Psyche Unbound is an extraordinary compilation of twenty-two essays that honor the pathbreaking lifework of Stanislav Grof, the world's leading researcher in psychedelic therapy, breathwork, and the exploration of non-ordinary states of consciousness. In honor of Grof's 90th birthday this year, the contributions range over the past half-century -- beginning exactly fifty years ago with Joseph Campbell's remarkable 1971 lecture in the Great Hall at Cooper Union setting forth the importance of Grof's findings, and Huston Smith's 1976 summary of their significance for the study of religion and mysticism, all the way through to the 2021 reflections by psychiatrists and researchers Charles Grob and Michael Mithoefer as part of the current renaissance of psychedelic therapy. In between are major essays that forward Grof's work on numerous fronts, both theoretical and therapeutic: transpersonal sexual experiences (Jenny Wade), implications for social and cultural change (William Keepin), comparative studies with Asian religious systems (Jeffrey Kripal, Tom Purton), the perinatal dimensions of Jean-Paul Sartre's transformational 1935 mescaline experience (Thomas Riedlinger), and parallel findings from quantum and relativistic physics (Fritjof Capra).