The Secret Doctrine by H.P. Blavatsky
A cornerstone of Theosophical literature, this extensive work explores cosmic evolution, ancient wisdom, and spiritual cosmology. Blavatsky integrates Eastern philosophy, esoteric teachings, and mythology to reveal the hidden structure of the universe and humanity's spiritual purpose.

Helena Petrovna Blavatsky (1831–1891) was a Russian occultist, author, and co-founder of the Theosophical Society. Her works, including The Secret Doctrine, explored esoteric wisdom, spiritual evolution, and ancient mysticism, shaping modern Western esotericism and spiritual movements.