Production for sale in a market in which the object is to realize the maximum profit is the essential feature of a capitalist world-economy. In such a system production is constantly expanded as long as further production is profitable, and men constantly innovate new ways of producing things that will expand the profit margin.
Immanuel Wallerstein (1979) The Capitalist World-Economy. p. 15.
The product of mental labor — science — always stands far below its value, because the labor-time necessary to reproduce it has no relation at all to the labor-time required for its original production.
Karl Marx Addenda, "Relative and Absolute Surplus Value" in Economic Manuscripts (1861–63).
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