We have seen that in the home circulation of a country, only one commodity serves as a measure of value. Since, however, that function is performed by gold in some countries and by silver in others, there is a double standard of value in the world market and money assumes two forms in all its other functions. The translation of the values of commodities from gold prices into silver prices and vice versa depends in each case upon the relative value of the two metals, which is constantly changing and, therefore, appears to be constantly in the process of determination. Commodity owners in every national sphere of circulation have to use gold and silver alternately for foreign circulation and thus to exchange the metal which is accepted as money at home for the metal which they happen to need as money abroad. Every nation is, therefore, utilizing both metals, gold and silver, as world money.
In the international circulation of commodities, gold and silver appear not as mediums of circulation, but as universal mediums of exchange. The universal medium of exchange performs its function only under its two developed forms of a means of purchase and of a means of payment, whose mutual relation in the world market is the very reverse of what it is at home. In the sphere of home circulation, money in the form of coin, played exclusively the part of a means of purchase, either as the intermediary in the dynamic unity C—M—C or as the representative of the transient form of exchange value in the unceasing change of positions by commodities. In the world market it is just the contrary. Gold and silver appear here as a means of purchase when the ex-
