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rest at all. If they rested for any length of time, then the lungs,
heart, stomach and all other parts of the body would stop work, and we
should die. But they really rest a part of the time. Like the heart,
they act for a second, and then stop for a second. They seem to act
all the time, but in all they rest half the time.

=148. Worry.=--The mind can do a great deal of work, if it gets good
sleep. If a person gets enough sleep and rest, he cannot harm his mind
by hard work. Sometimes the mind is troubled and worried over a danger
or a loss. Then it cannot rest, but soon wears itself out. Worry is
far more tiresome than hard work. By an effort, we can keep from
worrying. It never does us good to worry, and we ought to keep from it.

=149. Nervousness.=--The thoughts are able to rule all the rest of the
mind. They can keep us from feeling ill-tempered when we cannot have
our own way. Sometimes a little unpleasant feeling makes us very
unhappy, and keeps us from thinking about our work. A little noise or
pain keeps some children from study, while others can bear a great
deal without being disturbed by it. Some persons jump at a little
noise, and are afraid of a tiny bug or mouse. This is because their
feelings rule their thoughts. Such persons are called _nervous_.

A nervous person is very uncomfortable and makes others so too. Yet
any one can get over the habit of being nervous, if he will try. You
ought not to laugh at a nervous person if he is afraid of some little
thing while you are not. You should help him to get over his
nervousness and to become brave.

=150. Fear.=--Some persons are always brave. In danger they calmly
stop to think, and then know how to save themselves. A timid person
does not think, but rushes where his feelings lead. When a crowd is
in danger, all will rush to do one thing. All will run for a door, and
perhaps tread on one another. Then some one will surely be hurt. At a
fire, or in any other danger, you should always stop to think how to
act. If you rush with the crowd, you may be hurt. You will be more
likely to be safe, if you stay away from them. Then, if help comes,
you will be able to receive it. Besides, if you are cool and brave,
you will help others around you to be brave too.

=151. Fire drill.=--In schools the children are taught how to go out
of the building when there is a fire. A bell is struck when the
children do not expect it. Then every child must leave his seat at
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