The general formula of capital is M-C-M'. In other words, a sum of value is thrown into circulation to extract a larger sum out of it. The process which produces this larger sum is capitalist production. The process that realizes it is circulation of capital. The capitalist does not produce a commodity for its own sake, nor for the sake of its use-value, or his personal consumption. The product in which the capitalist is really interested is not the palpable product itself, but the excess value of the product over the value of the capital consumed by it. The capitalist advances the total capital without regard to the different roles played by its components in the production of surplus-value. He advances all these components uniformly, not just to reproduce the advanced capital, but rather to produce value in excess of it.
Although it is only the variable portion of capital which creates surplus-value, it does so only if the other portions, the conditions of production, are likewise advanced. Seeing that the capitalist can exploit labour only by advancing constant capital and that he can turn his constant capital to good account only by advancing variable capital, he lumps them all together in his imagination, and much more so since the actual rate of his gain is not determined by its proportion to the variable, but to the total capital, not by the rate of surplus-value, but by the rate of profit. And the latter, as we shall see, may remain the same and yet express different rates of surplus-value.
The costs of the product include all the elements of its value paid by the capitalist or for which he has thrown an equivalent into production. These costs must be made good to preserve the capital or to reproduce it in its original magnitude.
The value contained in a commodity is equal to the labour-time expended in its production, and the sum of this labour consists of paid and unpaid portions. But for the capitalist the costs of the commodity consist only of that portion of the labour materialized in it for which he has paid. The surplus-labour contained in the commodity costs the capitalist nothing, although, like the paid portion, it costs the labourer his labour, and although it creates value and enters into the commodity as a value-creating element quite like paid labour.
The capitalist's profit is derived from the fact that he has something to sell for which he has paid nothing. The surplus-value, or profit, consists precisely in the excess value of a commodity over its cost-price, i.e., the excess of the total labour embodied in the commodity over the paid labour embodied in it. The surplus-value, whatever its origin, is thus a surplus over the advanced total capital. The proportion of this surplus to the total capital is therefore expressed by the fraction s/C, in which C stands for total capital. We thus obtain the rate of profit s/C=s/(c+v), as distinct from the rate of surplus-value s/v.
The rate of surplus-value measured against the variable capital is called rate of surplus-value. The rate of surplus-value measured against the total capital is called rate of profit. These are two different measurements of the same entity, and owing to the difference of the two standards of measurement they express different proportions or relations of this entity.
The transformation of surplus-value into profit must be deduced from the transformation of the rate of surplus-value into the rate of profit, not vice versa. And in fact it was rate of profit which was the historical point of departure. Surplus-value and rate of surplus-value are, relatively, the invisible and unknown essence that wants investigating, while rate of profit and therefore the appearance of surplus-value in the form of profit are revealed on the surface of the phenomenon.
