I read through much of this book as a fun hobby/side project. I felt at times this was a book written by a genius for geniuses... For example, there's a chapter

I read through much of this book as a fun hobby/side project. I felt at times this was a book written by a genius for geniuses... For example, there's a chapter on numerics. Simple, right? PG's "example" was a full ray-tracing library in only about three pages. There were single pages that took me an hour to read and understand fully. Very cool/fun stuff, but also extremely terse, especially if you're new to lisp.