Money as defined by the US Constitution is gold and silver, and was still that way when the 3rd US Central Bank (not Federal and has no Reserve) came into existence in 1913.  The paper certificates (receipts) were exchangeable for real money at any bank.  Then in 1964 the silver coins that used to circulate, were no longer minted, and from that point, they were made from copper and nickel.  In 1971 the US reneged on its promise to other countries, that the US dollar was as good as gold, and gold exchangeability was discontinued.  So what we have today are Federal Reserve Notes (FRNs), or debt instruments, not dollars.  They are made to look like the silver certificates, and people have forgotten that these pieces of paper used to be receipts for money.  When I was a kid back in the early 60s, a gallon of gasoline could be purchased for on silver quarter.  Today, a gallon will cost anywhere from 2 1/2 to 3 or more FRNs.  I can still take one of those silver quarters, go to any coin shop, and exchange it for 2 1/2 or 3 FRNs and buy a gallon of gasoline.  The silver coins are manipulated (artificially held low) but they don't depreciate in value.  "Fortitudine et Deo Duce Ferro Comitante".