The law as to quantity of money in circulation, as it has been formulated in the analysis of the simple circulation of money, receives an essential modification when the circulation of the means of payment is taken into account. The rapidity of the circulation of money whether as circulating medium or as means of payment―being given, the total amount of money in circulation at a given time will be determined by the sum total of the prices of commodities to be realized, _plus_ the total amount of payments falling due at the same time, _minus_ the amount of payments balancing each other. The general law that the volume of money in circulation depends on the prices of commodities is not affected by this in the least, since the extent of the payments is itself determined by the prices stipulated in contracts. What is, however, strikingly demonstrated, is that even if the rapidity of circulation and the economy of payments be assumed to remain the same, the sum total of the prices of the commodities circulating in a given period of time, say one day, and the volume of money in circulation on the same day are by no means equal, because there is a large number of commodities in circulation whose prices have yet to be realized in money at a future date, and there is a quantity of money in circulation which constitutes the payment for commodities which have long gone out of circulation. The latter amount will depend on the sum of payments falling due on the same day although contracted for at entirely different periods.