... It is clear that the problem of the conservation of our natural resources is an interlocking one. If the forests are conserved in the rough lands and mountains, the streams will have an even flow, their navigability will be easily maintained, they will give a uniform water-power; the erosion of the soil will be lessened; the bottom lands along the stream will not be flooded. If the water-powers are developed, the consumption of coal will be lessened. If the elements which are changed from ore to metals are carefully saved--not being allowed to rust or to be lost--and thus utilized again and again, it will not be necessary to take from the mines so large an amount of ore, and thus less coal and power will be required for their extraction. The conservation of one resource assists in the conservation of all others. We should work with the agents of the earth rather than reverse their work, as we have been doing since American settlement began. Intimately connected with the conservation of the natural resources is the conservation of humanity itself. Just as we have been reckless in the use of our natural resources, so as a nation have we been reckless of human life. We now know enough in reference to the prevention and cure of communicable diseases, we know enough in reference to improving the conditions under which the industries are carried on, so that, according to Professor Irving Fisher, the average human life might be lengthened by a third. So far as we permit human beings to be created, it is plainly our duty to conserve them and, so far as possible, produce a happy environment for them. This great problem of the conservation of humanity is mentioned merely to put it in relation with the problems of the conservation of our natural resources, rather than to discuss it. How long shall this nation endure? Or, more exactly, how long shall human beings occupy this land? It is only within the past two centuries that the lands of the country have been subject to agriculture upon an extensive scale, and the main drafts upon the soil of this country have been within the last century. We should think, not of a hundred years, or of a thousand years, but of hundreds of thousands, or of millions of years of development of the human race. There is no reason, from a geological point of view, why human beings may not live upon this earth for millions of years to come, perhaps many millions of years, and, so far as we are concerned, such periods are practically infinite.