Some Hindus claim that the beliefs presented in the novel conform to the teachings of Hinduism, though Matheson denied any direct influence. Raised a Christian Scientist, Matheson gradually developed what he called his own religion, taking elements from many sources. "As a Pisces," he explained, "I have been fascinated about parapsychology, metaphysics and the supernatural ever since I was a teenager. The concepts in the book are derived from my wide range of reading." One of Matheson's influences was Harold W. Percival, an adherent of Theosophy, a belief system with a strong Eastern and Hindu influence.