'The annual production must in the first place furnish all those objects (use-values) from which the material components of capital, used up in the course of the year, have to be replaced. Deducting these there remains the net or surplus-product, in which the surplus-value lies. And of what does this surplus-value consist? Only of things destined to satisfy the wants and desires of the capitalist class, things which, consequently, enter into the consumption fund of the capitalists? Were that the case, the cup of surplus-value would be drained to the very dregs, and nothing but simple reproduction would ever take place. 'To accumulate it is necessary to convert a portion of the surplus-product into capital. But we cannot, except by a miracle, convert into capital anything but such articles as can be employed in the labour-process (i.e. means of production), and such further articles as are suitable for the sustenance of the labourer (i.e. means of subsistence). Consequently, a part of the annual surplus-labour must have been applied to the production of additional means of production and subsistence, over and above the quantity of these things required to replace the capital advanced. In one word, surplus-value is convertible into capital solely because the surplus-product, whose value it is, already comprises the material elements of new capital.'[332] The following conditions of accumulation are here laid down: (1) The surplus value to be capitalised first comes into being in the natural form of capital (as additional means of production and additional means of subsistence for the workers). (2) The expansion of capitalist production is achieved exclusively by means of capitalist products, i.e. its own means of production and subsistence. (3) The limits of this expansion are each time determined in advance by the amount of surplus value which is to be capitalised in any given case; they cannot be extended, since they depend on the amount of the means of production and subsistence which make up the surplus product; neither can they be reduced, since a part of the surplus value could not then be employed in its natural form. Deviations in either direction (above and below) may give rise to periodical fluctuations and crises--in this context, however, these may be ignored, because in general the surplus product to be capitalised must be equal to actual accumulation. (4) Since capitalist production buys up its entire surplus product, there is no limit to the accumulation of capital.