The human heart is a line, whereas my own is a circle, and I have the endless ability to be in the right place at the right time. The consequence of this is that I’m always finding humans at their best and worst. I see their ugly and their beauty, and I wonder how the same thing can be both.”

This quote comes near the end of Part Nine, after Rudy and Liesel find the enemy fighter pilot in his crashed plane and Rudy gives the pilot the teddy bear as he dies. Death has previously seemed practically human because of his sympathy for the people in his story and how personable he seems, but here he establishes himself as being apart from humanity. He refers to the fact that people are mortal, saying the human heart is a “line,” which means it has a beginning and end, whereas his is a “circle.” What he means is that he is immortal, and in standing outside of humanity he has a different perspective on it than people do. That perspective allows him to see people perhaps more objectively than people can see themselves, but that clarity leaves him confused since he can’t reconcile how people can be both so good and evil. In that sense the quote speaks directly to two of the dominant themes of the book, the dualities of Nazi-era Germany and the extreme kindness and cruelty of which people are capable. In fact, the quote comes near the conclusion of the book, and over the previous pages the reader, through Death’s narration, has seen both the best and worst of humanity.