Article 5 — Whether the movement of the heavens will cease at some time

The fifth point of inquiry is whether the movement of the heavens will cease at some time. (Parallel texts: SCG IV.97; In II Sent. 11.2.6, ad 3; In IV Sent. 43.1.1, ad 1; 43.1.3; 44.1.3, qa. 4; 44.2.3, qa. 2; 47.1.1, qa. 3; 47.2.2, qa. 1; 48.2.2; 48.2.3, ad 2.)

Obj. 1: And it seems that it will not. For it is written: all the days of the earth, seed time and harvest, cold and heat, summer and winter, night and day, shall not cease (Gen 8:22). Now, all these result from the movement of the heavens. Therefore, as long as the earth remains, the movement of the heavens will not rest. But the earth will stand forever (Eccl 1:4). Therefore, the movement of the heavens will also last into eternity.

Obj. 2: It might be said that the passage quoted refers to the earth as serving man in his present state of life, wherein by sowing and reaping he gathers a harvest for the support of his animal life, but not as serving him when glorified, when it will last into eternity for the greater enjoyment of the good.

On the contrary, it is written: thus says the Lord, who gives the sun for the light of the day, the order of the moon and of the stars for the light of the night, who stirs up the sea and the waves thereof roar, the Lord of hosts is his name. If these ordinances shall fail before me, then also the seed of Israel shall fail so as not to be a nation before me forever (Jer 31:35). Now, this does not refer to the fleshly Israel, seeing that by reason of their dispersion they can no longer be called a nation. Therefore, it must refer to the spiritual Israel, who will most be the nation before the Lord, since they shall see God in his essence. Therefore, in the state of beatitude, the aforesaid laws, which are consequent upon the movement of the heavens, will not cease, and consequently, neither will the movement of the heavens.

Obj. 3: As is clear from the Philosopher in Physics 2, anything that is rendered necessary by something that is already necessary is itself absolutely necessary; for example, an animal’s death is necessary on account of the necessity of its matter. (Aristotle, Physics 2.9, 199b34–200b9.) Now, the activities of incorruptible things, among which we must reckon the heavenly movement, are for the sake of the substances of the things whose activities they are, so they seem to have necessity by something prior, while the contrary obtains in corruptible things, whose substance is for the sake of their activities, so they have necessity from something posterior, as the Commentator remarks. Therefore, the heavenly movement is necessary absolutely, and so it will never cease. (Averroes, Commentary on the Physics 2.)

Obj. 4: The end of the heavenly movement is that the heavens by their movement become like God, inasmuch as they pass from potency to actuality by the renewal of their positions, which they actually acquire successively; for each thing becomes like God, who is pure act, to the degree that it is actual. Now, this end would cease if movement were to cease. Therefore, since movement does not cease unless the end that is its purpose is obtained, the movement of the heavens will never cease.

Obj. 5: It might be said that the heavenly movement is not for the sake of this end but for the sake of completing the number of the elect, and when this is complete, the heavens will rest.

On the contrary, nothing is for the sake of something that is more base, because the end is nobler than things that are for the sake of the end, since the end is the cause of goodness in the things for the sake of the end. Now, the heavens, since they are incorruptible, are nobler than generable and corruptible things. Therefore, it cannot be said that the movement of the heavens is for the sake of some generation in these lower things by which, nevertheless, the number of the elect can be completed.

Obj. 6: Yet, it might be said that the movement of the heavens is not for the sake of the generation of the elect as its principal end but as its secondary end.

On the contrary, that which is moved for the sake of the movement’s end does not rest when a secondary end has been obtained. If, then, the generation by which the number of the elect is made complete is the secondary end of the celestial movement, this movement will not cease when that number is reached.

Obj. 7: All that is in potency is imperfect until it is made actual. Now, in the consummation of the world, God will not leave anything imperfect. Since, then, the heaven’s potency to a where is not actualized otherwise than by movement, it seems that the heavenly movement will not cease even at the consummation of the world.

Obj. 8: If the causes of a certain effect be incorruptible and invariable, the effect itself will be everlasting. Now, all the causes of the celestial movement are incorruptible and invariable, whether we refer to the moving cause or to the thing itself that is moved. Therefore, the movement of heaven will last forever.

Obj. 9: That which is receptive of everlastingness will never be deprived of its everlastingness by God, as is clear in angels, the rational soul, and the substance of heavens. Now, the heavenly movement is susceptive of everlastingness, since circular movement alone can last forever, as is proved in Physics 8. (Aristotle, Physics 8.8, 261b27.) Therefore, the movement of heaven will last forever, like other things that have a natural aptitude to be everlasting.

Obj. 10: If the motion of the heaven were to rest, it would rest either in an instant or in a time.

If in an instant, it will follow that a thing is at rest and in motion simultaneously; for, because it was in motion during the whole preceding time, one must say that it was in motion at any given instant of that time in which the heaven is naturally apt to move. Now, in this given instant, in which it has been granted that heaven was at rest, the heaven is naturally apt to be in motion, since rest and motion apply to the same subject; now, this instant belongs to the preceding time, inasmuch as it is its term. Therefore, heaven would be moving in it. Yet, it was granted that it was at rest in it. Therefore, in the same instant it would be at rest and in motion, which is impossible.

On the other hand, if this cessation be in a time, it follows that there will be time after the celestial movement. But there is no time without the movement of heaven; therefore, the heavenly movement will continue after it has ceased, and this again is impossible.

Obj. 11: If the heavenly movement is ever to cease, it follows that time, which is its number, will cease also, as is clear from Physics 4. (Aristotle, Physics 4.10, 218a11–20; 4.12, 220b14, 221a7–222a9.) But it is impossible that time cease; therefore, it is impossible that the celestial movement cease. Proof of the middle: anything that is always in its beginning and its end never began to be and will never cease, because everything is subsequent to its beginning and previous to its end. Now, the only thing we can seize on in time is an instant, and this is the beginning of the future and the end of the past, so time is ever in its beginning and end. Therefore, time will never cease.

Obj. 12: The celestial movement is natural to the heavens, as the movement of heavy and light bodies is natural to them, as is clear in On the Heavens 1. (Aristotle, On the Heavens 1.5, 269b20–270a11; 1.18, 277b9–26.) There is this difference, however, that elemental bodies move naturally only when they are outside their proper place, while the heaven is moved even while it is in its proper place. Therefore, we may infer that the relation of an elemental body to its natural movement when it is outside its own place is like the relation of the heaven to its natural movement when it is in its own place. For an elemental body, when it is outside its proper place, does not rest there unless the rest is forced. Therefore, the heavenly body also cannot rest unless the rest is forced. But this is incongruous. For, since nothing violent can endure forever, it would follow that this heavenly rest does not last forever, and that at length the heaven would begin again to be moved, which is ridiculous. Therefore, we must not say that the heavenly movement will cease at some time.

Obj. 13: Things that succeed one another should have a certain order and proportion. But there is no proportion between the finite and the infinite. Therefore, it is incongruously asserted that the heaven moved for a finite time and later rests for an infinite time, and yet, this must be said if the movement of the heaven began and will end and will never begin again.

Obj. 14: To the degree that something becomes like God according to a nobler act, so to that degree assimilation is nobler; for example, man’s likeness to God, by reason of his rational soul, is nobler than that of a beast, which occurs by reason of its sensitive soul. Now, the second act is more excellent than the first, just as the consideration is better than the knowledge. Therefore, the heaven’s likeness to God in respect of its second act, which is to cause lower things, is nobler than its likeness in respect of brightness, which is its first act. If, then, in the consummation of the world, the principal parts of the world will be made better, it seems that the heaven will not cease to be moved when it is filled with a greater brightness.

Obj. 15: Magnitude, movement, and time are in sequence to one another in respect of division and finitude or infinitude. (Aristotle, Physics 6.2, 232b20–233a33; 6.6–8, 237a9–239b4.) Now, there is neither beginning nor end in a circular magnitude. Therefore, neither is there any end in a circular movement, so that the heavenly movement being circular, it would seem that it will never have an end.

Obj. 16: It might be replied to the last objection that, although a circular movement may have no end, according to its own nature, it will have an end by the will of God.

On the contrary, Augustine says: in discussing the origin of the world, we do not ask what God can do, but what the nature of things allows of being done. (Augustine, On the Literal Interpretation of Genesis 2.2 (PL 34:263).) Now, the consummation of the world corresponds to its origin, as the end corresponds to the beginning. Therefore, in discussing things pertaining to the end of the world, we must not have recourse to the divine will, but to the nature of things.

Obj. 17: The sun by its presence causes light and day in these lower things, and by its absence produces darkness and night. Now, the sun cannot be present in both hemispheres except through movement. Therefore, if the heavenly movement cease, the sun by its presence will cause day in one part of the world and night in the other, by being always absent; thus, the latter part will not be made better, but rather worse, in the consummation of the world.

Obj. 18: That which is equally open to two things will either cling to both or to neither. Now, the sun, so far as its own nature is concerned, is open to any particular position in the heavens. Therefore, it will either occupy every one of them or none of them. But it cannot occupy none, since every sensible body is somewhere. Therefore, it must occupy them all. But this is impossible except by successive movement. Therefore, it will always be in movement.

Obj. 19: At the consummation of the world, none of the things that will remain will lose their perfection, because the things that will remain will not be made worse in that state; rather, they will become better. Now, movement is a perfection of the heavens themselves; this is clear from the fact that motion is an entelechy of the mobile as such, as is said in Physics 2; and again, as is said in On the Heavens 2, by movement the heavens acquire perfect goodness. (Aristotle, Physics 2.1, 193a21–b8; On the Heavens 2.4, 286a7–b9.) Therefore, at the consummation of the world, the heavens will not lack movement.

Obj. 20: No body ever attains to the degree of a spiritual nature. Now, it belongs to a spiritual nature to have perfect goodness without movement, as is clear in On the Heavens 2. (Aristotle, On the Heavens 2.3–4, 285a27–286b9.) Therefore, the heaven will never have perfect goodness if its movement ceases, and this is contrary to the account of the world’s consummation.

Obj. 21: Nothing is removed except by its contrary. Now, there is nothing contrary to the heavenly movement, as is shown in On the Heavens 1. (Aristotle, On the Heavens 1.4, 269a2–b17; 1.6, 270a14–21.) Therefore, the heavenly movement will never cease.

On the contrary (1), it is written: the angel whom I saw standing upon the sea and upon the earth lifted up his hand to heaven, and he swore by him that lives forever and ever . . . that time shall be no longer (Rev 10:5). Now, time will endure as long as the heavens are moved. Therefore, at some time the heavens will cease to be moved.

Furthermore (2), it is written: man, when he is fallen asleep, shall not rise again till the heavens be broken; he shall not awake nor rise up out of his sleep (Job 14:12). Now, we must not understand that the heavens will be broken in their substance, because this will always remain, as proved above. Therefore, when the dead shall rise again, the heavens will be broken in the sense that their movement will cease.

Furthermore (3), commenting on Romans 8:22, every creature groans and travails even until now, a Gloss of Ambrose says: all the elements labor to fulfill their various duties; thus, the sun and moon, not without toil, run their appointed courses. This they do for our benefit: whence, when we are removed, they will rest. (Glossa ordinaria 6, 109, at Romans 8:22 (PL 114:497).) Therefore, at the resurrection of the saints, the movements of the heavenly bodies will cease.

Furthermore (4), Isidore writes: after the judgment, the sun will receive the reward of his labor, and thenceforward neither sun nor moon shall set, (Isidore of Seville (ca. 560–636 AD), De ordine creaturarum 5 (PL 83:924–25).) which is impossible as long as the heavens are in motion. Therefore, the heavens will then cease to be moved.

I answer that, following the teaching of holy men, we hold that at some time the celestial movement will cease, although this is more held by faith than capable of demonstration by reason. In order to make clear wherein this question offers difficulty, it must be observed that the heavenly movement is not natural to the heavenly body in the same way as the elemental body’s movement is natural to the elemental body. For the latter movement has a principle within the mobile thing, not only a material and receptive principle but also a formal and active one. For such a movement follows the form of the elemental body just as other natural properties also result from the essential principles; therefore, in these things, the generator is said to be the mover inasmuch as it gives the form that the movement follows on.

But this cannot be said with the heavenly body. For, because nature always tends determinately to one thing, not being open to many, it is impossible that any nature tend to movement as such, in that within every movement there is a certain diversity of form, inasmuch as the thing that moves does not stand in the same way, whereas unity of form of the mobile is contrary to the account of movement.

In consequence, nature never inclines to movement for the sake of movement, but for the sake of something definite that follows from the movement; for example, a heavy body inclines by nature to rest in the center, and consequently inclines to a downward motion insofar as it attains that place by that motion. However, the heaven, by its movement, does not attain some where to which it is inclined by its nature, because every where is the beginning and end of a movement; whence its movement cannot be natural as though following the inclination of a natural inherent power, in the way that to be carried upward is the natural movement of fire.

Now, circular movement is said to be natural to the heaven insofar as it has within its nature an aptitude for such a movement; and in this way it has within itself a passive principle for such movement, whereas the active principle of this movement is some separated substance, such as God, or an intelligence, or a soul (as some assert); which does not matter to the question at issue.

Accordingly, no argument for the permanence of this movement can be taken from any nature of the heavenly body, wherein there is only an aptitude for movement, but one must take that from the separated active principle. And seeing that every agent acts for the sake of an end, we must consider what is the end of the heavens’ movement; for if the termination of this motion at some time is congruent with its end, the heavens will at some time rest, whereas if rest is not compatible with its end, its motion will last forever. For it cannot be that it will cease through a change in its moving cause, since God’s will, like his nature, is unchangeable, and through it, whatever intermediate causes produce the heavenly movement may become unchangeable likewise.

Now, in making this observation, three things must be avoided.

In the first place, we must not say that the heaven is moved for the sake of the movement itself, as we have said that it exists for the sake of its very existence, wherein it becomes like God. For movement by its very account cannot be regarded as an end, since motion is a tendency to something else, so that it does not hold the account of an end, but more of something that is for an end. This is confirmed by the fact that movement is the act of the imperfect, as is said in On the Soul 3, whereas an end is an ultimate perfection. (Aristotle, On the Soul 3.7, 431a4–7; Physics 3.1–2, 200b12–202a2.)

Second, we must not say that the heavenly movement is for the sake of something more base; for, since the end is that whence the account is taken, the end must be more worthy than the things that are for the end. Now, the terminus of the activity of a nobler thing can happen to be more base, but not such that it be the intention’s end; for example, the safety of a peasant is the terminus at which the activity of the king’s government ends, yet the king’s regime is not ordered to the peasant’s safety as its end but to something better, namely, the common good. Consequently, it cannot be admitted that the generation of these lower things is the end of the heavenly movement, although it is its effect or terminus, because both the heaven itself is more excellent than these lower things and its movement than the movements and changes that take place here below.

Third, we must not suppose the end of the heaven’s movement to be something infinite, since to place infinity in a final cause is to destroy the end and the nature of the good, as is said in Metaphysics 2. (Aristotle, Metaphysics 2.2, 994b12.) For it is impossible to reach what is infinite, and nothing moves to what is impossible to attain, as is said in On the Heavens 1. (Aristotle, On the Heavens 1.2–3, 268a6–b16.) Therefore, it cannot be said that the end of the celestial movement is to attain in act a where to which it is in potency, although Avicenna would seem to say so. (Avicenna, The Metaphysics of the Healing 9.2.) For this it cannot possibly obtain, since it is infinite; for while it comes to be actually in one where, it is in potency to another where, in which it was in act before.

Therefore, we must assign as the end of the heavenly movement something that the heaven can obtain by its movement, something that is distinct from its movement and nobler than it.

Now, this admits of a twofold solution.

The first is that we assign as the end of the heavenly movement something in the heavens themselves and coexistent with movement. With this in view, some philosophers held that the end of the heavenly movement is its likeness to God in causing, which takes place during the movement itself. In this view, it is not fitting for this movement to cease, since were it to cease, the end resulting from the movement would cease also.

The second solution is that we assign as the end of the heavenly movement something outside the heaven that is obtained by that movement, and which can remain when that movement ceases, and this is the view that we adopt.

For we hold that the movement of the heavens is for the completion of the number of the elect. For the rational soul is nobler than any body whatsoever, even than the heavens itself. Therefore, there is nothing incongruous in supposing that the end of the heavenly movement is the multiplication of rational souls—not, of course, into infinity, since this could not result from the movement of the heavens, and in this way it could move to something that it could not obtain. Therefore, it is a definite multitude of rational souls that is the end of the heavenly movement. Whence, when this is reached, the movement of the heavens will cease.

Now, though either of these views can be rationally sustained, still the second, which belongs to faith, seems the more probable for three reasons.

First, because it does not matter whether we say that a certain thing’s end is its likeness to God in some particular respect, or that thing itself insofar as this likeness is attended to, just as we have said above that the end of things may be said to be either their very likening to God’s goodness, or the being of the things as becoming like God. Therefore, to say that the end of the heavenly motion is to be like God in causing is the same as to say that it is to cause. Now, to cause cannot be an end, since it is an activity that implies an effect and tends to something else; for in such activities, the effect is better than the activity, as is said in the Ethics 1; whence such actions cannot be the ends of their agents, for they do not perfect the makers but rather the things made; whence also the very things made are more the ends, as is clear in Metaphysics 9 and Ethics 1. (Aristotle, Metaphysics 9.7, 1049a18–b3; Nicomachean Ethics 1.1, 1094a1–18.) Now, the very things that are brought about are not the ends, since they are more base than the heavens, as stated above. Therefore, it is incongruous to hold that the end of the heavenly movement is likeness to God in causing.

Second, since the heavens are moved by an external active principle, while the heavens themselves have merely the aptitude for that movement, as stated above, it follows that the heavens are moved and act as an instrument; for such is the disposition of an instrument, as may be seen in the productions of art, for an axe has nothing more than the aptitude for its particular movement, while the principle of this movement is in the craftsman. Hence, as philosophers say, that which moves through being itself moved, moves as an instrument. Now, in an action that occurs through an instrument, there cannot be any end in the instrument, save accidentally insofar as the instrument is considered as a thing made and not as an instrument. Consequently, it is not probable that the end of the heavenly movement is some perfection of the heavens; rather, it is something outside the heavens.

Third, if likeness to God in causing is the end of the heavenly movement, this likeness will be found chiefly in the causality of that which is caused by God immediately, namely, that of the rational soul, to the causality of which the heavenly movement conduces also by disposing its matter. And therefore it is more probable that the end of the heavenly movement is the number of the elect than that it is its becoming like God in causing generation and corruption, as the philosophers say. For this reason, we grant that the heavens’ motion will end when the number of the elect is complete.

Reply Obj. 1: The text refers to the duration of the earth as subject to change, for it is thus that it receives the seed and gives the harvest. So long as the earth is in that state, the heavens will not cease to be in motion.

Reply Obj. 2: The text quoted refers not to the carnal Israel, but to the spiritual Israel, yet not as in God’s presence by contemplating him through his species in the heavenly fatherland, but as a wayfarer in the presence of God by faith. Therefore, the words of the text resemble those of our Lord to his disciples: behold I am with you . . . until the consummation of the world (Matt 28:20).

Reply Obj. 3: The preposition propter (“for the sake of”) indicates a cause: whence sometimes it indicates a final cause, which is posterior in being, and sometimes it indicates a material or efficient cause, which are prior. Now, when it is stated that, in incorruptible things, acts are for the sake of the agents, “for the sake of” indicates not the final cause, but the efficient cause, due to which necessity is present, and not due to the end. Accordingly, the celestial movement, if we refer it to the mobile itself, does not have its necessity from it as from its efficient cause, as we have proved; however, it does have this necessity from a mover, which, being a voluntary mover, does induce this necessity in the motion to the degree that it has been determined by the order of divine wisdom, and not so as to move forever.

Reply Obj. 4: The end of the heaven’s movement cannot consist in its becoming like God by actually reaching to various successive positions, which previously it occupied potentially: both because this is infinite, as we have shown, and because just as in one respect by the motion it approaches a divine likeness through the positions that were potential and come to be actual, so too in another respect, it withdraws from the divine likeness by the fact that positions that were actual become potential.

Reply Obj. 5: Although things subject to generation and corruption are more base than the heavens, the rational soul is nobler than the heavenly body; and yet, they are brought into being by God in matter disposed by the heavenly movement.

Reply Obj. 6: According to the teaching of faith, the completion of the number of the elect is not the secondary but the principal end of the heaven’s movement. It is not, however, its ultimate end, because the ultimate end of everything is the divine goodness, inasmuch as creatures in some way attain thereto, either by likeness or by rendering an appropriate service.

Reply Obj. 7: A thing is not called “imperfect” by reason of just any potency in it that has not been reduced to actuality, but only when the thing attains its completion through the reduction to act. For a man will not be imperfect because, being potentially in India, he is not there; rather, he is called “imperfect” if he lacks knowledge or virtue, which are his natural perfections. Now, the heaven is not perfected by its place, as are lower bodies, which are preserved in their proper where. Therefore, although its potency to be in this or that where is never reduced to actuality, it still does not follow that it is imperfect. For if we consider heaven in itself, it does not acquire greater perfection by being in one position than by being in another; rather, it is indifferent to all where, since it is moved naturally to any of them. Now, this very indifference conduces to rest more than to perpetual movement, unless we take into account the will of the mover and the one intending the end, just as even certain philosophers explained the earth’s rest in the center by assigning as its cause its indifference relative to each part of the heaven’s circumference.

Reply Obj. 8: Though all the causes of the celestial movement are everlasting, nevertheless, the mover on whom its necessity depends, moves by his will, nor is it necessary that he move it forever, but only according to the exigency of the end.

Reply Obj. 9: The heaven is according to its own nature capable of everlasting motion in a different way than it is capable of its own being. For its existence depends on the principles of its nature, from which it acquires a necessity of existing, since there is no possibility of non-existence in them, as we have shown above, whereas its motion in its nature has only an aptitude, but it has a necessity from its mover. Therefore also, according to the Commentator, heaven’s everlasting existence is from the principles of its own nature, but not its everlasting movement, which is from an extrinsic principle. (Averroes, Commentary on the Metaphysics 2; On the Substance of the Sphere.) Therefore, even those who hold that this movement will never cease say that the cause of the heavenly motion’s duration and everlastingness is God’s will. And yet, his unchangeableness does not, as they contend, necessarily prove the everlastingness of the celestial movement; for his will is not changeable if he wills that different things succeed one another according to the exigency of the end that he wills unchangeably. We must, therefore, seek the reason for an everlasting movement in the end rather than in the unchangeableness of the mover.

Reply Obj. 10: The heavenly movement will end in an instant, and in that instant there will be neither movement nor rest, but the terminus of movement and the beginning of rest. Moreover, the subsequent rest will not be in time, because rest is not measured by time primarily, but secondarily, as is said in Physics 4; so if the rest belongs to a body not subject to any kind of movement, it will not be measured by time. (Aristotle, Physics 4.12, 221b3–222a9.) Yet, if force is found in this, one might say that, after the movement in the heavens, there will be not rest but a certain immobility.

Reply Obj. 11: Just as the celestial movement will cease, so also will time be no more, as is apparent from the authority quoted from the Apocalypse (Rev 10:6). Now, the last instant of the whole of time will indeed be the end of the past but not the beginning of the future. For that the now is at once both the end of the past and the beginning of the future obtains insofar as it follows a continuous circular movement, in which every indivisible mark in it is both beginning and end in respect of different parts. Therefore, if the celestial movement cease, just as there will be a last indivisible in movement, so will there be in time.

Reply Obj. 12: We have already said that it is not on account of an active inclination of its formal principle to such a movement that the heaven’s movement is natural, as in the case of the elements; so it does not follow, if the heavens cease to be in motion, that their rest is forced.

Reply Obj. 13: If the celestial movement were not for the sake of something else, we should expect to find some kind of proportion between it and the subsequent rest, on the supposition that the movement is not everlasting. But because it is ordered to another end, this proportion must be referred in its order to the end and not in its order to the subsequent rest. Accordingly, we are to understand that God, in bringing all creatures into being out of nothing, himself instituted through his very self the first perfection of the universe, consisting in the universe’s essential parts and the various species of things. And for its final perfection, consisting in the completion of the order of the blessed, he ordained the various movements and activities of creatures—some natural, for instance, the movement of the heavens and the activities of the elements, by which matter is prepared to receive rational souls; some voluntary, such as the ministrations of the angels, who are sent to minister for them who shall receive the inheritance of salvation (Heb 1:14). Therefore, when this consummation has been attained and remains forever without change, those things that will be ordered to it will cease forever.

Reply Obj. 14: This argument is based on a second act that is an activity abiding in the agent and is the end of the agent, and therefore is more excellent than the form of the agent. But a second act that is an action tending to something made is not the end of the agent, nor is it nobler than the agent’s form, unless the very things made are nobler than their makers, as things produced by art are nobler than the instruments, being their ends.

Reply Obj. 15: Although there is no actual beginning or end in a circular magnitude, it is possible to indicate a beginning or end therein through the inclination or termination of a certain movement.

Reply Obj. 16: At the beginning of the world, nature was being established; therefore, in discussing its beginning, we must not omit what is proper to nature. On the other hand, at the end of the world, the activity of nature attains the end established for it by God; therefore, in discussing it, we must have recourse to God’s will which established that end.

Reply Obj. 17: When the heavens cease to be in motion, although the sun will always remain to the one side of the earth, there will not be utter darkness and gloom on the other side, because God will give brightness to the elements. Therefore, it is written: the city has no need of the sun nor of the moon . . . for the glory of God has enlightened it (Rev 21:23). And no inconsistency will follow if the part of the earth that was inhabited by the saints receive a greater brightness.

Reply Obj. 18: Though the heaven is indifferent to any position that is possible to it, its movement is not for the purpose of obtaining a position, but for something else; therefore, whatever position it remains in does not matter, so long as it has fulfilled that for which it existed.

Reply Obj. 19: Although movement is the act of the mobile, it is still an imperfect act. Therefore, if a thing is deprived of movement, we must not infer that it is deprived of perfection simply speaking, especially if the mobile acquires nothing by its movement. But when the Philosopher says that by movement the heaven acquires perfect goodness, he is expressing himself according to the first of the above-mentioned opinions about the end of the celestial movement, which end is consistent with the movement being everlasting.

Reply Obj. 20: The perfection of a spiritual nature is that it can be the cause of other things without being moved itself, a perfection that the heavens never attain. Nevertheless, the heavens will not, for this reason, be worse off, since their end does not consist in causing other things, as stated above.

Reply Obj. 21: The motion of the heavens will not rest on account of something contrary, but solely on account of the will of their mover.