Hard money with circulating silver and gold and paper redeemable in kind. Now we have “FR notes” and coins that are more copper than any other content.
With the exception of the years during and immediately after the WBTS this is correct.
I wonder if anybody has determined how a gold-based currency would work today? A massive gold strike somewhere would cause high inflation, as the amount of money is a direct reflection of the amount of gold in circulation.
Despite a precious-metals based economic system, the Hellenistic period and the early modern periods has high inflation. Caused respectively by Alexander’s looting the hoards of the Persian kings, and the Spanish looting of American gold and (especially) silver hoards and mines.
In addition, transmutation of metals is probably technologically and possibly even economically feasible today or in the near future, making a system based solely on precious metals somewhat precarious.