weak from lack of food and then killed him with many blows of a big
stone. With a sharp piece of flint he cut the fur of the animal's back.
Then he dried it in the sparse rays of the sun, put it around his own
shoulders and enjoyed the same warmth that had formerly kept the bear
happy and comfortable.

Then there was the housing problem. Many animals were in the habit of
sleeping in a dark cave. Man followed their example and searched until
he found an empty grotto. He shared it with bats and all sorts of
creeping insects but this he did not mind. His new home kept him warm
and that was enough.

Often, during a thunderstorm a tree had been hit by lightning. Sometimes
the entire forest had been set on fire. Man had seen these forest-fires.
When he had come too near he had been driven away by the heat. He now
remembered that fire gave warmth.

Thus far, fire had been an enemy.

Now it became a friend.

A dead tree, dragged into a cave and lighted by means of smouldering
branches from a burning forest filled the room with unusual but very
pleasant heat.

Perhaps you will laugh. All these things seem so very simple. They are
very simple to us because some one, ages and ages ago, was clever enough
to think of them. But the first cave that was made comfortable by the
fire of an old log attracted more attention than the first house that
ever was lighted by electricity.