'In that case'--the problem simply has not been solved, for after all B, B´, and B´´ have not cut down on their consumption and expanded their production just so as to buy each other's increased product, i.e. means of production. Even that, incidentally, would only be possible to a very limited extent. Marx assumes a certain division of labour in Department I itself: the A's turn out means of production for making producer goods and the B's means of production for making consumer goods, which is as much as to say that, though the product of A, A´, etc., need never leave Department I, the product of B, B´, etc., is by its natural form predestined from the first for Department II. Already the accumulation of B, B´, etc., it follows, must lead us to circulation between Departments I and II. Thus Marx's analysis itself confirms that, if Department I is to accumulate, the department for means of consumption must, in the last resort, increase its immediate or mediate demand for means of production, and so it is to Department II and its capitalists that we must look for buyers for the additional product turned out by Department I. Sure enough, Marx's second attack on the problem takes up from there: the demand of capitalists in Department II for additional means of production. Such a demand inevitably implies that the constant capital II_c_ is in process of expanding. This is where the difficulty becomes truly formidable: 'Take it now that A(I) converts his surplus-product into gold by selling it to a capitalist B in Department II. This can be done only by the sale of means of production on the part of A(I) to B(II) without a subsequent purchase of articles of consumption, in other words, only by a one-sided sale on A's part. Now we have seen that II_c_ cannot be converted into the natural form of productive constant capital unless not only I_v_ but also at least a portion of I_s_, is exchanged for a portion of II_c_, which II_c_ exists in the form of articles of consumption. But now that A has converted his I_s_ into gold by making this exchange impossible and withdrawing the money obtained from II_c_ out of circulation, instead of spending it for articles of consumption of II_c_, there is indeed on the part of A(I) a formation of additional virtual money-capital, but on the other hand there is a corresponding portion of the value of the constant capital B(II) held in the form of commodity-capital, unable to transform itself into natural productive constant capital. In other words, a portion of the commodities of B(II), and at that a portion which must be sold if he wishes to reconvert his entire constant capital into its productive form, has become unsaleable. To that extent, there is an over-production which clogs reproduction, even on the same scale.'[123]