I found this on a list of Tool's recommended reading. There is some very interesting information regarding the nature of the pineal gland (aka third eye) on the page with the letter in it. it also has some interesting information regarding Merkaba and 46 + 2. notice the symbol on the top of chapter one. i think this would be a very good book for any thinker or tool fan, as it's obviously been a huge influence on the band.
Re: "Nothing In This Book Is True, But It's Exactly the Way Things Are"
I've read this book it's pretty much just a condensed version of two other books. The Ancient Secrets of the Flower of Life: Volumes 1 and 2. Nothing is a way easier read though, The Ancient seems to drag in places and go off on tangets.