“Nobody should take for granted another 50 years of peace and prosperity in Europe. They are not for granted. That’s why I say: If the euro fails, Europe fails,” Merkel said, followed by a long applause from all political groups. …

Very drunk at a party at Perry de Haviland’s Chelsea flat several years ago, I made a surprisingly cogent argument about why the euro was doomed to fail. Put short: A currency can be only as extensive as labor is mobile.

Put longer: Our fifty-seven states do just fine with one currency and one monetary policy, because when California is in the dumpster, people can and do move to where the jobs are, in Texas. But the 17 members of the eurozone can’t use a single currency and a single monetary policy. Because if France goes into recession while Germany is enjoying boom times, a million Frenchmen aren’t going to pack up and head east across the Rhine.