" . . . the shock which he undoubtedly had felt was the result of not expecting people to murder other people. “Whereas they naturally do,” he said to himself. “The normal thing with an unpleasant intrusion is to try and exclude it – human or not. So silly not to be prepared for these things. Some people, as De Quincey said, have a natural aptitude for being murdered. To kill or to be killed as a perfectly reasonable thing . . . "