As the net national income, following the three great factors of all economic production, is divided into three great branches, rent, wages and interest on capital, the net income from any private business may be reduced to one or more of these branches.[148-2] The three great branches of income may be considered with advantage from a great many different points of view. We may inquire in the case of each of them: concerning its absolute magnitude, its relation to the aggregate national income, to the magnitude of the factor of production, of which it constitutes the remuneration; by what number of men it is shared, and what number of wants it satisfies.[148-3] Lastly, the difference between the amount stipulated for, and the original amount of both rent and wages, as well as the interest of capital, is of special importance. The former consists in the price paid by the borrower for the use of the factor of production to the owner; the latter in the immediate products which the employment of the same productive power brings on one's own account. Evidently, the original amount is, in the long run, the chief element in the determination of the stipulated amount. While the former depends more on the deeper and more durably effective elements of price, especially the cost of production, the value in use and the paying capacity of purchasers; the latter is conditioned more by the superficial variations of supply and demand, and even by custom. For our purposes, the former is by far the more important, but, at the same time, by far the more difficult to perceive. [Footnote 148-1: This is possible between labor and capital, at least in so far as a comparison can be instituted between the sacrifice of human rest there is in labor and the sacrifice of enjoyment in the building up of capital. But the person who introduces an entirely unimproved piece of land into the service of production, stands to the laborer as well as to the capitalist in a relation which is entirely incomparable with any other. (See § 156.) The doctrine of former agriculturists, that one-half of the harvest was to be ascribed to the soil and the other to the manure, would not suffice here, even if it were correct. Compare _Fraas_, Gesch. der Landbau- und Forstwissenschaft, 257. But in the production of a calf, the coöperation of a bull and cow are necessary. Yet no one is in condition to determine what portion of the calf is to be accounted as belonging to either. If the bull and cow belong to different owners, the relation of supply and demand, and the deeper causes that determine them, decide in what proportion the value of the calf is to be divided among them.]