The word thetan is Hubbard's and is deliberately not soul, spirit or self, all of which he considered contaminated by prior use. A thetan is the person: it has no mass, no wavelength and no location, it has existed for an incalculable time, and it has picked up and put down an enormous number of bodies. Practically, this is what makes Scientology cohere. Auditing works on a being that was present for events long before this lifetime, past-life material is treated as ordinary session content rather than as a curiosity, and the church's indifference to conventional psychiatry follows from the premise that the brain is equipment rather than the person. Scientologists describe the moment the premise lands as the point they joined.