Operating Thetan (OT) is a concept in Scientology referring to a state of spiritual ability in which a person is said to be "cause over life, thought, matter, energy, space and time". After reaching the state of Clear, Scientologists may progress through a series of confidential OT levels that the Church of Scientology presents as advanced spiritual training. These levels, numbered OT I through OT VIII, are available only at designated service organizations and require substantial financial outlay.