tration. He simply buys the commodity,
labor-power, at its full market price, as in the case of all other
commodities. No ethical argument enters into it at all. It is very
evident, however, that the interest of the capitalist will be to get as
much surplus-value as possible, by buying labor-power at the lowest
price possible, prolonging the working day, and intensifying the
productivity of the labor-power he buys, while the interest of the
workman will be equally against these things. Here we have the cause of
class antagonism--not in the speeches of agitators, but in the facts of
industrial life.

This is the Marxian theory of surplus-value in a nutshell. Rent,
interest, and profit, the three great divisions of capitalist income
into which this surplus-value is divided, are thus traced to the
exploitation of labor, resting fundamentally upon the ownership by the
exploiting class of the means of production. Other economists, both
before and since Marx, have tried to explain the source of capitalist
income in very different ways. An early theory was that profit
originates in exchange, through "buying cheap and selling dear." That
this is so in the case of individual traders is obvious. If A sells to B
commodities above their value, or buys commodities from him below their
value, it is plain that he gains by it. But it is equally plain that B
loses. If one group of capitalists gains what another group loses, the
gains and losses balance each other; there is no gain to the capitalist
class as a whole. Yet that is precisely what occurs--the capitalist
class as a whole does gain, and gain enormously, despite the losses of
individual members of that class. It is that gain to the great body of
capitalists, that general increase in their wealth, which must be
accounted for, and which exchange cannot explain. Only when we think of
the capitalist class buying labor-power from outside its own ranks,
generally at its natural value, and using it, is the problem solved. The
commodity which the capitalist buys creates a value greater than its own
in being used up.

The theory that profit is the wages of risk is answerable in
substantially the same way. It does not in any way explain the increase
in the aggregate wealth of the capitalist class to say that the
individual capitalist must have a chance to receive interest upon his
money in order to induce him to turn it into capital, to hazard losing
it wholly or in part. While the the