" Heisenberg’s biographer, David Cassidy, posed a large and testing question about Heisenberg’s behaviour before and during the war: How was it possible that Werner Heisenberg, one of the most gifted of modern physicists, a man educated in the finest tradition of Western culture, who was neither a Nazi nor a Nazi supporter, how was it possible that such a man would not only choose to remain in National Socialist Germany for its entire twelve years of existence, but also actively seek a prominent academic position in Berlin at the height of the war, a position that included the scientific directorship of nuclear fission research for the German Army at war?56 It’s a question, obviously, that is asked in hindsight. "

― Michael Frayn , Copenhagen