"The supernatural is only the natural not yet understood." Carl Wickland was a psychiatrist and psychical researcher. In the early 20's, he turned away from conventional medical psychology and toward the belief that psychiatric illnesses were the result of influence by spirits of the dead. Wickland came to believe that a large number of his patients had become possessed by what he called "obsessing spirits", and that low-voltage electric shocks could dislodge them, while his wife Anna acted as a medium to guide them to "progress in the spirit world". Spiritualists considered him an authority on "destructive spirits" and he wrote a book in 1924, Thirty Years Among the Dead, detailing his experiences as a psychical researcher.