In lending the authority of his name to an affirmation of the reality of demon-magic, Aquinas must share together with many writers before and after him responsibility for the witchcraft delusion and executions. And yet he tells us that there were already some persons by his time who denied that there was any such thing as witchcraft except in men’s imaginations and fears. Such persons argued that where the supposed sorcery was not entirely due to imaginary terror, it could be explained as the natural effect of occult causes. But Aquinas, who twice argues the question whether the consummation of marriage can be prevented by sorcery,[1991] declares that the authority of the saints and of the Catholic faith alike proclaim the reality of witchcraft and its power to obstruct carnal union. Men who dispute this are the same as denying the existence of the demons.[1992] Dear demons! What a treasured legacy of theology from paganism!
Divination.
Aquinas also tends to follow ecclesiastical tradition in condemning most arts of divination as the work of demons,[1993] and in carefully distinguishing from them divine prophecy, which can speak with certainty even of contingent matters.[1994] He grants, however, that some arts of divination have a natural basis, and that natural divination is permissible, if not extended to accidental occurrences and to human acts due to the reason and will.[1995] It is possible to forecast the future by interpretation of dreams which are produced by natural causes either within or outside the sleeper’s body.[1996] The commentary of Aquinas on Aristotle’s De somno et vigilia is, however, a perfunctory treatise, inferior to that by Albertus Magnus on the same theme, and advances no ideas of Thomas’ own on the subject of divination from dreams. Even augury may be natural divination, if the acts of the animals under observation are governed by the positions and movements of the stars.[1997] Aquinas also mentions chiromancy without disapproval, but will not admit that geomancy comes under the head of natural divination, since the figures upon which its predictions are based are the outcome either of chance or of voluntary human action.[1998] He condemns as superstitious the regarding as signs of the future such trivial occurrences as a sneeze or a dog’s running between two persons who are walking together.[1999]
Lot casting.
Lot casting of whatever sort is not natural divination. The Bible tells us, however, that God often rules the casting of lots, and “if practices which have a natural or human cause are blameless, much more so are those which depend on divine aid.”[2000] But Aquinas cautions against an appeal to God to decide the casting of lots unless there is real necessity, or without due reverence and devotion, or for purely human and worldly purposes, or in cases where direct divine inspiration should be sought, as in ecclesiastical elections. As Bede pointed out, it is true that Matthias was selected by lot before Pentecost, but after the reception of the Holy Ghost the seven deacons were elected by the disciples. And when men pry into hidden things more than they should, whether by lot casting or other methods, it is Aquinas’ opinion that demons are involved.[2001]
Occult virtues.
As Aquinas differentiated between natural divination and that due to demons, so he distinguishes from illicit magic “the occult works of nature.” On this theme he addressed a brief treatise to “a certain knight.”[2002] Besides those properties of natural objects which accord with the properties of their component elements and so have a manifest origin, there are occult virtues for which men can give no reason,[2003] as in the stock illustration of the magnet, as great a favorite with medieval writers as electricity is with modern preachers to inspire faith in the invisible and imperfectly known. Aquinas accounts for the existence of such occult virtues by the influence of the heavenly bodies upon the world of nature. In his Meteorology, too, he attributes the wonderful powers of precious stones to “a certain celestial and occult virtue.”[2004] In this he probably shows the influence of his master Albertus Magnus.
Alchemy and fascination.
Aquinas declares that alchemy is a true, although difficult art, and accounts for the efficacy of its operations by its utilization of occult forces of celestial virtue.[2005] Pico della Mirandola noted that while Thomas seemed to deny the art in his Commentary on the Sentences, he approved it in his theological Summa, which Pico accepted as his last word on the subject.[2006] Spurious works of alchemy were, however, subsequently ascribed to Aquinas in manuscripts of the fifteenth century. Fascination Aquinas also regards as a fact, and practically explains it as due to the power of the evil eye. The eye is affected by the strong imagination of the soul and then corrupts and poisons the atmosphere so that tender bodies coming within its range may be injuriously affected. It is thus that malicious old women injure children,[2007]—another faggot added by Aquinas to the pyres of the witchcraft delusion.
Amulets and incantations.