I really need to circle back to this book! I got sidetracked a while ago, and I was only two chapters from the end. I had also initiated a Study Group for it that's sadly lain dormant for quite some time now.
jema, I get what you mean about the idea that we can't focus on more than one thing at a time...but then again, I have to admit that the toughest thing for me in the entire experience of working with the book has been trying to simultaneously look at the physical cards laid out before me while conjuring the "astral plane imagery" Tyson describes. I know that if I close my eyes to shut out the physical world, I find visualization to be vastly easier, but that's not the method we're supposed to be using, so...I guess it's a skill I need to keep working at so I can strengthen it.
I do think it's a very cool book, and I found it to be very helpful in certain areas that might seem almost incidental (if still related) to the Tarot and magic pillars of its focus -- things like astrological attributions and Tarot history get summarized in very clear and understandable ways, I thought. I really like the book, and like I said, I need to get back to it, finish it, and maybe even take a second pass through to solidify my grasp on what it's teaching.
Ambrosia, I have no experience with the Renee book you mention, so I can't offer comparative thoughts on the two, sorry. Maybe someone else here can help...