_Natural Selection of Modes of procuring Usable Goods._--Under natural influences, as we have said, men select the most economical way to get what they use, or--what is the same thing--they select the mode of utilizing their own labor and capital that will give them the largest return in goods. There is competition between different methods of directly making goods, and the best method survives. The man with a good machine undersells the man with a poor one; this latter producer must improve his equipment, or fail, and appliances thus tend toward a maximum of efficiency. In like manner there is competition between the direct and the indirect mode of obtaining goods. The man who, by using a certain amount of labor for a week in making steel for exportation, can obtain in exchange fifteen yards of silk, can undersell and drive from the field the man who, by using the same amount of labor for a week in silk making, can produce ten yards of silk. The importer naturally supplants the manufacturer when, by bartering with foreigners the product of a given amount of labor, he can get from them more than can be produced at home by the same amount of labor. The manufacturers naturally survive when direct production gives the larger returns. In our studies of the economy of the society that is most advanced and central, we may treat whatever is imported as, in an indirect way, produced. In a sense the activities of that society are nearly self-contained since, by the direct or the indirect method, the people produce within their own boundaries the most of what they consume. In doing so they naturally use with a maximum of economy the forces at their command, and resort to traffic when that is profitable. _Mode of Treating the Exportation of Capital._--Capital is moving across the boundary mainly in an outward direction. This fact, standing alone, would be equivalent to a mere retarding of the rate of increase of capital within the economic center; but the exported capital, as it is used outside of the exporting society, produces an income for owners living within it. The income comes in kind, since it takes the form of goods which are an addition to those imported in the course of ordinary exchanges. This tribute paid to capitalists within the industrial center comes chiefly in the form of consumers' goods, the receiving of which does not entail the producing of something to send away in exchange for them. The material agent which creates the imported goods remains outside of the society, and sends its product into the society with no offset. The fact of such an income coming from beyond the pale of an economic society has compelled us to qualify the statement that the economy of the society is self-contained, for there is a small part of its income which is not created within its borders. This comes about by the exportation of capital and the importation of some of its products.