HKB
Whether We Ought to Distinguish Several Species of Divination?
Objection 1: It would seem that we should not distinguish several species of divination. Where the formality of sin is the same, there are not seemingly several species of sin. Now there is one formality of sin in all divinations, since they consist in entering into compact with the demons in order to know the future. Therefore there are not several species of divination.
Obj. 2: Further, a human act takes its species from its end, as stated above (I-II, Q. 1, A. 3; Q. 18, A. 6). But all divination is directed to one end, namely, the foretelling of the future. Therefore all divinations are of one species.
Obj. 3: Further, signs do not vary the species of a sin, for whether one detracts by word, writing or gestures, it is the same species of sin. Now divinations seem to differ merely according to the various signs whence the foreknowledge of the future is derived. Therefore there are not several species of divination.
On the contrary, Isidore enumerates various species of divination (Etym. viii, 9).
I answer that, As stated above (A. 2), all divinations seek to acquire foreknowledge of future events, by means of some counsel and help of a demon, who is either expressly called upon to give his help, or else thrusts himself in secretly, in order to foretell certain future things unknown to men, but known to him in such manners as have been explained in the First Part (Q. 57, A. 3). When demons are expressly invoked, they are wont to foretell the future in many ways. Sometimes they offer themselves to human sight and hearing by mock apparitions in order to foretell the future: and this species is called "prestigiation" because man's eyes are blindfolded (praestringuntur). Sometimes they make use of dreams, and this is called "divination by dreams": sometimes they employ apparitions or utterances of the dead, and this species is called "necromancy," for as Isidore observes (Etym. viii) in Greek, "nekron means dead, and manteia divination, because after certain incantations and the sprinkling of blood, the dead seem to come to life, to divine and to answer questions." Sometimes they foretell the future through living men, as in the case of those who are possessed: this is divination by "pythons," of whom Isidore says that "pythons are so called from Pythius Apollo, who was said to be the inventor of divination." Sometimes they foretell the future by means of shapes or signs which appear in inanimate beings. If these signs appear in some earthly body such as wood, iron or polished stone, it is called "geomancy," if in water "hydromancy," if in the air "aeromancy," if in fire "pyromancy," if in the entrails of animals sacrificed on the altars of demons, "aruspicy."