In comparison, the similarities and the profound discrepancies between Marx's diagram of reproduction and Quesnay's _Tableau Économique_ strike us at once. These two diagrams, the beginning and end of the period of classical economics, are the only attempts to describe an apparent chaos in precise terms, a chaos created by the interrelated movements of capitalist production and consumption, and by the disparity of innumerable private producers and consumers. Both writers reduce this chaotic jumble of individual capitals to a few broadly conceived rules which serve, as it were, as moorings for the development of capitalist society, in spite of its chaos. They both achieve a synthesis between the two aspects which are the basis of the whole movement of social capital: that circulation is at one and the same time a capitalist process of producing and appropriating surplus value, and also a social process of producing and consuming material goods necessary to civilised human existence. Both show the circulation of commodities to act as a mediator for the social process as a whole, and both conceive of the circulation of money as a subsidiary phenomenon, an external and superficial expression of the various stages within the circulation of commodities. It is socially necessary labour which creates value. This inspired fundamental law of Marx's theory of value which provided the solution of the money problem, amongst others, further led him first to distinguish and then to integrate those two aspects in the total reproductive process: the aspect of value and that of actual material connections. Secondly, Marx's diagram is based upon the precise distinction between constant and variable capital which alone reveals the internal mechanisms of the production of surplus value and brings it, as a value-relationship, into precise relation with the two material categories of production: that of producer and consumer goods.