I decided to read this because I read an article complaining that it had too many computer metaphors. I also really like Rabbi Aryeh Kaplan's books in general, and his translations as well, but that article pushed this book up in the priority queue :) I put Innerspace on my wishlist and I got it as a present from Laura לאה and I am really grateful for that!! Thank you!
Innerspace is really two books in one. (Note: my edition has no space in the title.) The first part is an overview of traditional Jewish Kabbalah, and the second part is a commentary on the first chapter of the book of Yechezkel. Both of these sections were edited from his lectures, but also, he'd written outlines and notes for them, which gave an idea of how he imagined the lectures as a book. The book itself was only published after his very early and untimely passing.
I thought both sections had very clear explanations and I personally really appreciated the modern analogies too. There wasn't an overbearing amount of them. I've also seen this book described as some kind of New Age tome, which really misses the point, this is a mainstream Orthodox Jewish book with no particularly outlandish ideas about Kabbalah. Nothing in it was really "out there" for me and it was mostly a restatement of things I'd already learned in Orthodox contexts, but it was all VERY clearly stated, and this book clarified some confusing spots for me that I hadn't even realized I'd been confused about.
I wish I'd had this book as a teen, because it ties a lot of disparate topics together really well, and it would have been great to have around. It is maybe a bit too dense for an introductory book - I could not read it in one sitting, my brain would have melted -, but it could be great as a second book on the topic + a reference book to have around, it has a thorough bibliography too. (For an introductory book, hmm, maybe The Thirteen-Petalled Rose by Rabbi Steinsaltz?)
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Source of the book: Gift from my wishlist bought by Laura לאה