Ruach (Hebrew: רוח, "wind, breath, spirit") is the sphere of Air in the world of Assiah (the material plane), corresponding to the 11th path (Aleph) on the Tree of Life. In Kabbalistic cosmology, Assiah is the lowest of the four worlds, and its heavens are the material counterparts of the Sephirotic paths. Ruach thus represents the elemental Air in its most concrete form. It is also the name of the second level of the human soul (the intellectual-emotional spirit) in the microcosmic Kabbalah, but here it is the macrocosmic sphere of Air. The path of Aleph connects Kether (the Crown) to Chokmah (Wisdom), and is associated with the letter Aleph, the element Air, and the "breath of the living God" in the Sepher Yetzirah. In Liber 777, Ruach is listed as the Assiah heaven for Path 11, while the higher worlds (Briah, Yetzirah, Atziluth) have Aleph as their heavens. This reflects the descent of the Air element through the planes.