A Select Collection of Scarce and Valuable Tracts on Money
VII.: There can be but one standard of money.
19th Century John Ramsay McCulloch (ed.) English- Hitherto, we have considered both silver and gold, as being either of them a fit material to be made, or used as money. But although there may be good reasons for coining each of them; yet it is very certain, that one only of these metals can be the money or standard measure of commerce, in any country. For the standard measure must be invariable, and keep the same proportion of value, in all its parts: Such is silver with respect to silver, and gold to gold; that is, an ounce of silver is always worth just an ounce of silver; and two ounces of the one or the other of these metals, is just double the value of one ounce of the same. But silver and gold, with respect to one another, are, like other commodities, variable in their value; according as the plenty of either, may be increased or diminished; and an ounce of gold that is worth a given quantity of silver to-day, may be worth more or less silver, a while hence. And therefore it is impossible, that both these metals can be a standard measure of the values of other things, at the same time; and one of them must be a mere commodity, with respect to the other.