"The Secret Doctrine" is a foundational text of Theosophy, written by Helena Petrovna Blavatsky and published in 1888. The work explores the nature of the universe, humanity, and spiritual evolution, drawing on various religious and philosophical traditions. It presents a synthesis of ancient wisdom and modern science, aiming to reveal the hidden truths behind existence. The book is divided into two volumes: the first focuses on cosmology and the origins of the universe, while the second delves into anthropology and the evolution of human consciousness. "The Secret Doctrine" emphasizes the interconnectedness of all life and the importance of spiritual development.