What does the book suggest about the meaning of “sanity” or “normality”?

One of the major themes in the novel is that of sanity, as opposed to insanity. For example, many of the patients in the hospital, though hurting and damaged, are actually quite sane. They may not fit into the society around them... they may be different, but "different" is the extent of their problems.... they are certainly not insane. Through the novel, the author challenges us as readers to question what is sane or normal.... do we, as individuals, have the right to define those two words, or more importantly, apply them to others.