The prevailing view seems to be that the idea of Europe as a cultural, political, and even economic institution is under threat. What threatens Europe? A glib response would be: "It's the UK, stupid!" We will find more than a grain of truth in this response. The UK straddles Europe's margins – at once a major economy dependent on European trade, adapting its legal institutions to a transnational European legal order where EU law has direct effect; but refusing the common currency, and resisting further political integration. But the deeper threat to Europe is the very thing that it was designed to overcome...