Imagine that you are a cosseted member of the French elite. One child is doing the khâgne, aiming for rue d’Ulm. Another is now a politechnicien. You are very comfortable, working for the state. You and your spouse are journalists, or writers, or one of that vast tribe of people conducting “recherches” and life is comfortable, good, the way it should be. Yes, you do notice more and more Muslims about you as you walk, no longer in the banlieues, but in the center of Paris, or Toulouse, or Lyon. And you remember how uneasy you felt, four years ago,...