shall not allow the farms of our country to lose five
hundred million dollars in value every year by letting the rich top-soil
drain off into our rivers, because we have cut away the trees whose
roots held the soil in place. It also means that we shall not steadily
rob the land of the elements that would produce good crops, and put
nothing back into the soil.

It means that we shall not kill the birds that destroy harmful insects
and thus invite the insects to destroy the crops that we have cultivated
with such care.

It does not mean that we shall let our mines of coal and iron lie
unused, as the miser does his gold, but that we shall, while taking what
we need, leave as little waste in the mine as possible, and shall use
what we take in the most economical way. This means a saving of money to
the user, as well as a conservation of resources. It means, too, that we
shall not allow our water-power to remain unused, while we burn millions
of tons of coal in doing the work that water-power would do better.

It means that we shall not allow enough natural gas to escape into the
air every day to light all the large cities in the United States. It
means that we shall take better care of the life and health of the
people.

This is the true conservation.

In the following chapters we shall take up each of the great resources
in turn, shall see what we have used, what we have wasted, what remains
to us, how long it will continue at the present rate, how it may be used
more wisely, and how it may be replaced, if that be possible, or what
may be used instead of those which can not be renewed.

We shall study how we may make the most of all that nature has given us
and develop our country to the highest possible point, how we may rise
far above our present level in comfort, convenience, and abundance, and
yet do all these things with much less waste than we now permit.

CHAPTER II

THE SOIL

The soil is the greatest of our natural resources. We may almost say
that it is greater than all the others combined, for from it comes all
of our food; a large part of it directly as plants which grow in the
soil and which we eat in the form of roots, leaves, grains, berries,
fruits, and nuts; and a part of it indirectly as animals, which have
received their food supply from the plants.

But this is not all. The soil supplies almost every known need. We build
our homes from the trees of the forest; combined with the iron