The Scientology Handbook (page i) states that:
"The essential tenets of Scientology are these: You are an immortal spiritual being. Your experience extends well beyond a single lifetime. And your capabilities are unlimited, even if not presently realized."
In these words, Scientology posits the existence of an entity which bears significant similarity to what in various other religions is termed a soul or a spirit. To avoid confusions with previous conceptions of the soul, Scientology terms this entity a thetan, from the Greek letter theta (*), a symbol for thought or life. The thetan is not a thing, nor is it the mind. It is the creator of things. It is the person himself -- the persisting identity which is the individual. The thetan is said to be immortal and to be capable of accomplishing anything, including the creation of mass, energy, space and time (The Scientology Handbook, p. xxiii; Scientology: The Fundamentals of Thought, p. 75).