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
Circular flow of income economics, economic reproduction refers to recurrent (or cyclical) processes by which the initial conditions necessary for economic activity to occur are constantly re-created. Economic reproduction involves the physical "production" and "distribution" of goods and services, the "trade" (the circulation via exchanges and transactions) of goods and services, and the "consumption" of goods and services (both productive or intermediate consumption and final consumption). Karl Marx developed the original insights of Quesnay to model the circulation of capital, money, and commodities in the second volume of "Das Kapital" to show how the reproduction process that must occur in any type of society