Chapter 115 - The Action of Corporeal Creatures

It is evident to our senses that bodies are active, as Aristotle says; and an active body acts according to its actuality on other bodies according as they are in potentia. But the opinion of Democritus is to be rejected, who taught that action is produced by the efflux of atoms from the acting body, and suffering, by their reception in the pores of the body acted upon; from which it would follow that one body does not suffer the action of another as a whole; also that the acting body would be diminished by the effect of its action.

The opinions of Avicebron and Plato are also to be rejected, who admitted only separate substantial forms, and reduced accidents to natural principles. They taught that corporeal agents act according to accidental forms, and dispose matter to substantial form, ascribing to an immaterial principle the perfection which is received by the advent of the substantial form. Hence they did not conclude that the corporeal principle is not active, but that it is not universally so.

And because terms are taken from perfections, and among bodies the living are the most perfect, the word "Nature" has been derived from the principle of life. For living things are generated through a joint principle; as the fruit of a tree, or a germ from the matrix - from which the word is taken. It is, moreover, manifest that the active and passive principles, which are the principles of generation, are the seeds from which living things are generated, and the origin of all natural motion. For, originally, these are seminal conceptions existing ideally in the Divine Word; secondly, they exist in the elements of the world as in universal causes, where they have been produced from the beginning; thirdly, they are in things produced through these universal causes, according to the succession of time; as in this plant or that animal; and after a fourth mode they are found in the seeds which are produced by these plants and animals: and these may be themselves compared to other particular effects, as the original universal causes to the first effects produced by them.

The celestial bodies, and principally the sun's light, are the cause of the motions which take place in the inferior bodies; because multitude proceeds from unity and every moveable from the immoveable, but their action is received differently according to the constitution of bodies. Thus it is not directly the cause of human actions which depend upon intellect and will, but only indirectly; otherwise there would be no difference between sense and intellect: for will and intellect are not acts of bodily organs susceptible of the action of the heavenly bodies. There is, however, some difference in this regard between the intellect and the will; for the intellect receives of necessity from the inferior apprehensive faculties, and is liable to be somewhat influenced by the passions, while the will remains always free. Hence physical impressions affect the will less than the intellect, though both are affected in so far as both receive what the bodily organs convey.

The demons, being intellectual substances, are in no way subject to the action of the celestial bodies.