Writing in the midst of the 1690s English Recoinage Crisis, John Locke vigorously refuted the efforts of contemporary political economists to alter the mint ratio and recoin the money supply at a reduced silver content. Silver was money was silver, Locke argued, it was impossible for money to have a value that differed from its precious metal weight. Silver, Locke concluded, ‘… is the Instrument and Measure of Commerce in all the Civilized and Trading Parts of the World. It is the Instrument of Commerce by intrinsick value … Silver is the Measure of commerce by its quantity.’

Locke's insistence on silver's intrinsic ‘natural’ value as money has puzzled and fascinated scholars ever since. Many of Locke's contemporaries had long abandoned a strict metallism (money as precious metals by weight) and merchants knew full well that their exchanges did not depend on the intrinsic value of silver Indeed, elsewhere, in his Two Treatises of Government (1690), for example, Locke seemed to suggest as much, pointing to money as a function of the ‘fancy’. In his Further Considerations Considering the Value of Money (1695), however, he inexplicably insisted that silver was money and promoted a metallist monetary policy that eventually spelled disaster for England's economy.

While Locke's monetary theories were not always current or consistent, the metallism he expressed during the Recoinage Crisis was consistent with his empiricism and theological voluntarism.