It's silly to provide a "read an excerpt" link that is just the generic intro-to-this-book copy that's approximately reproduced on the page that contains said link. "Hackers like to optimize things." Gee, thanks for that.
Excerpts should be meaty: show me what's going on in the third section of chapter 6. I may not understand all the prerequisites, but I can at least judge whether anything is actually happening in this book, before I give you money.