Psychedelics and the visionary states associated with them are demonized by the technological cultures of the 21st century and the mere possession of a psychedelic substance such as LSD, psilocybin or DMT can result in public humiliation, loss of property and reputation, and lengthy jail penalties. Things were very different in the antiquity. Indeed the evidence shows that many of the greatest civilizations of the past, from ancient Egypt to ancient Greece, and from ancient India to the ancient Americas, enshrined the use of psychedelics as a sacred practice and found immense value in the visions that ensued. Further back still, in the epoch of the great cave art 30,000 and more years ago, recent archaeological research suggests that shamanistic use of psychedelics was instrumental in the birth of the modern human mind. In this talk, Graham Hancock investigates the possibility that by demonising and criminalising the use of psychedelics, rather than seeking out ways to harness their power for altering consciousness in safe and nurturing spaces, our society may have set itself on a profoundly negative path -- a path that may even deny us the next step in our own evolution as a species.