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).
The amount of energy potentially available from the difference in the salt concentrations of seawater and river water around the world is 1.4 to 2.6 terawatts, or about 20 % of local electricity consumption. This natural process does not produce carbon dioxide or any other polluting combustion emissions, nor does it result in thermal pollution.
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