Objection 1. It seems that when the world is thus renewed the movement of the heavenly bodies will not cease. For it is written (Genesis 8:22): "All the days of the earth... cold and heat, summer and winter, night and day shall not cease." Now night and day, summer and winter result from the movement of the sun. Therefore the movement of the sun will never cease.
Objection 2. Further, it is written (Jeremiah 31:35-36): "Thus saith the Lord Who giveth the sun for the light of the day, the order of the moon and of the stars for the light of the night: Who stirreth up the sea, and the waves thereof roar... If these ordinances shall fail before Me... then also the seed of Israel shall fail, so as not to be a nation before Me for ever." Now the seed of Israel shall never fail, but will remain for ever. Therefore the laws of day and of the sea waves, which result from the heavenly movement, will remain for ever. Therefore the movement of the heaven will never cease.
Objection 3. Further, the substance of the heavenly bodies will remain for ever. Now it is useless to admit the existence of a thing unless you admit the purpose for which it was made: and the heavenly bodies were made in order "to divide the day and the night"; and to be "for signs, and for seasons, and for days and for years" (Genesis 1:14). But they cannot do this except by movement. Therefore their movement will remain for ever, else those bodies would remain without a purpose.
Objection 4. Further, in this renewal of the world the whole world will be bettered. Therefore no body will be deprived of what pertains to its perfection. Now movement belongs to the perfection of a heavenly body, because, as stated in De Coelo et Mundo ii, "those bodies participate of the Divine goodness by their movement." Therefore the movement of the heaven will not cease.
Objection 5. Further, the sun successively gives light to the various parts of the world, by reason of its circular movement. Therefore if the circular movement of the heaven ceases, it follows that in some part of the earth's surface there will be perpetual darkness, which is unbecoming to the aforesaid renewal.
Objection 6. Further, if the movement were to cease, this could only be because movement causes some imperfection in the heaven, for instance wear and tear, which is impossible, since this movement is natural, and the heavenly bodies are impassible, wherefore they are not worn out by movement (De Coelo et Mundo ii). Therefore the movement of the heaven will never cease.
Objection 7. Further, a potentiality is useless if it be not reduced to act. Now in whatever position the heavenly body is placed it is in potentiality to another position. Therefore unless this potentiality be reduced to act, it would remain useless, and would always be imperfect. But it cannot be reduced to act save by local movement. Therefore it will always be in motion.
Objection 8. Further, if a thing is indifferent in relation to more than one alternation, either both are ascribed to it, or neither. Now the sun is indifferent to being in the east or in the west, else its movement would not be uniform throughout, since it would move more rapidly to the place which is more natural to it. Therefore either neither position is ascribed to the sun, or both. But neither both nor neither can be ascribed to it, except successively by movement; for if it stand still, it must needs stand in some position. Therefore the solar body will always be in motion, and in like manner all other heavenly bodies.
Objection 9. Further, the movement of the heaven is the cause of time. Therefore if the movement of the heaven fail, time must needs fail: and if this were to fail, it would fail in an instant. Now an instant is defined (Phys. viii) "the beginning of the future and the end of the past." Consequently there would be time after the last instant of time, which is impossible. Therefore the movement of the heavens will never cease.
Objection 10. Further, glory does not remove nature. But the movement of the heaven is natural. Therefore it is not deprived thereof by glory.
On the contrary, It is stated (Apocalypse 10:6) that the angel who appeared, "swore by him that liveth for ever and ever... that time shall be no longer," namely after the seventh angel shall have sounded the trumpet, at the sound of which "the dead shall rise again" (1 Corinthians 15:52). Now if time be not, there is no movement of the heaven. Therefore the movement of the heaven will cease.
Further: "Thy sun shall go down no more, and thy moon shall not decrease" (Isaiah 60:20). Now the setting of the sun and the phases of the moon are caused by the movement of the heavens. Therefore the heavenly movement will cease at length.
Further, it is shown in De Gener. ii that "the movement of the heaven is for the sake of continual generation in this lower world." But generation will cease when the number of the elect is complete. Therefore the movement of the heaven will cease.
Further, all movement is for some end (Metaph. ii). But all movement for an end ceases when the end is obtained. Therefore either the movement of the heaven will never obtain its end, and thus it would be useless, or it will cease at length.
Further, rest is more noble than movement, because things are more likened to God, Who is supremely immovable, by being themselves unmoved. Now the movement of lower bodies terminates naturally in rest. Therefore since the heavenly bodies are far nobler, their movement terminates naturally in rest.
I answer that, There are three opinions touching this question. The first is of the philosophers who assert that the movement of the heaven will last for ever. But this is not in keeping with our faith, which holds that the elect are in a certain number preordained by God, so that the begetting of men will not last for ever, and for the same reason, neither will other things that are directed to the begetting of men, such as the movement of the heaven and the variations of the elements. Others say that the movement of the heaven will cease naturally. But this again is false, since every body that is moved naturally has a place wherein it rests naturally, whereto it is moved naturally, and whence it is not moved except by violence. Now no such place can be assigned to the heavenly body, since it is not more natural to the sun to move towards a point in the east than to move away from it, wherefore either its movement would not be altogether natural, or its movement would not naturally terminate in rest. Hence we must agree with others who say that the movement of the heaven will cease at this renewal of the world, not indeed by any natural cause, but as a result of the will of God. For the body in question, like other bodies, was made to serve man in the two ways above mentioned (1): and hereafter in the state of glory man will no longer need one of these services, that namely in respect of which the heavenly bodies serve man for the sustenance of his bodily life. Now in this way the heavenly bodies serve man by their movement, in so far as by the heavenly movement the human race is multiplied, plants and animals needful for man's use generated, and the temperature of the atmosphere rendered conducive to health. Therefore the movement of the heavenly body will cease as soon as man is glorified.
Reply to Objection 1. These words refer to the earth in its present state, when it is able to be the principle of the generation and corruption of plants. This is evident from its being said there: "All the days of the earth, seed time and harvest," etc. And it is simply to be granted that as long as the earth is fit for seed time and harvest, the movement of the heaven will not cease.
We reply in like manner to Objection 2 that the Lord is speaking there of the duration of the seed of Israel with regard to the present state. This is evident from the words: "Then also the seed of Israel shall fail, so as not to be a nation before Me for ever." For after this state there will be no succession of days: wherefore the laws also which He had mentioned will cease after this state.
Reply to Objection 3. The end which is there assigned to the heavenly bodies is their proximate end, because it is their proper act. But this act is directed further to another end, namely the service of man, which is shown by the words of Deuteronomy 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 the nations, that are under heaven." Therefore we should form our judgment of the heavenly bodies from the service of man, rather than from the end assigned to them in Genesis. Moreover the heavenly bodies, as stated above, will serve glorified man in another way; hence it does not follow that they will remain without a purpose.
Reply to Objection 4. Movement does not belong to the perfection of a heavenly body, except in so far as thereby it is the cause of generation and corruption in this lower world: and in that respect also this movement makes the heavenly body participate in the Divine goodness by way of a certain likeness of causality. But movement does not belong to the perfection of the substance of the heaven, which substance will remain. Wherefore it does not follow that, when this movement ceases, the substance of the heaven will lose something of its perfection.
Reply to Objection 5. All the elemental bodies will have in themselves a certain clarity of glory. Hence though part of the surface of the earth be not lit up by the sun, there will by no means be any darkness there.
Reply to Objection 6. A gloss of Ambrose on Romans 8:22, "Every creature groaneth," etc. says explicitly that "all the elements labor to fulfill their offices: thus the sun and moon fill the places appointed to them not without work: this is for our sake, wherefore they will rest when we are taken up to heaven." This work, in my opinion, does not signify that any stress or passion occurs to these bodies from their movement, since this movement is natural to them and nowise violent, as is proved in De Coelo et Mundo i. But work here denotes a defect in relation to the term to which a thing tends. Hence since this movement is ordained by Divine providence to the completion of the number of the elect, it follows that as long as the latter is incomplete, this movement has not reached the term whereto it was ordained: hence it is said metaphorically to labor, as a man who has not what he intends to have. This defect will be removed from the heaven when the number of the elect is complete. Or it may refer to the desire of the future renewal which it awaits from the Divine disposal.
Reply to Objection 7. In a heavenly body there is no potentiality that can be perfected by place, or that is made for this end which is to be in such and such a place. But potentiality to situation in a place is related to a heavenly body, as the craftsman's potentiality to construct various houses of one kind: for if he construct one of these he is not said to have the potentiality uselessly, and in like manner in whatever situation a heavenly body be placed, its potentiality to be in a place will not remain incomplete or without a purpose.
Reply to Objection 8. Although a heavenly body, so far as regards its nature, is equally inclined to every situation that it can possibly occupy, nevertheless in comparison with things outside it, it is not equally inclined to every situation: but in respect of one situation it has a more noble disposition in comparison with certain things than in respect of another situation; thus in our regard the sun has a more noble disposition at daytime than at night-time. Hence it is probable, since the entire renewal of the world is directed to man, that the heaven will have in this renewal the most noble situation possible in relation to our dwelling there. Or, according to some, the heaven will rest in that situation wherein it was made, else one of its revolutions would remain incomplete. But this argument seems improbable, for since a revolution of the heaven takes no less than 36,000 years to complete, it would follow that the world must last that length of time, which does not seem probable. Moreover according to this it would be possible to know when the world will come to an end. For we may conclude with probability from astronomers in what position the heavenly bodies were made, by taking into consideration the number of years that have elapsed since the beginning of the world: and in the same way it would be possible to know the exact number of years it would take them to return to a like position: whereas the time of the world's end is stated to be unknown.
Reply to Objection 9. Time will at length cease, when the heavenly movement ceases. Yet that last "now" will not be the beginning of the future. For the definition quoted applies to the "now" only as continuous with the parts of time, not as terminating the whole of time.
Reply to Objection 10. The movement of the heaven is said to be natural, not as though it were part of nature in the same way as we speak of natural principles; but because it has its principle in the nature of a body, not indeed its active but its receptive principle. Its active principle is a spiritual substance, as the Commentator says on De Coelo et Mundo; and consequently it is not unreasonable for this movement to be done away by the renewal of glory, since the nature of the heavenly body will not alter through the cessation of that movement.
We grant the other objections which argue in the contrary sense, namely the first three, because they conclude in due manner. But since the remaining two seem to conclude that the movement of heaven will cease naturally, we must reply to them. To the first, then, we reply that movement ceases when its purpose is attained, provided this is a sequel to, and does not accompany the movement. Now the purpose of the heavenly movement, according to philosophers, accompanies that movement, namely the imitation of the Divine goodness in the causality of that movement with respect to this lower world. Hence it does not follow that this movement ceases naturally.
To the second we reply that although immobility is simply nobler than movement, yet movement in a subject which thereby can acquire a perfect participation of the Divine goodness is nobler than rest in a subject which is altogether unable to acquire that perfection by movement. For this reason the earth which is the lowest of the elements is without movement: although God Who is exalted above all things is without movement, by Whom the more noble bodies are moved. Hence also it is that the movements of the higher bodies might be held to be perpetual, so far as their natural power is concerned, and never to terminate in rest, although the movement of lower bodies terminates in rest.
Source: Summa Theologica (New Advent)