What’s returning from the past, as American primacy wanes, is a certain kind of great-power consolidation and competition, echoing the late-1800s dynamics of European empire but this time with global rather than mostly Western players.

In this analogy the United States resembles both Victorian Britain (the great naval power and global imperium) and late-19th-century France (the republic torn apart by culture war) — a long-dominant power haunted by the specter of decline.

Then contemporary China, India, Russia and arguably the European Union all have goals that echo the ambitions of 19th-century Germany and Italy, the Russia of the Romanovs and eventually the Empire of Japan: to establish the largest possible political union based on shared ethnicity or cultural inheritance; to grow strong enough to challenge Anglo-Saxon hegemony; to project power in regions of the globe that lack a dominant nation-state, whether in Central Asia and the Middle East or Africa and Latin America.

Within this multipolar world, you have emergent alliances that echo alignments of the kind that preceded World War I — for now, Russia and China against Europe and America.