But you children who have good eyes that can see, do you really see things when you look at them? You can train your eyes just as you can train your ears. You can teach them to read quickly down a page, and to find things in pictures, and, better still, to see things out of doors, in the garden and the woods and on the seashore. We hear a great deal about "sharp eyes," but most of us see very little of all we might see. Our eyes are on the lookout, too, to protect us from dangers that may come; with our skin and nose and ears, they are constantly on the watch; so the better we see the safer we are. Even if your eyes are perfect now, you will need to take good care of them to keep them strong. Don't let any story, no matter how interesting it is, tempt you to read in a dim light or a light that is too strong. And if you can't see the blackboard easily, or can't read big print, like the school calendar, across the room, tell your mother or your teacher, so that she can ask the doctor to find out what the matter is. IV. A DRINK OF WATER It is astonishing what thirsty work studying is! Scarcely is the second recitation over before your throat begins to feel dry, and up goes your hand--"May I get a drink?" If anyone even says the word "water," it makes you thirsty. It is so good that just the thought of it makes you want some. I should like you to notice how much water you drink every day. Perhaps a glass in the morning when you get up, and one at night before you go to bed, and three or four in between. Why do we need so much water? Well, how much do you weigh? Perhaps you will find it hard to believe, but more than half of that weight is water; and because we are always giving off water from the skin and from the body, we need plenty more to take its place. No living thing can grow without water. Take a bean, for instance, and put it in an empty glass on the window sill; and even if the sun shines full upon it, nothing will happen, except that after a few days it will shrivel and dry up. But fill the glass with water, and in a few hours the bean will begin to swell; and in a few days it will burst, and a little shoot will grow out of one end of it and a tiny root at the other. The water and the warmth together have made it sprout and grow. [Illustration: A DRINKING-CUP EASILY MADE] Children at school and people on trains should have their own private cups, for serious diseases may be caught from the mouths of other people. You can get a metal pocket folding cup for ten or fifteen cents, or paper ones for a few cents a dozen. If you don't have your own cup, I hope you will get one and carry it. Here is a pattern for a paper cup that you can easily make for yourselves. Try it and see. When you have once learned how, you can make it very quickly and have a fresh cup every time you want one; but of course you should be sure first that the paper itself is clean.