And more than anything, she wondered if one could take leave of one's senses, even if one had no previous occasions of mental incapacity, simply by being isolated from others. Is that what pushed the man over the edge of all measured thought? Were his thoughts so distilled, without the calibrating effect of a normal life led among others, that he ceased to recognize the distinction between right and wrong, between good and evil, or between having a voice and losing it? And if that were so, might an ordinary woman living alone with her memories, with her work, with the walls of her flat drawing in upon her, be at some risk of not seeing the world as it is?
--Among the Mad: A Maisie Dobbs Novel (2009)