Life is but a dream. Totalitarianism is, to Hannah Arendt, someone else's dream invading your body, until it becomes a nightmare. You wake up, screaming, because you are just one of a million heads making up the body of a real-life Leviathan.
The traumatizing image above is from Thomas Hobbes's Leviathan. His concept was that all of our implied consent as citizens created this Voltron with a sovereign at its head. This could just as well portray Arendt's idea of totalitarianism. She describes it as "One Man of gigantic dimensions."
Imagine yourself waking up inside this One Man, no longer a legal, social, or even personal person yourself. You're just the third-faceless-thing-in from Leviathan's armpit. Do you even have a mouth to scream? In a totalitarian state, Arendt, would say, the answer is no. In the concentration camp, the laboratory of totalitarian control, it's not that people are killed. It's that they never existed at all.
For a human to die in a totalitarian state is just Leviathan sloughing off some skin cells in the shower. Who cares? One life is just a thing, replaced by other things in a state that will live for a thousand years, a movement fated to take over the world. This is how the totalitarian state views every human being. Just a mindless cell in the body of one gigantic man in constant, frenetic motion.