The circuit of productive capital has the general formula P ... C' — M' — C ... P. It signifies the periodical renewal of the functioning of productive capital, hence its reproduction, or its process of production as a process of reproduction aiming at the self-expansion of value; not only production but a periodical reproduction of surplus-value; the function of industrial capital in its productive form, and this function performed not once but periodically repeated, so that the renewal is determined by the starting-point. A portion of C' may (in certain cases, in various branches of industrial capital) re-enter directly as means of production into the same labour-process out of which it came in the shape of a commodity. This merely saves the transformation of the value of this portion into real money or token-money or else the commodity finds an independent expression only as money of account. This part of value does not enter into the circulation. Thus values enter into the process of production which do not enter into the process of circulation. The same is true of that part of C' which is consumed by the capitalist in kind as part of the surplus-product. But this is insignificant for capitalist production. It deserves consideration, if at all, only in agriculture.
