OCCASIONALLY, IT SEEMS, WHEN THE WORLD DRIFTS UNKNOWINGLY to the edge of an abyss, nature conspires to prolong a particularly glorious summer, as if to forestall the impending disaster, or to heighten the irony future historians will read into the prelude. Take, for example, the idyllic summer of 1914, coming at the end of the elegant and oblivious years leading up to the First World War known nostalgically as the Edwardian Summer. Or the New York autumn in 1929, when a heat wave lingered after vacationers had returned from the beach.
