The effects which follow too constant and intense a
concentration upon evil are always disastrous. Those who
crusade, not
for God in themselves, but
against the devil in
others, never succeed in making the world better, but leave it
either as it was, or sometimes even perceptibly worse than it
was, before the crusade began. By thinking primarily of evil
we tend, however excellent our intentions, to create occasions
for evil to manifest itself.
-- Aldous Huxley "The Devils of Loudun"