How does Vienna contrast the character of Keller?

Vienna seems oddly familiar to Paul, alluding to how much Keller's knowledge and perceptions have shifted onto Paul. Paul has journeyed both physically and intellectually from his distant place of origin to the center of his teacher's pain and suffering. While details of Keller's life have been disclosed throughout the story, this chapter finally brings the story to a climax by revealing the full truth behind Keller's past.

Henisch's room and piano are both described as "dark," an ominous characterization that reflects the sobering information contained in the room. Paul is shocked to hear that Keller played for Hitler, and this experience is a final loss of innocence for Paul.

Henisch and Paul go back and forth describing two very different Kellers. Ultimately Paul says, "If we were discussing the same man, how different our two versions. Or perhaps I was mistaken. Perhaps they were not the same man, in a sense." This seemingly paradoxical statement reflects Paul's realization of how far Keller has tried to distance himself from his past. Paul realizes that perhaps Henisch's version of Keller did die in 1944.