Very little systematic and serious attention was given to a variety of phenomena that have been described over centuries within the framework of the world’s great religions, as well as temple mysteries, mystery religions, initiation rites, and various mystical schools.
Grof argues that LSD psychotherapy uniquely opens scientific access to transpersonal phenomena previously dismissed by mainstream psychiatry as psychotic, thereby expanding the empirical basis of depth psychology.
, Varieties of Transpersonal Experiences: Observations from LSD Psychotherapy, 1972thesis