Question Two of Chapter Four of the Third Decade
On the miracles of Pharaoh’s magicians and of necromancers
It is asked: if demons cannot by their own power immediately produce a true natural effect, as was said above, how did the magicians produce frogs before Pharaoh, and how have necromancers produced many animals through the power of demons?
To this Augustine responds in Book III On the Trinity, saying that, since corporeal nature obeys good and evil angels at will with respect to corporeal motion, as was said above, demons can therefore also make all transmutations of corporeal things which can be made through any natural powers.
Therefore, since serpents, frogs, lice, fleas, and effects of this kind can be produced through transmutations and motion of corporeal things—as we see, because they can arise through putrefaction and through sweat—demons, since they are most wise and learned, produce certain natural effects of this kind by applying seeds which they know to exist in the elements of the world, or in plants and animals, and so forth.
For they know how to join determinate active things to determinate passive things, from which conjunction some natural effect follows, just as was done in the generation of a human being through a succubus and an incubus, as has been said and will be said below.
Hence, when demons and magicians or necromancers appear to produce certain effects immediately by their own power, this is not true. Rather, they produce all things through the mediation of seminal reasons and active and passive powers.
And since demons are exceedingly swift agents, their works therefore appear to us as though they were miracles, as will be said.
But if it is argued to the contrary that demons also produce many effects without seeds—for example, conjunctions and divisions of stones, as is evident in idols—it is answered that there are three genera of effects.
One is a new effect without the introduction of any form, but produced either through the division of parts from a whole, as an idol is made through carving, or through the conjunction of things with one another, as a wall is made through the conjunction of stones. Such an effect can be made by a demon.
Another is an effect which does not occur without the introduction of a form, such as a lion or a worm. A demon cannot form this effect immediately by its own power, except by applying the appropriate active things to the appropriate passive things.
Another is an effect which does not occur without the introduction of a substantial form, but over which a natural agent has no power, such as the transmutation of matter from form into form, so that a human body is changed into a bestial body, or the raising of a dead person. Over these a good or evil angel has no power except through some illusion, as will be said.
These things are from Thomas in the questions concerning demons and Johannes de Blibia of Bologna in the Quodlibets.
Addition
A demon can transmute material things according to place or into an artificial form, but not immediately into a natural form.
Hence the Commentator upon Book VII of the Metaphysics says: “It is impossible for separated forms to transmute matter.”
Therefore, if certain marvels are done through magical arts—by applying active causes to passive ones, since magicians know the constellations of the stars and the powers of inferior bodies—they are all great falsehoods.
But they appear marvelous because those things which nature is accustomed to accomplish over a longer time and in a more customary manner are accomplished in the briefest time and in an unaccustomed manner.
See Augustine, Book III On the Trinity, chapter 8.
It also supports this that, at the end of Book IV of the Meteorology, Aristotle demonstrates that alchemists cannot truly transmute the species of metals.