Ian Fleming had an idea about it…

From “Diamonds are Forever”. A new friend of Bond’s offers him help while on his mission… “Money?” Kerim reached into a drawer and took out a flat pack of new green notes. “Here’s a thousand Turkish pounds. Their real value, and their rate on the black market is about twenty to the pound. The official rate is seven. Tell me when you’ve finished them and I’ll give you as many more as you want. We can do our accounts after the game.” “It’s muck anyway. Ever since Croesus, the first millionaire, invented gold coins, money has depreciated. And the face of the coin has been debased as fast as it’s value. First the faces of gods were on the coins. Then the faces of kings. Then of presidents. Now there’s no face at all. Look at this stuff!” Kerim tossed the money over to Bond. “Today it’s only paper, with a picture of a public building and the signature of a cashier. Muck! The miracle is that you still buy things with it.”