What is inflation? The answer seems obvious: when things get more expensive, that’s inflation, and it’s bad. But an alternative view is Milton Friedman’s. In a talk in 1963, the hugely influential economist defined inflation as “a steady and sustained rise in prices” and added that “inflation is always and everywhere a monetary phenomenon”.

The distinction matters. Consider two scenarios that might illuminate it. In both of them, consumer prices have increased by 10 per cent over the past year.

In Inflation World, there’s too much money around. Everything is getting more expensive at much the same rate, including labour. With your wages rising at the same rate as prices, the situation is disorienting and slightly inconvenient, but it’s not a crisis. The main risk is that inflation becomes self-perpetuating, and the main responsibility for solving the problem lies with the central bank.