I loved this book. Lewis is a wonderful writer who does a great job of explaining exactly how the brain responds to various substances. He stepped me through the most intricate feedback loops with patience and explanations I could understand. I was fascinated by the parts about the mechanics of the brain, as I expected to be. I was also riveted by Lewis' own addiction story, which he wove throughout. I want him to write more books about the brain, right away. Highly recommended, if you like this sort of thing.