The nerve of sight can not bear too bright a light. It asks to have the pupil made small, and even the eyelid curtains put down, when the light is too strong.
Once, there was a boy who said boastfully to his playmates: "Let us see which of us can look straight at the sun for the longest time."
Then they foolishly began to look at the sun. The delicate nerves of sight felt a sharp pain, and begged to have the pupils made as small as possible and the eyelid curtains put down.
But the foolish boys said "No." They were trying to see which would bear it the longest. Great harm was done to the brains as well as eyes of both these boys. The one who looked longest at the sun died in consequence of his foolish act.
The second story is about a little boy who tried to turn his eyes to imitate a schoolmate who was cross-eyed. He turned them; but he could not turn them back again. Although he is now a gentleman more than fifty years old and has had much painful work done upon his eyes, the doctors have never been able to set them quite right.
You see from the first story, that you must be careful not to give your eyes too much light. But you must also be sure to give them light enough.
When one tries to read in the twilight, the little nerve of sight says: "Give me more light; I am hurt, by trying to see in the dark."
If you should kill these delicate nerves, no others would ever grow in place of them, and you would never be able to see again.
THE EARS.
What you call your ears are only pieces of gristle, so curved as to catch the sounds and pass them along to the true ears. These are deeper in the head, where the nerve of hearing is waiting to send an account of each sound to the brain.