in his writings and lectures, hubbard describes incidents said to have occurred to thetans during the past few trillion years. most of these followed a consistent pattern, wherein a hostile alien civilization captured and brainwashed free thetans. often, instances of implantation are termed "incidents", while the subject of the implants are often termed "goals". some incidents are simply unusual and traumatic events, whereof the memory is said to linger for trillions of years. according to hubbard, only scientology's methods can remove the resulting neuroses.