We eventually stop growing because certain of the cells of the body lose their ability of increasing in size and producing other cells. It is one of the marvels of the construction of the human body that this is so and one of the wisest provisions also. At first the cells of the body crave lots of food and increase in size, divide and then the parts go on growing until they become of a certain size, when they again divide and each part goes on growing, etc., and thus we grow. A growing boy needs more fond than a mature man, because he needs some of it to grow with, while the man only has to keep what growth he has going, i. e., alive. We say this limit of growth is a wise provision of nature because if there were no limit to the size we might become, we would not know how large to build houses, barns, etc., or else we would have to build them so large to start with that we would be lost in them for a long time. We would constantly be forced to change these things and there would be no basis to reckon from. Dogs might be as big as elephants and then they would be of no use to us, or of what use would a dog as big as an elephant be to a boy of five years. You see it would not do at all to have this rule changed. Why Do We Grow Aged? We age directly in accordance with the lives we lead. You can bend a wire back and forth a number of times at the same point without breaking it, but eventually it will break. Just so with the human body. You can use each part of it for its own purposes a number of times, but eventually the break will come. Or, you can fail to make a part of it perform its regular functions, and it will die--the break will come. The human body is the most wonderful machine in the world, but even it will eventually wear out. Every time you move your arm, leg or some other part of your body, you destroy some tissues. The body replenishes and builds up those tissues again for a certain time. When you bend a joint in your body, the body oils the joint naturally, but as you grow older, or rather, as you use the different parts of your body more and more, it brings nearer always the time, when the body cannot, of its own accord, build up again the tissues you have destroyed. That is why some people become very old at forty and others are still comparatively young at seventy. It requires a great deal of care and attention and the elimination of all abuse of the body to keep us young when we are old. The use of drink, lack of sufficient sleep and other abuses prevent the body from restoring the tissues which have been destroyed. Worry and sorrow age us very rapidly, because these things affect the nerves. If the nerves are not quiet we cannot get any rest and without rest we grow old very rapidly. What Causes Wrinkles?