The money economy has made barter easier rather than harder. . . . The feature of the money economy which has thus refined and improved barter is the standard of value (common measure of value) function of money. This standard of value function, be it noted, makes no call on money itself, necessarily. The medium of exchange and ‘bearer of options’ functions of money are the chief sources of such addition to the value of money as come from money use. But the fact that goods have money-prices, which can be compared with one another quite easily, in objective terms, makes barter, and barter equivalents, a highly convenient and very important feature of the most developed commercial system.#Quoted in Randall Kroszner, “On The Microfoundations of Money” (1990)