4. Things we ought not to do: To run or play hard just before or after eating; to strain our muscles by lifting too heavy weights; to exercise so violently as to get out of breath; to lie, sit, stand, or walk in a cramped position, or awkward manner; to wear the clothing so tight as to press hard upon the muscles.
5. Good food is necessary to make the muscles strong and healthy.
6. Alcohol makes the muscles weak, although at first it makes us feel stronger.
7. A boy who uses tobacco will not grow as strong and well as one who does not.
8. The use of strong tea and coffee may injure the muscles.
CHAPTER XXII.
HOW WE FEEL AND THINK.
1. How we Think.—With what part of the body do we think? You will at once say that we think with the head; but we do not think with the whole head. Some parts of the head we use for other purposes, as the mouth to eat and speak with, and the nose to smell and breathe with. The part we think with is inside of the skull, safely placed in a little room at the top and back part of the head. Do you remember the name of this organ which fills the hollow place inside of the skull? We learned some time ago that it is called the brain. It is with the brain that we study and remember and reason. So the brain is one of the most important organs in our body, and we must try to learn all we can about it.