Objection 1. It would seem that formlessness of matter preceded in time its formation. For it is said (Genesis 1:2): "The earth was void and empty," or "invisible and shapeless," according to another version [Septuagint]; by which is understood the formlessness of matter, as Augustine says (Confess. xii, 12). Therefore matter was formless until it received its form.
Objection 2. Further, nature in its working imitates the working of God, as a secondary cause imitates a first cause. But in the working of nature formlessness precedes form in time. It does so, therefore, in the Divine working.
Objection 3. Further, matter is higher than accident, for matter is part of substance. But God can effect that accident exist without substance, as in the Sacrament of the Altar. He could, therefore, cause matter to exist without form.
On the contrary, An imperfect effect proves imperfection in the agent. But God is an agent absolutely perfect; wherefore it is said of Him (Deuteronomy 32:4): "The works of God are perfect." Therefore the work of His creation was at no time formless. Further, the formation of corporeal creatures was effected by the work of distinction. But confusion is opposed to distinction, as formlessness to form. It, therefore, formlessness preceded in time the formation of matter, it follows that at the beginning confusion, called by the ancients chaos, existed in the corporeal creation.
I answer that, On this point holy men differ in opinion. Augustine for instance (Gen. ad lit. i, 15), believes that the formlessness of matter was not prior in time to its formation, but only in origin or the order of nature, whereas others, as Basil (Hom. ii In Hexaem.), Ambrose (In Hexaem. i), and Chrysostom (Hom. ii In Gen.), hold that formlessness of matter preceded in time its formation. And although these opinions seem mutually contradictory, in reality they differ but little; for Augustine takes the formlessness of matter in a different sense from the others. In his sense it means the absence of all form, and if we thus understand it we cannot say that the formlessness of matter was prior in time either to its formation or to its distinction. As to formation, the argument is clear. For it formless matter preceded in duration, it already existed; for this is implied by duration, since the end of creation is being in act: and act itself is a form. To say, then, that matter preceded, but without form, is to say that being existed actually, yet without act, which is a contradiction in terms. Nor can it be said that it possessed some common form, on which afterwards supervened the different forms that distinguish it. For this would be to hold the opinion of the ancient natural philosophers, who maintained that primary matter was some corporeal thing in act, as fire, air, water, or some intermediate substance. Hence, it followed that to be made means merely to be changed; for since that preceding form bestowed actual substantial being, and made some particular thing to be, it would result that the supervening form would not simply make an actual being, but 'this' actual being; which is the proper effect of an accidental form. Thus the consequent forms would be merely accidents, implying not generation, but alteration. Hence we must assert that primary matter was not created altogether formless, nor under any one common form, but under distinct forms. And so, if the formlessness of matter be taken as referring to the condition of primary matter, which in itself is formless, this formlessness did not precede in time its formation or distinction, but only in origin and nature, as Augustine says; in the same way as potentiality is prior to act, and the part to the whole. But the other holy writers understand by formlessness, not the exclusion of all form, but the absence of that beauty and comeliness which are now apparent in the corporeal creation. Accordingly they say that the formlessness of corporeal matter preceded its form in duration. And so, when this is considered, it appears that Augustine agrees with them in some respects, and in others disagrees, as will be shown later (69, 1; 74, 2).
As far as may be gathered from the text of Genesis a threefold beauty was wanting to corporeal creatures, for which reason they are said to be without form. For the beauty of light was wanting to all that transparent body which we call the heavens, whence it is said that "darkness was upon the fact of the deep." And the earth lacked beauty in two ways: first, that beauty which it acquired when its watery veil was withdrawn, and so we read that "the earth was void," or "invisible," inasmuch as the waters covered and concealed it from view; secondly, that which it derives from being adorned by herbs and plants, for which reason it is called "empty," or, according to another reading [Septuagint], "shapeless"--that is, unadorned. Thus after mention of two created natures, the heaven and the earth, the formlessness of the heaven is indicated by the words, "darkness was upon the face of the deep," since the air is included under heaven; and the formlessness of the earth, by the words, "the earth was void and empty."
Reply to Objection 1. The word earth is taken differently in this passage by Augustine, and by other writers. Augustine holds that by the words "earth" and "water," in this passage. primary matter itself is signified on account of its being impossible for Moses to make the idea of such matter intelligible to an ignorant people, except under the similitude of well-known objects. Hence he uses a variety of figures in speaking of it, calling it not water only, nor earth only, lest they should think it to be in very truth water or earth. At the same time it has so far a likeness to earth, in that it is susceptible of form, and to water in its adaptability to a variety of forms. In this respect, then, the earth is said to be "void and empty," or "invisible and shapeless," that matter is known by means of form. Hence, considered in itself, it is called "invisible" or "void," and its potentiality is completed by form; thus Plato says that matter is "place" [Timaeus, quoted by Aristotle, Phys. iv, text. 15. But other holy writers understand by earth the element of earth, and we have said (1) how, in this sense, the earth was, according to them, without form.
Reply to Objection 2. Nature produces effect in act from being in potentiality; and consequently in the operations of nature potentiality must precede act in time, and formlessness precede form. But God produces being in act out of nothing, and can, therefore, produce a perfect thing in an instant, according to the greatness of His power.
Reply to Objection 3. Accident, inasmuch as it is a form, is a kind of act; whereas matter, as such, is essentially being in potentiality. Hence it is more repugnant that matter should be in act without form, than for accident to be without subject.
In reply to the first argument in the contrary sense, we say that if, according to some holy writers, formlessness was prior in time to the informing of matter, this arose, not from want of power on God's part, but from His wisdom, and from the design of preserving due order in the disposition of creatures by developing perfection from imperfection.
In reply to the second argument, we say that certain of the ancient natural philosophers maintained confusion devoid of all distinction; except Anaxagoras, who taught that the intellect alone was distinct and without admixture. But previous to the work of distinction Holy Scripture enumerates several kinds of differentiation, the first being that of the heaven from the earth, in which even a material distinction is expressed, as will be shown later (3; 68, 1). This is signified by the words, "In the beginning God created heaven and earth." The second distinction mentioned is that of the elements according to their forms, since both earth and water are named. That air and fire are not mentioned by name is due to the fact that the corporeal nature of these would not be so evident as that of earth and water, to the ignorant people to whom Moses spoke. Plato (Timaeus xxvi), nevertheless, understood air to be signified by the words, "Spirit of God," since spirit is another name for air, and considered that by the word heaven is meant fire, for he held heaven to be composed of fire, as Augustine relates (De Civ. Dei viii, 11). But Rabbi Moses (Perplex. ii), though otherwise agreeing with Plato, says that fire is signified by the word darkness, since, said he, fire does not shine in its own sphere. However, it seems more reasonable to hold to what we stated above; because by the words "Spirit of God" Scripture usually means the Holy Ghost, Who is said to "move over the waters," not, indeed, in bodily shape, but as the craftsman's will may be said to move over the material to which he intends to give a form. The third distinction is that of place; since the earth is said to be under the waters that rendered it invisible, whilst the air, the subject of darkness, is described as being above the waters, in the words: "Darkness was upon the face of the deep." The remaining distinctions will appear from what follows (71).
Source: Summa Theologica (New Advent)