Not too long ago I discovered the book History of Non-dual Meditation Methods by Javier Alvarado Planas and translated into English by Arturo González Pérez. I don’t remember how I stumbled upon it, but it was a fantastic find! Initially, what seemed to me a dry title caused hesitation, but I’m happy I delved within!
The author clearly put an incredible amount of work into thorough research and also into the clear and well-organized presentation of the material. The topic areas are in roughly chronological order starting with Advaita Vedanta and then moving through Greco-Egyptian Hermetism, the Kabbalah, Pythagoras, Plato, Plotinus, and the Stoics. These sections were fascinating and written in a way that preserved a sense of evolution from one strain of thought to the next.
The final parts of the book are dedicated to tracing the history of nondual Christianity. Planas starts with an exploration of contemplation before moving on to Gregory of Nyssa, Augustine, Evagrius Ponticus, John Cassian, Dionysius the Areopagite, Meister Eckhart, the Cloud of Unknowing, Nicholas of Cusa, Teresa of Jesus, John of the Cross, and Miguel de Molinos. As with the earlier sections of the book, the author, notwithstanding the title of this book, spends a fairly equal amount of time on theory and practice.
Something I appreciated about Planas’ writing is that it suggests a proper humility on the topic. Other authors, when referencing metaphysics, might veer into language that suggests a great intellectual confidence in the model being examined, but Planas always reminds us that the type of knowledge being sought is not related to intellect. For example, when writing on the practices of Kabbalists, he writes:
The Nothingness, despite intellectually incomprehensible, represents the disappearance of the ordinary knowledge, understood as a subject-object relationship. Should the process of knowledge involve the three elements, a subject-knower, a known object and the action of knowing, the intuitive knowledge or, strictly speaking, the non-knowledge transcends that personal or individual relationship, unifying those cognitive borders. Within the Nothing, there is no difference between subject and object, not because the subject that knows is at the same time all what is known, but because there is Nobody who knows or Nothing to be known.
In summary I would very much recommend this book, and that’s before mentioning the very useful bibliography. As far as I know this book is out of print, but it may be freely downloaded as a PDF here:
https://www2.uned.es/dpto-hdi/History%20of%20Non-dual%20Meditation%20Methods.pdf