The proportion of supply and demand recapitulates, first, the relation of use-value to exchange-value, of commodity to money, and of buyer to seller; and, second, that of producer to consumer, although both of them may be represented by third parties, the merchants. In considering buyer and seller, it suffices to counterpose them individually in order to present their relationship. Three individuals are enough for the complete metamorphosis of a commodity, and therefore for the process of sale and purchase taken as a whole. A converts his commodity into the money of B, to whom he sells his commodity, and reconverts his money again into commodities, when he uses it to make purchases from C; the whole process takes place among these three. Further, in the study of money it had been assumed that the commodities are sold at their values because there was absolutely no reason to consider prices divergent from values, it being merely a matter of changes of form which commodities undergo in their transformation into money and their reconversion from money into commodities. As soon as a commodity has been sold and a new commodity bought with the receipts, we have before us the entire metamorphosis, and to this process as such it is immaterial whether the price of the commodity lies above or below its value. The value of the commodity remains important as a basis, because the concept of money cannot be developed on any other foundation, and price, in its general meaning, is but value in the form of money. At any rate, it is assumed in the study of money as a medium of circulation that there is not just one metamorphosis of a certain commodity. It is rather the social interrelation of these metamorphoses which is studied. Only thus do we arrive at the circulation of money and the development of its function as a medium of circulation. But however important this connection may be for the conversion of money into a circulating medium, and for its resulting change of form, it is of no moment to the transaction between individual buyers and sellers.