Writers in the fields of parapsychology and occultism have written that OBEs are not psychological, and that a soul, spirit or subtle body can detach itself out of the body and visit distant locations. Out-of-the-body experiences were known during the Victorian period in spiritualist literature as "travelling clairvoyance". In old Indian scriptures, such a state of consciousness is also referred to as Turiya, which can be achieved by deep yogic and meditative activities, during which a yogi may be liberated from the duality of mind and body, allowing them to intentionally leave the body and then return to it. The body carrying out this journey is called "Vigyan dehi" (""Scientific body""). The psychical researcher Frederic Myers referred to the OBE as a "psychical excursion". An early study that described alleged cases of OBE was the two-volume "Phantasms of the Living", published in 1886 by the psychical researchers Edmund Gurney, Myers, and Frank Podmore. The book was largely criticized by the scientific community because the anecdotal reports in almost every case lacked evidential substantiation.