrase, the Creator's more private and sacred studio, for his magnum opus. Now, look at a hen's egg, which is a convenient one to study, because it is large enough and built solidly enough to look at and handle easily. That would be the form I would choose for my thinking-cell. Build me an oval with smooth, translucent walls, and put me in the centre of it with Newton's “Principia” or Kant's “Kritik,” and I think I shall develop “an eye for an equation,” as you call it, and a capacity for an abstraction. But do tell me,--said the Astronomer, a little incredulously,--what there is in that particular form which is going to help you to be a mathematician or a metaphysician?