 Aristotle identified the three functional properties of money that remain canonical: money serves as a unit of account (a measure), a medium of exchange (replacing barter), and a store of value (stockpile of wealth). Furthermore, he noted that the denomination is purely conventional and that legal authorities might alter this at whim. Money was but a yardstick to measure the exchange-value of goods but unlike those goods, lacked a use-value as the fable of Midas proved all too well. He also asserted that it made no difference what substance is used for money, but then went on to assert that the fetish for gold and silver had made metallic coins unique in human society. Moreover, precious metals offered certain advantages: they are durable, divisible, transportable, and easily stamped with the value of the coin. Finally, his analysis of monopolistic pricing displays a firm grasp of the principles of supply and demand.