First published more than 20 years ago and now with a new introduction by the author, this classic work presents the methods and conclusions of more than 25 years of experimentation with the isolation-tank meditative experience. Drawing on the personal testimony of many who tried it, including Burgess Meredith, Gregory Bateson, E. J. Gold, and Jerry Rubin, the evidence shows how, by eliminating the presence of shifting physical input patterns, the tank allows participants to dive deep into their subconscious and focus immediately on their inner perceptions. The different domains of reality and how various experiences with solitude affect different people are discussed along with practical details on the standards for isolation tank manufacture and use.