What metaphors are used in The Berlin Stories: The Last of Mr. Norris, Goodbye to Berlin by Christopher Isherwood?

In the story, Goodbye to Berlin, Isherwood uses the crazy world of the Nowaks as a metaphor for the Nazi-inspired madness of Germany at the time - in other words, the author/narrator's growing discomfort with life in the apartment is a metaphoric echo of his growing discomfort with life under looming Nazi oppression.