In the course of my professional employment, I have frequently conversed with persons, who imagined that they saw demons, and heard them speak. This species of delusion admits of many gradations, and distinctions, exclusive of actual insanity. When the brain is partially irritated, the patient fancies that he sees spiders crawling over his bed-clothes, or person; or beholds them covering the roof and walls of his room. If the disease increases, he imagines that persons who are dead, or absent, flit round his bed; that animals croud into his apartment, and that all these apparitions speak to him. These impressions take place, even while he is convinced of their fallacy. All this occurs sometimes, without any degree of delirium. I had occasion to see a young married woman, whose first indication of illness was a spectral delusion. She told me, that her apartment appeared suddenly to be filled with devils, and that her terror impelled her to quit the house with great precipitation. When she was brought back, she saw the whole staircase occupied by diabolical forms, and was in agonies of fear for several days. After this first impression wore off, she heard a voice tempting her to self-destruction, and prohibiting her from all exercises of piety. Such was the account given by her, when she was sensible of the delusion, yet unable to resist the horror of the impression. When she was nearly recovered, I had the curiosity to question her, as I have interrogated others, respecting the forms of the demons with which they had been alarmed; but I never could obtain any other account, than that they were small, very much deformed, and had horns and claws, like the imps of our terrific modern romances. I have been forced to listen with much gravity, to a man partially insane, who assured me that the devil was lodged in his side, and that I should perceive him thumping and fluttering there, in a manner which would perfectly convince me of his presence. Another lunatic believed that he had swallowed the devil, and had retained him in his stomach. He resisted the calls of nature during several days, lest he should set the foul fiend at liberty. I overcame his resolution, however, by administering an emetic in his food. In Mather’s _Wonders of the invisible World_, containing the trials of the American witches, in 1692, a work which may be regarded as official, it appears that the visions of several persons who thought themselves bewitched, were occasioned by the night-mare.