For Americans who came of age in the 1960s, hallucinogenic drugs like LSD and mescaline are inextricably linked to that decade's counterculture and guru Timothy Leary's call to "Turn on, tune in, drop out." More recently, studies have shown significant efficacy for hallucinogens in treating a range of psychiatric illnesses, including depression, anxiety, and-ironically-substance use disorders. Beyond recreational micro-dosing and Michael Pollan's "ego dissolution," psilocybin may prove the source of a revolution in mental health. This lecture explores the history of these mind-altering substances, the evidence for their therapeutic value, and the complex ethical and legal issues that keep them out of reach of most Americans. This talk is given by Jacob Appel of Icahn School of Medicine at Mount Sinai.