Where Do Tears Come From?
Tears are not made only when we cry. They seem to come only when you cry, because it is then that they spill over. A little part of you is making tears all the time, and your eyes are constantly washing themselves in them. You have often noticed how you wink every few seconds? You have often tried to keep from winking—to see how long you could keep from winking. Boys and girls often do that, and when you keep from winking what seems a long time, you notice how your eyes ache and feel very dry just before you have to let them wink, in spite of how hard you try not to, and just when you think you are not going to. I will tell you just what winking does for the eyes. All of the time your eyes are open the front, or the part you see things with, is exposed to the dust and dirt that fills the air at all times, although we cannot always see the dust. The wind, too, is constantly making them dry. But have you ever noticed that although you never wash the inside of the front of the eye, or pupil, it is always clean? Well, it is because your eye washes itself every time you wink. I will tell you how this is done. Up above each eye, inside, of course, there is a little gland called the tear-gland. This gland is busy all the time you are awake making tears. As soon as the front of your eye becomes dry, or if a particle of dust or anything else strikes it, the nerves you have there tell the brain, and almost at once the eyelid comes down with a tear inside of it, and so washes the front of your eye clean again. It does its work perfectly and as often as necessary. There is always a tear ready to be used in this way.