"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them:
The Gutenberg Galaxy: The Making of Typographic Man
Since its first appearance in 1962, the impact of The Gutenberg Galaxy has been felt around the world. It gave us the concept of the global village; that phrase has now been translated, along with the rest of the book, into twelve languages, from Japanese to Serbo-Croat. It helped establish Marshall McLuhan as the original 'media guru.'