The Hammer of Witches

...the canon. He will diligently inspect and consider four things that preachers and priests must preach with all persistence to the people committed to their churches. First, that no one should think there is any power or divinity outside the one God. Second, that to ride with Diana a Roman goddess often associated in medieval folklore with a "Wild Hunt" of spirits or Herodias the biblical figure who demanded the head of John the Baptist, later conflated with Diana in folk myths is to travel with the devil, who fashions himself in this way and uses these names. Third, that such riding is then fantastical; for the devil agitates the mind subjected to him through infidelity in such a way that things which happen only in the spirit are believed to happen bodily. Fourth, that they must obey such a mistress in all things. Therefore, it is absurd to extend these words to maleficial maleficiales; acts of harmful or "black" magic acts, since they are different species of acts. However, whether witches are also locally transported in their own form by superstition, or only in imagination like soothsayers phitones; derived from the Pythoness of Delphi, meaning those possessed by a spirit of divination, will be treated in the third chapter of the second part, showing that it happens in both ways. And thus the second error is struck down along with the first regarding the foundation and sound understanding of the canon. Moreover, a third error, which asserts from the words of the canon that the effect of witchcraft is only fantastical, is also struck down. For in that it says: "whoever believes any creature can be made, or changed for better or worse, or transformed into another species or likeness by anyone other than the Creator of all," etc., such a person is worse than an infidel. These three parts, if understood plainly, are against the progression of Scripture and the determination of the Doctors. For that some creatures can be made by witches—namely, certain true but imperfect animals this refers to "spontaneous generation" of creatures like insects or frogs, which medieval science believed could be produced from decaying matter or "seeds" gathered by demons—one should look at the following canon. Nor is it a wonder, after the cited canon Episcopi, what Augustine St. Augustine of Hippo, a primary authority for medieval theologians determines concerning the magicians of Pharaoh who turned rods into serpents; look at the gloss upon that passage in Exodus 7. One should also look at the gloss of Strabo Walafrid Strabo, a Carolingian scholar, which says that demons run through the world because, through the incantations of witches, they strive to achieve something and collect various "seeds," and from the adaptation of these, various species can break forth. Look also at Albertus Albert the Great, a famous 13th-century scientist and theologian in On Animals. Look also at Saint Thomas Thomas Aquinas in Part 1, Question 114, Article 4. Their words are omitted here for the sake of brevity.

This alone remains: that "to be made" there is understood as "to be created." Second, that they can be "transformed for better or worse" should be understood as happening only by God’s authority for correction or even punishment, though He often performs these things through the ministry of demons. And just as it says of the first: "The Lord strikes and He heals," and "I will kill and I will make to live." So of the second, it speaks of an "infliction through evil angels," as was touched upon above. In the aforementioned chapter Nec Mirum, let the words of Augustine be inspected, where they describe witches and what kind of operations they perform, since they sometimes bring upon men not only infirmities but even death. It is also useful to understand the third point soundly, since modern witches often transform into wolves and other beasts through the work of demons. But the canon speaks of real and essential transformation meaning a literal change of the soul or biological essence, and not of the illusory prestigiosa; from "prestige," meaning a magical illusion or trick of the senses kind which more often occurs. Concerning this, Augustine in The City of God, Book 18, Chapter 18, relates many things, such as the most famous witch Circe, and the companions of Diomedes, and the father of Praestantius. This matter will be made clear in the chapters of the second part. And whether the witches are always present or absent, and whether the devil assumes that form or the man himself sees it so, will be discussed in Chapters 6 and 7.

But because the second part of the question says
that to stubbornly assert the opposite of these things
is to be a heretic, it is asked:
whether such people should be held as "manifestly caught" in heretical depravity the legal term for the crime of heresy, or only as "vehemently suspected" of heresy. And it seems it is the first way. For Bernard Bernard of Parma, a canon lawyer in the Ordinary Gloss on the chapter Ad Abolendam, declares that a person is judged "manifestly caught" in three ways: by the evidence of the fact (for example, if one publicly preaches heresy), or by legitimate proof through witnesses, or from one's own confession. And because such people publicly preach or rashly oppose all the aforementioned things by asserting that witches do not exist, or that they can in no way harm men, they are therefore contained under this distinction as being "manifestly caught" in depravity. To this same sense is the opinion...