How did we get here?

For there was once a time when no such thing as money existed....a material was selected which, being given a stable value by the state, avoided the problems of barter by providing a constant medium of exchange. That material, struck in due form by the mint, demonstrates its utility and title not by its substance as such but by its quantity, so that no longer are the things exchanged both called wares but one of them is termed the price. And today it is a matter for doubt whether one can talk of sale when no money passes. - Julius Paulus Prudentissimus, circa 230 C.E

Two thousand years ago, the Roman Emperor Severus Alexander’s legal adviser described what makes up sound money. Today, we're on the brink of another monetary system - central bank digital currencies.