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WHEN GREAT powers begin to experience erosion in their global standing, their leaders inevitably strike a pose of denial. At the dawn of the twentieth century, as British leaders dimly discerned such an erosion in their country’s global dominance, the great diplomat Lord Salisbury issued a gloomy rumination that captured at once both the inevitability of decline and the denial of it. “Whatever happens will be for the worse,” he declared. “Therefore it is our interest that as little should happen as possible.” Of course, one element of decline was the country’s diminishing ability to influence how much or how little actually happened.