How we cite our quotes: (Chapter.Section.Paragraph) or (Chapter.Paragraph)
Quote #10
The fact that half a day's labour is necessary to keep the worker alive during 24 hours does not in any way prevent him from working a whole day. Therefore the value of labour-power, and the value which that labour-power valorizes in the labour-process, are two entirely different magnitudes; and this difference was what the capitalist had in mind when he was purchasing the labour-power [...] What was really decisive for him was the specific use-value which this commodity possesses of being a source not only of value, but of more value than it has itself. (7.2.22)
This is the trick of capitalism, according to Marx. Workers might need to work only half a workday to produce enough value to support themselves. But that doesn't prevent capitalists from requiring them to labor the entire workday to receive any wages at all. There's all this surplus or unnecessary labor being done to produce surplus-value. Workers try to shorten the workday through class struggle, but as long as capitalism exists, capitalists have to find surplus-value and so will continue to exploit workers, or make them labor more than is required for them to sustain themselves at a given standard of living.