The young Hannah Arendt had written her doctoral dissertation under the great German philosopher Karl Jaspers, and the topic of her work was the concept of love in the writings of Saint Augustine. One of the most significant intellectual breakthroughs of Augustine’s life was the insight that evil is not something substantial, but rather a type of non-being, a lack of some perfection that ought to be present. Thus, a cancer is evil in the measure that it compromises the proper functioning of a bodily organ, and a sin is evil in the measure that it represents a distortion or twisting of a rightly functioning will. Accordingly, evil does not stand over and against the good as a kind of co-equal metaphysical force, as the Manichees would have it. Rather, it is invariably parasitic upon the good, existing only as a sort of shadow.
J.R.R. Tolkien gave visual expression to this Augustinian notion in his portrayal of the Nazgul in The Lord of the Rings. Those terrible and terrifying threats, flying through the air on fearsome beasts, are revealed, once their capes and hoods are pulled away, to be precisely nothing, emptiness. And this is exactly why, to return to Arendt’s description, evil can never be radical. It can never sink down into the roots of being; it can never stand on its own; it has no integrity, no real depth or substance. To be sure, it can be extreme and it can, as Arendt’s image suggests, spread far and wide, doing enormous damage. But it can never truly be.