“Money, as discussed in Chapter 10, is unique in that it is the one good that is obtained purely to be exchanged for something else. It is not consumed, like consumer goods, nor is it used in the production of other goods, as capital goods are. Since its sole purpose is to be passed on, and it performs no physical function to its owner, a claim on it, or a substitute for it, is capable of playing its role in a way that cannot be played by any substitute or claim on another consumer or capital good. A voucher for a steak cannot be eaten, a receipt for a machine cannot produce the goods that the machine produces, and an airplane ticket cannot make you fly. But a claim on money can perform the essential function of money: It can be exchanged for other goods.”