The books that change our lives

I was delighted yesterday, to learn that Rebecca Stead's wonderful book, When You Reach Me, was awarded the Newbery Prize. When You Reach Me was one of my favorite books of last year, a quietly lovely book that grew into something extraordinary, and the story has become one of those that I find myself thinking of often. (My original review is here.)

I originally decided to read it because I had heard about the connection between When You Reach Me and A Wrinkle in Time (also a Newbery winner, 1963). Those of you who have been reading here for a while know that A Wrinkle in Time is a book that means a great deal to me. When I look back over my life (and look forward to what I want my life to be) it is a book that is always there, and I can see the shape of its influence. And A Wrinkle in Time seems to be one of those books that is beloved by everyone who picks it up.

So I'm curious: what is the book that changed your life?