Authors/Thomas Aquinas/physics/L8/lect1

Lecture 1 Opinions on the beginning and end of motion

Latin	English
	Lecture 1 Opinions on the beginning and end of motion
lib. 8 l. 1 n. 1 Postquam philosophus in praecedenti libro ostendit quod necesse est ponere primum mobile, et primum motum, et primum motorem; in hoc libro intendit inquirere qualis sit primus motor, et primus motus, et primum mobile. Et dividitur in partes duas: in prima praemittit quoddam quod est necessarium ad sequentem investigationem, scilicet motum esse sempiternum; in secunda procedit ad investigationem propositi, ibi: principium autem considerationis et cetera. Circa primum tria facit: primo movet dubitationem; secundo ostendit veritatem secundum suam opinionem, ibi: incipiemus autem primum etc.; tertio solvit ea quae in contrarium obiici possunt, ibi: contraria autem his et cetera. Circa primum tria facit: primo proponit dubitationem; secundo ponit opiniones ad utramque partem, ibi: sed quanti quidem etc.; tertio ostendit utilitatem huius considerationis, ibi: considerandum igitur de hoc et cetera. Circa primum duo facit: primo proponit dubitationem de qua investigare intendit; secundo respondet tacitae quaestioni, ibi: esse quidem igitur et cetera.	965. After showing in the preceding book that it is necessary to posit a first mobile, and a first motion, and a first mover, the Philosopher intends in this present book to inquire after a description of the first mover, and first motion, and first mobile, The book is divided into two parts: In the first he premises something necessary to the following investigation, namely, that motion is sempiternal; In the second he proceeds to investigate what is proposed, (L. 5). About the first he does three things: First he raises a problem; Secondly, he states the truth according to his own opinion, (L. 2); Thirdly, he answers possible objections to the contrary, (L. 4)# In regard to the first he does three things: First he proposes his problem; Secondly, he gives opinions for both sides, at 968; Thirdly, he shows the usefulness of this consideration, at 970. About the first he does two things: First he proposes the problem he intends to investigate; Secondly, he responds to a tacit question, at 967.
lib. 8 l. 1 n. 2 Circa primum sciendum est, quod Averroes dicit quod Aristoteles in hoc capitulo non intendit inquirere in universali utrum motus sit sempiternus, sed de primo motu. Sed si quis consideret et verba et processum philosophi, hoc est omnino falsum. Verba enim philosophi universaliter de motu loquuntur, quia dicit: utrum factus sit aliquando motus, cum non esset prius, et corrumpitur iterum sic quod moveri nihil sit. Ex quo manifeste apparet quod non de aliquo motu determinato quaerit, sed universaliter: utrum aliquando nihil fuerit motus. Ex ipso etiam Aristotelis processu apparet hoc esse falsum. Primo quidem quia consuetudo sua est, semper ad propositum ex propriis argumentari; si quis autem sequentes rationes consideret quas inducit, in nulla earum sumitur aliquid pro medio, quod proprie ad primum motum pertineat, sed ad motum in communi. Unde ex hoc satis apparet quod intendit hic inquirere de sempiternitate motus in communi. Secundo quia, si iam probatum esset quod est aliquis motus unus vel plures sempiterni, frustra inquireret inferius, utrum aliqua moveantur semper; cum hoc iam esset probatum. Ridiculum est etiam dicere quod Aristoteles inferius reiteret suam considerationem a principio, quasi aliquid omisisset, ut Commentator fingit. Erat enim copia Aristoteli corrigendi librum suum, et supplendi in loco debito quod fuerat omissum, ut non inordinate procederet. Si enim hoc capitulum exponatur secundum praedicti Commentatoris intentionem, omnia sequentia confusa et inordinata apparebunt. Nec est mirum: quia uno inconvenienti posito, alia sequuntur. Adhuc autem manifestius hoc apparet per hoc, quod Aristoteles inferius inquirere intendens de sempiternitate primi motus, utitur eo quod hic demonstratur, quasi principio: quod nullo modo faceret, si hic probasset primum motum esse aeternum. Ratio autem ex qua Averroes motus fuit, omnino frivola est. Dicit enim quod si dicatur quod Aristoteles hic intendit inquirere de sempiternitate motus in communi, sequetur quod consideratio Aristotelis hic sit diminuta; quia non apparet per id quod hic determinatur, quomodo motus semper possint continuari ad invicem. Sed hoc nihil est: quia Aristoteli sufficit in hoc capitulo probare in communi quod motus semper fuerit; qualiter autem sempiternitas motus continuetur, utrum per hoc quod omnia semper moveantur, vel per hoc quod omnia quandoque moveantur et quandoque quiescant, vel per hoc quod quaedam semper moventur, quaedam vero quandoque moventur et quandoque quiescunt, statim immediate inquiret. Sic igitur secundum hanc intentionem exponendum est praesens capitulum, quod intendit hic inquirere de motu in communi. Quaerit ergo secundum hoc, utrum motus in communi aliquando esse inceperit, ita quod prius nihil unquam motum fuerit; et quandoque sic deficiat quod nihil postmodum moveatur: aut e contrario, neque unquam inceperit, neque unquam deficiet; sed semper erat, et semper erit. Et ponit exemplum in animalibus, propter hoc quod quidam dixerunt mundum esse quoddam animal magnum. Videmus enim quod animalia vivunt, quamdiu apparet in eis aliquis motus: cessante autem omni motu, dicuntur animalia mori. Sic igitur et in tota universitate naturalium corporum motus consideratur ut vita quaedam. Si ergo motus semper fuit et semper erit, ista quasi vita naturalium corporum erit immortalis et sine cessatione.	966. In regard to the first it should be known that Averroes says that Aristotle in this book does not intend to inquire whether motion is sempiternal universally, but limits his question to the first motion. But if one considers both the words and procedure of the Philosopher, this is entirely false. For the words of the Philosopher speak of motion in a universal sense. He says in effect: “Was there ever a becoming of motion before which it had no being and is it perishing again so as to leave nothing in motion?” From this it is clear that he is not inquiring about one definite motion but about motion universally, asking whether at any time there was no motion. The falseness of Averroes’ statement appears also from the very procedure of Aristotle. First, it is Aristotle’s custom always to argue to his proposition from proper causes. Now, if anyone will consider the arguments he adduces, he will see that in none of them does Aristotle argue from a middle term that refers properly to the first motion, but he argues rather from a middle proper to motion in general. Hence this alone shows that he intends to inquire here about the sempiternity of motion in general. Secondly, if he had already proved that there is one or a number of sempiternal motions, he would have been foolish to ask below whether anything is eternally in motion, for that question would have been already answered. It also is ridiculous to say that Aristotle would repeat from the start his consideration of a problem he had already settled, and act as though he had omitted something, as the Commentator pretends. For Aristotle had the opportunity to correct his book and fill in at the proper place any section he had omitted, so as not to proceed in a disorderly way. For if this chapter had been treated in the way charged by the Commentator, everything that follows would be confused and disorderly. This is not strange, for, having supposed an initial impossibility, others then follow. Furthermore, the correctness of our view is shown by the fact that Aristotle later on uses what he proves here, as a principle to prove the eternity of the first motion. He would never have done this, had he already proved that the first motion is eternal. The reason which moved Averroes is wholly frivolous. For he says that if Aristotle is here intending to inquire into the eternity of motion in common, it will follow that the consideration of Aristotle has been diminished, because it is not evident from what he proves in this place, how motions could be always continued one to the other. But this has no weight, because it is enough for Aristotle to prove in this chapter in a general way that motion has always been. But how the eternity of motion is continued—whether it is because all things are always in motion, or because all things are sometimes in motion and sometimes at rest, or because some things are always in motion and others sometimes in motion and sometimes at rest—is a question he raises immediately after the present one. Thus the present chapter must be explained according to this intention, namely, that he intends to inquire about motion in common. According to this, therefore, he asks: “Did motion in common begin to be at some time, so that previously there had never been any motion, and so that at some time it will perish so as to leave nothing in motion, or, on the other hand, did it never begin and will it never cease, so that it always was and always will be? And he gives an example taken from animals, for some philosophers have said that the world is a certain large animal. For we see animals as alive so long as motion is apparent in them, but when all motion ceases in them they are said to be dead. Accordingly, motion in the whole universe of natural bodies is taken as a kind of life. If, therefore, motion always was and always will be, then this sort of life of natural bodies will be immortal and never-failing.
lib. 8 l. 1 n. 3 Deinde cum dicit: esse quidem igitur etc., respondet tacitae quaestioni. In praecedentibus enim libris Aristoteles locutus fuerat de motu in communi, non applicando ad res: nunc autem inquirens an motus semper fuerit, applicat communem considerationem motus ad esse quod habet in rebus. Posset ergo aliquis dicere, quod in hac consideratione prius erat quaerendum de motu, an habeat esse in rebus, quam quaeratur an sit sempiternus: et praecipue, cum quidam negaverint esse motum. Ad hoc respondet, dicens quod omnes qui locuti sunt de natura rerum, affirmant quod motus sit. Et hoc patet per hoc, quod dicunt mundum esse factum; et quod omnes considerant de generatione et corruptione rerum, quae non potest esse sine motu. Est igitur communis suppositio in scientia naturali, quod motus habeat esse in rebus. Unde de hoc non est quaerendum in scientia naturali: sicut nec in aliqua scientia movetur quaestio de suppositionibus illius scientiae.	967. Then at (749 250 b15) he answers a tacit question. For in the preceding books Aristotle had discussed motion in common, without applying it to things; but now, inquiring whether motion has always existed, he applies his general doctrine about motion to the existence it has in things. Therefore, someone could say that in this consideration the first question should have been about whether motion has existence in things rather than whether it is eternal, especially since there are some who have denied that motion exists. To this he responds that all who have spoken about the nature of things admit that motion exists. This is evident from their statements that the world was made, and from their consideration of the generation and ceasing-to-be of things, which cannot occur without motion. It is therefore a common supposition in natural science that motion has existence in things. Hence there is no need to raise this question in natural science any more than in other sciences are raised questions about the suppositions of the science.
lib. 8 l. 1 n. 4 Deinde cum dicit: sed quanti quidem etc., ponit opiniones ad utramque partem quaestionis motae. Et primo ponit opiniones dicentium motum semper esse; secundo opiniones ponentium motum non semper esse, ibi: quicumque autem et cetera. Ad evidentiam ergo primae partis sciendum est, quod Democritus posuit prima rerum principia corpora indivisibilia per se et semper mobilia, ex quorum aggregatione dicebat mundum casualiter factum: et non solum istum in quo nos sumus, sed infinitos alios, secundum quod accidit in diversis partibus infiniti vacui, praedicta corpora congregata mundos fecisse. Nec tamen hos mundos ponebat in perpetuum duraturos; sed quosdam eorum fieri per aggregationem atomorum, quosdam vero corrumpi per eorum segregationem. Quotcumque igitur philosophi hoc ponunt cum Democrito, dicunt semper esse motum; quia semper dicunt esse generationes et corruptiones aliquorum mundorum, quas necessarium est esse cum motu.	968. Then at (750 250 b18) he presents opinions for both sides of the question he proposed. First he gives the opinions which declare that motion is eternal; Secondly, those who declare that motion is not eternal, at 969. In explanation of the first part (750 250 b18), therefore, it should be known that Democritus supposed that the first principles of things are bodies that are per se indivisible and always mobile and that the world came to be by the chance aggregation of these bodies—not only the world in which we exist but an infinitude of other worlds, since these bodies congregated to form worlds in diverse parts of infinite void. Still he did not posit these worlds as fated to endure forever; rather, some came into existence as a result of atoms combining, and others passed out of existence as a result of the same atoms scattering. Therefore all the philosophers who agree with Democritus assert the eternity of motion, because they say that the generation and ceasing-to-be of certain worlds is always going on-and that necessarily involves motion.
lib. 8 l. 1 n. 5 Deinde cum dicit: quicumque autem etc., ponit opiniones ad partem contrariam. Et dicit quod quicumque ponunt unum solum mundum, et non esse eum sempiternum, etiam de motu ponunt quod consequitur secundum rationem, ut scilicet non semper sit. Si ergo ponatur quod sit aliquod tempus in quo nihil movebatur, oportet quod hoc accidat duobus modis, sicut etiam duobus modis potest poni hic mundus non semper fuisse: uno modo quod mundus iste sic inceperit quod nunquam antea fuerit, sicut posuit Anaxagoras; alio modo quod mundus sic inceperit quod aliquo tempore non fuerit, sed ante illud tempus iterum fuerit, ut posuit Empedocles. Et similiter circa motum Anaxagoras dixit quod quondam omnia simul erant unum cum alio commixtum, et nihil erat ab alio segregatum: in qua quidem rerum mixtura necesse fuit ponere quod omnia quiescerent: motus enim non est absque disgregatione; omne enim quod movetur, ab aliquo recedit, ut in aliud tendat. Hanc ergo rerum mixturam et quietem posuit praeextitisse in tempore infinito, ita quod nunquam antea fuerat aliquis motus; et quod intellectus, qui solus non erat permixtus, incepit de novo facere motum, et disgregare res ab invicem. Empedocles vero dixit quod in aliqua parte temporis est aliquid moveri, et iterum in alia parte temporis est omnia quiescere. Ponebat enim Empedocles quod amicitia et discordia sunt prima rerum moventia: amicitiae autem proprium est quod ex multis faciat unum, discordiae vero quod ex uno faciat multa. Quia vero ad esse corporis mixti requiritur quod elementa sint in unum commixta, ad esse vero mundi requiritur quod elementa sint in locis suis per ordinem distributa: ponebat quod amicitia est causa generationis corporum mixtorum, discordia vero causa corruptionis; sed e contrario in toto mundo amicitia causa corruptionis, et discordia generationis. Sic ergo ponebat moveri totum mundum, cum vel amicitia ex multis facit unum, vel discordia multa facit ex uno: sed quietem ponebat esse in mediis temporibus, non quidem ita quod nihil moveretur, sed quantum ad generalem mundi mutationem. Et quia posuit sententiam Empedoclis, ponit etiam eius verba, quae difficultatem habent, quia metrice scripsit. Sic ergo suam sententiam expressit Empedocles his verbis, quae sic construenda sunt: didicit nasci, idest sic consuetum est aliquid generari, inquantum ex pluribus fit unum; et iterum, idest alio modo, ex uno geminato, idest composito, perficiuntur plurima, idest fiunt multa per disgregationem: quaedam enim sunt quae generantur per compositionem, quaedam vero per disgregationem. Et sicut hoc videmus in particularibus generationibus, sic fiunt res, idest sic est intelligendum in universali rerum generatione quantum ad totum mundum. Et nullo modo est ipsius saeculum unum, idest non est unus status durationis rerum; sed quandoque generatur mundus, quandoque corrumpitur, quandoque medio modo se habet: saeculum enim dicitur mensura durationis alicuius rei. Distinctionem autem horum saeculorum exprimit subdens, sic autem permutantur; quasi dicat: unum saeculum est in quo res permutantur per congregationem vel segregationem. Et ne aliquis opinaretur quod ad generationem mundi non requiritur saeculum, idest tempus aliquod, sed mundus fit in instanti, ad hoc excludendum subiungit: neque simul perficiuntur, sed per multam moram temporis. Deinde de alio saeculo subdens dicit: sic autem semper sunt immobiles; quia scilicet in medio tempore generationis et corruptionis posuit res quiescere. Et ne aliquis crederet quod semper antea fuerit permutatio, et postea semper futura sit quies, ad hoc excludendum dicit, secundum circulum; quasi dicat: circulariter hoc contingit, quod permutantur res et postea quiescunt, et iterum permutantur, et sic in infinitum. Deinde subduntur verba Aristotelis exponentis praedicta verba Empedoclis, maxime quantum ad hoc quod dixit, sic autem permutantur. Dicit ergo quod opinandum est in hoc quod dixit, sic permutantur, intellexisse ab hinc inde, idest a quodam principio usque nunc; non quod semper fuerit motus, vel quod postquam incepit, sit interruptus.	969. Then at (751 250 b21) he gives the opinions of the other side. And he says that whoever declare that there is just one world which is not eternal, also declare what reasonably follows with respect to motion, namely, that it is not eternal. Therefore, if there be supposed a time in which nothing was in motion, this could happen in two ways, just as it is in two ways that this world could be supposed not always to have been: in one way, that this world began in such a way that previously it never existed at all, as Anaxagoras held; in another way, that the world so began to be that it did not exist for some time previously, but that it again had existed before that time, as Empedocles held. In like manner with respect to motion, Anaxagoras said that at one time all things were a mixture of one thing with another and nothing was segregated from anything else—in which mixture it was necessary to posit that all things were at rest, for motion does not occur without separation, since whatever is in motion separates from one terminus in order to tend to another. Therefore Anaxagoras posited the pre-existence of this mixture and rest in infinite time, in such a way that at no time before (the present world) had there been any motion at all, and that it was Mind, which alone was unmixed, that caused motion in the first instance and began to separate things one from another. Empedocles, on the other hand, said that in one period of time some things are in motion, and again in another period all things are at rest. For he posited Friendship and Discord as the first movers of things: Friendship’s property was to make a unity of all things, and Discord’s to make many things from the one. But because the existence of a mixed body requires a mingling of the elements so as to form one thing, whereas the existence of a world required that the elements be dispersed in orderly fashion, each to its respective place, he posited that Friendship is the cause of the coming-to-be of mixed bodies, and Discord the cause of their ceasing-to-be; but that, contrariwise, in the whole world Friendship was the cause of its ceasing-to-be and Discord the cause of its coming-to-be. Accordingly, he posited that the whole world is being moved, when either Friendship makes one from the many or when Discord makes many of the one; but during the intermediate times, he supposed there was rest—not in the sense that there was no motion at all, but none with respect to the general change of the world. Because Aristotle had mentioned the opinion of Empedocles, he also gave the very words, which are difficult to interpret because they are in metre. Thus, therefore, did Empedocles express his opinion in this arrangement of words : “It has learned to be born,” i.e., it is customary for something to be generated, “the one from the manifold”; “and again,” i.e., in another way, “from the one commingled,” i.e., composed of a mixture, “the manifold arises,” i.e., the many come to be through separation—for some things are generated by combining with others, and others by separating. And according to what we observe in regard to particular instances of coming-to-be, so “thus do things come to be,” i.e., the same must be understood in the universal coming-t-o-be of things with respect to the whole world. “Nor is their era one,” i.e., there is not just one period of duration of things; but at one time a world is generated, at another it is destroyed, and in between there is rest: for “era” is taken to mean the measure of the duration of a thing.. He expresses the distinction of these eras when he adds, “Thus are they changed,” i.e., as though stating that the time in which things pass through the cycle of combining or separating is called one era. And lest anyone suppose that the generation of a world does not require an era, i.e., a period of time, but that the universe comes to be in an instant, Empedocles adds, “nor are they made perfect all at once,” but after a long interval of time. Then speaking of the other era he adds, “thus are they always immobile,” i.e., in the time between the generation and corruption cycle, he supposed that things are at rest. And lest anyone believe that before there was always change, and that later there will be continual rest, he excludes this by saying “alternately,” i.e., as though saying that this happens in cycles, namely, that things change and then rest, and then change again, and so on ad infinitum. Then the words of Aristotle are added to explain the foregoing words of Empedocles, especially the expression, “thus they change.” He says therefore that following the words, “thus they change,” must be understood the addition, “from then hence,”, i.e., from a definite beginning up to the present—not in the sense that motion always was, or that after it began it had been interrupted.
lib. 8 l. 1 n. 6 Deinde cum dicit: considerandum igitur etc., ostendit utilitatem huius considerationis. Et dicit quod considerandum est quomodo se habeat veritas circa hanc quaestionem: quia scire veritatem huius quaestionis est praeopere, idest pernecessarium, non solum ad considerationem scientiae naturalis, sed etiam ad scientiam de primo principio: quia et hic in octavo et in Metaphys., ad probandum primum principium, utitur aeternitate motus. Haec enim via probandi primum principium esse, est efficacissima, cui resisti non potest. Si enim mundo et motu existente sempiterno, necesse est ponere unum primum principium; multo magis sempiternitate eorum sublata; quia manifestum est quod omne novum indiget aliquo principio innovante. Hoc ergo solo modo poterat videri quod non est necessarium ponere primum principium, si res sunt ab aeterno. Unde si etiam hoc posito sequitur primum principium esse, ostenditur omnino necessarium primum principium esse.	970. Then at (752 251 a5) he shows the usefulness of considering the question he has proposed. And he says that we must consider just what is the truth about this question, for to know the truth about it is most necessary not only for natural science but the science of the first principle as well, since both here and in the Metaphysics he uses the eternity of motion to prove the first principle. This method of proving the existence of a first principle is most efficacious and irresistible. For if on the supposition that both motion and the world existed forever, it is necessary to posit one first principle, then, if the eternity thereof should be rejected, it is all the more necessary, for it is clear that every new thing requires a principle bringing it into being. Now the only reason why it could seem that no first principle would be necessary, would be if things were ab aeterno. But if the existence of a first principle follows even on that supposition, i.e., that the world existed ab aeterno, it is clear that the existence of a first principle is absolutely necessary.