You are quite right, I changed my mind and do no longer speak of “radical evil.” … It is indeed my opinion now that evil is never “radical,” that it is only extreme, and that it possesses neither depth nor any demonic dimension. It can overgrow and lay waste the whole world precisely because it spreads like a fungus on the surface. It is “thought-defying,” as I said, because thought tries to reach some depth, to go to the roots, and the moment it concerns itself with evil, it is frustrated because there is nothing. That is its “banality.” Only the good has depth that can be radical.(letter to Scholem from December 1964)
~ Hannah Arendt