Warren Buffet said of the financial crash of 2008, which he had spotted in advance: “I violated the Noah rule; predicting rain doesn’t count, building an ark does.” And now the invasion of Ukraine has shocked us all. If we knew in the abstract that great power conflict might return, we failed to take action and prepare for it. We too violated the Noah rule—and a bonfire of our complacency has left us stunned and horrified.