Which book has had the biggest impact on your life?

Have you read it over and over? Or did it cause an epiphany or existential bolt from the blue?

My youngest son was turning 18 recently and his Grandmother asked him what he wanted as a gift

He paused, smiled and said, "can you buy me a copy of the book that had the biggest impact on you growing up?"

So I ask that question of you: Whether it was a book when you were a kid, or as an adult. What single book has had the biggest impact on you, and should you care to say so, why is that?

And below is a partial list I've collected when asking that question to family, friends and colleagues

• The Sacred Mushroom and the Cross

• The Portrait of Dorian Gray by Oscar Wilde

• Sophie's World by Jostein Gaarder

• The Art of Possibility by Rosamund Stone Zander and Benjamin Zander

• Atlas Shrugged by Ayn Rand

• The Untethered Soul - Michael Singer

• House of Leaves by Mark Z. Danielewski

• Prometheus Rising by Robert Anton Wilson

• Midnight Library by Matt Haig

What book would you add to the list and why?