Our investigation of the reproductive process has already made us familiar with this explanation, and we are equally familiar with its defects; for one thing, the answer rests on the moment of the first transition from simple reproduction to accumulation. The capitalists only yesterday consumed their entire surplus value, and thus had in hand an appropriate amount of money for their circulation. To-day they decide to 'save' part of the surplus value and to invest it productively instead of squandering it. Provided that material means of production were manufactured instead of luxury goods, they need only put part of their personal money fund to a different use. But the transition from simple reproduction to expanded reproduction is no less a theoretical fiction than simple reproduction of capital itself, for which reason Marx immediately goes on to say: 'Now, by means of the additional productive capital, its product, an additional quantity of commodities, is thrown into circulation. Together with this additional quantity of commodities, a portion of the additional money required for its circulation is thrown into circulation, so far as the value of this mass of commodities is equal to that of the productive capital consumed in their production. This additional quantity of money has precisely been advanced as an additional money-capital, and therefore it flows back to the capitalist through the turn-over of his capital. Here the same question reappears, which we met previously. Where does the additional money come from, by which the additional surplus-value now contained in the form of commodities is to be realised?'[142] The problem could not be put more precisely. But instead of a solution, there follows the surprising conclusion: 'The general reply is again the same. The sum total of the prices of the commodities has been increased, not because the prices of a given quantity of commodities have risen, but because the mass of the commodities now circulating is greater than that of the previously circulating commodities, and because this increase has not been offset by a fall in prices. The additional money required for the circulation of this greater quantity of commodities of greater value must be secured, either by greater economy in the circulating quantity of money--whether by means of balancing payments, etc., or by some measure which accelerates the circulation of the same coins,--or by the transformation of money from the form of a hoard into that of a circulating medium.'[143]