Writings on madness fill entire libraries, but until now nobody has thought to engage exclusively with the idea of sanity; we define it simply as that bland and nebulous state of not being mentally ill. But what is sanity? How broad, how eccentric is its range of behavior? And how do we go about crafting a creative and fluid definition of a sane existence, one we can guide ourselves by? Madness is always present in our lives -- in the chaos of our...