A Treatise on Magic or, On the Intercourse between Spirits and Men

Magic is the art of producing supernatural effects, by the agency of spirits. If, for that purpose, a good spirit is employed, it is called Theurgy; if an evil spirit is put to work, it is Sorcery.The performers of such operations are generally styled Magicians. From this definition it appears, that the interposition of supernatural beings is absolutely required to magical practices: Consequently, exhibitions that are founded on mere natural causes, however surprising they may appear, are not to be ranked among magical arts. To that class belong all tricks of sleight of hand, practised by jugglers; all performances that require a certain apparatus, e. g. the restoration of written instruments burnt to ashes; all exhibitions that depend upon physical or mathematical experiments, and finally all effects produced by chymical operations, for instance, the palingenesis of plants. Even astrology, when considered merely as a science of foretelling future: events from the position of the stars, and grounded on a supposition that they possess a natural foreboding power, ought not to be called magic: but it comes under that name, when, by it, is understood the art of discovering secrets, of predicting future accidents, of changing metals, or of curing distempers by the influence of certain spirits ruling over the celestial bodies. The practice of auguring, so common among the ancients, was therefore no effect of magic, because they believed some foreboding power to be inherent in the very signs which they had observed, without the concurrence of supernatural beings.