Might the eurozone break up? Until recently I would have answered: absolutely no. This is not because I thought the currency union a wise idea. I thought it a risky idea, made more so by the decision to accept member countries so different from those of the zone's northern core. But the commitment to make it work seemed fundamental to the policies of Europe's principal powers. Is that still true? I do not know.

So what has gone wrong? What is happening now? What happens next? What does it mean for both the eurozone and the world economy?

On the first question, the European orthodoxy is that the crisis is, at root, fiscal. Marco Annunziata of UniCredit summarises it in a recent note: “In hindsight, it seems obvious that the flaw in the eurozone's institutional setup is both extremely serious and extremely simple: first, a currency union cannot work without sufficient fiscal convergence or integration; second, the eurozone has been unable to create incentives for fiscal discipline.” Mr Annunziata's chart (reproduced above) shows that this view is wrong. Just consider the frequency of breaches of the rules requiring fiscal deficits of less than 3 per cent of gross domestic product. Greece is a bad boy. But Italy, France and Germany had far more breaches than Ireland and Spain.