The particular practices which Aquinas attributes to magicians have nothing at all to do with the monstrous deeds that were later to be ascribed to witches. Indeed, in this respect he understates. He says not a word about sacrifices, whether of animals or of the flesh of corpses, and has little to say about maleficium. He recognizes that demons can make a man impotent with his wife, but neither that nor any other form of maleficium much concerns him. His interest is concentrated almost entirely on the practice of divination, i.e. foretelling the future. He insists that any attempt to foretell the future, beyond what can be foreseen by human reason or what has been revealed by God, is sinful. And the reason why it is sinful is that it involves dealing with a demon. It is one example — the commonest — of what Aquinas calls a “pact”.
For Aquinas, any human being who accepts help from a demon, in the hope of accomplishing something which transcends the powers of nature, has entered into a pact with that demon. Such a pact may be either explicit or tacit. It is explicit when the human operator invokes the demon’s help — and that is so whether the demon responds or not; in other words, the act of conjuration involves an explicit pact. A tacit pact is involved when, without conjuration, a human being performs an act with a view to some effect which cannot naturally follow, and which is not to be expected, either, from the intervention of God.(24)
The notion of the pact was not new — it is to be found already in Augustine — but it took on a new significance when, in the Europe of the thirteenth and fourteenth centuries, it was applied to the magical practices then proliferating. Aquinas argues that every attempt to communicate with a demon, whether explicit or tacit, is not merely sinful but amounts to apostasy from the Christian faith. It does so because, in every such attempt, some part of the worship that ought to be rendered to God alone is diverted to one of God’s creatures, and a fallen, rebellious angel at that. In all this Aquinas was speaking as a representative of contemporary orthodoxy.
In practice the ecclesiastical authorities took a far more serious view of those forms of magic which involved an “explicit pact”, i.e. the deliberate invocation of particular demons, than of those which did not. In 1258 Pope Alexander IV laid down the principle that inquisitors were not to concern themselves with cases of divination as such, but only with those which “manifestly savoured of heresy”.(25) This can only refer to the invocations characteristic of ritual magic. And the pronouncements of Pope John XXII in the 1320s, which Burr mistakenly supposed to be concerned with witchcraft, likewise turn out to refer to ritual magic.
In 1320 the pope, disturbed by reports that were reaching him concerning the practice of ritual magic at the papal court at Avignon itself, decided that the time had come to clarify and define the relationship between magic and heresy. After first taking written opinions from five bishops, two generals of monastic orders and three masters of theology, and then discussing the matter with them at a special consistory at Avignon, the pope wrote to the cardinal of St Sabina, who in turn wrote to the inquisitors of Toulouse and Carcassonne.(26) Henceforth the inquisitors were empowered to act against practitioners of ritual magic as heretics; and in 1326 or 1327 the pope tried to reinforce their efforts by a bull, Super illius specula.(27) Between them, the letter of authorization and the bull show perfectly clearly what practices were involved. On the one hand magicians were trying to win the favour of demons by adoring them, doing them homage, entering into pacts with them, giving them written documents and other pledges; on the other hand they were trying to bind demons to their service by enclosing them in specially made rings, mirrors, phials and the like, so that they could ask them questions and extract answers, and generally compel their assistance. The purposes for which these things were done were themselves “most foul”, but it was the involvement of demons that made the whole undertaking heretical. The bull makes this perfectly plain. Christians are given eight days to abandon such practices, after which they become liable to almost all the penalties for heresy. Within eight days, too, all books and writings on magic are to be handed over for burning, on pain of excommunication and maybe worse penalties as well.
The Treatise against the invokers of demons of Nicolas Eymeric. which is often referred to as the earliest book on witchcraft, exists only in manuscript; though a summary of it is included in his celebrated Directorium Inquisitorum or Inquisitors’ Guide.(28) Eymeric, a Spaniard, had been functioning for some twelve years as inquisitor-general for Aragon when he wrote it, in or just after 1369; so it can be taken as a fair account of everything that an experienced investigator knew or believed about the occult arts in the last part of the fourteenth century. On inspection it turns out to be not about witchcraft but, once again, about ritual magic.
Like Pope Alexander IV, whom he quotes, Eymeric recognizes that_ some forms of divination, however deplorable, are not heretical and so do not concern the Inquisition; such are divination by palmistry or by drawing lots. But heresy is present in any divination that involves the cult of demons — whether that cult take the form of latria, the worship due to God alone, or of dulia, the adoration paid to the saints. Eymeric knows of many ways in which latria and dulia can be expressed. When a magician sacrifices birds or animals to a demon, or makes offerings of his own blood, or promises the demon obedience, or kneels to it, or sings songs in its praise, or observes chastity or mortifies the flesh out of reverence for it, or lights candles or burns incense in its honour, or begs something of it by means of signs and unknown names, or adjures it in the name of a superior demon — all this is latria. Dulia includes less familiar practices, such as praying to God through the names and merits of demons, as though they were mediators like the saints. But Eymeric also knows of magical ceremonies by which a demon can be invoked without either latria or dulia; as when the magician makes a circle on the ground, places an assistant within it, and reads spells from a book.
Eymeric’s account is much fuller than anything offered by Aquinas or by John XXII. He had certain advantages: he mentions that he had seized and read many books of magic before burning them. His motives are also rather different from his predecessors’: as a leading inquisitor, he is concerned to show that practitioners of ritual magic come under the jurisdiction of the Inquisition. To prove his point he cites a large number of authorities, including Aquinas and the bull Super illius specula — indeed, he gives the complete text of the bull, and that is the earliest copy of it we possess. His conclusion is that all ritual magic is heretical, even when neither latria nor dulia is involved; for the very act of invoking demons is heretical. Those who do these things are all heretics, and are liable to the same penalties as other heretics: if penitent, they are to be perpetually immured; if they are obdurate, or if after repenting they relapse, they are to be handed over to the secular arm for execution.