What has been said above allows us to understand why machines do not produce value. If value is abstract labour performed by labourers under capitalist relations of production, the less labour is expended the less value is created, by definition. This becomes clear in the hypothetical case of a fully automated economy. In this case, machines could not create value or surplus value, they could only transform use values. In fact, the non-owners of the means of production would cease to exist as labourers and capitalists could sell their different products (use values) only to each other. But then value, the expenditure of labour by a class for another class, would cease to exist. Capitalists would cease to exist too and would become producers of use values both for their own consumption and for exchange. Since value is a socially specific concept, based on the existence of two categories of agents of production, if one category, the labourers, disappears, the other category, the capitalists and their agents, disappears too: the owners of the means of production cease to be capitalists and become independent producers. The advent of a fully automated economy would mean the end of capitalism, but it would not necessarily mark the birth of socialism. [Guglielmo Carchedi (1992): Frontiers of Political Economy, Verso: 105]