Does it not seem a heartless thing for us, who call ourselves civilized, to destroy so completely any species of animal or plant that not one of its kind remains alive? No species which we destroy will ever come back again, and its place will always remain empty. There are a few predatory animals and birds that destroy vast numbers of useful ones. We should keep these in check by every means in our power, but for our thoughtless destruction of the valuable ones the world will always be poorer.
What of the mineral treasures hidden away in the earth? Will these be replaced when once they have all been used up? It took Nature a very long time to make coal out of the vegetation which had gathered in some ancient swamp. It took her fully as long to make the oil and gas from the bodies of the little organisms that once lived in the sea.
The bodies of the little creatures from which oil is made are still gathering upon the bottom of the sea, and there are many swamps where we find vegetation and peat accumulating. But it is a long story from these substances to oil and coal. I am afraid we should get tired of waiting for Nature to make a new supply.
Gold, silver, copper, and other minerals, so useful to us, are found in very small quantities scattered throughout most of the solid rocks of the earth. It would be impossible for us to obtain these from rocks, because there is so little in any one place. But Nature has collected a part of them in veins in the rocks. We sink shafts upon these veins and mine the ores. It will be a long time before we shall have mined all there is of these minerals. Because they are so hard to get we are not likely to waste them. But it is quite certain that there is a limit to the supply of mineral treasures, and equally certain that they can be renewed either very, very slowly, or not at all. Shall we cause our remote descendants to suffer for our carelessness?
CHAPTER EIGHT
THE SOIL—THE MOST IMPORTANT GIFT OF NATURE
An ancient story tells us that men were made from the dust of the earth. This dust under our feet, which soils our shoes, this dust which the wind sometimes sweeps along in blinding clouds, is indeed precious. The delicate tissues of our bodies are made from the food we eat. If it be plant food, it comes directly from the soil. If it be meat or eggs or milk, it comes from animals which live upon the plants, that in turn got their nourishment from the soil.
This soft, dark substance which covers the rocky skeleton of the earth we call the soil. How common and cheap it looks when it is placed by the side of a piece of gold! But how much more wonderful it would seem if we could know all about it. The soil is far more necessary to our comfort and prosperity than gold. Gold, silver, or precious stones cannot keep us alive. They are of little worth to us compared with food and clothing. The soil, then, is the real wealth of the world. The farmer, who tills the soil, is the one worker we could not possibly do without. All the wealth of the world, all the comforts which we have, all the luxuries brought from far corners of the earth, come in the first place from the soil.