Recent trials of psilocybin, a close pharmacological cousin to LSD, have demonstrated that a single guided psychedelic session can alleviate depression when drugs like Prozac have failed; can help alcoholics and smokers to break the grip of a lifelong habit; and can help cancer patients deal with their “existential distress” at the prospect of dying. At the same time, studies imaging the brains of people on psychedelics have opened a new window onto the study of consciousness, as well as the nature of the self and spiritual experience. Perhaps the most significant new evidence for the therapeutic value of psychedelics arrived in a pair of phase 2 trials (conducted at Johns Hopkins and NYU and published in the Journal of Psychopharmacology in 2016) in which a single high dose of psilocybin was administered to cancer patients struggling with depression, anxiety and the fear of death or recurrence. Eighty percent of the Hopkins cancer patients who received psilocybin showed clinically significant reductions in standard measures of anxiety and depression, an effect that endured for at least six months after their session. Results at NYU were similar. Curiously, the degree to which symptoms decreased in both trials correlated with the intensity of the “mystical experience” that volunteers reported, a common occurrence during a high-dose psychedelic session. Few if any psychiatric interventions for anxiety and depression have ever demonstrated such dramatic and sustained results.