The Money Commodity Is Demanded and Held Only Because It Is More Marketable than Other Commodities

To return to the concept of the evenly rotating economy, the error of the mathematical economists is to treat it as a real and even ideal state of affairs, whereas it is simply a mental concept enabling us to analyze the market and human activities on the market. It is indispensable because it is the goal, though ever-shifting, of action and exchange; on the other hand, the data can never remain unchanged long enough for it to be brought into being. We cannot conceive in all consistency of a state of affairs without change or uncertainty, and therefore without action. The evenly rotating state, for example, would be incompatible with the existence of money, the very medium at the center of the entire exchange structure. For the money commodity is demanded and held only because it is more marketable than other commodities, i.e., because the holder is more sure of being able to exchange it. In a world where prices and demands remain perpetually the same, such demand for money would be unnecessary. Money is demanded and held only because it gives greater assurance of finding a market and because of the uncertainties of the person’s demands in the near future. If everyone, for example, knew his spending precisely over his entire future—and this would be known under the evenly rotating system—there would be no point in his keeping a cash balance of money. It would be invested so that money would be returned in precisely the needed amounts on the day of expenditure. But if no one wishes to hold money, there will be no money and no system of money prices. The entire monetary market would break down. Thus, the evenly rotating economy is unrealistic, for it cannot actually be established and we cannot even conceive consistently of its establishment. But the idea of the evenly rotating economy is indispensable in analyzing the real economy; through hypothesizing a world where all change has worked itself out, we can analyze the directions of actual change.

—Murray N. Rothbard, Man, Economy, and State with Power and Market, 2nd ed. of the Scholar's ed. (Auburn, AL: Ludwig von Mises Institute, 2009), 328-329.