Psychiatrist Stan Grof, M.D., has more than fifty years experience researching the effects of non-ordinary states of consciousness on human health and wellbeing, and has written several books sharing his insights. Dr. Grof’s extensive research includes experiential psychotherapy using psychedelics as well as non-drug techniques, especially holotropic breathwork.
"In one of my early books I suggested that the potential significance of LSD and other psychedelics for psychiatry and psychology was comparable to the value the microscope has for biology and medicine, or the telescope has for astronomy. My later experience with psychedelics only confirmed this initial impression."
"The use of psychedelic substances can be traced back for millennia, to the dawn of human history. Since time immemorial, plant materials containing powerful, consciousness-expanding compounds were used to induce non-ordinary states of consciousness or, more specifically, an important subgroup of them, which I call "holotropic". These plants have played an important role in shamanic practice, aboriginal healing ceremonies, rites of passage, mysteries of death and rebirth, and various other spiritual traditions. The ancient and native cultures using psychedelic materials held them in great esteem and considered them to be sacraments, flesh of the gods."
Read his very interesting blog at Reality Sandwich.