"Ooooh." said Vi, feeling very very stupid. "So the book made up all that stuff? Just off-the-cuff?" "Off-the-margin, you mean?" "Huh?" "Never you mind. You said when you fil ahead the pages are blank?" Vi noded. "The magic on the book senses who's reading it; that's why only you can read it. It wants to only be read by you, so when anyone else tries, there's some kind of trap triggered..."

— Night Angel Nemesis by Brent Weeks (The Kylar chronicles, #1) (Page 444)