"It was suddenly borne in upon him that her purity and peace were not, as they had seemed, things settled and inevitable like the purity and peace of an animal-that they were alive and therefore breakable, a balance maintained by a mind and therefore, at least in theory, able to be lost. There is no reason why a man on a smooth road should lose his balance on his bicycle; but he could." -C.S. "Jack" Lewis from Perelandra