by Evelyn Underhill 
The classic study of the path to oneness, written by a leading student of Mysticism.
Mysticism, Christian and Buddhist
by Daisetz Teitaro Suzuki. [1957, not renewed]
Suzuki compares and contrasts Buddhism with Meister Eckhart's mystical outlook.
The Candle of Vision
by AE (George William Russell) 
Essays on Celtic mysticism.
The Works of Dionysius the Areopagite (ca. 400 C.E.)
by Dionysius the Areopagite, tr. by John Parker 
A very early Christian mystic writer with Neoplatonist influences.
The Adornment of the Spiritual Marriage (b. 1293 d. 1381)
by Jan van Ruysbroeck, tr. by C. A. Wynschenk Dom, ed. by Evelyn Underhill 
Writings of an influential Flemish Christian mystic.
The Cloud of Unknowing (ca. 1400)
by Anonymous, ed. by Evelyn Underhill 
Meditations of an anonymous 14th century Christian mystic.
Imitation of Christ (ca. 1418)
by Thomas a Kempis, tr. by William Benham 
A contemplative classic of Christian mysticism.
The Interior Castle
or, The Mansions, by St. Teresa of Avila 
A roadmap to mystical union with God.
Jesus, the Last Great Initiate
by Edouard Schuré, tr. by F. Rothwell 
The historical context of Jesus, and the esoteric significance of his teachings.
The Signature of All Things
by Jacob Boehme, translated by Anonymous .
A Christian mystic explains the hidden meanings implicit in everything.
The Confessions of Jacob Boehme
by Jacob Boehme, compiled and edited by W. Scott Palmer, Introduction by Eveyln Underhill .
A succinct look at the world-view of Boehme, a Renaissance German mystic.
Mysteries of the Qabalah
by Elias Gewurz
(pseud. William Walker Atkinson?)
Theosophy infused with Jewish mysticism
The Upanishads, Part I (SBE 1)
Max Müller, translator 
The Chandogya, Talavakara, Aitreya-Aranyaka, the Kaushitaki-Brahmana, and the Vajasaneyi Samhita Upanishads
The Upanishads, Part II (SBE 15)
Max Müller, translator 
Katha, Mundaka, Taittirîyaka, Brihadâranyaka, Svetâsvatara, Prasña, and Maitrâyana Brâhmana Upanishads.
by S.N. Dasgupta 
by E.H. Palmer 
Decoding the cloaked Sufi narrative of the journey to God.
The Secret Rose Garden
of Sa'd Ud Din Mahmud Shabistari,
Translated by Florence Lederer 
The Mystics of Islam
by Reynold A. Nicholson. . 267,991 bytes
Studies in Islamic Mysticism
by Reynold Alleyne Nicholson, .
The lives and writings of three early Sufi masters.
The Kabbalah Unveiled
S.L. MacGregor Mathers, Translator. 
An extensive introduction to the Kabbalah. Includes translations of three texts from branch of the Kabbalah known as the Zohar: The Book of Concealed Mystery, The Greater Holy Assembly, and The Lesser Holy Assembly.
translated by Isidor Kalisch 
Includes English translation and pointed Hebrew for this key text of the Kabbalah.
The Zohar: Bereshith to Lekh Lekha
by Nurho de Manhar (pseud.) [1900-14]
The Zohar is a Kabbalistic commentary on the Hebrew Bible.
This is the only extensive English translation
of a portion of the Zohar currently in the public domain.
Covers Adam to Abraham.
by J. Abelson 
The Kabbalah in the context of the history of Jewish Mysticism.
The Kabbalah, or the Religious Philosophy of the Hebrews
by Adolphe Franck 
Did the Kabbalah originate from Zoroastrianism?
by Bernhard Pick 
A short critical introduction to the Kabbalah.
The Varieties of Religious Experience
by William James 
A comprehensive study of the psychology of conversion, saintliness, and mysticism.
The Science of Geting Rich
by Wallace Delois Wattles 
Life and Its Mysteries
by Frank L. Hammer 
Plain answers to the big metaphysical questions, including "Where do animals go when they die?".
The Rosicrucians, Their Rites and Mysteries
by Hargrave Jennings [4th ed., 1907, orig. pub. 1870]
Was sacred sexuality at the core of the Rosicrucians' legendary powers to halt aging, transmute matter and attain spiritual perfection?
The Tao Teh King: A Short Study in Comparative Religion
Translated with commentary by C. Spurgeon Medhurst 
Echoes of mystical Christianity in the Tao te Ching.