In 1988, if you had told anyone that the Soviet Union would cease to exist just four years later, you would have been dismissed as a crank. The institutions looked solid, the bureaucracy entrenched, and the power absolute. Yet by 1992, it was history. Today, European politicians in Brussels, Berlin, and Paris suffer from the same dangerous optimism. They believe they are so safely ensconced in their institutional frameworks that public anger can never truly throw them out of the saddle. But looking at the trajectory of the European Union, I believe we are closer to a revolutionary moment than...