Members of the euro zone are suffering from a severe bout of buyers’ remorse. Many would like to disassemble the kit they bought almost 20 years ago and put together in the late 1990s and 2000s. But they can only break it, together with the entire structure of European co-operation. Meanwhile, the world looks on in horror at the possibility that the euro zone is about to unleash a wave of sovereign debt and banking crises. If so, it would not be the first time that European folly has brought ruin on the world.

The idealism that drove the project has vanished. But self-interest is proving an insufficient replacement. The fumblings of national politicians, answerable to frustrated electorates, are making things worse. Jacques Cailloux, chief European economist of Royal Bank of Scotland, stresses the errors in a recent paper. Euro zone leaders have, he charges, failed to understand the scale and nature of the crisis, played heedlessly to domestic galleries and focused on putting malefactors in the dock, even though bad lending is as culpable as bad borrowing. He is right. Now, he adds, two new elements have entered: first, German opinion is turning against their central bank; and, second, a number of politicians, including Mark Rutte, Dutch prime minister, are suggesting the possibility of forced exit.