What book has mentally scarred you the most?

American Psycho is not for everyone. It's an amazing and well written book, but it doesn't shy away from *anything*. And Ellis does have a way with description. It's a beautiful look into a fractured mind, but a lot of people have problems with it. The thing I've read that bothered me the most - I'm not bothered by much - was The Testament of Magdalene Blair, by Alasteir Crowley himself. He was known as The Beast for his disturbing writings and occult practices. Very well written story, but it really struck a chord with me and made me uneasy. I can't think of it to this day without a chill.