SUMMA THEOLOGICA. Thomas Aquinas
bodies to be of the nature of the four elements, for it may be said that they were formed out of matter already existing, as animals and plants were formed. For those, however, who hold the heavenly bodies to be of another nature from the elements, and naturally incorruptible, the answer must be that the lights were substantially created at the beginning, but that their substance, at first formless, is formed on this day, by receiving not its substantial form, but a determination of power. As to the fact that the lights are not mentioned as existing from the beginning, but only as made on the fourth day, Chrysostom (Hom. vi in Gen.) explains this by the need of guarding the people from the danger of idolatry: since the lights are proved not to be gods, by the fact that they were not from the beginning.
Reply to Objection 2: No difficulty exists if we follow Augustine in holding the light made on the first day to be spiritual, and that made on this day to be corporeal. If, however, the light made on the first day is understood to be itself corporeal, then it must be held to have been produced on that day merely as light in general; and that on the fourth day the lights received a definite power to produce determinate effects. Thus we observe that the rays of the sun have one effect, those of the moon another, and so forth. Hence, speaking of such a determination of power, Dionysius (Div. Nom. iv) says that the sun's light which previously was without form, was formed on the fourth day.
Reply to Objection 3: According to Ptolemy the heavenly luminaries are not fixed in the spheres, but have their own movement distinct from the movement of the spheres. Wherefore Chrysostom says (Hom. vi in Gen.) that He is said to have set them in the firmament, not because He fixed them there immovably, but because He bade them to be there, even as He placed man in Paradise, to be there. In the opinion of Aristotle, however, the stars are fixed in their orbits, and in reality have no other movement but that of the spheres; and yet our senses perceive the movement of the luminaries and not that of the spheres (De Coel. ii, text. 43). But Moses describes what is obvious to sense, out of condescension to popular ignorance, as we have already said ( Question [67], Article [4]; Question [68], Article [3]). The objection, however, falls to the ground if we regard the firmament made on the second day as having a natural distinction from that in which the stars are placed, even though the distinction is not apparent to the senses, the testimony of which Moses follows, as stated above (De Coel. ii, text. 43). For although to the senses there appears but one firmament; if we admit a higher and a lower firmament, the lower will be that which was made on the second day, and on the fourth the stars were fixed in the higher firmament.
Reply to Objection 4: In the words of Basil (Hom. v in Hexaem.), plants were recorded as produced before the sun and moon, to prevent idolatry, since those who believe the heavenly bodies to be gods, hold that plants originate primarily from these bodies. Although as Chrysostom remarks (Hom. vi in Gen.), the sun, moon, and stars cooperate in the work of production by their movements, as the husbandman cooperates by his labor.
Reply to Objection 5: As Chrysostom says, the two lights are called great, not so much with regard to their dimensions as to their influence and power. For though the stars be of greater bulk than the moon, yet the influence of the moon is more perceptible to the senses in this lower world. Moreover, as far as the senses are concerned, its apparent size is greater.
Whether the cause assigned for the production of the lights is reasonable?
Objection 1: It would seem that the cause assigned for the production of the lights is not reasonable. For it is said (Jer. 10:2): "Be not afraid of the signs of heaven, which the heathens fear." Therefore the heavenly lights were not made to be signs.
Objection 2: Further, sign is contradistinguished from cause. But the lights are the cause of what takes place upon the earth. Therefore they are not signs.
Objection 3: Further, the distinction of seasons and days began from the first day. Therefore the lights were not made "for seasons, and days, and years," that is, in order to distinguish them.
Objection 4: Further, nothing is made for the sake of that which is inferior to itself, "since the end is better than the means" (Topic. iii). But the lights are nobler than the earth. Therefore they were not made "to enlighten it."
Objection 5: Further, the new moon cannot be said "to rule the night." But such it probably did when first made; for men begin to count from the new moon. The moon, therefore, was not made "to rule the night."
On the contrary, Suffices the authority of Scripture.
I answer that, As we have said above ( Question [65], Article [2]), a corporeal creature can be considered as made either for the sake of its proper act, or for other creatures, or for the whole universe, or for the glory of God. Of these reasons only that which points out the usefulness of these things to man, is touched upon by Moses, in order to withdraw his people from idolatry. Hence it is written (Dt. 4:19): "Lest perhaps lifting up thy eyes to heaven, thou see the sun and the moon and all the stars of heaven, and being deceived by error thou adore and serve them, which the Lord thy God created for the service of all nations." Now, he explains this service at the beginning of Genesis as threefold. First, the lights are of service to man, in regard to sight, which directs him in his works, and is most useful for perceiving objects. In reference to this he says: "Let them shine in the firmament and give life to the earth." Secondly, as regards the changes of the seasons, which prevent weariness, preserve health, and provide for the necessities of food; all of which things could not be secured if it were always summer or winter. In reference to this he says: "Let them be for seasons, and for days, and years." Thirdly, as regards the convenience of business and work, in so far as the lights are set in the heavens to indicate fair or foul weather, as favorable to various occupations. And in this respect he says: "Let them be for signs."
Reply to Objection 1: The lights in the heaven are set for signs of changes effected in corporeal creatures, but not of those changes which depend upon the free-will.
Reply to Objection 2: We are sometimes brought to the knowledge of hidden effects through their sensible causes, and conversely. Hence nothing prevents a sensible cause from being a sign. But he says "signs," rather than "causes," to guard against idolatry.
Reply to Objection 3: The general division of time into day and night took place on the first day, as regards the diurnal movement, which is common to the whole heaven and may be understood to have begun on that first day. But the particular distinctions of days and seasons and years, according as one day is hotter than another, one season than another, and one year than another, are due to certain particular movements of the stars: which movements may have had their beginning on the fourth day.
Reply to Objection 4: Light was given to the earth for the service of man, who, by reason of his soul, is nobler than the heavenly bodies. Nor is it untrue to say that a higher creature may be made for the sake of a lower, considered not in itself, but as ordained to the good of the universe.
Reply to Objection 5: When the moon is at its perfection it rises in the evening and sets in the morning, and thus it rules the night, and it was probably made in its full perfection as were plants yielding seed, as also were animals and man himself. For although the perfect is developed from the imperfect by natural processes, yet the perfect must exist simply before the imperfect. Augustine, however (Gen. ad lit. ii), does not say this, for he says that it is not unfitting that God made things imperfect, which He afterwards perfected.
Whether the lights of heaven are living beings?