This is an example of the pure form 255 of capitalistic exchange, wherein money is exchanged for commodities, and these again for money plus an increment; the formula for which, as given by Marx, is M-C—M.
The next question we have to consider is how the surplus, the increment above-mentioned, obtained by this process of exchange, is realised,—or, in plain language, where it comes from.
Marx now shows “how the trick 1s done,” that is, the process by which the capitalist exploits the labourer under the present system of wages and capital.
We now come to the two instruments which the capitalist uses in his exploitation of labour, and which are named constant and variable capital; constant capital being the raw material and instruments of production, and variable capital the labour-power to be employed in producing on and by means of the former.
The labourer, as we have seen, adds a value to the raw material upon which he works; but by the very act of adding a new value he preserves the old; in one character he adds new value, in another he merely preserves what already existed. 256 He effects this by working in a particular way, e.g. by spinning, weaving, or forging, that is, he transforms things which are already utilities into new utilities proportionately greater than they were before.
“It is thus,” says Marx, "that the cotton and spindle, the yarn and the loom, the iron and the anvil become constituent elements of a new use-value.” That is, in order to acquire this new value, the labour must be directed to a socially useful end, to a general end, that is, to which the general labour of society is directed, and the value added is to be measured by the average amount of labourpower expended; i.e. by the duration of the average time of labour.