NICHOLAS D. KRISTOF is an op-ed columnist for The New York Times, where he was previously bureau chief in Hong Kong, Beijing, and Tokyo. He is the coauthor, with his wife, Sheryl WuDunn, of five previous books: Tightrope, A Path Appears, Half the Sky, Thunder from the East, and China Wakes. He was awarded two Pulitzer Prizes, one with WuDunn in 1990 for their coverage of China, and the second in 2006 for his columns on Darfur.