ral
forces, as stated above (Q. 114, A. 4, ad 2) they take into account
the aptitude of bodies for the intended result. Now it is manifest
that "the brain is the most moist of all the parts of the body," as
Aristotle says [*De Part. Animal. ii, 7: De Sens. et Sensato ii: De
Somn. et Vigil. iii]: wherefore it is the most subject to the action
of the moon, the property of which is to move what is moist. And it
is precisely in the brain that animal forces culminate: wherefore
the demons, according to certain phases of the moon, disturb man's
imagination, when they observe that the brain is thereto disposed.

Reply Obj. 2: Demons when summoned through certain constellations,
come for two reasons. Firstly, in order to lead man into the error
of believing that there is some Divine power in the stars. Secondly,
because they consider that under certain constellations corporeal
matter is better disposed for the result for which they are summoned.

Reply Obj. 3: As Augustine says (De Civ. Dei xxi, 6), the "demons are
enticed through various kinds of stones, herbs, trees, animals,
songs, rites, not as an animal is enticed by food, but as a spirit by
signs"; that is to say, forasmuch as these things are offered to them
in token of the honor due to God, of which they are covetous.
_______________________

SIXTH ARTICLE [I, Q. 115, Art. 6]

Whether Heavenly Bodies Impose Necessity on Things Subject to Their
Action?

Objection 1: It would seem that heavenly bodies impose necessity on
things subject to their action. For given a sufficient cause, the
effect follows of necessity. But heavenly bodies are a sufficient
cause of their effects. Since, therefore, heavenly bodies, with their
movements and dispositions, are necessary beings; it seems that their
effects follow of necessity.

Obj. 2: Further, an agent's effect results of necessity in matter,
when the power of the agent is such that it can subject the matter to
itself entirely. But the entire matter of inferior bodies is subject
to the power of heavenly bodies, since this is a higher power than
theirs. Therefore the effect of the heavenly bodies is of necessity
received in corporeal matter.

Obj. 3: Further, if the effect of the heavenly body does not follow
of necessity, this is due to some hindering cause. But any corporeal
cause, that might possibly hinder the effect of a heavenly body, must
of necessity be reducible to some heavenly principle: since the
heavenly bodie