You’re only as young as the last time you changed your mind.

Timothy Leary (1920–1996) was an American psychologist who was known for his strong advocacy of psychedelics. He and his colleague Richard Alpert (who would later become known as Ram Dass) were both involved in Harvard’s research into psilocybin until they were dismissed from the university, at which point Leary became a well-known figure in the 1960s counterculture movement, also writing and lecturing about transhumanism. His most famous slogan, “Turn on, tune in, drop out,” epitomizes the hippie drug culture of the ‘60s, and he is attributed with pioneering of the importance of “set and setting” in the experience of taking psychedelics.