From the book "Gods About Us", Max Rempel
So how did it come about that human souls agreed to the role of slaves? The answer to this question is complex and ambiguous. The first human souls found themselves on earth out of necessity - they were people, refugees from other planets who were fleeing wars and persecution. Such is celestial mechanics that if a human body dies on earth, its soul will most likely continue to reincarnate on this same planet. Why distance is a barrier for souls is not entirely clear to me, but I have come across quite a few stories of alien souls drawn into the earthly reincarnation cycle in this way.
The second reason, often cited by sources from the higher realms, is that our souls themselves chose such a difficult path, because it leads to a more radical purification and perfection. That they preferred to start from the very bottom in order to climb to especially great heights. By the slingshot principle, the harder you stretch the rubber band, the higher you shoot. Our souls were promised that upon completion of the many-thousand-year cycle - that is, in our own years - the light would be switched on, water would be poured into the pool, and a human being would suddenly be transformed from a slave into an angel possessing a body and living on Earth. This is roughly like being taken up to heaven alive, only without leaving the planet. So the higher sources tell us, and in a non-radical, non-literal interpretation it seems to be true: we are in the process of a most fundamental change, in which we are squeezing the slave out of ourselves no longer drop by drop, but by whole bucketfuls.