"Then came the crisis of 1933." This is Bonhoeffer's own phrase in a letter that documents a turning point in his own life as well as that of the nation. Of Bonhoeffer's own life at this time, his biographer writes, "The period of learning and roaming" from 1928 until 1931 "had come to an end" as the young lecturer, age 26, began to teach "on a faculty whose theology he did not share" and to preach "in a church whose self-confidence he regarded...