The “Demand for Money” Is Not and Cannot Be Unlimited; Demand on the Market Refers to “Effective” Demand (By the Fact That Something Else Is “Supplied” for It)

A popular fallacy rejects the concept of “demand for money” because it is allegedly always unlimited. This idea misconceives the very nature of demand and confuses money with wealth or income. It is based on the notion that “people want as much money as they can get.” In the first place, this is true for all goods. People would like to have far more goods than they can procure now. But demand on the market does not refer to all  possible entries on people’s value scales; it refers to effective demand, to desires made effective by being “demanded,” i.e., by the fact that something else is “supplied” for it. Or else it is reservation demand, which takes the form of holding back the good from being sold. Clearly, effective demand for money is not and cannot be unlimited; it is limited by the appraised value of the goods a person can sell in exchange and by the amount of that money which the individual wants to spend on goods rather than keep in his cash balance.

Furthermore, it is, of course, not “money” per se that he wants and demands, but money for its purchasing power, or “real” money, money in some way expressed in terms of what it will purchase. (This purchasing power of money, as we shall see below, cannot be measured.) More money does him no good if its purchasing power for goods is correspondingly diluted.

--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), 772-773.