(It should be noted that although this article regularly refers to Xenu, Hubbard in many of his lectures and writings actually uses the name Xemu).
In Hubbard's efforts to shift from a psychotherapeutic to a spiritual program, he introduced the concept of thetans: a set of godlike, non-corporeal entities capable of creating and shaping universes, later trapped in the MEST and confined, by reincarnation, to physical bodies.