We all make mistakes and some of us learn from them. What is even better is to learn from other people's mistakes, where they pay for those mistakes while we learn free of charge. Many Americans who say that we should learn from other people, especially Europeans, mean that we should imitate what they did. That may make those who talk this way feel superior to other Americans. But let us never forget that the most disastrous ideologies of the 20th century — Communism, Fascism and Nazism — all originated in Europe. So did both World Wars. More recently, Europe...