The 27th Aethyr, ZAA, is the Aethyr of solitude and your adventure in being alone. Two things you will notice upon entering ZAA is its lunar, almost sublime nature, and the absence of anything except yourself. On the Tree of Life, ZAA is somewhere in and around the region of Netzach and Tiphareth.
Except for a few Angels, the sense of loneliness here can seem oppressive. It can be likened to entering a dark and silent chamber and remaining there for a very long time by yourself. The guide here is the dual aspect the goddess Diana (young, energetic, and attractive) and her alter-ego Hecate (old, selfish, and repulsive). Most people will meet the younger more attractive Diana first. Later, as you become more familiar with this Aethyr, you will meet Hecate and realize that she and Diana are the same guide. You may also come across the Egyptian deities Isis and her sister Nephthys. Isis is warm, loving, and motherly, while Nephthys is cold, stern, and impersonal.
The loneliness in ZAA is the sense of separation that we all share. You must accept individuality but not loneliness. The terrible sense of loneliness in ZAA is a result of incorrect thinking, for you are never alone. The entire universe and all the beings within it are always a part of yourself. Realizing this element is a great leap in your progress toward divinity and a good preparation for the higher Aethyrs.
ZAA is a region of introspection and is designed to allow you to digest the various experiences of your life. It is also a region of rest, as it is a quiet place and is closely associated with the deep, dreamless sleep state that you enter periodically at night.
* additional source material: "Enochian Magick" by Gerald J. Schueler, "The Golden Dawn" by Israel Regardie