The next picture (Fig. 136) shows you a seed cut across, and so magnified that you can see plainly its many cells. In the middle portion of the seed the cells are six-sided, and laid against one another in an orderly and beautiful fashion, while the outer ones are mostly round. All animals, we ourselves, all plants, began life as a single cell. Sometimes a cell will spend its life alone. When the time comes for it to add to the life of the world, it divides into two or more “daughter cells,” as they are called. These break away from one another, and in like manner divide again. But usually the single cell which marks the beginning of a new life adds to itself other cells; that is, the different cells do not break away from one another, but all cling together, and so build up the perfect plant or animal. By just such additions the greatest tree in the forest grew from a single tiny cell. [Illustration: FIG. 136] By just such additions you children have grown to be what you are, and in the same way you will continue to grow. Every living thing must eat and breathe, and so all living cells must have food and air. These they take in through their delicate cell walls. The power to do this comes from the bit of living substance which lies within these walls. This strange, wonderful material within the little cell is what is alive in every man and woman, in every boy and girl, in every living thing, whether plant or animal. We know this much about it, and not the wisest man that ever lived knows much more. For though the wise men know just what things go to make up this material, and though they themselves can put together these same things, they can no more make life, or understand the making of it, than can you or I. But when we get a good hold of the idea that this material is contained in all living things, then we begin to feel this; we begin to feel that men and women, boys and girls, big animals and little insects, trees and flowers, wayside weeds and grasses, the ferns and rushes of the forest, the gray lichens of the cliffs and fences, the seaweeds that sway in the green rock pools, and living things so tiny that our eyes must fail to see them,—that all these are bound into one by the tie of that strange and wonderful thing called life; that they are all different expressions of one mysterious, magnificent idea. While writing that last sentence, I almost forgot that I was writing for boys and girls, or indeed for any one but myself; and I am afraid that perhaps you have very little idea of what I am talking about. But I will not cross it out. Why not, do you suppose? Because I feel almost sure that here and there among you is a girl or boy who will get just a little glimmering idea of what I mean; and perhaps as the years go by, that glimmer will change into a light so bright and clear as to become a help in dark places.