The narrator changes subjects: even though he's writing a book on Dresden, it's not a well-known air raid in the States. Lots of Americans don't know that more people died there than in the bombing of Hiroshima.
He meets a guy at a University of Chicago cocktail party who tells him about concentration camps where Germans made soap and candles out of the rendered fat of Jewish bodies.
The narrator can only say, "I know, I know. I know" (1.64).