If you've ever tried read Marx's Capital: A Critique of Political Economy, you know that it's a struggle to isolate any particular moment in the course of what is a carefully organized and highly systematic text. Nevertheless, I'll posting occasional notes, excerpts, and reflections as I work my way through it over the coming months. (At this point, I should probably mention that I'm doing this as part of a collective effort among friends, many of whom know the material much better than I do.)
By the end of this section we've learned that, besides the relative ease of its transferability, there is nothing necessary or natural about the money form; even its size and weight are essentially meaningless. Money first appears as an exchangeable commodity and is eventually raised above exchange relations to its status as the sole measure of value. Here, Marx deploys several memorable characters--the hoarder and the miser--as figures who fundamentally misunderstand the value of money (that is, as an end in itself, a source of value beyond the relations of exchange).
Money is best expressed through the formula C-M-C, which refers to the circulation of commodities (defined, at this point, by their different use values). Here the passage between commodities is mediated by the form of money, which stands in as a form of appearance for exchange value. Despite this straightforward logic of circulation, contradictions inevitably emerge, even before the enigmatic appearance of capital (coming in Part II):
There is a contradiction immanent to the function of money as a means of payment. When the payments balance each other, money functions only nominally, as money of account, as a measure of value. But when actual payments have to be made, money does not come onto the scene as a circulating medium, in its merely transient form of an intermediary in the social metabolism, but as the individual incarnation of social labour, the independent presence of exchange value, the universal commodity. This contradiction bursts forth in that aspect of an industrial and commercial crisis which is known as monetary crisis. Such crisis occurs only where the ongoing chain of payments has been fully developed, along with an artificial system for settling them. Whenever there is a general disturbance of the mechanism, no matter what its cause, money suddenly and immediately changes over from its merely nominal shape, money of account, into hard cash. Profane commodities can no longer replace it. The use-value of commodities become valueless, and their value vanishes in the face of their own form of value. The bourgeois, drunk with prosperity and arrogantly certain of himself, has just declared that money is a purely imaginary creation. 'Commodities alone are money,' he said. But the opposite cry resounds over the markets of the world: only money is a commodity. As the hart pants for fresh water, so pants his soul after money, the only wealth. In a crisis, the antithesis between commodities and their value-form, money, is raised to the level of an absolute contradiction. Hence money's form of appearance is here also a matter of indifference. The monetary famine remains whether payments have to be made in gold or in credit-money, such as bank-notes. (237)