Origin of the general Opinions respecting Demonology among Mankind. The Belief in the Immortality of the Soul is the main inducement to credit its occasional re-appearance. The Philosophical Objections to the Apparition of an Abstract Spirit little understood by the Vulgar and Ignorant. The situations of excited Passion incident to Humanity, which teach Men to wish or apprehend Supernatural Apparitions. They are often presented by the Sleeping Sense. Story of Somnambulism. The Influence of Credulity contagious, so that Individuals will trust the Evidence of others in despite of their own Senses. Examples from the ‘Historia Verdadera’ of Bernal Dias del Castillo, and from the Works of Patrick Walker. The apparent Evidence of Intercourse with the Supernatural World is sometimes owing to a depraved State of the bodily Organs. Difference between this Disorder and Insanity, in which the Organs retain their tone, though that of the Mind is lost. Rebellion of the Senses of a Lunatic against the current of his Reveries.