a theory similar to that held by certain
philosophers of antiquity, who taught that water was a body infinite
in dimension, and the primary element of all bodies. Thus in the
words, "Darkness was upon the face of the deep," the word "deep" might
be taken to mean the infinite mass of water, understood as the
principle of all other bodies. These philosophers also taught that not
all corporeal things are confined beneath the heaven perceived by our
senses, but that a body of water, infinite in extent, exists above
that heaven. On this view the firmament of heaven might be said to
divide the waters without from those within--that is to say, from all
bodies under the heaven, since they took water to be the principle of
them all.

As, however, this theory can be shown to be false by solid reasons, it
cannot be held to be the sense of Holy Scripture. It should rather be
considered that Moses was speaking to ignorant people, and that out of
condescension to their weakness he put before them only such things as
are apparent to sense. Now even the most uneducated can perceive by
their senses that earth and water are corporeal, whereas it is not
evident to all that air also is corporeal, for there have even been
philosophers who said that air is nothing, and called a space filled
with air a vacuum.

Moses, then, while he expressly mentions water and earth, makes no
express mention of air by name, to avoid setting before ignorant
persons something beyond their knowledge. In order, however, to
express the truth to those capable of understanding it, he implies in
the words: "Darkness was upon the face of the deep," the existence of
air as attendant, so to say, upon the water. For it may be understood
from these words that over the face of the water a transparent body
was extended, the subject of light and darkness, which, in fact, is
the air.

Whether, then, we understand by the firmament the starry heaven, or
the cloudy region of the air, it is true to say that it divides the
waters from the waters, according as we take water to denote formless
matter, or any kind of transparent body, as fittingly designated
under the name of waters. For the starry heaven divides the lower
transparent bodies from the higher, and the cloudy region divides
that higher part of the air, where the rain and similar things are
generated, from the lower part, which is connected with the water
and included under that name.

Reply Obj. 1: If by the firm