The more the productiveness of labour increases, the more can the working day be shortened; and the more the working day is shortened, the more can the intensity of labour increase.
 Karl Marx, Das Kapital (1867). copy citation

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Author Karl Marx
Source Das Kapital
Topic intensity labour
Date 1867
Language English
Reference
Note Translated by Samuel Moore and Edward Aveling
Weblink https://www.marxists.org/archive/marx/works/download/pdf/Capital-Volume-...

Context

“would considerably expand, and the labourer would lay claim to an altogether different standard of life. On the other hand, because a part of what is now surplus labour, would then count as necessary labour; I mean the labour of forming a fund for reserve and accumulation. The more the productiveness of labour increases, the more can the working day be shortened; and the more the working day is shortened, the more can the intensity of labour increase. From a social point of view, the productiveness increases in the same ratio as the economy of labour, which, in its turn, includes not only economy of the means of production, but also the avoidance of all useless labour.” source