What Books Have Greatly Influenced Your Life & Thought?

As I was reading tonight, a curious thought crossed my mind. There is no other book that will ever be more influential to our lives as Christians than the Bible. That's why it is so important for us to stay rooted in the Word. However, other than Scripture, there are many other books that greatly influence our lives. I know what books besides the Bible have shaped my life. I'll share those in a later post.

My curious thought this evening was this... What books (other than the Bible) have greatly influenced your life and thought? I'm a curious guy. You can answer this question by leaving a comment on this post. If enough people reply, I might tally the replies and see what the "most influential book" among you all is.