In a reading givn on May 8, 1942 for a thirty yeard old naval officer, the entranced Cayce discussed the past life of an Atlantean prince named On-Xor and his role in the events that led to first period of upheaval.
Before that the entity was in the Atlantean experience, when there were the disturbances that arose which later brought the first upheavals. For, the entity was of the children of the Law of One; yet the combative influences wrought by the activities of the sons of Belial brought those periods of indeterminate activity - or that which finds expression in the present as of not fully being convinced deep within self save by practical experience. And as this had little to do with the final outcome in the material experience, there came doubts and fears. Then the name was On-Xor, and the entity was a prince in that experience. (ECR: 2746-1)
To understand the context of this past life, keep in mind the struggle between the two main factions within Atlantean society of that era. The Law of One group posssessed crystal technology that could be used for good or ill. The Belial group with rather selfish and short-centered values managed to gain access to this energy.
With the powerful technology available for use by the Belial faction, the first of the upheavals was brought about when the Belial group insisted upon using the crystal technology developed by the Law of One Faction to exterminate the menacing beasts that roamed the world at that time. Cayce states that Atlanteans turned the etheric rays from the sun into the facet of activity that produced a volcanic upheaval. The continent of Atlantis was fractuered.
Cayce called it a misapplication of knowledge. The forces that should have been used for constructive purposes were used for destruction.
In creating the imagery for the story of On-Xor, I have placed him on an Atlantean aircraft - a balloon type vessel adapted for warfare against the marauding animals. He was assigned to oversee the expedition, but he lost his sense of purpose and failed to provide strong, wise leadership.
Prince On-xor's "indeterminate activity" (lack of positive assertiveness) was just one facet of the complex interactions that produced the first of the Atlantean upheavals. See the account of Esdro-m for another perspective of this dramatic episode in the story of Atlantis.