From his father...[Bonhoffer] learned, what characterizes all that he wrote, an insitent realism, a "turning away from the phraseological to the real." For him Christianity could never be merely intellectual theory, doctrine divorced from life, or mystical emotion, but always it must be responsible, obedient action, the discipleship of Christ in every situation of concrete everday life, personal and public. And it was this that led him in the end to prison and death. Six years before his imprisonment by the Gestapo he had written, "When Christ calls a man, he bids him come and die."

John Doberstein in the introduction to Dietrich Bonhoeffer's LIFE TOGETHER