Webster defines "obsession" as "the state of a person vexed or besieged by an evil spirit, antecedent to possession." The latter term he defines as "the state of being possessed, as by an evil spirit," etc. Allan Kardec employs obsession as a generic term, to include _simple obsession_, which accords with Webster's definition of the term; _fascination_, which is "an illusion produced by direct action on the medium's thought," paralyzing his judgment; and _subjugation_, which completely paralyzes the will, and causes the medium to act in spite of himself. For our purpose these fine distinctions are immaterial, as they merely represent different stages or degrees of intensity of the same phenomenon. The theory of obsession is a modernizing of the old idea of being possessed of a devil, or devils, as the case might be. It consists in being dominated, to a greater or less extent, by the idea that the person is besieged or controlled by a foreign spirit, good or bad, angel or devil. It seems superfluous to remark that the same principles prevail in these cases as in all others where the idea of spirits has been suggested to the subjective mind. It matters not how the suggestion originated, the result is the same. In ancient times the idea prevailed that any one was liable at any time to be taken possession of by a devil. When that idea was in vogue it frequently happened that persons who easily entered the subjective condition found themselves possessed of one or more devils. In those times the profession of exorcist was very profitable. The priesthood generally monopolized the business, for the obvious reason that they were supposed to entertain a spirit of more or less antagonism to devils generally. Besides, devils were supposed to have a mortal fear of anything holy; they had an especial dread of the sight of a copy of the Scriptures, and of hearing the name of God pronounced. Accordingly it came to pass that, upon the command of the exorcist, the devil would often incontinently fly, leaving the patient in his normal condition. Sometimes, however, he would be more stubborn, and the patient would go into convulsions upon hearing the magic words pronounced; and then more severe measures would have to be adopted, such as employing more exorcists. But persistence was generally rewarded with success. In later years devils have generally gone out of fashion, and their place is taken by bad spirits of dead men. And so it has come to pass that many spirit mediums are sorely afflicted with spirits, who pester them most outrageously. The exorcist is now replaced by the family doctor, who is generally scientific to the last degree, and accordingly endeavors to get rid of the spirit by means of physic or clysters. Recently, however, such cases have been treated successfully by means of hypnotism, which is the obvious remedy, in case the hypnotist realizes the power of suggestion.