In Thelema, the Abyss represents a metaphysical concept that signifies the great chasm or void separating the manifest world from its divine source. Aleister Crowley, the founder of Thelema, extensively explored and integrated this concept into his esoteric teachings, imbuing it with deep spiritual significance.

The Abyss represents the formidable barrier that the adept must traverse to attain the grade of Magister Templi. This journey involves the complete dissolution of the ego and confronting Choronzon, the demon guardian of the Abyss, who embodies the chaotic and fragmentary nature of the mind that resists spiritual unification. Successfully crossing the Abyss signifies a profound transformation, marking the aspirant's progression towards higher consciousness and spiritual enlightenment.

Before attempting to cross the Abyss, a magician must achieve a significant milestone: the Knowledge and Conversation of the Holy Guardian Angel (K&C of the HGA). This attainment is crucial, as only those who have successfully established this divine communication are considered prepared to navigate the perils of the Abyss. The concept is deeply influenced by earlier mystical and esoteric traditions, particularly those of Jewish Kabbalah and Hermeticism, reflecting a synthesis of ancient wisdom and Crowley's innovative interpretations.

In the Qabalistic Tree of Life, the Abyss is symbolized by Da'ath, the hidden sephira that separates the lower sephiroth from the supernal triad of Kether, Chokmah, and Binah. This separation marks a significant metaphysical divide between the material and the divine.

In the Hermetic Order of the Golden Dawn, the concept of the Abyss as a significant divide was incorporated into their Qabalistic studies. The Golden Dawn also adopted and further developed Enochian magic, a system created by Dr. John Dee and Edward Kelley in the 16th century, which involves communication with angelic beings and the exploration of otherworldly realms. This foundational understanding influenced many members, including Aleister Crowley.

Aleister Crowley, a former member of the Golden Dawn, significantly expanded upon these teachings in his Thelemic system. His experiences and visions, particularly those documented in The Vision and the Voice, played a crucial role in shaping his understanding of the Abyss. During his exploration of the Enochian Aethyrs in the Algerian desert in 1909, Crowley, accompanied by his disciple Victor Benjamin Neuburg, encountered Choronzon, the demon guardian of the Abyss, an event that became a cornerstone of his metaphysical writings.

In Crowley's Thelemic system, it represents the point at which the individual ego must be completely annihilated to achieve higher states of consciousness and spiritual enlightenment, serving as a prerequisite for assuming the grade of Magister Templi (Master of the Temple) in the A∴A∴. Crowley's interpretation of the Abyss reflects his synthesis of various mystical traditions. He drew upon the teachings of Jewish Kabbalists, Hermeticists, and his own visionary experiences to create a unique understanding of this concept within Thelema.

In this framework, the Abyss represents the profound chasm separating the lower sephiroth from the supernal triad of Kether, Chokmah, and Binah. This divide is symbolized by Da'ath, the hidden sephira, which signifies knowledge and the point of transition between the manifest and the divine.