We have seen that the process of circulation of commodities comes to a completion in C―C, appearing as mere barter carried on by means of money; further, that C―M―C represents in general not only two isolated processes, but their dynamic union as well; but to draw from that the conclusion that purchase and sale form an indivisible unit, is a mode of thinking the criticism of which belongs to the domain of logic, and not to that of economics. The separation of purchase and sale in the process of exchange destroys all local, primitive, patriarchal and naively genial barriers to interchange of matter in society. It is, moreover, the general form of the separation of the points of coincidence and opposition in this interchange, carrying within it the possibility of commercial crises, because the antagonism of commodity and money is the abstract and general form of all antagonisms with which the capitalistic system of labor is pregnant. Hence, circulation of money is possible without crises, but crises can not occur without money circulation. In other words, where labor based on the system of private exchange has not reached the stage marked by the existence of money, it is less capable of producing those phenomena which presuppose the full development of the capitalistic mode of production. Bearing this in mind we can appreciate the depth of the criticism which proposes to do away with the “shortcomings” of capitalistic production by abolishing the “privilege” enjoyed by the precious metals and introducing a so-called “rational monetary system.” As a sample of economic defence of an opposite character may serve the following piece of reasoning which has been proclaimed exceedingly keen. JAMES MILL, the father of the well-known English economist, John Stuart Mill, says: “Whatever ... be the amount of the annual produce, it never can exceed the amount of the annual demand.... Of two men who perform an exchange, the one does not come with only a supply, the other with only a demand; each of them comes with both a demand and a supply.... The supply which he brings is the instrument of his demand; and his demand and supply are of course exactly equal to one another. It is therefore, impossible that there should ever be in any country a commodity or commodities in quantity greater than the demand, without there being, to an equal amount, some other commodity or commodities in quantity less than the demand.”[70]