ith
much skill. The owl moves noiselessly through the night air. Birds of
prey search out their victims with keen vision.

Nearly all birds build skillfully made nests with their bills and feet.
Some make them out of straw, and the little birds usually line them
with wool. The large birds of prey build theirs from small sticks and
twigs. For the most part they hatch the eggs with the warmth of the
body. Many birds are highly valued on account of their eggs, while
others are prized for their flesh and feathers. Still others charm us
with their songs.

LESSON XXV

SLEEP

Of all the wonderful things about us, sleep is one of the most
wonderful. How it comes, why it comes, how it does its kind, helpful
work, not even the wisest people are able to tell. We do not have much
trouble in seeking it, it comes to us of itself. It takes us in its
kindly arms, quiets and comforts us, repairs and refreshes us, and
turns us out in the morning quite like new people.

Sleep is necessary to life and health. We crave it as urgently as we
do food or drink. In our waking hours, rest is obtained only at short
intervals; the muscles, the nerves, and the brain are in full activity.
Repair goes on every moment, whether we are awake or asleep; but during
the waking hours the waste of the tissues is far ahead of the repair,
while during sleep the repair exceeds the waste. Hence a need of rest
which at regular intervals causes all parts of the bodily machinery to
be run at their lowest rate. In other words, we are put to sleep.

Sleep is more or less sound, according to circumstances. Fatigue, if
not too great, aids it; idleness lessens it. Anxious thought, and
pain, and even anticipated pleasure, may keep us awake. Hence we
should not go to bed with the brain excited or too active. We should
read some pleasant book, laugh, talk, sing, or take a brisk walk, or
otherwise rest the brain for half an hour before going to bed.

The best time for sleep is during the silence and darkness of night.
People who have to work nights, and to sleep during the day, have a
strained and wearied look.

The amount of sleep needed depends upon the temperament of each
individual. Some require little sleep, while others need a great deal.

Eight hours of sleep for an adult, and from ten to twelve hours for
children and old people is about the average amount required.

Some of the greatest men in history are known to have been light