From crisis and its relation to the commodity and money, Marx then moves to capital:
But now the further development of the potential CRISIS has to be traced — the real crisis can only be educed from the real movement of capitalist production, competition and credit — in so far as crisis arises out of the special aspects of capital which are peculiar to it as capital, and not merely comprised in its existence as commodity and money.
It is here that Marx makes important points about the unity of the production and circulation process in his theory of capital:
[XIII-716] The mere (direct) production process of capital in itself, cannot add anything new in this context. In order to exist at all, its conditions are presupposed. The first section dealing with capital — the direct process of production — does not contribute any new element of crisis. Although it does contain such an element, because the production process implies appropriation and hence production of surplus value. But this cannot be shown when dealing with the production process itself, for the latter is not concerned with the realisation either of the reproduced value or of the surplus value. Page me32.143
This can only emerge in the circulation process which is in itself also a process of reproduction.
Furthermore it is necessary to describe the circulation or reproduction processbefore dealing with the already existing capital — capital and profit — since we have to explain, not only how capital produces, but also how capital is produced. But the actual movement starts from the existing capital — i.e. the actual movement denotes developed capitalist production, which starts from and presupposes its own basis. The process of reproduction and the predisposition to crisis which is further developed in it, are therefore only partially described under this heading and require further elaboration in the chapter on “Capital and Profit”.
The circulation process as a whole or the reproduction process of capital as a whole is the unity of its production phase and its circulation phase, so that it comprises both these processes or phases. Therein lies a further developed possibility or abstract form of crisis.The economists who deny crises consequently assert only the unity of these two phases. If they were only separate, without being a unity, then their unity could not be established by force and there could be no crisis. If they were only a unity without being separate, then no violent separation would be possible implying a crisis. Crisis is the forcible establishment of unity between elements that have become independent and the enforced separation from one another of elements which are essentially one.
From here Marx moves to enumerate these capitalist forms of crisis:
He starts with the general possibility of crisis. ( I exclude his more specific forms for sake of brevity)
The general possibility of crisis is given in the process of metamorphosis of capital itself, and in two ways: in so far as money functions as means of circulation, there is the separation of purchase and sale, and in so far as money functions as means of payment, it has two different aspects, it acts as measure of value and as realisation of value. These two aspects become separated. If in the interval between them the value has changed, if the commodity at the moment of its sale is not worth what it was worth at the moment when money was acting as a measure of value and therefore as a measure of the reciprocal obligations, then the obligation cannot be met from the proceeds of the sale of the commodity, and therefore the whole series of transactions which retrogressively depend on this one transaction, cannot be settled. If even for only a limited period of time the commodity cannot be sold then, although its value has not altered, money cannot function as means of payment, since it must function as such in a definite given period of time. But as the same sum of money acts for a whole series of reciprocal transactions and obligations here, inability to pay occurs not only at one, but at many points, hence a crisis arises.