The Indefinite Boundary

The Indefinite Boundary examines the relationship between matter and spirit through Guy Lyon Playfair’s review of evidence for psychic phenomena. The book considers claims that appear to challenge a strictly material explanation of human experience, presenting them within the wider tradition of psychical research rather than as established fact.

Playfair approaches the subject as an investigation, weighing reported phenomena and the arguments surrounding them. Published during the 1970s revival of popular interest in parapsychology, it reflects the author’s early work before his later investigations into poltergeists and hauntings. The result is a period psychical-research title concerned with where accepted explanations may end and claims of mind, spirit and other forces begin.