sarily be
rounded, or convex, above. Secondly, that the waters above the
firmament are not fluid, but exist outside it in a solid state, as a
mass of ice, and that this is the crystalline heaven of some writers.

Reply Obj. 3: According to the third opinion given, the waters above
the firmament have been raised in the form of vapors, and serve to
give rain to the earth. But according to the second opinion, they
are above the heaven that is wholly transparent and starless. This,
according to some, is the primary mobile, the cause of the daily
revolution of the entire heaven, whereby the continuance of
generation is secured. In the same way the starry heaven, by the
zodiacal movement, is the cause whereby different bodies are
generated or corrupted, through the rising and setting of the stars,
and their various influences. But according to the first opinion
these waters are set there to temper the heat of the celestial
bodies, as Basil supposes (Hom. iii in Hexaem.). And Augustine says
(Gen. ad lit. ii, 5) that some have considered this to be proved by
the extreme cold of Saturn owing to its nearness to the waters that
are above the firmament.
_______________________

THIRD ARTICLE [I, Q. 68, Art. 3]

Whether the Firmament Divides Waters from Waters?

Objection 1: It would seem that the firmament does not divide waters
from waters. For bodies that are of one and the same species have
naturally one and the same place. But the Philosopher says (Topic.
i, 6): "All water is the same species." Water therefore cannot be
distinct from water by place.

Obj. 2: Further, should it be said that the waters above the
firmament differ in species from those under the firmament, it may be
argued, on the contrary, that things distinct in species need nothing
else to distinguish them. If then, these waters differ in species, it
is not the firmament that distinguishes them.

Obj. 3: Further, it would appear that what distinguishes waters from
waters must be something which is in contact with them on either
side, as a wall standing in the midst of a river. But it is evident
that the waters below do not reach up to the firmament. Therefore
the firmament does not divide the waters from the waters.

_On the contrary,_ It is written (Gen. 1:6): "Let there be a
firmament made amidst the waters; and let it divide the waters from
the waters."

_I answer that,_ The text of Genesis, considered superficially, might
lead to the adoption of