e heaven are set for signs of changes
effected in corporeal creatures, but not of those changes which
depend upon the free-will.

Reply Obj. 2: We are sometimes brought to the knowledge of hidden
effects through their sensible causes, and conversely. Hence nothing
prevents a sensible cause from being a sign. But he says "signs,"
rather than "causes," to guard against idolatry.

Reply Obj. 3: The general division of time into day and night took
place on the first day, as regards the diurnal movement, which is
common to the whole heaven and may be understood to have begun on
that first day. But the particular distinctions of days and seasons
and years, according as one day is hotter than another, one season
than another, and one year than another, are due to certain
particular movements of the stars: which movements may have had their
beginning on the fourth day.

Reply Obj. 4: Light was given to the earth for the service of man,
who, by reason of his soul, is nobler than the heavenly bodies. Nor
is it untrue to say that a higher creature may be made for the sake
of a lower, considered not in itself, but as ordained to the good of
the universe.

Reply Obj. 5: When the moon is at its perfection it rises in the
evening and sets in the morning, and thus it rules the night, and it
was probably made in its full perfection as were plants yielding
seed, as also were animals and man himself. For although the perfect
is developed from the imperfect by natural processes, yet the perfect
must exist simply before the imperfect. Augustine, however (Gen. ad
lit. ii), does not say this, for he says that it is not unfitting
that God made things imperfect, which He afterwards perfected.
_______________________

THIRD ARTICLE [I, Q. 70, Art. 3]

Whether the Lights of Heaven Are Living Beings?

Objection 1: It would seem that the lights of heaven are living
beings. For the nobler a body is, the more nobly it should be adorned.
But a body less noble than the heaven, is adorned with living beings,
with fish, birds, and the beasts of the field. Therefore the lights of
heaven, as pertaining to its adornment, should be living beings also.

Obj. 2: Further, the nobler a body is, the nobler must be its form.
But the sun, moon, and stars are nobler bodies than plants or
animals, and must therefore have nobler forms. Now the noblest of all
forms is the soul, as being the first principle of life. Hence
Augustine (De Vera Relig. xxix) says: