This presentation examines the challenge of integrating the spiritual dimension of a pharmacological experience within the framework of medical research, drawing on the history of psilocybin’s discovery and the development of experimental therapies around this molecule. Starting from indigenous Amerindian uses and tracing a path toward clinical trials in Euro-Atlantic hospitals, the talk draws a parallel with Iboga — asking what is gained, what is lost, and what must be preserved when a sacred plant enters the medical system.