Sam Harris speaks with Roland Griffiths about the current state of research on psychedelics. They discuss the historical prohibition against their use; the clinical and scientific promise of psilocybin, mescaline, LSD, DMT, MDMA, and other compounds; the risks associated with these drugs; the role of “set and setting”; the differences between psychedelics and drugs of abuse; MDMA and neurotoxicity; experiences of unity, sacredness, love, and truth; the long-term consequences of psychedelic experiences; synthetic vs natural drugs; the prospects of devising new psychedelics; microdosing; research on psilocybin and long-term meditators; the experience of encountering other apparent beings; psilocybin treatment of addiction; and other topics. In his Afterword, Sam discusses his experience on a large dose of psilocybin—his first psychedelic experience in 25 years. If the Making Sense podcast logo in your player is BLACK, you can SUBSCRIBE to gain access to all full-length episodes at samharris.org/subscribe.