Throughout the series, Rowling has stressed the way in which evil, instead of freeing, enslaves; instead of increasing, diminishes. Indeed, after his first attempt to kill Harry, Voldemort becomes a disembodied shell, kept alive only by his horcruxes, a parasite feeding off the blood of innocent unicorns, seeking a body in which to lodge his wandering spirit. In the end, the very devices he chooses to gain absolute control turn against him, in an illustration of another classical teaching, namely, that vice is its own punishment — that it harms and ultimately defeats the perpetrator.
