Any IoU that is accepted in payment for services rendered can be regarded as money. There is a legendary exam question about a traveller who paid for a meal on a remote island by cheque. The natives were so impressed by this strange piece of paper that they passed it from hand to hand without anyone attempting to cash it. Who then paid for the traveller’s meal? (Please don’t tell me.) This story illustrates the difficulty of defining, measuring and controlling the money supply; and civil wars among the monetarists on such issues have put off many people.

More practically, the money supply has been out of favour because attempts to regulate the economy via monetary targets have proved unsuccessful. Many economic technicians obviously hate money. They prefer to forecast the real economy directly from variables such as investment and trends in consumer spending. They then add something for inflation, which they try to relate to the degree of slack or overheating that exists at any one time.