As the incarnation of labor-time gold is a pledge for its own value, and since it is the embodiment of _universal_ labor-time, the process of circulation pledges gold its constant rôle of exchange value. Owing to the mere fact that the owner of commodities can retain his commodity in the form of exchange value or retain the exchange-value as a commodity, the exchange of commodities for the purpose of retaining them in the transformed shape of gold becomes circulation’s own motive. The metamorphosis C―M takes place for the sake of the metamorphosis, i. e., in order to transform it from particular natural wealth into universal social wealth. Instead of change of matter, change of form becomes its own purpose. From a mere form of the movement exchange value becomes its substance. Commodity is preserved as wealth, as commodity, only in so far as it keeps within the sphere of circulation, and it keeps in that fluent state only in so far as it solidifies in the form of silver and gold. It remains in the stream of circulation as its crystal. At the same time gold and silver themselves become money only in so far as they do not play the part of mediums of circulation. _As non-mediums of circulation they become money._ The withdrawal of a commodity from circulation in the form of gold is therefore the only means of keeping it constantly within the sphere of circulation. The owner of commodities can receive money from circulation only in return for a commodity which he gives to it. Constant selling, continual throwing of commodities into circulation is, therefore, the first condition of hoarding from the standpoint of the circulation of commodities. On the other hand, money as a medium of circulation constantly disappears in the very process of circulation by being realized all the time in use-values and becoming dissolved in fleeting pleasures. It must, therefore, be taken out of the all-consuming stream of circulation or the commodity must be kept up in its first metamorphosis, so that money is prevented from performing its function of a means of purchase. The commodity owner who has now become a hoarder, must sell as much as possible and buy as little as possible, as old Cato had taught: “patrem familias vendacem, non emacem esse.” While industry constitutes the positive condition of hoarding, saving forms the negative one. The less the equivalent of a commodity is withdrawn from circulation in the form of particular commodities or use-values, the more it is withdrawn in the shape of money or exchange value.[91] The acquisition of wealth in its universal form thus requires abstinence from wealth in its material reality. Thus the stimulating impulse for hoarding is _greed_, the objects of which are not commodities as use-values, but exchange value as commodity. In order to get possession of the surplus in its universal form, the particular wants must be treated as so much luxury and excess. Thus