The irritation of the eurozone with Greece is at extreme levels. After all, 80 per cent of Greeks say they are in favour of staying in the euro, but then they fail to elect politicians prepared to implement the agreed programme. This drives creditors crazy. Increasingly, the latter are inclined to accept Greek exit, even welcome it. But they should be careful what they wish for.

A departure would create severe dangers. The danger of contagion is obvious. The long-run danger is more subtle. But the eurozone either is an irrevocable currency union or it is not. If countries in difficulty leave, it is not. It is then an exceptionally rigid fixed-currency system. That would have two dire results: people would not trust in its survival and the economic benefits of the single currency would largely disappear.

These perils are not of concern to the eurozone alone. Taken as a whole, this is the world’s second-largest economy, with the largest banking system. The risk that a bigger eurozone upheaval would cause a global crisis is real. As frightening is the likelihood that eurozone crises would become permanent features of the world economy.