The value of money is grounded by the fact that you have to pay your taxes in it or you go to jail. This doesn't determine the absolute value or prices, but it

The value of money is grounded by the fact that you have to pay your taxes in it or you go to jail. This doesn't determine the absolute value or prices, but it stabilises them. This stability is the inductive step that allows the "base case" value derived from the gold standard to filter through to the present (minus inflationary effects).