Perilous Journeys into the Mind
A journey to the depths of the mind involves great personal risks because we may not be able to endure what we find there. That is why all religions have insisted that the mystical journey can only be undertaken under the guidance of an expert. The master monitors the experience, guides the novice past the perilous places, and makes sure he is not exceeding his strength. All mystics stress the need for intelligence and mental stability. Zen masters say that it is useless for a neurotic person to seek a cure in meditation, for that will only make him sicker. Jewish mystics also had to be married to insure that he was in good sexual health.
— Karen Armstrong, A History Of God, p. 213
Emphasis mine.
