Right off the bat, the novel's title raises an interesting association. The novel is about Murau's relationship to his home, to the estate, and to his parents whom he dislikes because they are pretentious in the wrong was. They think just because their house looks nice that they are automatically high class, but they don't enjoy art, and they don't appreciate Murau's brilliant philosophies about art and society. The question of the novel is therefore what death adds to Murau's perception about his parents.
Here, the title is helpful. What does Extinction typically refer to? One might say the word doesn't apply because the parents are people, not animals. And yet, when Murau takes their full measure, defining the course of their life in its proper context—the context of birth and death—what he sees is that they are animals. This revelation is subtle but powerful. Why would he hate instinctual animals for behaving the way they were conditioned to? Should he feel such spiritual and godlike attachment to his animal parents?
But, more importantly, he realizes that he was misperceiving them the whole time. One way of understanding this mistaken perception might be like this; Murau prides himself in the immortal qualities of life, the legacy of genius art, the transcendental beauty of powerful literature—basically whatever a human does that an animal does not. So why did he hate his parents? Because they were mortal. He doesn't want them to be mortal, and the reality is overwhelming to him. When he sees the house he has sworn to hate, the novel shows that he doesn't actually hate it. Actually, secretly, he loves the house and probably always has. He even loves his parents, even for their base animal nature.