Four years ago to this day, United Airlines Flight 93 was flying over unremarkable farmland near Somerset, Pennsylvania. Inside the plane there was chaos, as the passengers started to organize their legendary resistance. “Let’s Roll,” said Todd Beamer, as he and his fellows charged into the cockpit of the enormous jet. Here is where they and the other passengers are now resting forever. This is not a political memorial. I see no racism, no attacks on Islam, just a moving tribute to a much-beloved group of people. There has been a great controversy about the idea of a permanent memorial,...