In Primo Levi's "Survival in Auschwitz" what does Levi say is the dominant trait of Nazi insanity?

The dominant feature of Nazi insanity is the practice of institutionalized genocide, whereby millions—Jews, Poles, criminals, and other elements deemed "undesirable"—were forcibly deported to concentration camps where they were mass murdered and their remains cremated. The degradation of Jews extended even beyond their anonymous death—the ashes from the crematorium were often used as industrial products to, for example, manufacture new roadways.