But the commonest form of argument is that, under free exchange, the United States would become purely an “agricultural” country, its social horizon would become narrowed, and a lower standard of industrial activity would then ensue; instead of which, it is said, we should, by protection, keep in existence diversified industries by which the national mind may be better stimulated, and greater enterprise may be encouraged in all branches of industry. This argument for “diversity of industries,” however, is not merely a sociological question; it can only be fully discussed from an economic stand-point, and deserves even more than the brief attention we can give it here.
In the first place, as soon as any purely agricultural country gains even a slight density of population—a density only such as to warrant the introduction of the principle of division of labor—there comes an inevitable differentiation of pursuits, wholly outside of legislation, and through the operation of natural causes. Not all of any population is required in agriculture to provide the whole with food. By a division of labor, one man in agriculture can produce the sustenance of himself and many others. “The United States have at the present time but five persons engaged in agriculture for each square mile of settled area.” By the side of the farm must early spring up a wide circle of industries—the shoemaker, the carpenter, the blacksmith, the wagon-maker, the painter, the builder, the mason, and all the ordinary employments which arise in any small community from the earliest division of labor. Moreover, “agriculture” is often used in a too limited sense as confined to producing food alone (although even in that limited sense employing nearly one half of the total number of our laborers). In a new country the natural field of employment is found in the “extractive industries,” which include the preparation for the market not only of food, but also of all ores, coal, minerals, oils, hides, leather,