If you were like me and missed this achievement throughout normal gameplay, you can quickly get this achievement by:
- Kill the Cripple.
- Take the crutches.
- Enter the boat.
- Go to the sleeping guy in the graveyard (head to the right hand side after arriving, he's in the coffin).
- Poke his face, he'll wake up.
- Stab his face and take the book.
- Go to the bowman in the torture area (area at the back of the crucifixions, on the left upon arrival).
- Prompt him to shoot the apple.
- After he shoots the apple, place the book on the tree guy's head.
- Prompt the bowman to shoot the book.
- He will shoot the book, and the achievement will unlock.