History of economic thought died, Engels completed the second volume of "Das Kapital" from his notes. Marx wrote his magnum opus "Das Kapital" (1867) at the British Museum's library in London. Karl Marx begins with the concept of commodities. Before capitalism, says Marx, production was based on slavery – in ancient Rome for example – then serfdom in the feudal societies of medieval Europe. The current mode of labor exchange has produced an erratic and unstable situation allowing the conditions for revolution. People buy and sell their labor as people buy and sell goods and services. People themselves have become disposable commodities. As Marx
Karl Marx and the Close of His System labour value, he argues that the basic error in Marx's system resulted from a self-contradiction of Marx's law of value, namely how the rate of profit and the prices of production of the third volume of Marx's "Capital" contradict Marx's theory of value in the first volume. He maintains that since the law of value is not directly controlling in capitalist production, the theory of value must be abandoned. Bawerk also attacks Marx for downplaying the influence of supply and demand in determining permanent price, and for deliberate ambiguity with such concepts. "Karl Marx and the Close of His System"