SUMMA THEOLOGICA. Thomas Aquinas
above the firmament will not be of the same nature as the elemental waters, but just as, according to Strabus, one heaven is called empyrean, that is, fiery, solely on account of its splendor: so this other heaven will be called aqueous solely on account of its transparence; and this heaven is above the starry heaven. Again, if the firmament is held to be of other nature than the elements, it may still be said to divide the waters, if we understand by water not the element but formless matter. Augustine, in fact, says (Super Gen. cont. Manich. i, 5,7) that whatever divides bodies from bodies can be said to divide waters from waters.
If, however, we understand by the firmament that part of the air in which the clouds are collected, then the waters above the firmament must rather be the vapors resolved from the waters which are raised above a part of the atmosphere, and from which the rain falls. But to say, as some writers alluded to by Augustine (Gen. ad lit. ii, 4), that waters resolved into vapor may be lifted above the starry heaven, is a mere absurdity. The solid nature of the firmament, the intervening region of fire, wherein all vapor must be consumed, the tendency in light and rarefied bodies to drift to one spot beneath the vault of the moon, as well as the fact that vapors are perceived not to rise even to the tops of the higher mountains, all to go to show the impossibility of this. Nor is it less absurd to say, in support of this opinion, that bodies may be rarefied infinitely, since natural bodies cannot be infinitely rarefied or divided, but up to a certain point only.
Reply to Objection 1: Some have attempted to solve this difficulty by supposing that in spite of the natural gravity of water, it is kept in its place above the firmament by the Divine power. Augustine (Gen. ad lit. ii, 1), however will not admit this solution, but says "It is our business here to inquire how God has constituted the natures of His creatures, not how far it may have pleased Him to work on them by way of miracle." We leave this view, then, and answer that according to the last two opinions on the firmament and the waters the solution appears from what has been said. According to the first opinion, an order of the elements must be supposed different from that given by Aristotle, that is to say, that the waters surrounding the earth are of a dense consistency, and those around the firmament of a rarer consistency, in proportion to the respective density of the earth and of the heaven.
Or by the water, as stated, we may understand the matter of bodies to be signified.
Reply to Objection 2: The solution is clear from what has been said, according to the last two opinions. But according to the first opinion, Basil gives two replies (Hom. iii in Hexaem.). He answers first, that a body seen as concave beneath need not necessarily 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 to Objection 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.
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.
Objection 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.
Objection 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 (Gn. 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 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 to Objection 1: If by the firmament is understood the starry heaven, the waters above are not of the same species as those beneath. But if by the firmament is understood the cloudy region of the air, both these waters are of the same species, and two places are assigned to them, though not for the same purpose, the higher being the place of their begetting, the lower, the place of their repose.
Reply to Objection 2: If the waters are held to differ in species, the firmament cannot be said to divide the waters, as the cause of their destruction, but only as the boundary of each.
Reply to Objection 3: On account of the air and other similar bodies being invisible, Moses includes all such bodies under the name of water, and thus it is evident that waters are found on each side of the firmament, whatever be the sense in which the word is used.
Whether there is only one heaven?
Objection 1: It would seem that there is only one heaven. For the heaven is contrasted with the earth, in the words, "In the beginning God created heaven and earth."But