SUMMA THEOLOGICA. Thomas Aquinas
I answer that, It is commonly said that the first things created were these four---the angelic nature, the empyrean heaven, formless corporeal matter, and time. It must be observed, however, that this is not the opinion of Augustine. For he (Confess. xii, 12) specifies only two things as first created---the angelic nature and corporeal matter---making no mention of the empyrean heaven. But these two, namely, the angelic nature and formless matter, precede the formation, by nature only, and not by duration; and therefore, as they precede formation, so do they precede movement and time. Time, therefore, cannot be included among them. But the enumeration above given is that of other holy writers, who hold that the formlessness of matter preceded by duration its form, and this view postulates the existence of time as the measure of duration: for otherwise there would be no such measure.
Reply to Objection 1: The teaching of Augustine rests on the opinion that the angelic nature and formless matter precede time by origin or nature.
Reply to Objection 2: As in the opinion of some holy writers matter was in some measure formless before it received its full form, so time was in a manner formless before it was fully formed and distinguished into day and night.
Reply to Objection 3: If the movement of the firmament did not begin immediately from the beginning, then the time that preceded was the measure, not of the firmament's movement, but of the first movement of whatsoever kind. For it is accidental to time to be the measure of the firmament's movement, in so far as this is the first movement. But if the first movement was another than this, time would have been its measure, for everything is measured by the first of its kind. And it must be granted that forthwith from the beginning, there was movement of some kind, at least in the succession of concepts and affections in the angelic mind: while movement without time cannot be conceived, since time is nothing else than "the measure of priority and succession in movement."
Reply to Objection 4: Among the first created things are to be reckoned those which have a general relationship to things. And, therefore, among these time must be included, as having the nature of a common measure; but not movement, which is related only to the movable subject.
Reply to Objection 5: Place is implied as existing in the empyrean heaven, this being the boundary of the universe. And since place has reference to things permanent, it was created at once in its totality. But time, as not being permanent, was created in its beginning: even as actually we cannot lay hold of any part of time save the "now."
ON THE WORK OF DISTINCTION IN ITSELF (FOUR ARTICLES)
We must consider next the work of distinction in itself. First, the work of the first day; secondly, the work of the second day; thirdly the work of the third day.
Under the first head there are four points of inquiry:
(1) Whether the word light is used in its proper sense in speaking of spiritual things?
(2) Whether light, in corporeal things, is itself corporeal?
(3) Whether light is a quality?
(4) Whether light was fittingly made on the first day?
Whether the word "light" is used in its proper sense in speaking of spiritual things?
Objection 1: It would seem that "light" is used in its proper sense in spiritual things. For Augustine says (Gen. ad lit. iv, 28) that "in spiritual things light is better and surer: and that Christ is not called Light in the same sense as He is called the Stone; the former is to be taken literally, and the latter metaphorically."
Objection 2: Further, Dionysius (Div. Nom. iv) includes Light among the intellectual names of God. But such names are used in their proper sense in spiritual things. Therefore light is used in its proper sense in spiritual matters.
Objection 3: Further, the Apostle says (Eph. 5:13): "All that is made manifest is light." But to be made manifest belongs more properly to spiritual things than to corporeal. Therefore also does light.
On the contrary, Ambrose says (De Fide ii) that "Splendor" is among those things which are said of God metaphorically.
I answer that, Any word may be used in two ways---that is to say, either in its original application or in its more extended meaning. This is clearly shown in the word "sight," originally applied to the act of the sense, and then, as sight is the noblest and most trustworthy of the senses, extended in common speech to all knowledge obtained through the other senses. Thus we say, "Seeing how it tastes," or "smells," or "burns. "Further, sight is applied to knowledge obtained through the intellect, as in those words: "Blessed are the clean of heart, for they shall see God" (Mt. 5:8). And thus it is with the word light. In its primary meaning it signifies that which makes manifest to the sense of sight; afterwards it was extended to that which makes manifest to cognition of any kind. If, then, the word is taken in its strict and primary meaning, it is to be understood metaphorically when applied to spiritual things, as Ambrose says (De Fide ii). But if taken in its common and extended use, as applied to manifestation of every kind, it may properly be applied to spiritual things.
The answer to the objections will sufficiently appear from what has been said.
Whether light is a body?
Objection 1: It would seem that light is a body. For Augustine says (De Lib. Arb. iii, 5) that "light takes the first place among bodies."Therefore light is a body.
Objection 2: Further, the Philosopher says (Topic. v, 2) that "light is a species of fire." But fire is a body, and therefore so is light.
Objection 3: Further, the powers of movement, intersection, reflection, belong properly to bodies; and all these are attributes of light and its rays. Moreover, different rays of light, as Dionysius says (Div. Nom. ii) are united and separated, which seems impossible unless they are bodies. Therefore light is a body.
On the contrary, Two bodies cannot occupy the same place simultaneously. But this is the case with light and air. Therefore light is not a body.
I answer that, Light cannot be a body, for three evident reasons. First, on the part of place. For the place of any one body is different from that of any other, nor is it possible, naturally speaking, for any two bodies of whatever nature, to exist simultaneously in the same place; since contiguity requires distinction of place.
The second reason is from movement. For if light were a body, its diffusion would be the local movement of a body. Now no local movement of a body can be instantaneous, as everything that moves from one place to another must pass through the intervening space before reaching the end: whereas the diffusion of light is instantaneous. Nor can it be argued that the time required is too short to be perceived; for though this may be the case in short distances, it cannot be so in distances so great as that which separates the East from the West. Yet as soon as the sun is at the horizon, the whole hemisphere is illuminated from end to end. It must also be borne in mind on the part of movement that whereas all bodies have their natural determinate movement, that of light is indifferent as regards direction, working equally in a circle as in a straight line. Hence it appears that the diffusion of light is not the local movement of a body.
The third reason is from generation and corruption. For if light were a body, it would follow that whenever the air is darkened by