The Plague by Albert Camus

The evil in the world comes almost always from ignorance, and goodwill can cause as much damage as ill-will if it is not enlightened. People are more often good than bad, though in fact that is not the question. But they are more or less ignorant and this is what one calls vice or virtue, the most appalling vice being the ignorance that thinks it knows everything and which consequently authorizes itself to kill. The murderer's soul is blind, and there is no true goodness or fine love without the greatest possible degree of clear-sightedness.

- Albert Camus / The Plague