According to the current view, the maintenance of sound monetary conditions is only possible with a 'credit balance of payments'. The confutation of this and related objections is implicit in the Quantity Theory and in Gresham's Law. The Quantity Theory shows that money can never permanently flow abroad from a country in which only metallic money is used (the 'purely metallic currency' of the Currency Principle). The tightness in the domestic market called forth by the efflux of part of the stock of money reduces the prices of commodities, and so restricts importation and encourages exportation, until there is once more enough money at home. The precious metals which perform the function of money are distributed among individuals, and consequently among separate countries, according to the extent and intensity of the demand of each for money. State intervention to assure to the community the necessary quantity of money by regulating its international movements is supererogatory.

The Theory of Money and Credit