Page:Das Kapital (Moore, 1906).pdf/348



portion of the working-day which merely produces an equivalent for the value paid by the capitalist for his labour-power, has, up to this point, been treated by us as a constant magnitude; and such in fact it is, under given conditions of production and at a given stage in the economical development of society. Beyond this, his necessary labour-time, the labourer, we saw, could continue to work for 2, 3, 4, 6, &., hours. The rate of surplus-value and the length of the working day depended on the magnitude of this prolongation. Though the necessary labour-time was constant, we saw, on the other hand, that the total working-day was variable. Now suppose we have a working-day whose length, and whose apportionment between necessary labour and surplus-labour, are given. Let the whole line a c, ab—c, represent, for example, a working-day of 12 hours; the portion of a b 10 hours of necessary labour, and the portion b c 2 hours of surplus-labour. How now can the production of surplus-value be increased, i.e., how can the surplus-labour be prolonged, without, or independently of, any prolongation of a c?

Although the length of a c is given, b c appears to be capable of prolongation, if not by extension beyond its end c, which is also the end of the working day a c, yet, at all events, by pushing back its starting point b in the direction of a. Assume that b'—b in the line, a b' b c is equal to half of b c

ab'—b—c 342