PSI or parapsychological phenomena have been investigated by serious researchers for well over a century. Despite some diehard skeptics, the existence of PSI has now been solidly established by competent scientists using the most rigorous methodologies. Yet, a complete understanding of the phenomena of telepathy, precognition, clairvoyance, and psychokinesis has remained elusive for two reasons. First, a new worldview was needed to replace the outdated materialism assumed by so many scientists and philosophers. That view, “Mental Realism,” was developed in Keith Chandler’s last book, The Mind Paradigm: A Unified Model of Mental and Physical Reality. Second, a thorough review of the evidence for PSI was required to expose the erroneous assumptions that had hindered its theoretical progress. That task has been successfully undertaken by the author enabling him to entitle this book simply: PSI: What it is and How it works. With this book, Keith Chandler has now brought us full circle from the clockwork, sensory-bound world of Descartes and Newton to an understanding of our universe as a manifestation of purposeful, intelligent psychic energy. He has also finally removed parapsychology from the category of the “occult” and placed it where it belongs, in the domain of legitimate science.