them what to do. If the brain-"Central" should fail in
its duty, or get out of order, then the body would be in serious
trouble at once.

Every day we read in the papers of accidents because somebody didn't
think, as well as see or hear. People see cars and automobiles coming,
but don't give them a thought and so are run down and hurt. They hear
the whistle of the engine at the crossing, but drive on just the same,
without seeming to have heard it at all. They are absent-minded; the
operator in the "central office" seems to be off duty, or busy about
something else. But if we are going to get on in this world of cars
and automobiles and all sorts of unexpected things, we must always
"have our wits about us," as the saying goes, ready to send the
messages out to the muscles in our legs and arms and fingers just as
soon as any one of our "Five Senses" "rings up" the "Central" in our
brain.

Our body wires do not look at all like telephone wires; and the brain,
if you could see it, would never suggest to you a central office.

The nerves are fine white cords, the smallest ones finer than a hair,
and the largest so big and strong that you could lift the body by it;
and their branches run all over the body, to the muscles and the blood
tubes and the skin and all the other parts, as the picture shows. You
have already read how the skin can tell you when you feel warm and
when you feel cold and when something hurts you.

The brain is a soft wrinkled mass, partly gray and partly white. It is
in the head; and because it is very soft and easily hurt, Mother
Nature has put around it a strong wall, or shell, of bone--the
_skull_, or brain box. Feel your head and see how very hard this bone
is. Solomon, the Hebrew poet-king, called it the "golden bowl." I
suppose he called it a "bowl" because it is round like one, and
"golden" because it is so precious. People do not often grow well
again if the "golden bowl" is broken or even cracked.

[Illustration: THE NERVOUS SYSTEM--OUR BODY TELEPHONE

The picture shows the brain, or "Central," and the thick nerve
cord that runs down through the backbone, and the principal
nerves of the back and the arms.]

The big _nerve cable_, called the _spinal cord_, that connects the
brain with the rest of the body, and carries all the messages backward
and forward, runs down the back and is protected by the backbone, or
_spine_, which is hollow, so that the cord can run down throu