DT... yes, seems to me I recall making a reference. I know the book is somewhat familiar to some who are or have been on TOT. I followed here for about a year before registering and during that time there was a thread where reference was made followed by 2 or 3 comments acknowledging they were familiar. In both that thread and where I made the reference, I don't recall the context.
Since you've expressed an interest in looking further into this, here is some more information... because... this can be dangerous stuff to anyone who might go past themselves with it.
If U looked at the Amazon link then U know there other books as well. The one I linked is the 1st of 8, commonly referred to as the Right Use of Will (RUOW) series published between 1984 and 1999. The titles along with subtitles and short blurb about each are listed by the author in order of publication here immediately following the Feelings Matter – Keys To The Unexplored Self book, the author's most recent publication. I highly, highly recommend reading Feelings Matter before exploring the RUOW series. Particularly since I think you will find that it dovetails very nicely with the Sopolsky video.
Finally, nothing I can say here can come close to what it says in the very first para on pg i of the intro to Right Use Of Will – Healing and Evolving the Emotional Body...
If this book is for you, you will know it from these first few pages. This book may stir emotional response. Please realize that this book is meant to trigger you and is not meant to be just a mental exercise. If you feel emotions being stirred, please do your best to allow these emotions direct expression as any sounds they want to make. Pleased do not act in response to what is being triggered; just be present with your emotions.
IOW... as wim hof put it... U WILL FEEL IT... "if this book is for you"...
I personally know people who went into this material and ended up having a psychotic break (and worse) and I have heard stories of others. Some come back, some don't. Of the ones that do, some still work with the material having realized it was they who went past themselves at some point in the process and NOT the material that triggered the break.
We all have an inner compass. Going past that relative to this material and/or treating this information as a mental exercise can be a chilling way to find out why curiosity killed the cat...