Whether the Heavenly Bodies Are the Cause of What Is Produced in
Bodies Here Below?
Objection 1: It would seem that the heavenly bodies are not the cause
of what is produced in bodies here below. For Damascene says (De Fide
Orth. ii, 7): "We say that they"--namely, the heavenly bodies--"are
not the cause of generation or corruption: they are rather signs of
storms and atmospheric changes."
Obj. 2: Further, for the production of anything, an agent and matter
suffice. But in things here below there is passive matter; and there
are contrary agents--heat and cold, and the like. Therefore for the
production of things here below, there is no need to ascribe
causality to the heavenly bodies.
Obj. 3: Further, the agent produces its like. Now it is to be
observed that everything which is produced here below is produced
through the action of heat and cold, moisture and dryness, and other
such qualities, which do not exist in heavenly bodies. Therefore the
heavenly bodies are not the cause of what is produced here below.
Obj. 4: Further, Augustine says (De Civ. Dei v, 6): "Nothing is more
corporeal than sex." But sex is not caused by the heavenly bodies: a
sign of this is that of twins born under the same constellation, one
may be male, the other female. Therefore the heavenly bodies are not
the cause of things produced in bodies here below.
_On the contrary,_ Augustine says (De Trin. iii, 4): "Bodies of a
grosser and inferior nature are ruled in a certain order by those of
a more subtle and powerful nature." And Dionysius (Div. Nom. iv) says
that "the light of the sun conduces to the generation of sensible
bodies, moves them to life, gives them nourishment, growth, and
perfection."
_I answer that,_ Since every multitude proceeds from unity; and since
what is immovable is always in the same way of being, whereas what is
moved has many ways of being: it must be observed that throughout the
whole of nature, all movement proceeds from the immovable. Therefore
the more immovable certain things are, the more are they the cause of
those things which are most movable. Now the heavenly bodies are of
all bodies the most immovable, for they are not moved save locally.
Therefore the movements of bodies here below, which are various and
multiform, must be referred to the movement of the heavenly bodies,
as to their cause.
Reply Obj. 1: These words of Damascene are to be understood as
denying that the heavenly bodies are the first cause of generation
and corruption here below; for this was affirmed by those who held
that the heavenly bodies are gods.
Reply Obj. 2: The active principles of bodies here below are only the
active qualities of the elements, such as hot and cold and the like.
If therefore the substantial forms of inferior bodies were not
diversified save according to accidents of that kind, the principles
of which the early natural philosophers held to be the "rare" and the
"dense"; there would be no need to suppose some principle above these
inferior bodies, for they would be of themselves sufficient to act.
But to anyone who considers the matter aright, it is clear that those
accidents are merely material dispositions in regard to the
substantial forms of natural bodies. Now matter is not of itself
sufficient to act. And therefore it is necessary to suppose some
active principle above these material dispositions.
This is why the Platonists maintained the existence of separate
species, by participation of which the inferior bodies receive their
substantial forms. But this does not seem enough. For the separate
species, since they are supposed to be immovable, would always have
the same mode of being: and consequently there would be no variety in
the generation and corruption of inferior bodies: which is clearly
false.
Therefore it is necessary, as the Philosopher says (De Gener. ii, 10),
to suppose a movable principle, which by reason of its presence or
absence causes variety in the generation and corruption of inferior
bodies. Such are the heavenly bodies. Consequently whatever generates
here below, moves to the production of the species, as the instrument
of a heavenly body: thus the Philosopher says (Phys. ii, 2) that "man
and the sun generate man."
Reply Obj. 3: The heavenly bodies have not a specific likeness to the
bodies here below. Their likeness consists in this, that by reason of
their universal power, whatever is generated in inferior bodies, is
contained in them. In this way also we say that all things are like
God.
Reply Obj. 4: The actions of heavenly bodies are variously received
in inferior bodies, according to the various dispositions of matter.
Now it happens at times that the matter in the human conception is
not wholly disposed to the male sex; wherefore it is formed sometimes
into a male, sometimes into a female. Augustine quotes this as an
argument against divination by stars: because the effects of the
stars are varied even in corporeal things, according to the various
dispositions of matter.
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