" It also follows that even if the social working day (i.e. the labour spent by the entire working class over a whole year), just like each individual working day, can be simply broken down into two parts, i.e. into necessary labour plus surplus labour, and even though the value produced by this working day can therefore be similarly broken down into two parts, i.e. the portion of value with which the worker buys his own means of reproduction, and the surplus-value that the capitalist can spend for his individual consumption – yet, from the social standpoint, one part of the social working day is spent exclusively on the production of fresh constant capital, i.e. of products that are exclusively destined to function in the labour process as means of production, and therefore as constant capital in the accompanying process of valorization. "
― Karl Marx , Capital: A Critique of Political Economy, Volume 2