The great masterpieces of alchemy in twentieth century writing are, of course, Le Mystère des Cathédrales and Les Demeures Philosophales. Not only do they offer clues to understanding, but they are also brilliant guides to tracking down esoteric sites in France. I recommend Paul Sedir’s History of the Rosicrucian Brotherhood, which contains an excellent, illuminating account of the greatest flowering of Christianized alchemy. The Zelator by David Ovason is good on this subject, as is Steiner’s The Mysteries of the Rosicrucians. To anyone wishing to research alchemy further, I recommend the writing website of Adam Maclean, a fascinating archive of historical documents.
Steiner’s predecessor, Madame Blavatsky, is a bit of a problem, if only because her anti-Christian animus seems in retrospect a bit impish and perverse. I prefer to see Blavatsky as an exemplar of a splendid Victorian tradition — the writing of monstrously large rag bags of books packed with strange ideas and obscure but often fascinating erudition. With the possible exception of Sir James Frazer’s The Golden Bough — which is at least permanently in print — these books are hardly read at all now. In fact I sometimes wondered whether I was the first person to read some of these pages for perhaps over a hundred years. Their wisdom has become discarded wisdom, but there is wisdom to be found, and I have had a lot of fun rummaging around in the following: The Secret Doctrine and Isis Unveiled by Madame Blavatsky, Theosophy and Psychological Religion by F. Max Muller. Fragments of a Faith Forgotten and Orpheus by G.R.S. Meade, The Egyptian Book of the Dead and Gnostic and Historic Christianity by George Eliot’s friend, Gerald Massey, Ancient Theories of Revelation and Inspiration by Edwyn Bevan, Oedipus Judaicus by William Drummond, The Lost Language of Symbolism, and Archaic England by Harold Bayley, The Canon by William Stirling, Architecture: Mysticism and Myth by William Lethaby, Pagan and Christian Creeds by Edward Carpenter, Introduction to Tantra Sastra and The Serpent Power by Sir John Woodroffe, The History of Magic by Eliphas Levi, The Kabbalah Unveiled by S.L. Macgregor Mathers, Mysticism by Evelyn Underhill, Studies in Mysticism and Certain Aspects of the Secret Tradition by A.E. Waite, Cosmic Consciousness by Richard Bucke, The Initiates by Eduard Schure, The Eleusian and Bacchic Mysteries by Thomas Taylor, The Veil of Isis by W. Winwood Reade.
Occult physiology is a key part of this book. I have used The Occult Causes of Disease by E. Wolfram, The Encyclopedia of Esoteric Man by Benjamin Walker, Occult Principles of Health and Healing by Max Heindel, Occult Anatomy and the Bible by Corinne Heline and An Occult Physiology, Initiation and its Results, Occult Science and Occult Development by Steiner. The Parable of the Beast by John Bleibtreu, while not framed in esoteric philosophy, has fascinating information, especially on the Third Eye.
Occult art is also key. I have used Symbolists and Symbolism by Robert L Delevoy, Legendary and Mythological Art by Clara Erskine Clement, Hieronymus Bosch by Wilhelm Fraenger, Symbols in Christian Art by Edward Hulme, Three Lectues on Art by René Huyghe — particularly good on El Greco — The Occult in Art by Fred Gettings, The Two Children by David Ovason, Marcel Duchamp by Octavio Paz on Marcel Duchamp, John Richardson’s three volume biography, A Life of Picasso and Mark Harris’s insightful essay on Picasso’s Lost Masterpiece, The Foundations of Modern Art by Ozenfant, Sacred and Legendary Art by Mrs Jameson, Surrealism and Painting by André Breton, Surrealism and the Occult by Nadia Choucha.
The books of Albert Pike and A.E. Waite on Freemasonry fall into the baggy Victorian monster category. Together with Manly Hall these men are established as the great writers on the Freemasonic mysteries, and I have used their Morals and Dogma, History of Freemasonry and Secret Teachings of All Ages, as well as The Temple Legend by Rudolf Steiner. I’d like to mention in the same breath, The Secret Zodiacs of Washington DC by David Ovason and The Seven Ordeals of Count Cagliostro by Ian McCalman. I’d also like to credit the independent-minded research of Robert Lomas, who has co-written with Christopher Knight several bestselling books on the origins of Freemasonry — including The Hiram Key, The Second Messiah and Uriel’s Machine. Like another bestselling writer in the alternative history field, Robert Bauval, Lomas is an engineer, and so able to see things that more theoretically-minded writers have missed. Something I’ve tried to insist on in my own book is that the fact that esoteric teachings have useful, practical application makes them much more likely to be true. A.E. Waite’s The Hidden Church of the Holy Grail is the best account of the various sources of the Grail legend.