"The Yellow Book: The Divine Mother, Kundalini, and Sexual Yoga." It was first published in Spanish as "El Libro Amarillo" and later translated into various languages to reach a broader international audience.The book covers a range of esoteric topics related to Gnostic teachings, including the concept of the Divine Mother (often associated with the feminine aspect of divinity), Kundalini energy (a powerful spiritual force believed to lie dormant at the base of the spine), and the practice of Sexual Yoga (a discipline aimed at harnessing and transmuting sexual energy for spiritual awakening)."The Yellow Book" delves into the relationship between spirituality, sexuality, and human consciousness, emphasizing the importance of cultivating purity, self-awareness, and spiritual discipline. It presents a path of inner work and self-discovery, with the ultimate goal of achieving self-realization and a profound connection with the Divine.