Under more primitive conditions the typical, individual income, as we have just seen, was made up of several indistinct parts. For his labor he received wages; for his land, rent; for his capital, interest; and for his business skill, profits. He had, at the best, but a hazy notion of the size of each share. The same situation still holds in agriculture. No farmer can estimate even with any degree of accuracy just what portion of his yearly income ought to be attributed to wages, to rent, to interest, or to business ability; and no one else can do it for him; for the four factors, being embodied in one person, are inseparable. In most other productive lines no such difficulty is encountered. There, we can usually determine what portion of the product each factor gets, though the problem of how much each factor ought to get still remains unsolved. There, for example, the wages of the laborer approximates his total income. His returns in the form of rent or interest are likely to be comparatively small. Likewise, to a less degree, the income of the landowner (not farmer) is rent; of the capitalist, interest; and of the enterpriser, profits.

Here we have the cause for distribution tending to become a class problem. Each group, having lost an interest in the shares of the other groups, strives to increase its own share at their expense. The result is mutual misunderstanding. Labor complains of the greediness of capital, while capital in turn complains of labor's unwarranted demands. Neither appreciates the part the landowner plays, while all three resent having to pay tribute to the enterpriser, whose duty it is to bring them together for productive labor.