Wow. I admit that I was tepid about this book much of the way through it. Still I read on, gripped by the story in spite of myself. The ending, however, was phenomenal, and after reading it, I felt all the pieces I thought hadn't fit together well throughout the book just kind of slide into place. 
 I particularly like the idea that there is an invisible barrier between the awful thoughts we might have and our actions, and that the most terrifying thought is the reality that there truly is no barrier. I remember having a feeling like this when I first got my drivers license and I realized that there was really nothing keeping me from driving off the road. Around the same teenage time, I remember sitting in a quiet class and thinking there was nothing keeping me from just screaming. I never drove off the road and I never screamed in class, and until reading this book, I never thought of why exactly it was I hadn't.