When Hannah Arendt wrote “The Origins of Totalitarianism” in the years just after the Holocaust, she struggled to explain what made the Nazi genocide so unprecedentedly evil. What separated this atrocity from all previous atrocities, she decided, was not the number of victims. It was, rather, the new institution of the concentration camp, which Arendt described as the supreme expression of the monstrous ambition of totalitarianism: to eradicate the individual human being.

“The murder of the moral person in man,” Arendt wrote, was “the real masterpiece of the SS.” This moral murder was accomplished by placing the victim beyond the reach of imagination, and therefore of sympathy and solidarity. What happened in Auschwitz was literally unimaginable because, like a black hole, what the camp consumed could never be recovered: No one outside the gates could ever know what happened inside. “The human masses sealed off in [the camps] are treated as if they no longer existed, as if what happened to them were no longer of interest to anybody,” Arendt wrote. “The inmates, even if they happen to keep alive, are more effectively cut off from the world of the living than if they had died, because terror enforces oblivion.”