History Of Mysticism: The Unchanging Testament (3rd Rev. Ed.) (1996)
Reading more of Shankara (pages 187-196) in History of Mysticism, by S. Abhayananda, I find his Avaita Vedanta philosophy to be very stimulating.
The Visionary Window: Quantum Enlightenment
The Sacred Network: Megaliths, Cathedrals, Ley Lines, and the Power of Shared Consciousness, Chris H. Hardy Ph.D. (2011)
Enlightenment is a Four-Letter Word (2014)
The main theme here is: “Divinize the human and Humanize the Divine.”
Other books of interest in Enlightenment Studies:
The Void: Inner Spaciousness and Ego Structure A.H. Almaas (2000)
Ken: Almaas has written about 13 books, all really excellent, especially the DIAMOND HEART series. I absolutely LOVE this one , The VOID, as it’s the “place” I frequently try to rest in whenever possible.
Spiritual Enlightenment: The Damnedest Thing; Spiritually Incorrect Enlightenment; and, Spiritual Warfare, by Jed McKenna,
From Onions to Pearls and From Seekers to Finders, both by Satyam Nadeen,
The Power of NOW; and, Stillness Speaks, both by Eckhart Tolle,
and finally The Heart of Awareness (a translation of the Ashtavakra Gita), by Thomas Byron.
-These books are a good preparation for Peace and Harmony in Daily Living, by Ramesh S. Balsekar.
Books, such as The Heart of Awareness, write about more general insights into the spiritual life. My Confessions of an Ex-Jesuit, Vols 1-3, on the other hand, attempt to apply the more generic to the concrete specific happenings/thoughts in my life.
The Course in Miracles (Christian perspective)