War would not have come to Europe, with or without the euro. A prediction made by Harvard economist Martin Feldstein in 1997 seems closer to reality. He argued that the introduction of the euro would lead to major friction within the European Union, because the problems in maintaining a common currency among so many countries would create confrontations and a rebirth of nationalism.

Feldstein was right. The current euro crisis has frayed nerves so much that Europeans have become more aggressive and even nationalistic again…

The other fear in 1990 was that, without the euro, a reunified Germany would again dominate the continent. If Germany gave up its currency, France would support its reunification; the euro would help keep Berlin tied to Europe. German Chancellor Angela Merkel never tires of repeating this mantra — “If the euro fails, the entire European project will be at stake” — when she calls for another bailout of Greece or Portugal or whoever else is on the brink.

But in the past 20 years, the opposite has happened. The Germans reformed their economy. Today, instead of being controlled by the French, they are acting independently as they call the shots in an E.U. of 500 million people.