ABSTRACT
In economies where human production is organized through the exchange of products as commodities, the statistical regularities of the exchange process establish ratios at which different commodities trade. While the definition of the term value is relatively straightforward because it invokes ordinary day-to-day categories like money price and quantity, the term labour presents more fundamental difficulties. Karl Marx, in the context of his analysis of the wage labour relation in capitalist economies, noted that what the capitalist purchases in the wage contract is not labour, but the capacity or potential to labour, that is labour-power, which can be measured in terms of time. The mobility of labour, then, tends to equalize the relation between the money wage and the subjective disadvantages of labour effort across employments. Marx uses the term surplus value to denote the sum of profits, interest, and rent in a capitalist economy.
