In volume iii, Marx says quite explicitly, when demonstrating the process of capitalist production as a whole: 'Let us suppose that the whole society is composed only of industrial capitalists and wage workers. Let us furthermore make exceptions of fluctuations of prices which prevent large portions of the total capital from reproducing themselves under average conditions and which, owing to the general interrelations of the entire process of reproduction, such as are developed particularly by credit, must always call forth general stoppages of a transient nature. Let us also make abstraction of the bogus transactions and speculations, which the credit system favours. In that case, a crisis could be explained only by a disproportion of production in various branches, and by a disproportion of the consumption of the capitalists and the accumulation of their capitals. But as matters stand, the reproduction of the capitals invested in production depends largely upon the consuming power of the non-producing classes; while the consuming power of the labourers is handicapped partly by the laws of wages, partly by the fact that it can be exerted only so long as the labourers can be employed at a profit for the capitalist class.'[337] This last quotation refers to the question of crises with which we are not here concerned. It can leave no doubt, however, that the movement of the total capital, 'as matters stand', depends in Marx's view on three categories of consumers only: the capitalists, the workers and the 'non-productive classes', i.e. the hangers-on of the capitalist class (king, parson, professor, prostitute, mercenary), of whom he quite rightly disposes in volume ii as the mere representatives of a derivative purchasing power, and thus the parasitic joint consumers of the surplus value or of the wage of labour. Finally, in _Theories of Surplus Value_,[338] Marx formulates his general presuppositions with regard to accumulation as follows: 'Here we have only to consider the forms through which capital passes during the various stages of its development. Thus we do not set out the actual conditions of the real process of production, but always assume that the commodity is sold for what it is worth. We ignore the competition of capitalists and the credit system; we also leave out of account the actual constitution of society which never consists exclusively of the classes of workers and industrial capitalists, and where there is accordingly no strict division between producers and consumers. The first category (of consumers, whose revenues are partly of a secondary, not a primitive nature, derived from profits and the wage of labour) is much wider than the second category (of producers). Therefore the manner in which it spends its income, and the extent of such income, effects very large modifications in the economic household, and especially so in the process of circulation and reproduction of capital.'