The theosophist Arthur Powell (1927) was an early author to advocate the subtle body theory of OBEs. Sylvan Muldoon (1936) embraced the concept of an etheric body to explain the OBE experience. The psychical researcher Ernesto Bozzano (1938) had also supported a similar view describing the phenomena of the OBE experience in terms of bilocation in which an "etheric body" can release itself from the physical body in rare circumstances. The subtle body theory was also supported by occult writers such as Ralph Shirley (1938), Benjamin Walker (1977), and Douglas Baker (1979). James Baker (1954) wrote that a mental body enters an "intercosmic region" during the OBE. Robert Crookall supported the subtle body theory of OBEs in several publications.