Let's talk about your favorite books

A favorite is Sophie's World by Jostein Gaarder which is a novel about the history of philosophy.  I read this when I was in high school and it's what got me interested in philosophy.

There's a lot going on in this book.  It has a narrative centered around young Sophie Amundsen and the questions she receives in her mailbox:

"Who are you?" 

and

"Where does the world come from?" 

I don't want to give away too much.

Generally the book is well received, and it will definitely make you think.