177. This name is given to mediums suitable to the obtaining of direct writing, which is not given to all writing mediums. This faculty is, as yet, extremely rare; it is, probably, developed by exercise; but, as we have said, its practical utility is limited to the patent verification of the intervention of an occult power in the manifestations. Experience alone can prove its possession : a person can try, and also ask it of a protecting spirit, through other means of commu- nication. According to the degree of power possessed by the medium, simple marks, signs, letters, words, phrases, and even whole pages are obtained. It suf- fices, ordinarily, to fold a piece of paper, put it in some place designated by the spirit, for ten minutes, or a quarter of an hour, or sometimes longer. Prayer and concentration of thought are essential conditions ; this is why it may be looked upon as impossible to obtain anything in a reunion of persons but little serious, or who might not be animated by sympathetic and benevolent sentiments. (See Theory of Direct Writing, Chapter VIII., Laboratory of the Invisible World, No. 127, &c., and Chapter XII, Pneumatography)
We shall treat, in a special manner, of writing medi- ums in the following chapters.