Anyone who comments publicly on economic affairs receives regular correspondence from monetary cranks, who espouse schemes for securing peace and prosperity by reforming the world’s money. Bitcoin, the private cyber currency whose supply is fixed to prevent inflation, is only the latest entrant to a lengthy catalogue. Bitcoin also attracts anarchists and libertarians. The web should be free, they cry, blithely disregarding its dependence on telephone networks funded by middle-aged people in grey suits, servers provided by large corporations and protocols negotiated in international conferences.

Finally there are the nerds and quants, for whom the computational complexity behind the Bitcoin software is itself a virtue. The algorithms behind it are so elaborate that their implementation imposes a significant load on power supplies. Goodness knows the nature of the problem such effort is designed to solve.

The Bitcoin story stumbles towards its inevitable sad conclusion, and we will probably never penetrate the mixture of naivety and venality that lies behind it. But these events prompt reflection on the relationship between price and value. The growth of the trading culture has encouraged the belief that that the only measure of value is what someone is willing to pay. The terms “fair value” and “market price” are today used almost interchangeably. But this is a mistake.