This sociological principle pervades the whole of Socialist economics. It appears in every economic definition, practically, and the terminology of the orthodox political economists is thereby often given a new meaning, radically different from that originally given to it and commonly understood. The student of Socialism who fails to appreciate this fact will most frequently land in a morass of confusion and difficulty, but the careful student who fully understands it will find it of great assistance. Take, as an illustration, the phrase "the abolition of capital" which frequently occurs in Socialist literature. The reader who thinks of capital as consisting of _things_, such as machinery, materials of production, money, and so on, finds the phrase bewildering. He wonders how it is conceivable that production should go on if these things were done away with. But the student who fully understands the sociological principle outlined above comprehends at once that it is not proposed to do away with the _things_, but with _certain social relations expressed through them_. He understands that the "abolition of capital" no more involves the destruction of the physical things than the abolition of slavery involved the destruction of the slave himself. What is aimed at is the social relation which is established through the medium of the things commonly called capital. II In common with all the great economists, Socialists hold that wealth is produced by human labor applied to appropriate natural objects. This, as we have seen, does not mean that labor is the sole source of wealth. Still less does it mean that the mere expenditure of labor upon natural objects must inevitably result in the production of wealth. If a man spends his time digging holes in the ground and filling them up again, or dipping water from the ocean in a bucket and pouring it back again, the labor so expended upon natural objects would not produce wealth of any kind. Nor is the productivity of mental labor denied. In the term "labor" is implied the totality of human energies expended in production, regardless of whether those energies be physical or mental. In modern society wealth consists of social use-values, commodities.