We have also omitted from consideration the function of the metal reserve as a security for bank-note convertibility and as the pivot of the entire credit system. The central bank is the pivot of the credit system. And the metal reserve, in turn, is the pivot of the bank.[18] The change-over from the credit system to the monetary system is necessary, as I have already shown in Vol. I (Ch. III) in discussing means of payment. That the greatest sacrifices of real wealth are necessary to maintain the metallic basis in a critical moment has been admitted by both Tooke and Loyd-Overstone. The controversy revolves merely round a plus or a minus, and round the more or less rational treatment of the inevitable.[19] A certain quantity of metal, insignificant compared with the total production, is admitted to be the pivotal point of the system. Hence the superb theoretical dualism, aside from the appalling manifestation of this characteristic that it possesses as the pivotal point during crises. So long as enlightened economy treats "of capital" ex professo, it looks down upon gold and silver with the greatest disdain, considering them as the most indifferent and useless form of capital. But as soon as it treats of the banking system, everything is reversed, and gold and silver become capital par excellence, for whose preservation every other form of capital and labour is to be sacrificed. But how are gold and silver distinguished from other forms of wealth? Not by the magnitude of their value, for this is determined by the quantity of labour incorporated in them; but by the fact that they represent independent incarnations, expressions of the social character of wealth. [The wealth of society exists only as the wealth of private individuals, who are its private owners. It preserves its social character only in that these individuals mutually exchange qualitatively different use-values for the satisfaction of their wants. Under capitalist production they can do so only by means of money. Thus the wealth of the individual is realised as social wealth only through the medium of money. It is in money, in this thing, that the social nature of this wealth is incarnated. — F.E.] This social existence of wealth therefore assumes the aspect of a world beyond, of a thing, matter, commodity, alongside of and external to the real elements of social wealth. So long as production is in a state of flux this is forgotten. Credit, likewise a social form of wealth, crowds out money and usurps its place. It is faith in the social character of production which allows the money-form of products to assume the aspect of something that is only evanescent and ideal, something merely imaginative. But as soon as credit is shaken — and this phase of necessity always appears in the modern industrial cycle — all the real wealth is to be actually and suddenly transformed into money, into gold and silver — a mad demand, which, however, grows necessarily out of the system itself. And all the gold and silver which is supposed to satisfy these enormous demands amounts to but a few millions in the vaults of the Bank. [20]