Adm. Mike Mullen recalled a dinner he had with the Pakistani ambassador in 2007, one month before he was sworn in as chairman of the Joint Chiefs of Staff.As Admiral Mullen left the dinner, the ambassador, Mahmud Ali Durrani, handed him a gift. It was a long, thin, oddly shaped book, done by the British just after the epic partition that divided the region along religious lines, displaced 20 million people and led to an estimated two million deaths in sectarian violence.“You need to read this,” Mr. Durrani told Admiral Mullen.“Why?” the admiral asked.“Because nothing has changed,” Mr. Durrani replied.