Capital, Volume Three: The Process of Capitalist Production as a Whole by Karl Marx

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 realises 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. The only way in which he can convert the value of his advanced variable capital into a greater value is by exchanging it for living labour and exploiting living labour. But he cannot exploit this labour unless he makes a simultaneous advance of the conditions for performing this labour, namely means of labour and subjects of labour, machinery and raw materials, i.e., unless he converts a certain amount of value in his possession into the form of conditions of production; for he is a capitalist and can undertake the process of exploiting labour only because, being the owner of the conditions of labour, he confronts the labourer as the owner of only labour-power. As already shown in the first book [English edition: Vol. 1, pp. 168-69. 714-16. –Ed.], it is precisely the fact that non-workers own the means of production which turns labourers into wage-workers and non-workers into capitalists.

The capitalist does not care whether it is considered that he advances constant capital to make a profit out of his variable capital, or that he advances variable capital to enhance the value of the constant capital; that he invests money in wages to raise the value of his machinery and raw materials, or that he invests money in machinery and raw materials to be able to exploit labour. 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.