quickly than those who were dull. Each discovery of some new way of doing things aided them in making others, and in this way people finally came to have all the comforts of today. Those people less quick to learn the secrets of Nature, or those who lived in countries to which Nature had given little, gained few comforts and even now remain savage.

After our ancestors had learned to cultivate the soil, to use the minerals and the forests, and had tamed the animals and birds, they were still unsatisfied. They attempted to make the forces of Nature work for them. For a long time people made flour by crushing grain in a mortar. Next, two flat stones were used, one being made to turn upon the other by a handle. After that some animal, such as an ox or a horse, was harnessed to larger stones which, as they slowly turned, ground the grain. This was a great deal of work, and so some one thought of making the water tumbling over a ledge of rock grind the grain for them. The water was made to go over a water wheel. This wheel then made the millstones go around. It was a great deal easier.

H. W. Fairbanks

The wild home of early men.

Where there was no water power, wind was made to do the same work. A crude windmill gathered the power of the rapidly moving air. After wind and water had been forced to serve them, some one who had seen the lid of a tea kettle dancing up and down, thought of using steam. Then electricity, which in the form of jagged lightning had seemed so fearful a thing to the early people, was harnessed and made the greatest servant of all the forces of Nature.

The discovery of powder led to the making of guns so destructive that dozens of birds could be killed at one shot.

Some people became greedy and used all these wonderful discoveries to rob Nature. It seemed as if in some places all the wild life would be destroyed. Fires were allowed to burn the forest unhindered. The soil was made to produce crops until it grew poor.

If we become selfish and indifferent and neglect to care for the treasures which Nature has placed in our hands, very serious things will happen to us, as they have happened to other people. How to use the storehouse of Nature without wasting or destroying these treasures is what we mean by conservation.

CHAPTER TWO

HOW OUR NEEDS DIFFER FROM THOSE OF THE FIRST MEN

We have seen that the first men, like the other animals, depended upon the food that Nature supplied them, and when this was lacking they went hungry. When men had learned the use of fire they took the first step in making Nature serve them better than she did the lower animals. Today she works for us in so many ways that we can hardly name them all.

After the use of fire the next thing that men learned was to make better homes, to tame some of the wild animals, and to raise a part of their food supplies, instead of depending entirely upon what they could pick up here and there.

As the number of people increased, the question of securing food became more and more important. Would it not seem pretty hard to have to go out and hunt for your breakfast in the woods, or fields, or along the water? If you were alone you might find enough to eat, but if there were thousands of other people doing the same thing, you would probably go hungry. For this reason people began to cultivate berries, fruits, roots, and grains, and to take better care of their herds.

Living as they did, in those parts of the world where the climate was warm, they usually found an abundance of food. But when these places became too crowded, and some of them had to move to new regions, they often found less food and a climate not always comfortable.

In this way people spread into the colder and drier parts of the earth. The need for things which they did not have there sharpened the wits of these people. It led to one discovery after another. New needs were felt and new ways of satisfying them were sought. They kept finding out more about Nature and how she works. After many years they knew much more and were also far more comfortable than those people who continued to live where Nature supplied everything.

There are now so many more people on the earth than there were long ago that to furnish them all with food is a very great task. Besides, there are now many people engaged in work other than farming, hunting, and fishing. All such people have to be provided for by those whose business it is to get food. People of the great cities are dependent upon those in the country for all that they eat! We can picture to ourselves the suffering that would follow if for only one week every one had to get his own food.

We need many things that the first people thought nothing about, because their manner of life was so much simpler than ours. Let us see now what they are.

We live in tightly closed houses, and so have less trouble in keeping warm and dry. But we do not always get the supply of fresh air that we need. Many of us are sickly and weak because of this. Our ancestors lived in the open air, which is always pure and fresh. A supply of pure air, then, is one of the things that we must now provide for.

People once gave no thought to the purity of the water that they drank. When there were few people, water did not easily become impure. One could drink water wherever one found it and there was small risk of harm. Now in many places there are so many thousands of people gathered together that they have to take the greatest care about drinking water, in order to keep in good health. To get pure water it is often necessary to bring it many miles from mountainous regions where no one lives.

Clothing is another thing that concerns us very much. Our ancestors were not troubled about their clothing. In the warm countries they went almost naked. Where it was cold the skins of animals served very well. Changes of fashion did not disturb them and cause them to throw away warm covering. To supply ourselves now with clothing we call upon Nature for many things. As she cannot, without our help, furnish what we need, we have to keep a great number of flocks, for their wool and skins, and cultivate vast fields of cotton and flax.

When Nature raised in her own way the berries, grains, and roots that the first men ate, no thought was given to the soil in which these things grew. In truth, it was not necessary to pay any attention to the soil. Nature is very careful in her way and never makes the soil poor by growing more plants than it can support. In her own gardens she always renews the foods in the soil which the plants require as fast as they take them away.

The needs of men have increased so fast that the soil has often been forced to grow more than it ought. Men have been a long time in learning that they cannot keep on growing the same crops on the same soil year after year without supplying to the soil extra foods, or fertilizers, as we call them. The care of the soil is another thing to which we have to give attention, but which did not worry our ancestors.

Nature clothes the earth with a carpet of grasses, bushes, or trees. When the rain falls on the ground, their roots hold the soil so firmly that it usually washes away only very slowly. When men first began to cultivate the soil, they paid no attention to the fact that water washes away the loose earth very easily. In this loose earth at the top