of the ground is stored most of the food which the plants require. Care of the surface of the ground is, then, another thing which we have to keep in mind.

Men at first made shelters for themselves from anything that was at hand, such as bark, skins, rock, or earth. When they learned to make sharp-edged tools, they began to use trees. Where it is cold, much wood is required to build warm houses. As the numbers of men increased, they used greater and greater quantities of wood. Wood also proved to be most useful for many other purposes than house building. In order to plant larger fields the trees were cut down or burned off, without thought of doing any harm. In time trees became scarce in many parts of the world and men began to realize that care must be used or the supply of wood might fail them.

Coal was finally discovered and men said, "Now we have something that will last always, for there must be an inexhaustible amount in the earth beneath our feet. All that we shall have to do is to dig it out." When men grew wiser they learned that coal must not be used carelessly any more than the other gifts of Nature; otherwise the supply may give out and leave them with nothing to take its place.

George J. Young

Sierra junipers above Tuolumne Meadows, near the Yosemite Valley, showing how roots will force their way in apparently most unfavorable places.

Hunting and fishing continued to be the business of many. They invented destructive weapons with which they were able to kill such large numbers of wild creatures that some kinds disappeared entirely. Fish, also, of which people thought the sea and the rivers contained a never failing supply, became scarcer. They did not know that fish live mostly in the shallow waters along shores, and that the great ocean depths contain very few.

Thus, as the earth became thickly settled with men and their wants increased, they discovered that they had to treat Nature in a very different way from that of their early ancestors.

Because of our great numbers we have to be careful not to use the earth in such a way as to lessen its fertility and productiveness. Where people have been careless, famine has often resulted. Poverty and suffering have come to many parts of the earth, as we shall learn farther along in this little book.

THE CITY ON THE PLAIN

Millard F. Hudson,
in American Forestry, XIV. 42

Pillsbury's Pictures, Inc.

"'Where are my beautiful trees,' he cried,
'That grew on the side of the mountain?'"

CHAPTER THREE

THE EARTH AS IT WAS BEFORE THE COMING OF CIVILIZED MEN

William Cullen Bryant,
A Walk at Sunset

The earth has not always been as it is now. Those parts now possessed by the more civilized peoples have been very greatly changed. If we could look back and see some of the countries as they were long ago, we should hardly know them. In certain lands the forests have been cut down, the wild creatures driven away, and the soil so carelessly cultivated that it has become poor. In other lands Nature's gifts have been carefully used; even the barren deserts have been turned into green fields and blooming gardens for hundreds of miles.

Let us try to picture to ourselves how our own country looked when white men first found and explored it. A few hundred years ago it was the home of wild animals and Indians only. We have been given our freedom in one of