I was saddened, but not fully surprised, by the British vote to "Leave" the European Union. It marks a political and historical watershed. It's all downhill from now on. That's why I used the title of Robert Graves' memoir, which looked back on the lost days before 1914 and the terrible ones just after.
The Brexit vote is only the most dramatic and immediately consequential development in Europe. Other ominous signs include: growing extreme right sentiment in several countries, with Austria set to revote on its president; continuing migrant problems; unresolved economic settlements with Greece and others. Any one of these problems could erupt or be superseded by power shifts in upcoming elections in France and Germany.
The best metaphor for this, I think, is unraveling. [CFR President Richard Haass used it two years ago as a general term for global trends, but it's even more applicable to Europe now.] For several decades Europe has been growing tighter together, economically, politically, culturally. Each of those layers, however, is now rending. Nationalism is poking holes through the fabric of cooperation. Each tear makes it harder to hold the rest together.
I would hate to see a Europe without Britain, or Britain without a key place inside Europe. This may sound like nostalgia, which it partly is, but it's based on the strategic reality of strength in unity.