ial 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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FOURTH ARTICLE [I, Q. 115, Art. 4]

Whether the Heavenly Bodies Are the Cause of Human Actions?

Objection 1: It would seem that the heavenly bodies are the cause of
human actions. For since the heavenly bodies are moved by spiritual
substances, as stated above (Q. 110, A. 3), they act by virtue
thereof as their instruments. But those spiritual substances are
superior to our souls. Therefore it seems that they can cause
impressions on our souls, and thereby cause human actions.

Obj. 2: Further, every multiform is reducible to a uniform principle.
But human actions are various and multiform. Therefore it seem