"Nothing about his life is more strange to [man] or more unaccountable in purely mundane terms than the stirrings he finds in himself, usually fitful but sometimes overwhelming, to look beyond his animal existence and not be fully satisfied with its immediate substance. He lacks the complacency of the other animals: he is obsessed by pride and guilt, pride at being something more than a mere animal, built at falling short of the high aims he sets for himself."