Free Transpersonal and Spiritual Books
Browse and read classic books on spirituality
Read Classic Books on Transpersonal Topics
The Internet Archive (archive.org) provides free access to hundreds of classic books on religion, religious experience, spirituality, mythology, metaphysical philosophy and psychology.
For your convenience, we have gathered together more than 280 of those that we consider most relevant to the history and study of the transpersonal, arranged in alphabetical order by author.
Here you will find classics of religious philosophy (East and West), metaphysics, mysticism, mythology, comparative religion, esotericism, spiritualism, theosophy, psychical research, new thought, and humanistic, existential and transpersonal psychology.
Click on the VIEW buttons to open each book for immediate inspection and reading.
You can also click on the archive.org links to download the books to your own ebook collection.
Abelson, Joshua (1873-1940)
Jewish Mysticism (1913)
Assagioli, Roberto (1888-1974)
Wikipedia
Some Collected Works of Dr Roberto Assagioli, M.D. [Compiled by Philippe de Coster, 2010]
Atkinson, William Walker [aka Theron Q. Dumont; Yogi Ramacharaka] (1862-1932)
Wikipedia
The Law of the New Thought: A Study of Fundamental Principles and Their Application (1902)
Fourteen Lessons in Yogi Philosophy and Oriental Occultism [as Yogi Ramacharaka] (1904)
A Series of Lessons in Gnani Yoga [as Yogi Ramacharaka] (1906)
The Inner Consciousness (1908)
The Life Beyond Death [as Yogi Ramacharaka] (1909)
Mental Therapeutics [as Theron Q. Dumont] (1916)
Power of Concentration [as Theron Q. Dumont] (1918)
Augustine, St. (354-430)
Wikipedia
The Confessions of St. Augustine (397-400)
Aurobindo, Sri [Aurobindo Ghose] (1872-1950)
Wikipedia
The Life Divine (1947)
The Synthesis of Yoga (1955)
A Practical Guide to Integral Yoga (1959)
Avalon, Arthur [Sir John Woodroffe] (1865-1936)
Wikipedia
The Great Liberation (1913)
Principles of Tantra (1914)
Sakti and Sakta (1918)
The Serpent Power (1919)
Bahá'u'lláh (1817-1892)
Wikipedia
Gleanings from the Writings of Bahá'u'lláh (2005)
The Hidden Words of Bahá'u'lláh (2005)
The Proclamation of Bahá'u'lláh (2005)
Bergson, Henri (1859-1941)
Wikipedia
Creative Evolution (1911)
Dreams (1914)
Mind-Energy: Lectures and Essays (1920)
Besant, Annie Wood (1847-1933)
Wikipedia
Annie Besant: An Autobiography (1897)
Death -- And After? [Theosophical Manuals, No. 3] (1893)
The Ancient Wisdom: An Outline of Theosophical Teachings (1897)
An Introduction to Yoga (1908)
Popular Lessons on Theosophy (1912)
The Spiritual Life (1912)
Psychology (1919)
Blavatsky, Helena Petrovna (1831-1891)
Wikipedia
Isis Unveiled: A Master-Key to the Mysteries of Ancient and Modern Science and Theology: Vol. I. Science (1877)
Isis Unveiled: A Master-Key to the Mysteries of Ancient and Modern Science and Theology: Vol. II. Theology (1877)
The Secret Doctrine: The Synthesis of Science, Religion, and Philosophy. Volume I: Cosmogenesis (1888)
The Secret Doctrine: The Synthesis of Science, Religion, and Philosophy. Volume II: Anthropogenesis (1888)
The Secret Doctrine: The Synthesis of Science, Religion, and Philosophy. Volume III (1893)
The Secret Doctine: The Synthesis of Science, Religion, and Philosophy. Index to Vols. I, II and III (1895)
From the Caves and Jungles of Hindostan (1892)
The Theosophical Glossary (1918)
Brinton, Daniel Garrison (1837-1899)
Wikipedia
The Religious Sentiment: Its Source and Aim (1876)
Bucke, Richard Maurice (1837-1902)
Wikipedia
Man's Moral Nature: An Essay (1879)
Cosmic Consciousness: A Study in the Evolution of the Human Mind (1901)
Bulfinch, Thomas (1796-1867)
Wikipedia
Bulfinch's Mythology (1913)
Bunyan, John (1628-1688)
Wikipedia
The Pilgrim's Progress (1678/1903)
Campbell, Joseph (1904-1987)
Wikipedia
The Hero with a Thousand Faces (1949)
The Masks of God. Vol I. Primitive Mythology (1959)
The Masks of God. Vol II. Oriental Mythology (1962)
Cohen, Chapman (1868-1954)
Wikipedia
Religion & Sex: Studies in the Pathology of Religious Development (1919)
Dalai Lama, H.H. [Tenzin Gyatso] (1935- )
Wikipedia
The Way to Freedom (1994)
Descartes, René (1596-1650)
Wikipedia
The method, meditations and philosophy of Descartes (Trans. John Veitch, 1901)
Dresser, Horatio Willis (1866-1954)
Wikipedia
A History of the New Thought Movement (1919)
Durkheim, Émile (1858-1917)
Wikipedia
The Elementary Forms of the Religious Life: A Study in Religious Sociology (1912)
Eliade, Mircea (1907-1986)
Wikipedia
Cosmos and History:The Myth of the Eternal Return (1954)
Patterns in Comparative Religion (1958)
Rites and Symbols of Initiation (1958)
A History of Religious Ideas. Vol 1: From the Stone Age to the Eleusinian Mysteries (1978)
A History of Religious Ideas. Vol 2: From Gautama Buddha to the Triumph of Christianity (1982)
A History of Religious Ideas. Vol 3: From Muhammad to the Age of Reforms (1985)
Eliot, Charles (1862-1931)
Wikipedia
Hinduism and Buddhism: An Historical Sketch. Vol. I (1921)
Hinduism and Buddhism: An Historical Sketch. Vol. II (1921)
Hinduism and Buddhism: An Historical Sketch. Vol. III (1921)
Evans-Wentz, Walter Yeeling (1878-1965)
Wikipedia
The Tibetan Book of the Dead (1927)
Tibetan Yoga and Secret Doctrines (1935)
Frankl, Viktor E. (1905-1997)
Wikipedia
Man's Search for Meaning (1946/1984)
Frazer, James George (1854-1941)
Wikipedia
The Golden Bough: A Study in Magic and Religion. Vol. I (1900)
The Golden Bough: A Study in Magic and Religion. Vol. II (1900)
The Golden Bough: A Study in Magic and Religion. Vol. III (1900)
Freud, Sigmund (1856-1939)
Wikipedia
The Interpretation of Dreams (1913)
Totem and Taboo: Resemblances Between the Psychic Lives of Savages and Neurotics (1918)
The Future of an Illusion (1927/1961)
Civilization and its Discontents (1930)
Guenther, Herbert Vighnāntaka (1917-2006) & Trungpa, Chögyam (1939-1987)
Wikipedia
The Dawn of Tantra (1975)
Gurney, Edmund (1847-1888)
Wikipedia
Phantasms of the Living, Volume I [with Frederic W.H. Myers and Frank Podmore] (1886)
Phantasms of the Living, Volume II [with Frederic W.H. Myers and Frank Podmore] (1886)
Hartshorne, Charles (1897-2000)
Wikipedia
Beyond Humanism: Essays in the New Philosophy of Nature (1937)
The Divine Relativity: A Social Conception of God (1948)
Heindel, Max (1865-1919)
Wikipedia
The Rosicrucian Cosmo-Conception: Or Christian Occult Science (1910)
The Rosicrucian Mysteries: An Elementary Exposition of Their Secret Teachings (1911)
The Rosicrucian Philosophy in Questions and Answers (1922)
Hesse, Hermann (1877-1962)
Wikipedia
Siddhartha: An Indian Tale (1922)
Huxley, Aldous (1894-1963)
Wikipedia
The Perennial Philosophy (1945)
The Doors of Perception (1954)
Hyslop, James Hervey (1854-1920)
Wikipedia
Borderland of Psychical Research (1906)
Contact with the Other World: The Latest Evidence as to Communication with the Dead (1919)
Enigmas of Psychical Research (1906)
Life After Death: Problems of the Future Life and its Nature (1918)
Psychical Research and Survival (1913)
Psychical Research and the Resurrection (1908)
Science and a Future Life (1905)
Ignatius of Loyola, St. (1491-1556)
Wikipedia
The Spiritual Exercises of St. Ignatius of Loyola (Trans. Charles Seager, 1847)
The Autobiography of St. Ignatius (Ed. Joseph F.X. O'Conor, 1900)
Inge, William Ralph (1860-1954)
Wikipedia
Christian Mysticism (1899)
Light, Life and Love: Selections from the German Mystics of the Middle Ages (1904)
Jacobi, Jolande (1890-1973)
Wikipedia
The Psychology of C.G. Jung: An Introduction with Illustrations (1942/1951)
James, William (1842-1910)
Wikipedia
The Will to Believe, and Other Essays in Popular Philosophy (1897)
Human Immortality: Two Supposed Objections to the Doctrine (1898)
Varieties of Religious Experience: A Study in Human Nature (1902)
Pragmatism: A New Name For Some Old Ways of Thinking (1907)
A Pluralistic Universe: Hibbert Lectures (1909)
Some Problems of Philosophy: A Beginning of an Introduction to Philosophy (1911)
Essays in Radical Empiricism (1912)
Jastrow, Morris (1861-1921) & Clay, Albert Tobias (1866-1925)
Wikipedia
An Old Babylonian Version of the Gilgamesh Epic (1920)
John of the Cross, St. (1542-1591)
Wikipedia
The Dark Night of the Soul (Trans. Gabriela Cunninghame Graham, 1905)
A Spiritual Canticle of the Soul and the Bridegroom Christ (Trans. David Lewis, 1919)
Johnston, Charles (1867-1931)
Wikipedia
The Yoga Sutras of Patanjali: The Book of the Spiritual Man (1912)
Julian of Norwich (c.1342-c.1416)
Wikipedia
Revelations of Divine Love (1902)
Jung, Carl Gustav (1875-1961)
Wikipedia
Psychological Types (1923)
Two Essays on Analytical Psychology (1928)
Contributions to Analytical Psychology (1928)
Modern Man in Search of a Soul (1933)
Psychiatric Studies (1945)
Essays on Contemporary Events (1947)
Man and His Symbols (1964/1988)
Kant, Immanuel (1724-1804)
Wikipedia
Dreams of a Spirit-Seer (1766, Trans. Emanuel F. Goerwitz, 1900)
Critique of Pure Reason (1781, Trans. Norman Kemp Smith, 1929)
Critique of Practical Reason (1788, Trans. Thomas Kingsmill Abbott, 1898)
Kardec, Allan [Hippolyte Léon Denizard Rivail] (1804-1869)
Wikipedia
Experimental Spiritism: Book on Mediums; Or, Guide for Mediums and Invocators (1874)
Spiritualist Philosophy: The Spirits' Book. Containing the Principles of Spiritist Doctrine (1893)
Koestler, Arthur (1905-1983)
Wikipedia
The Ghost in the Machine (1967)
Krishnamurti, Jiddu (1895-1986)
Wikipedia
At the Feet of the Master [as Alcyone] (1910)
Education as Service [as Alcyone] (1912)
The Wholeness of Life: Dialogues with physicist David Bohm and psychiatrist David Shainberg (1978)
Can Humanity Change?: J. Krishnamurti in Dialogue with Buddhists (2003)
Lakshmi Narasu, Pokala (c.1846-1934)
The Essence of Buddhism (1907)
Lang, Andrew (1844-1912)
Wikipedia
Myth, Ritual and Religion, Vol. I (1887)
Myth, Ritual and Religion, Vol. II (1887)
Lawrence, David Herbert (1885-1930)
Wikipedia
Psychoanalysis and the Unconscious (1921)
Fantasia of the Unconscious (1922)
Leadbeater, Charles Webster (1854-1934)
Wikipedia
The Astral Plane: Its Scenery, Inhabitants, and Phenomena (1896)
An Outline of Theosophy (1902)
The Inner Life (1911)
A Textbook of Theosophy (1912)
The Life After Death, and How Theosophy Unveils It (1912)
Leary, Timothy (1920-1996)
Wikipedia
The Politics of Ecstasy (1968)
High Priest (1968/1995)
Confessions of a Hope Fiend (1973)
The Game of Life (c.1979)
Change Your Brain (1988)
Your Brain is God (1988)
Start Your Own Religion (2005)
Legge, James (1815-1897)
Wikipedia
The Sacred Books of China: The Texts of Confucianism. Part I (1879)
The Sacred Books of China: The Texts of Confucianism. Part II [The Yi King] (1885)
The Sacred Books of China: The Texts of Confucianism. Part III (1885)
The Sacred Books of China: The Texts of Confucianism. Part IV (1885)
The Sacred Books of China: The Texts of Taoism. Part I [includes Tao Teh King] (1891)
MacIntyre, Alasdair Chalmers (1929- )
Wikipedia
After Virtue: A Study in Moral Theory (1981)
Maslow, Abraham Harold (1908-1970)
Wikipedia
Motivation and Personality (1954/1970)
The Farther Reaches of Human Nature (1971)
May, Rollo (1909-1994)
Wikipedia
The Meaning of Anxiety (1950)
Symbolism in Religion and Literature (Ed. Rollo May, 1960)
McIvor-Tyndall, Alexander James [aka Ali Nomad] (1870-1940)
Cosmic Consciousness: The Man-God whom we Await [as Ali Nomad] (1913)
Menzies, Allan (1845-1916)
History of Religion: A Sketch of Primitive Religious Beliefs and Practices, and of the Origin and Character of the Great Systems (1895)
The Religions of India: Brahmanism and Buddhism (1903)
Mercer, John Edward (1857-1922)
Wikipedia
Nature Mysticism (1913)
Müller, Friedrich Max (1823-1900)
Wikipedia
Introduction to the Science of Religion [Four Royal Institution lectures with two essays] (1873)
Lectures on the Origin and Growth of Religion: As Illustrated by the Religions of India [Hibbert Lectures] (1878)
Natural Religion [Gifford Lectures] (1888/1892)
Physical Religion [Gifford Lectures] (1890/1891)
Anthropological Religion [Gifford Lectures] (1892)
Theosophy, or Psychological Religion [Gifford Lectures] (1892/1895)
The Upanishads [Trans. F. Max Muller] Part I (1879)
The Upanishads [Trans. F. Max Muller] Part II (1884)
The Dhammapada [Trans. F. Max Muller] (1881)
Murray, Margaret (1863-1963)
Wikipedia
The Witch-cult in Western Europe: A Study in Anthropology (1921)
Myers, Frederic William Henry (1843-1901)
Wikipedia
Human Personality and its Survival of Bodily Death, Vol. I (1903)
Human Personality and its Survival of Bodily Death, Vol. II (1903)
Nicholson, Reynold Alleyne (1868-1945)
Wikipedia
The Mystics of Islam (1914)
Studies in Islamic Mysticism (1921)
Otto, Rudolf (1869-1937)
Wikipedia
Naturalism and Religion (Trans. J. Arthur Thomson, 1907)
The Philosophy of Religion Based on Kant and Fries (1909, Trans. E.B. Dicker, 1931)
The Idea of the Holy (Trans. John W. Harvey, 1923/1950)
The Original Gita: The Song of the Supreme Exalted One (Trans. J.E. Turner, 1939)
Paramahansa Yogananda (1893-1952)
Wikipedia
Autobiography of a Yogi (1946)
Man's Eternal Quest and Other Talks (1957)
Plato (c.425-c.348 BCE)
Wikipedia
Euthyphro, The Apology, Crito, Phaedo, Phaedrus (Trans. Harold North Fowler, 1914)
The Republic. Vol. I. (Trans. Paul Shorey, 1937)
The Republic. Vol. II. (Trans. Paul Shorey, 1937)
Podmore, Frank (1856-1910)
Wikipedia
Apparitions and Thought Transference: An Examination of the Evidence for Telepathy (1894)
Mesmerism and Christian Science: A Short History of Mental Healing (1909)
Modern Spiritualism: A History and a Criticism, Vol. I (1902)
Modern Spiritualism: A History and a Criticism, Vol. II (1902)
Studies in Psychical Research (1897)
Telepathic Hallucinations: The New View of Ghosts (1909)
The Naturalisation of the Supernatural (1908)
The Newer Spiritualism (1911)
Quimby, Phineas Parkhurst (1802-1866)
Wikipedia
The Quimby Manuscripts (Ed. Horatio Willis Dresser, 1921)
Ramana Maharshi (1879-1950)
Wikipedia
Talks with Sri Ramana Maharshi (1955/2005)
Ramanuja (trad. 1017-1137)
Wikipedia
See Thibaut, George Frederick William
Regardie, Francis Israel (1907-1985)
Wikipedia
The Golden Dawn: An Account of the Teaching, Rites and Ceremonies of the Order of the Golden Dawn. Vol. 1 (1937)
The Golden Dawn: An Account of the Teaching, Rites and Ceremonies of the Order of the Golden Dawn. Vol. 2 (1938)
The Golden Dawn: An Account of the Teaching, Rites and Ceremonies of the Order of the Golden Dawn. Vol. 3 (1939)
The Golden Dawn: An Account of the Teaching, Rites and Ceremonies of the Order of the Golden Dawn. Vol. 4 (1940)
The Middle Pillar: The Balance Between Mind and Magic (1938/2004)
The Tree of Life: A Study in Magic (1968)
Foundations of Practical Magic: An Introduction to Qabalistic, Magical and Meditative Techniques (1979)
The Golden Dawn (6th Edition, Revised and enlarged, 1986)
Rogers, Carl R. (1902-1987)
Wikipedia
Counseling and Psychotherapy: Newer Concepts in Practice (1942)
Russell, Bertrand (1872-1970)
Wikipedia
The Problems of Philosophy (1912)
Mysticism and Logic and Other Essays (1917)
History of Western Philosophy (1947)
Scholem, Gershom (1897-1982)
Wikipedia
On the Kabbalah and Its Symbolism (1960)
Origins of the Kabbalah (1967)
Scott, William Major (??-??)
Aspects of Christian Mysticism (1907)
Shankaracharya (788-820)
Wikipedia
The Bhagavad-Gita with the Commentary of Sri Shankaracharya (Trans. Alladi Mahadevi Sastry, 1897)
See also: Thibaut, George Frederick William
Smart, Ninian (1927-2001)
Wikipedia
Doctrine and Argument in Indian Philosophy (1964)
The Yogi and the Devotee: The Interplay Between the Upanishads and Catholic Theology (1968)
Buddhism and Christianity: Rivals and Allies (1993)
Smith, Huston (1919-2016)
Wikipedia
Forgotten Truth: The Common View of the World's Religions (1976)
Why Religion Matters: The Fate of the Human Spirit in an Age of Disbelief (2001)
Smith, Margaret (1884-1970)
Wikipedia
Studies in Early Mysticism in the Near and Middle East (1931/1995)
Soothill, William Edward (1861-1935)
Wikipedia
The Analects of Confucius (1910)
Stace, Walter Terence (1886-1967)
Wikipedia
The Teachings of the Mystics (1960)
Mysticism and Philosophy (1960)
Suzuki, Daisetz Teitaro (1870-1966)
Wikipedia
Essays in Zen Buddhism [First Series] (1927)
Essays in Zen Buddhism [Second Series] (1933)
Essays in Zen Buddhism [Third Series] (1934)
The Zen Doctrine of No-Mind (1949)
Manual of Zen Buddhism (1950)
Studies in Zen (1955)
Swedenborg, Emanuel (1688-1772)
Wikipedia
Heaven and Its Wonders and Hell, from Things Heard and Seen (1758, trans. 1905)
Of the New Jerusalem and Its Heavenly Doctrine (1758, trans. 1829)
Concerning the Earths in Our Solar System (1758, trans. 1839)
Angelic Wisdom Concerning the Divine Love and the Divine Wisdom (1763, trans. 1915)
Angelic Wisdom Concerning the Divine Providence (1764, trans. 1840)
The Apocalypse Revealed Vol. I (1766, trans 1883)
The Apocalypse Revealed Vol. II (1766, trans 1887)
On the Intercourse Between the Soul and the Body (1769, trans. 1848)
The Gist of Swedenborg (Compiled by Julian K. Smyth and William F. Wunsch, 1920)
Szasz, Thomas (1920-2012)
Wikipedia
The Myth of Mental Illness: Foundations of a Theory of Personal Conduct (1961/1974)
Teilhard de Chardin, Pierre (1881-1955)
Wikipedia
The Heart of Matter (1950)
The Phenomenon of Man (1955)
Man's Place in Nature: The Human Zoological Group (1956)
The Divine Milieu: An Essay on the Interior Life (1957)
The Future of Man (1964)
Let Me Explain (1966)
On Love and Happiness (1966/1967)
Teresa of Ávila, St. (1515-1582)
Wikipedia
The life of St. Teresa of Jesus, of the Order of Our Lady of Carmel (Trans. David Lewis, 1916)
The Interior Castle, or The Mansions (Trans. Prior Zimmerman, 1921)
Thibaut, George Frederick William (1848-1914)
Wikipedia
The Vedanta Sutras (Trans. George Thibaut) Part I, with the Commentary of Shankarakarya (Trans. 1896)
The Vedanta Sutras (Trans. George Thibaut) Part II, with the Commentary of Shankarakarya (Trans. 1896)
The Vedanta Sutras (Trans. George Thibaut) Part III, with the Commentary of Ramanuga (Trans. 1904)
Thích Nhất Hạnh (1926- )
Wikipedia
Zen Keys (Trans. 1974)
The Miracle of Mindfulness (1975)
The Heart of the Buddha's Teaching (1998)
No Death, No Fear: Comforting Wisdom for Life (2002)
Being Peace (2005)
The Art of Power (2007)
Thomas à Kempis (1380-1471)
Wikipedia
Of the Imitation of Christ (1903)
Thomas Aquinas, St. (1225-1274)
Wikipedia
The 'Summa Theologica' of St. Thomas Aquinas, Part I. (Trans. 1912)
On Prayer and the Contemplative Life (by Hugh Pope, 1914)
An Introduction to the Metaphysics of St. Thomas Aquinas (Trans. James F. Anderson, 1953)
Trungpa, Chögyam (1939-1987)
Wikipedia
Born in Tibet (1966/1995)
See also Guenther, Herbert Vighnāntaka
Underhill Evelyn (1875-1941)
Wikipedia
Mysticism: A Study of the Nature and Development of Man's Spiritual Consciousness (1912)
The Mystic Way: A Psychological Study in Christian Origins (1913)
Practical Mysticism: A Little Book for Normal People (1914)
The Essentials of Mysticism and Other Essays (1920)
Man and the Supernatural (1927)
Various
The Oxford Book of English Mystical Verse (1917)
Vivekananda, Swami (1893-1902)
Wikipedia
Address on Vedanta Philosophy: The Ideal of a Universal Religion (1896)
Addresses on the Vedanta Philosophy: Bhakti Yoga (1896)
Vedanta Philosophy: Lectures on Karma Yoga (1896)
Vedanta Philosophy: Lectures on Raja Yoga (1896)
Vedanta Philosophy: Lectures on Jnana Yoga (1902)
Wallis Budge, Ernest Alfred Thompson (1857-1934)
Wikipedia
The Book of the Dead [Egyptian] (1895/1909)
Egyptian Magic (1899)
The Gods of the Egyptians, or Studies in Egyptian Mythology. Vol. I (1904)
The Gods of the Egyptians, or Studies in Egyptian Mythology. Vol. II (1904)
The Egyptian Heaven and Hell. Vol. I (1905-1906)
The Egyptian Heaven and Hell. Vol. II (1905-1906)
The Egyptian Heaven and Hell. Vol. III (1905-1906)
Legends of the Gods (1912)
The Literature of the Ancient Egyptians (1914)
Watts, Alan (1915-1973)
Wikipedia
The Philosophies of Asia (1995)
The Spirit of Zen: A Way of Life, Work and Art in the Far East (1936)
The Book on the Taboo Against Knowing Who You Are (1969)
Weber, Max (1864-1920)
Wikipedia
The Religion of China: Confucianism and Taoism (Trans. 1951)
The Sociology of Religion (Trans. 1956)
The Religion of India: The Sociology of Hinduism and Buddhism (Trans. 1958)
Whitehead, Alfred North (1861-1947)
Wikipedia
Process and Reality: An Essay on Cosmology (1929/1978)
Wilber, Ken (1949- )
Wikipedia
Grace and Grit (1991/2001)
A Summary of My Psychological Model (or, Outline of an Integral Psychology) (2006)
Wood, Ernest Egerton (1883-1965)
Wikipedia
Natural Theosophy (1930)
Seven Schools of Yoga: An Introduction (1931/1976)
Concentration: An Approach to Meditation (1949)
The Glorious Presence (1952)
Great Systems of Yoga (1954)
Woods, James Haughton (1864-1935)
The Yoga-System of Patañjali (1914)
Zaehner, Robert Charles (1913-1974)
Wikipedia
Mysticism: Sacred and Profane (1957)
