The 21st Aethyr, ASP, is the Aethyr where you meet your own unique path back to God. When you first enter ASP you will be totally alone. There will be no colors, no sounds, and no forms. However this veil will slowly lift with a sense of time and destiny merging. It is a euphoric feeling of knowing that where you are now in life is part of the journey of where you are going.
Eventually, as you explore ASP, you will come to an Angel who may may be seated on a throne. The angel here puts out an energy of authority, which is often perceived as cold and masculine. There is no verbal communication permitted with this angel. You must use ideas or think your thoughts to him. He will answer in the same way. Most often you do not really notice the oddity of this form of communicating until after the encounter and you are back in your physical body. However if you do try to speak to him with words, don't be surprised if you find you can't speak or that your words fall of deaf ears.
Now if you look carefully you may notice that this angel's eyes are looking downward. It is symbolic, as he is looking toward the lower Aethyrs from which you have just come. If he were to look upward to the higher Aethyrs, you would cease to exist in all the Aethyrs below ASP including the physical plane. His refusal to look upward is your guarantee of returning safely to your physical body, after this encounter. This encounter is initiatory. If successful, you will realize that this angel is your own reincarnating ego. It is that part of yourself that takes on manifestation into the lower realms of existence to express itself in time, space, and form. It anchors itself here in ASP and will remain here till you leave the physical plane permanently.
The lesson here is that you will keep reincarnating in physical form, until you complete all the things you have come to experience and fully traveled the destiny you have laid out for yourself. It is a path that you yourself have set and it is a path that you yourself must take.
* additional source material: "Enochian Magick" by Gerald J. Schueler, "The Golden Dawn" by Israel Regardie