Virtual reality has long been one of the dominant cliches of science fiction. Now virtual reality is a reality: from the startling beauty of lifelike video games to the place where war veterans overcome PTSD, surgeries are trialled, and aircraft and cities are designed. VR is, in fact now, the most effective device ever invented for researching what a human being actually is - and how we think and feel. More than thirty years ago, legendary computer scientist, visionary and artist Jaron Lanier pioneered its invention. Here he blends scientific investigation, philosophical thought experiment and his memoir of a life lived at the centre of digital innovation to explain what VR really is: the science of comprehensive illusion; the extension of the intimate magic of earliest childhood into adulthood; a hint of what life would be like without any limits. We are standing on the threshold of an entirely new realm of human creativity, expression, communication and experience, and as we use VR to test our relationship with reality, it may test us in return.