Until it was supplanted by LSD in the 1950’s and 60’s, mescaline was the best known and most popular psychedelic in the world. It’s the key psychoactive ingredient in peyote, which has been used for millennia among indigenous people in the Americas and often demonized and prohibited by civil and religious authorities who feared it. Mike Jay, whose latest book is entitled Mescaline: A Global History of the First Psychedelic, is broadly regarded as the outstanding historian of psychoactive drugs around the world. We talked about that rich history, which included experimentation with mescaline by writers, poets, painters and scientists as well as the head of the Mormon Church, its impact on psychiatry, investigation into its potential as a truth serum and weapon by the CIA and the military, its use by prominent counter-cultural figures, and why it was largely displaced by LSD and other psychedelics.