According to Daniel Johnson, Europe is in grave trouble. These days, few would disagree. To the many longstanding and unsolved problems facing the continent over the last decades, several new ones have recently been added: the economic disaster in Greece and similar economic straits elsewhere, the mass invasion of refugees from the Middle East and Africa, and the looming prospect of a British exit (“Brexit,” for short). Among the latest books about the condition of Europe, none bears the confident title of Mark Leonard’s Why Europe will Run the 21st Century, published only a short decade ago.