In the same way we will bring down the distance of the Moon from the Earth. We will let _each thousand miles_ of all that space in the sky shrink into a tiny _half-inch_. Then, instead of two hundred and forty thousand miles, we shall only have to think of one hundred and twenty inches, which make ten feet. So the smaller ball, or walnut, must be put _ten feet_ off from the larger ball, or cocoa-nut. That will give you a picture, not only of the size of the earth, compared with the size of the Moon, but also of the distance between the two. Besides putting the two balls ten feet apart you have to think of them as two little shining worlds. That is not quite so easy, is it? Why should they shine? We know that bodies in the sky do shine; but bodies on the Earth more commonly do not. By “bodies” I mean “things.” A marble does not shine, nor a grape, nor a walnut, nor an apple, nor an orange, nor a school-globe, nor a balloon. At least they do not shine of themselves. Any of them can be made to shine a little, if not much, by being placed in bright sunshine. Suppose that the two balls--the little imitation-Earth and the little imitation-Moon--were made of glass, or of some smooth metal, such as tin or silver. And suppose you were to hang them up, by wires, out-of-doors, in pitch darkness. Would they shine? Certainly not. How could they? But suppose there was another ball, also out in the darkness; a much larger ball, shining with great brilliance, like an electric light. Would the glass or metal balls show any brightness then at all? Yes; for the shining of the large brilliant ball would light them up, at least on one side, and would make them bright. Light is always _thrown back_ from a smooth surface. If you have a looking-glass in a dark room it does not shine; but if you hold it in full sunlight it flashes radiantly. Yet the looking-glass has no brightness of its own. It only takes and gives out again of the Sun’s light. That is just how our Earth shines, and how the Moon shines. In themselves both are dull and dark worlds; but, like the looking-glass, they receive radiance from the Sun and give it out again. Before we go on I want you to be quite clear in your mind as to what is really meant by this bringing down of large sizes to small sizes. In coming pages you will often hear of it again. Suppose you have two very large toy-carts, big and heavy. One of them is four feet long and two feet wide, the other of them is three feet long and one foot and a half wide. And suppose that you are trying to explain, to somebody who has not seen them, _how much bigger_ one cart is than the other cart. You may do it by talking, and by showing with your hands about how high they each stand. Or you may do it in quite a different manner, and much more exactly, by making a kind of little model of each cart--in paper, or cardboard, or wax.