“The civil exchange of opinions can create a veneer of tolerance, but it requires no serious thinking. Opinions rarely change. Nor, when they do, is their change necessarily the sign of any intellectual engagement. Opinions are fixed in place by a network of socially directed impulses of fear and ambition. We change our minds when we change our clique, our social circle. At the level of opinion, our reasoning powers operate backward to justify predetermined choices. Our social world is our intellectual comfort zone. To break its bonds, so as to actually learn something, requires a sort of intellectual violence: the pain inflicted by a torturously realistic book, by an unanswerable question, or by the presence of an intelligent human being who is oriented differently than we are.”