So I did a quick skim of this novel, trying to refresh my memory of a book that I read more than 20 years ago. I remember liking the novel back then - but I’m not so sure I like it that much now. But my point lies elsewhere.
The novels present crystals that are world spaces in which wealthy and powerful ancient Athasians would enter thier souls into before death. Inside the crystal world there are no limitations on space or environment, even though the crystals themselves can fit in the palm of your hand in the real world. The ancients had their crystals linked up so they could meet each other across their crystal worlds. Over thousands of years this system broke down and they became isolated and alone within their crystals.
This brings up an interesting notion. If you accept this part of the novel as canon, then the ancients must have had a good understanding of the Gray, and that there was no reward in the afterlife, only slowly having their souls drain away before oblivion.
This must have been a terrifying thought. With no afterlife, the ancients came up with a psionic means of providing themselves with a man made afterlife, inside an artificial crystal virtual reality.