Chi (Χ, χ) is the twenty-second letter of the Greek alphabet, with a numerical value of 600 in the Isopsephy system. Its name derives from the Phoenician samekh, meaning 'fish' or 'support,' and its shape—two intersecting lines—evokes the crossing of paths, the union of opposites, and the foundational axis of the cosmos.

Position on the Tree of Life

Chi is assigned to the ninth Sephirah, Yesod (Foundation), on the Tree of Life. Yesod represents the lunar sphere, the realm of reflection, imagination, and the subconscious. As the foundation, it is the final filter through which the energies of the higher Sephiroth pass before manifesting in Malkuth. Chi’s crossed form mirrors the interweaving of forces that stabilize and structure this foundation, acting as a gateway between the astral plane and the physical world.

Astrological and planetary correspondence

In the 777 system, Yesod is governed by the Moon. Chi thus carries lunar attributes: receptivity, cyclical change, and the power of reflection. The letter’s angular, intersecting lines suggest the cross of matter and spirit, a theme echoed in the lunar phases that govern tides, growth, and the rhythms of the unconscious.

Historical context

Chi holds a prominent place in Greek and later Western esoteric traditions. In ancient Greek, it was used as a numeral (600) and appears in the earliest alphabetic inscriptions. Its most famous symbolic use is the Chi-Rho (☧), a monogram of Christ formed from the first two letters of Christos (ΧΡΙΣΤΟΣ), which became a sacred emblem in early Christianity. In the Greek magical papyri, Chi appears in invocations and amulets, often representing the cross of the four elements or the intersection of the divine and mortal realms. The letter’s shape also resembles the crux decussata (X-shaped cross), a symbol of balance and transformation in Pythagorean and Neoplatonic thought. In the Kabbalistic tradition adapted by the Hermetic Order of the Golden Dawn, Chi is linked to the path of the Moon on the Tree of Life, emphasizing its role as a mediator between the supernal and the mundane.

In Liber 777

In the table of Liber 777, Chi appears as the Greek letter corresponding to Yesod (scale step 9). Its placement underscores the foundational, lunar, and reflective qualities of this Sephirah, serving as a glyph of the crossing that stabilizes the Tree’s structure before the final descent into Malkuth.