This essay tries to show that belief in Witchcraft in seventeenth-century New England was not so much an aberration as it was a product of mind and hence an integral part of culture. The focus of attention, then, is on the theoretical foundation of the belief in demons and witches. The first chapter examines the Scholastic basis of demonology, namely, the Aristotelian idea that motion is the product of the relationship between mover and moved. This distinction batmen mover and moved made it possible for Scholastic and later, Puritan demonologists to explain how a demon -- a spirit and hence a mover -- produce effects on the material world and the human body--the things moved. The next chapter treats of the peculiarly Puritan contribution to demonology, the providential idea of nature. The Puritans believed that God enforced his judgments on the chosen people for their sins by sending natural disasters to punish them. One of these punishments, however, was not strictly natural -- namely the destruction that God allowed the devils to work. It was instead praeternatural. The demons worked, not above nature as God would nor according to nature, but rather above the ordinary course thereof. Thus the Puritans could say that although the operations of evil spirits were invisible and for the most part beyond human comprehension, they were nonetheless real and providential. The operation of the demon on the human being required an elaborate theoretical explanation. The devil could not possess the rational soul, for that contained the divine spark. But such possession brought mental distress as well as physical agony. Thus such possession had to be in sane sense mental. Puritans such as Cotton Mather and Charles Morton built an explanation. The human personality contained not just body and soul, but body, spirit, and soul. Mather and Morton borrowed this idea of the spirit of Man from the philosophical medicine of Paracelsus and van Helmont, who had used it to explain bow each man's reaction to disease and treatment was unique. Mather and Morton extended the meaning of spirit. It became the constituent in man particularly susceptible of and responsive to diabolical or praeternatural influences. The faculty of imagination became the seat of the spirit of men. By working on the animal spirits in the imagination that flowed to other parts of the body, the devil could produce his torments. The relation between the etch and the devil also required an elaborate theory for its explanation, and the New-England divine borrowed much on this score from their contemporaries in England, the Cambridge Platonist, Henry More, and his associate Joseph Glanvil. This relation of witch to demon hinged again on a correspondence between the internal power of imagination over the spirit of man and the external power of the demon. In this way the seventeenth-century demonologists conceived a praeternatural universe, and Morton could say that "the Phantastic Air, ...Huddles, and is precipitant in all things."