Timothy Leary, an American psychologist born in 1920, gained fame in the 1960s for advocating psychedelic drugs like LSD, especially during his tenure as a Harvard University professor. He believed psychedelics could profoundly alter consciousness, coining the phrase “Turn on, tune in, drop out.” His work made him a key figure in the counterculture movement but led to controversy, legal issues, and his dismissal from Harvard. Despite this, Leary continued promoting the transformative potential of psychedelics, leaving a complex legacy in science, spirituality, and culture.