Questions.—By which senses does the mind get most of its knowledge? What is fragrance? How does the mind know any thing about it? What is said of the extent of the organ of smell? What is said of the smell of some animals? Of the acute smell of some persons? What is said of the enjoyment afforded by the sense of smell? How are offensive odors sometimes useful? What is said of the sense of taste? What are its uses? Where is the sense of touch? Where is it especially active? What do the nerves of touch in the fingers tell the mind? In what way do they help us in using the muscles? Tell about the two skins of our bodies. Why is the outer skin needed? What makes the curved lines on the tips of the fingers? What is said of touch in animals that have hoofs? What are the whiskers of the cat for? What is said of the feelers of insects? What is told about the bees?
CHAPTER XV.
THE BONES.
I have told you, in the last few chapters, how it is that the mind learns about the world around it by the senses. But the mind does something besides learn. It tells others about what it learns. It does this by the muscles in various ways. When you tell any thing by speaking, it is the muscles of the throat, and mouth, and chest that do it. When you write, the muscles of your hand are telling what the mind directs them to tell. When your face expresses your thoughts and feelings, it is the muscles of the face that tell what the mind thinks and feels.
How the mind uses what it learns.
The mind not only tells things, but it does things also, and it does them by the muscles. You see a man busily at work making something: his muscles are doing the work. The mind is directing them how to do it by the nerves that spread to them from the brain. How does his mind know in what way to direct them? It is by knowledge gained through the senses—by his eyes and ears. He has seen people do the same kind of work and they have told him about it. His mind uses with the muscles what it has learned by the senses.
You see, then, that the mind makes use of what it learns by the senses in two ways: it tells about it, and it uses it in doing things; and in both telling and doing it uses the muscles. Our knowledge, then, goes into the mind by the senses—they are its inlets; but it comes out by the muscles—they are its outlets. If a mind were in a body that had the senses, but had no muscles, it might know a great deal, but it could never let any body know what it knew, and it could not do any thing.
The chief things that are moved in the body by the muscles are the bones, and I shall tell you about these before I tell you about the muscles.
The joints of the bones.
When you bend your arm, the muscles make the bones in the lower part of the arm bend on the bone in the upper part. There is a joint at the elbow for this purpose; and there are joints in many other parts of the body, so that the muscles can move one bone upon another.