Rufus Osgood Mason (January 22, 1830, in Sullivan, New Hampshire – May 11, 1903, in New York City) was a physician, surgeon, and teacher and an early researcher in parapsychology and hypnotherapy.
In 1859, he graduated from the College of Physicians and Surgeons in New York City (now a part of Columbia University).
[3] Between leaving Union Theological Seminary and entering the medical profession, he became an instructor at a public school in Cleveland, Ohio.
His main publication was the book Telepathy and the Subliminal Mind (1897), and his work focused on case studies and popularization.
His chief contributions to the field are considered to be the latter, in the United States, particularly relating to the work of the Society for Psychical Research and the theories of Frederic William Henry Myers.