HKB
OF THE ACTION OF THE CORPOREAL CREATURE (In Six Articles)
We have now to consider the action of the corporeal creature; and fate, which is ascribed to certain bodies. Concerning corporeal actions there are six points of inquiry:
(1) Whether a body can be active?
(2) Whether there exist in bodies certain seminal virtues?
(3) Whether the heavenly bodies are the causes of what is done here by the inferior bodies?
(4) Whether they are the cause of human acts?
(5) Whether demons are subject to their influence?
(6) Whether the heavenly bodies impose necessity on those things which are subject to their influence?
FIRST ARTICLE [I, Q. 115, Art. 1]
Whether a Body Can Be Active?
Objection 1: It would seem that no bodies are active. For Augustine says (De Civ. Dei v, 9): "There are things that are acted upon, but do not act; such are bodies: there is one Who acts but is not acted upon; this is God: there are things that both act and are acted upon; these are the spiritual substances."
Obj. 2: Further, every agent except the first agent requires in its work a subject susceptible of its action. But there is not substance below the corporeal substance which can be susceptible of the latter's action; since it belongs to the lowest degree of beings. Therefore corporeal substance is not active.
Obj. 3: Further, every corporeal substance is limited by quantity. But quantity hinders substance from movement and action, because it surrounds it and penetrates it: just as a cloud hinders the air from receiving light. A proof of this is that the more a body increases in quantity, the heavier it is and the more difficult to move. Therefore no corporeal substance is active.
Obj. 4: Further, the power of action in every agent is according to its propinquity to the first active cause. But bodies, being most composite, are most remote from the first active cause, which is most simple. Therefore no bodies are active.
Obj. 5: Further, if a body is an agent, the term of its action is either a substantial, or an accidental form. But it is not a substantial form; for it is not possible to find in a body any principle of action, save an active quality, which is an accident; and an accident cannot be the cause of a substantial form, since the cause is always more excellent than the effect. Likewise, neither is it an accidental form, for "an accident does not extend beyond its subject," as Augustine says (De Trin. ix, 4). Therefore no bodies are active.
On the contrary, Dionysius says (Coel. Hier. xv) that among other qualities of corporeal fire, "it shows its greatness in its action and power on that of which it lays hold."