I put together a music playlist based on Grof’s recommendations for your benefit. The songs are in random order. Let me know if I should add/remove any:

Holotropic Breathing – Beginning

Holotropic Breathing – Middle

Holotropic Breathing – End

Also, informative interview with Grof:

In a suitable analogy, Grof declares LSD to be psychiatry’s fundamental tool; it is like the astronomer’s telescope or the biologist’s microscope.  Grof refers to the powerful ability of LSD to facilitate the revealing of deep unconscious systems like that of sonar or radar, revealing the largest and most relevant emotional disturbances beneath the surface of the unconscious ocean. It allows therapists to have a direct reading of a patient’s relevant thought systems and important experiences. Readers begin to realize how incredibly important this molecule is for the well-being of the psyche and the spiritual and mental development of humanity.

For a simple introduction, I would suggest The Holotropic Mind rather than this book. Or if you prefer an audio book, Audible has The Transpersonal Vision. I would also recommend joining the email list for the Multidisciplinary Association for Psychedelic Studies (MAPS).

Some of Hancock’s previous books, like Heavens Mirror, Fingerprints of Gods, Sign and Seal, and Underworld, I read and enjoyed more than seven years ago. I saw Supernatural when it came out in mid 2000’s, but I was not interested. At the time I thought, “Clearly Hancock has gone too far into the abyss of crazy.” It took me more than ten years to mature and discover the greatness of this work. I must say that Hancock does an incredible job and I can not wait to read his newest book, releasing in a few days. Supernatural has the power to shape your perceptions of reality and everything you thought you knew and understood. It is not to be taken lightly and I would suggest first reading Strassman’s DMT: The Spirit Molecule and perhaps even Jeremy Narby’s The Cosmic Serpent.

“Whatever the Thinker thinks, the Prover proves”

And he makes it clear that his book is itself a tunnel-reality written in English to appeal to the third circuit semantic logic of the reader. It is a book to help the reader escape tunnel-realities which is itself a tunnel-reality. That is meta! Meta-programming the reader’s own mental software to become aware of infinity is the subject of chapter 14. Topics include everything from physics to strange loops to Leary to UFOs to evolution to yoga.

Attempting to elevate the reader’s awareness to a higher state with verbal or written language is like trying to “fit a camel through the eye of a needle.” Hence the studying of Koans by students of Zen, religious fasting to deprive the mind, etc… Read Alan Watt’s The Way of Zen for more on that. This book was written by Wilson, who, in his terminology might be a thinker on a higher circuit, trying to communicate to the vast mass of humanity living on the 1st – 3rd circuits. Once a critical mass of humanity becomes aware, society will under-go a quantum leap in development. With that being said, the book is only an introduction, a starting point for a new perspective to grasp human psychology and human existence as “domesticated primates” on Earth. What is left is for the reader to explore the exercises at the end of each chapter and spread the word.

But some may argue that Wilson is himself subject to the same principals he outlines in his book; yes indeed, perhaps the entire book is the ramblings of a man attempting to brainwash his readers into having thoughts of freedom and liberty…