or to one hour’s labour-time. If now, in a c, the working day of 12 hours, we move the point b to b', b c becomes b' c; the surplus-labour increases by one-half, from 2 hours to 8 hours, although the working day remains as before at 12 hours. This extension of the surplus labour-time from b c to b' c, from 2 hours to 8 hours, is, however, evidently impossible, without a simultaneous contraction of the necessary labour-time from a b into a b', from 10 hours to 9 hours. The prolongation of the surplus-labour would correspond to a shortening of the necessary labour; or a portion of the labour-time previously consumed, in reality, for the labourer’s own benefit, would be converted into labour-time for the benefit of the capitalist. There would be an alteration, not in the length of the working day, but in its division into necessary labour-time and surplus labour-time.
On the other hand, it is evident that the duration of the surplus-labour is given, when the length of the working day, and the value of labour-power, are given. The value of labour-power, i.e., the labour-time requisite to produce labour-power, determines the labour-time necessary for the reproduction of that value. If one working hour be embodied in sixpence, and the value of a day’s labour-power be five shillings, the labourer must. work 10 hours a day, in order to replace the value paid by capital for his labour-power, or to produce an equivalent for the value of his daily necessary means of subsistence. Given the value of these means of subsistence, the value of his labour-power is given;[1] and given the value: of his labour-power, the duration of his necessary labour-time is given. The duration of the surplus-labour, how-
- ↑ The value of his average daily wages is determined by what the lahourer requires“so as to live, labour, and generate.” (Wm. Petty: ‘Political Anatomy of Ireland,” 1672, p. 64.) “The price of Labour is always constituted of the price of necessaries … whenever … the labouring man’s wages will not, suitably to his low rank and station, as a labouring man, support such a family as is often the lot of many of them to have,” he does not receive proper wages. (J. Vanderlint, l. c. p. 15.) “Le simple ouvrier, qui n’a que ses bras et son industrie, n’a rien qu’autant qu’il parvient à vendre à d’autres sa peine.… En tout genre de travail il doit arriver, et il arrive en effet, que le salaire de l’ouvrier se borne à ce qui lui est nécessaire pour lui procurer sa substance.” (Turgot, Réflexions, &c., Oeuvres ed. Dairet I. p. 10). “The price of the necessaries of life is, in fact, the cost of producing labour.” (Malthus, Inquiry into, &c., Rent, London, 1815, p. 48 note).
