There is knowledge, then, going all the time to the mind by the nerves from these instruments. It can not get there in any other way. Suppose the mind was locked up in the brain, and had no nerves going out from it. It could not learn any thing about what is around it; there might be eyes, and fingers, and ears, and a nose, and a mouth, but these would be of no use to the mind if there were no nerves.
How the mind learns about things.
See how the child learns about the world of things all around him. When he is first born he does not know any thing. He does not know how any thing feels, or looks, or tastes, or smells. But with his little nerves his mind gets messages from the senses, and so he learns every day about the things that are around him. Eyes, ears, nose, mouth, and fingers are all the time telling his mind something through the nerves. They tell him first about those things that are in the room where he is, and then, after a while, when he is carried out, they tell him about things that are out of doors, and thus he knows more and more every day.
And then, too, the mind thinks about what the senses tell it. It lays up what comes to it by the nerves, and looks it over, as we may say, and in this way it learns a great deal. There is great difference in people in this thinking about what the mind knows by the senses. Some that see and hear a great many things do not know as much as some that see and hear few things. It is because they do not think much about what the senses tell the mind.
You see, then, that all that we learn in this world really comes into the mind by the way of the nerves from the senses—the sight, the hearing, the touch, the smell, and the taste. The senses are the inlets or openings by which knowledge enters, and the nerves are the passages by which it gets to the mind in the brain; and after it gets there the mind thinks about it and uses it in various ways.
The deaf and the blind.
Deaf and dumb.
How the blind read.
Some persons, you know, do not have all these inlets for knowledge open. For example, some are deaf; in them no knowledge can get into the mind by the ears. Some are blind, and no knowledge can get into their minds by the eyes. More knowledge comes into the mind by the sight than by the hearing; it is therefore a greater misfortune to be blind than it is to be deaf.
It is astonishing to see how much the deaf and the blind can learn if they try. If the mind is wide awake and ready to learn, it can get a great deal of knowledge even when one of the openings for it is shut up. It can use the knowledge gained by the other senses in such a way as to make up very much for the loss. A lazy mind, with all the senses letting in knowledge, will not know as much as a busy mind will with one of the senses shut up. In the deaf and dumb the eyes have to answer for both eyes and ears in getting knowledge. They have to do double duty; and they do it very well if the mind is only wide awake and attentive to all that it can learn by the eyes. In the blind the ears have to do a great deal more than in those that can see. The fingers also of the blind are very busy, for they learn very much about what is around them by the sense of feeling. There are books now made for their use with raised letters. By passing their fingers over them, they read just as you do by looking at printed letters.