AT NINE o'clock on the morning of September 11th 2001, President George Bush sat in an elementary school in Sarasota, Florida, listening to seven-year-olds read stories about goats. “Night fell on a different world,” he said of that day. And on a different America. At first, America and the world seemed to change together. “We are all New Yorkers now,” ran an e-mail from Berlin that day, mirroring John F. Kennedy's declaration 40 years earlier, “Ich bin ein Berliner”, and predicting Le Monde's headline the next day, “Nous sommes tous Américains”. And America, for its part, seemed to become more...