Empirical study led L. Ron Hubbard to the principles on which Scientology is based. He never claimed to have had a revelation. He spelled the principles out in 1950 in Dianetics: The Modern Science of Mental Health, the bestselling self-help treatise in which he presents rationality as our birthright. The human mind, he wrote, is a perfect computer corrupted by ‘incorrect data’. He urged readers to reflect on their lives and ask themselves: ‘Where is the error?’ With the help of a lay therapist, called an ‘auditor’, they could uncover early traumas – mothers who wanted to abort them, or slept with too many men – and become less irrational: ‘Many of the things which Freud thought might exist,’ he wrote, ‘such as “life in the womb”, “birth trauma”, we in Dianetics have … confirmed.’