Scientology is defined as a set of beliefs written by science fiction author L. Ron Hubbard. Scientology describes itself as the study and handling of the spirit in relationship to itself, others, and all of life. One purpose of Scientology, as stated by the Church of Scientology, is to become certain of one's spiritual existence and one's relationship to God, or the "Supreme Being." One belief of Scientology is that a human is an immortal alien spiritual being, termed a thetan, that is trapped on planet Earth in a physical body. Hubbard described these "thetans" in "The Space Opera" cosmogony.The thetan has had innumerable past lives and it is accepted in Scientology that lives preceding the thetan's arrival on Earth lived in extraterrestrial cultures. Descriptions of space opera incidents are seen as true events by Scientologists.Scientologists believe that an individual should discover for himself that Scientology works by personally applying its principles and observing or experiencing desirable results.