Stanislav Grof, on the other hand, operates with a cartography consisting of three kinds of territories: the realm of the sensory barrier and the personal unconscious (described by psychoanalysis), the perinatal or birth-related realm (organizing principles for the psyche), and the transpersonal realm. According to this view proper engagement with the first two realms sets the stage for an ascent to the third, transpersonal, realm. His early therapy, and research, was carried out with the aid of psychedelic substances such as lysergic acid diethylamide (LSD), psilocybin, mescaline, dipropyl-tryptamine (DPT), and methylene-dioxy-amphetamine (MDA). Later, when LSD was prohibited, Grof developed other methods of therapy, such as holotropic breathwork.