Part 7

The bony part of the tooth, on the other hand, starts as a paper-thin sheet, but full sized. The living cells which build the hard bone, lie on the inside of this shell. They keep building on more bone on the inner surface, pushing themselves toward the middle of the tooth, until the tooth wall is so thick that only a narrow space is left in the center. But their long roots which they leave behind, still reach thru to the outer surface of the bone, ready to ache when there is occasion. Meantime, the outside of the tooth pocket, as we have learned, has been plastering on enamel on the outside of the shell, and pushing itself farther and farther away.

A plant’s roots, like its branches, grow at the tips; and the nerves in our own bodies grow in somewhat the same way, beginning at the inner end, and somehow finding their way thru and around the other tissues of the body, till they find the place to which they were sent. But the muscles and the fat grow thruout their mass, like dough being raised for bread. Most of the hollow tubes of the body—the blood vessels, for example, and the red lane down which our breakfast goes—grow in this way. But the hollow bones, as they grow, are taken down on the inside to enlarge the hollow, and built up again on the outside with old material and new to enlarge the shaft.

Even the blood grows, the watery portion coming from the food we eat and the water we drink; but the red and white corpuscles which float in the watery part, are made in special factories in the body (some of them in the marrow of the bones) and turned loose in the blood stream.

Growing, you see, tho easy to do, is by no means so simple as it appears.

How We Grow Up

Ten years from now, you who are reading these sentences will be grown up. Once you were little pink and white babies, all soft and sweet and clean. And because you were soft and unresisting, you grew at a tremendous rate. At first you probably doubled your weight in six months. Then it took three years; then six or eight. By the time you are twelve, you probably will be half as heavy as you ever will be. In all the rest of your lives, you will do no more growing than you did in the first 180 days of them.

You will grow, too, as you have grown, by fits and starts. Sometimes you will shoot up like sunflower stalks. Sometimes, again, you will stop growing large, and begin growing hard. You will not seem to be getting bigger; but you will be getting stronger. Then, when you start growing again, you will perhaps find that you really can’t do so much as you could when you were a year younger, nor do it so well.

So you will keep on, sometimes growing large and sometimes growing hard, but almost never both at once, until you come to the full stature of men and women, and your soft baby flesh that couldn’t lift its head from the pillow has changed to tough muscle and hard bone. That is, of course, supposing that you have taken care of yourselves. If you haven’t—why then it may be different.

This growing up is so common an affair, so many of us do it, puppies and calves and kittens and little rabbits and baby birds, that we usually forget how wonderful a matter it is. Wonderful indeed it is; yet hardly less strange is it that after we have grown a while, then we stop. Yet our hair, as we know, doesn’t stop, nor the skin, nor the nails. Sometimes parts of the body which have hardly grown at all in youth, start up and grow in middle life. But the parts of the body which count, the parts which if they did grow would make us larger, these somehow know enough to stop.

It is not so with some other living creatures. A tree does not stop growing so long as it lives; nor does a fish. The big oak or the big trout may have grown faster than the little one; most likely it has simply been growing longer. We call any creature adult when it is large enough to have children of its own. But the oak bears acorns and the trout lays eggs, and then keeps on growing till it is ten, twenty, fifty times bigger than it was when it first had little ones. It is as if the cat, when her kittens were growing up, kept on growing along with them; and next year when there were more kittens kept on growing nearly as fast as they; and kept on year after year as long as it lived until it got to be as large as an elephant. And still its kittens would be just kittens, no larger than before.

Many animals manage their growing this way. The star-fish egg, you remember, is for size like a minute grain of dust, and the baby star when he first hatches out is hardly bigger. After that, he eats all he can get and grows as fast as he can, like any other kind of baby.

But suppose the little star-fish, as large say as a pin head, doesn’t find enough to eat. Does he then starve? Not a bit. He simply doesn’t grow. The eggs hatch out in the late spring within a few weeks of one another, and the little stars which do not happen upon a good boarding place, go practically without food all summer long. They remain perfectly healthy; but they scarcely grow at all, so that at the end of the summer they are still the pin heads that they were six months before.

On the other hand, when a star-fish happens to be born where he can find plenty of barnacles or small clams or mussels, he doesn’t do much but eat, and grows to match. It may happen, then, that of two stars, hatched on the same day, the one which has been well fed will be no less than five thousand times larger than the other which has gone hungry. Now a grown man is only about fifteen times as large as a new-born babe. But this is as if two babies, each six months old, should be, one no heavier than at birth, while the other weighed twenty-five tons and was as large as a whale.

So you can’t judge by appearances. The star-fish that you pick up at the shore may be a very young animal which has been well fed, or a very old one which has gone on short rations, while a young star, still growing, may be twenty times larger than his own great-grandfather.

How We Grow Old

After we grow up, we grow old. People say that we first grow up to men and women; then we continue adults; then we grow old. Really, however, we begin to grow old the day we are born; while we shall never again grow old so fast as we did when we were babes in arms.

For growing old is simply growing hard. We begin life as squashy little babies. Our bones are like green sticks. Our flesh is like dough, only the softest cloth must touch our skins, and Nurse has to hold her hand under our poor backs to keep our heads from dropping off. Children are not squashy, but they are still soft. You can pinch children. Sometimes you do. But you can’t pinch a grown man, any more than you can pinch a board. Children are of course, much harder than babies. All the same, if you put your fingers in your mouths, or stand too much on one leg or slouch over your books or shrug your shoulders up beside your ears when you play first base, or sit on one foot when you curl up in the big chair in the library, or do any other of the forty-leven things that somebody has to tell you forty-leven times a day not to do, then you will pull your bones all out of shape as if they were so much India rubber; and when you grow up and your bones and muscles set, then you can’t get back into shape again—tho you’ll wish you could.

For get hard you will. Then you will be grown up. When you are just hard enough, you will be in the prime of life, able to work as easily as you now play, and liking it, I hope, even better. But still you will keep on getting hard; and when you get too hard, then you are old.

So growing old is growing hard. And since the younger you are, the faster you grow, you never grew old so fast as when you were a tiny baby, and you never again will grow old so fast as you are growing old now.

And the moral is, as the Duchess used to tell Alice, that since we stay young and soft only a very short while, and grown-up and hard most of our days, we’d better, as much as we possibly can, make the short end of our lives help out the long one.

What I mean is this. While we are young, we are soft and plastic and teachable. As we grow older, not only do our bodies harden, but our minds also. We can do a great deal more after we are grown up than we can while we are children; and I think we are, if less light-hearted, on the whole quite as happy. But we shall be a great deal less able to take up anything new. Let us, therefore, practice while we are young those things which will bring us most happiness, after we are too old to change.

For example, suppose a boy is fond of out-door games, as every normal and healthy boy ought to be. He plays baseball all the spring, tennis all summer, football thruout the autumn, and what there is left of the year goes into ice hockey. He plays expertly, has a glorious time; and he grows up manly and strong. This is as it should be—so far.

But suppose the same boy, thru school and college and at work. There is no more football for him, and no more ice hockey. For a few years he may get an occasional game of baseball; if he is very lucky he will get a little tennis. But tell me, boy who is reading this page, how many of your father’s friends and associates ever play at all the games at which you spend your spare time?

Now while we are supposing, let us suppose that this boy of ours, instead of spending all his spare time at games, spent only half. The other half he shall devote to sports which are not games. He shall learn to ride a horse, to fish, to handle a sail boat, to swim, row, paddle, to climb mountains, to take care of himself in the woods, and above all to walk thru level country and enjoy the sight of all he sees. By and by, this boy will grow up. In the natural course of things, he will put away bat and ball and hockey stick before he is thirty, but rod and saddle and oar will bring him happiness and health almost to the end of his days.

There is a difference too in games. One plays football thru school and perhaps in college—eight years at the outside. But one world’s champion tennis player was well by forty; he must have played thirty years. A golfer gets forty or fifty years of pleasure for the trouble of learning his game. You may think you will learn the boy’s game now, and the man’s game later. But you won’t. You will learn the man’s game now along with the boy’s, or else you won’t learn it at all. You will be too old to learn, and go gameless to your grave.

Or suppose a girl is fond of music, and learns to play, very nicely, the banjo. It will be charming enough, summer evenings on the porch—so long as one is young and has only a girl’s soul to express in music. But by and by she will grow up to be a woman, and have little children of her own. Will she get out her banjo Sunday evenings and play for them hymns and solemn songs, or tinkle coon melodies for them when they are sick? Indeed she will not. She will put that banjo on the top shelf of the spare bed room closet, and wish she had spent her effort learning some other instrument more worth while.

So it is with everything else. If, while we are young, we train our ears to enjoy good music, and our eyes to love good pictures and good furniture, cloudy landscapes and great trees, and our minds to care for the important things of life, literature and religion and art and science and politics and history, we shall still possess growing sources of happiness longer after we have ceased to care to read stories or to be able to play ball. A wise child will study the happiest adults whom he knows, and learn to like and to do whatever most helps to make them blessed.

However, I meant to tell about how we grow old, rather than how we can best get ready to be so.