and that today the amount necessary is $1,000, and, furthermore, that the amount exploited from labor is now five times as large as then, i. e., that whereas the surplus which labor formerly produced was $50, today it is $250. In this case the quantity of the surplus has increased absolutely; nevertheless, in proportion to the quantity of capital invested, the surplus value has decreased. A hundred years ago this proportion was 50 per cent, today it is only 25 per cent. This instance is simply an illustration meant to point out a tendency.
The total amount of surplus yearly produced in this, as a capitalist country, increases rapidly; but still more rapidly grows the total amount of capital invested by the capital class in their establishments. If now it be considered that taxation and rent carry off yearly an ever larger portion of the capitalists' surplus, the phenomenon may be explained that the quantity of surplus that will accrue to a certain amount of capital tends steadily to diminish, notwithstanding that the amount of exploitation of labor tends steadily to increase.
Accordingly, profit, that is to say. the portion of the surplus produced by labor which a capitalist retains, shows a tendency to decline in proportion to the quantity of capital he invests. Or, to put it another way, in the course of the development of the capitalist system of production, the profit which a given quantity of capital yields tends to go down. This, of course, holds good only on the average and during long periods of time. An evidence of this downward tendency of profit is the steady decline of interest.
