Essay on superstition; being an inquiry into the effects of physical influence on the mind, in the production of dreams, visions, ghosts, and other supernatural appearances.

In this conceptual anticipation of later ideas in psychopharmacology Newnham argued that dreams, visions, apparitions and other apparently spiritual manifestations, whether good or bad, arose from physiological rather than supernatural causes. He provided evidence that the effects on the brain from disease, medications (including nitrous oxide and opium) and trauma, causing "disturbance of brainular function", could produce such experiences. Digital facsimile from the Internet Archive at this link.