Authors/Thomas Aquinas/metaphysics/liber11/lect9

Lecture 9

Latin	English
lib. 11 l. 9 n. 1 Postquam determinavit philosophus de ente per accidens, hic determinat de motu. Et dividitur in partes tres. In prima determinat de motu secundum se. In secunda de infinito quod est quaedam passio motus et aliorum continuorum, ibi, infinitum autem. In tertia determinat de divisione motus in suas species, ibi, praetermittatur autem. Prima dividitur in partes duas. In prima ostendit quid sit motus. In secunda ostendit in quo sit, ibi, et quod est in mobili. Circa primum tria facit. Primo praemittit quaedam quasi necessaria ad definiendum motum. Secundo distinguit ipsum, ibi, diviso autem et cetera. Tertio probat definitionem bene esse assignatam, ibi, quod autem bene. Circa primum ponit quatuor, ex quibus concludit quintum. Quorum primum est, quod ens dividitur per actum et potentiam. Et hoc est quod dicit, quod entium quoddam est actu, sicut primum movens, quod Deus est; quoddam potentia tantum, ut materia prima, quoddam potentia et actu, sicut omnia intermedia. Vel esse actu tantum dicit id quod iam perfecte habet formam, puta quod perfecte iam est album. Est autem potentia tantum, quod nondum habet formam; puta, quod nullo modo est album. Actu autem et potentia est, quod etsi nondum perfecte habet formam, est tamen in moveri ad formam.	2289. Having settled the issue about accidental being, the Philosopher now states his views about motion; and this is divided into three parts. First (974)C 2289), he deals with motion in itself; second (989:C 2314), with infinity, which is a property of motion and of other continuous things (“The infinite”); and third (1005:C 2355), with the division of motion into its species (“Everything which is changed”). The first is divided into two parts. First, he explains what motion is; and second (984:C 2308), he points out what the subject of motion is (“That motion”). In regard to the first he does three things. First, he prefaces his discussion with some points which are necessary for defining motion. Second (975:C 2294), he defines’ motion (“Now since each”). Third (979:C 2299), he proves that the definition of motion is a good one (“That this account”). In treating the first member of this division he gives four points from which he infers a fifth. The first is that being is divided by actuality and by potentiality. He says that one kind of being is actual only, such as the prime mover, which is God; another is potential only, such as prime matter; and others are both potential and actual, as all intermediate things. Or by the phrase actual only he means what already has a form completely, as what is now completely white; and by potential only, what does not have a form, as what is not white in any way; and by potential and actual, what does not yet have a form completely but is being moved to a form.
lib. 11 l. 9 n. 2 Secundum est quod ens dividitur per decem praedicamenta: et hoc est quod dicit, quod entium quoddam est per se, idest substantia; quoddam est quantum, quoddam quale, et sic de aliis generibus.	2290. The second point is that being is divided by the ten categories, as is implied when he says that there is one kind of being which exists of itself, i.e., substance, and another is quantity, and another is quality, and so on for the other categories.
lib. 11 l. 9 n. 3 Tertium est quod motus non habet aliquam aliam naturam separatam a rebus aliis; sed unaquaeque forma secundum quod est in fieri, est actus imperfectus qui dicitur motus. Hoc enim ipsum est moveri ad albedinem, quod est albedinem incipere actu fieri in subiecto. Sed non debet esse in actu perfecto. Et hoc est quod dicit quod motus non est aliquid praeter res; omne enim quod mutatur, mutatur secundum praedicamenta entis. Et sicut non est aliquid commune decem praedicamentis quod sit genus eorum, ita non est aliquod genus commune omnium motuum. Et propter hoc motus non est aliquod unum praedicamentum distinctum ab aliis praedicamentis; sed sequitur alia praedicamenta.	2291. The third point is that motion does not have a distinct nature separate from other things; but every form insofar as it is in a state of becoming is an imperfect actuality which is called motion. For to be moved to whiteness is the same as for whiteness to begin to become actual in a subject; but it need not be in complete actuality. This is his meaning in saying that motion is not something apart from things themselves; for everything which is being changed is being changed according to the categories of being. And just as the ten categories have nothing in common as their genus, in a similar way there is no genus common to all the kinds of motion. Hence motion is not a category distinct from the others but is a natural concomitant of the other categories.
lib. 11 l. 9 n. 4 Quartum est quod in unoquoque genere invenitur aliquid dupliciter, scilicet secundum perfectionem et imperfectionem; sicut in genere substantiae unum est ut forma, et aliud ut privatio. Et in genere qualitatis hoc est, quod est perfectum, ut album quod habet perfectum colorem, et hoc est ut nigrum, quod est imperfectum in genere coloris. Et in quantitate unum est perfectum quod dicitur magnum, et aliud imperfectum quod dicitur parvum. Et in ubi in quo est locatio, idest motus localis, est sursum et deorsum, et grave et leve, secundum quod grave dicitur quod actu subsidet, et leve quod actu supereminet. Et horum unum est ut perfectum, et aliud ut imperfectum. Et ratio huius est, quia omnia genera dividuntur per contrarias differentias; contrariorum autem semper alterum est ut perfectum, alterum ut imperfectum.	2292. The fourth point is that a thing is found in any genus in two ways, namely, perfectly and imperfectly; for example, in the genus of substance one thing has the character of a form, and another the character of a privation; and in the genus of quality there is one thing which is perfect, as a white thing, which has a perfect color, and another which is imperfect, as a black thing, which is imperfect in the genus of color. And in the genus of quantity one thing is perfect, and this is called “great,” and another is imperfect, and this is called “small”; and in the genus of place, in which “motion in space” is found, i.e., local motion, one thing tends upwards and another downwards, or one is light and another heavy inasmuch as that is called light which actually rises upwards, and that heavy which actually sinks downwards; and one of these has the character of something perfect and the other the character of something imperfect. The reason is that all the categories are divided by contrary differences; and one contrary always has the character of something perfect, and the other the character of something imperfect.
lib. 11 l. 9 n. 5 Ex his quatuor concludit quintum; scilicet quod tot sunt species motus et permutationis quot sunt species entis. Quod quidem non dicit eo quod in quolibet genere entis sit motus; sed quia sicut ens dividitur per actum et potentiam, per substantiam et quantitatem, et huiusmodi, et secundum perfectum et imperfectum, ita et motus. Et hoc sequitur ex eo quod dictum est, quod motus non est praeter res. Quomodo autem differant permutatio et motus, infra dicetur.	2293. From these four points he infers a fifth, namely, that there are as many kinds of motion and change as there are of being. He does not say this because there is motion in every genus of being, but because, just as being is divided by actuality and potentiality and by substance and accident and the like, and in terms of perfect and imperfect, so also is motion. This follows from his assertion that motion is not something apart from things. The way in which change and motion differ will be explained below.
lib. 11 l. 9 n. 6 Deinde cum dicit divisio autem definit motum. Et primo ponit definitionem ipsam, dicens, quod cum ens secundum unumquodque genus entis dividatur per potentiam et actum, motus dicitur esse actus eius, quod est in potentia inquantum huiusmodi.	2294. Now since each (975). Next, he defines motion. First, he gives its definition, saying that, since in each genus of being, being is divided by potentiality and actuality, motion is said to be the actualization of what is potential insofar as it is such.
lib. 11 l. 9 n. 7 Secundo ibi, quod autem exponit positam definitionem. Et circa hoc duo facit. Primo exponit id quod ponitur in definitione ex parte subiecti motus. Secundo id quod ponitur in definitione quasi genus motus, ibi, quod quidem enim est. Circa primum duo facit. Primo exponit hanc particulam eius, quod est in potentia. Secundo hanc, inquantum huiusmodi, ibi, dico autem inquantum. Dicit ergo primo, quod ex hoc manifestum est verum esse, motum esse hoc quod dictum est. Manifestum est enim quod aedificabile significat aliquid existens in potentia. Et ista potentia significatur esse reducta in actum per hoc quod dicitur aedificari. Et iste actus vocatur aedificatio. Et similiter in omnibus aliis motibus, ut in ambulatione et alteratione et huiusmodi. Dicitur autem aliquid moveri, cum huiusmodi fiat in actu, et huiusmodi fuerit in potentia, et non prius nec posterius. Cum ergo ita sit, sequetur, quod motus est alicuius existentis in potentia, cum sit reductum ad actum. Et hoc dico, scilicet quod sit reductum ad actum, inquantum est mobile; nam mobile dicitur aliquid per hoc, quod est in potentia ad moveri; et sic reducitur huiusmodi potentia in actum quando movetur actu: non autem habet reduci in actum per motum id quod in potentia est inquantum ipsum, idest secundum id quod actu est, et secundum seipsum. Nam hoc etiam est in actu antequam incipiat moveri. Neque etiam reducitur ad actum per motum, secundum quod est in potentia ad terminum motus, qui dum movetur adhuc remanet in potentia ad terminum motus. Sed solum per motum reducitur aliquid de potentia in actum, de illa potentia quae significatur cum dicitur aliquid esse mobile, idest potens moveri.	2295. That our account (976). Second, he explains the definition which has been given; and in regard to this he does two things. First (976:C 2295), he explains what was given in the definition with regard to the subject of motion; and second (978:C 2297), what was given as the genus of motion (“That motion is this”). In regard to the first member of this division he does two things. First, he explains the part of the definition, what is potential; and second (977:C 2296), the part, insofar as it is such (“And by the phrase”). He accordingly says, first (976), that it is evidently true from this that motion is as we have described it to be. For it is clear that the term buildable signifies something in potentiality, and that the potentiality in question is presented as being brought to actuality by what is designated as being built; and this actuality is called the process of building. The same thing is also true of other motions, such as walking, altering, and the like. And a thing is said to be being moved when it is coming to be such and such actually and has been such and such potentially, and neither before nor after. If this is so, then, it follows that motion belongs to a thing in potentiality when it is being brought to actuality; and by this I mean that it is being brought to actuality insofar as it is movable; for a thing is said to be movable because it is in potentiality to motion. Hence a potentiality of this kind is being brought to actuality when it is actually being moved; but what is potential “inasmuch as it is itself,” i.e., in reference to what it actually is and in itself, does not have to be brought to actuality by motion. For it actually is this before it begins to be moved. And neither is it being brought to actuality by motion insofar as it is in potentiality to the terminus of motion, because so long as it is being moved it still remains in potentiality to the terminus of motion. But a thing is being brought from potentiality to actuality by motion only in the case of that potentiality which is signified when a thing is said to be movable, i.e., capable of being moved.
lib. 11 l. 9 n. 8 Deinde cum dicit dico autem exponit hanc particulam positam in definitione motus; scilicet inquantum huiusmodi, vel inquantum tale. Ad cuius expositionem dicit quod aes est in potentia ad statuam. Et sic idem est subiectum aes, et aes in potentia ad statuam. Tamen non est idem ratione. Sed alia est ratio aeris inquantum aes, et alia est ratio aeris inquantum habet aliquam potentiam. Et hoc est quod dicit quod non est idem aeri esse, et alicui potentiae. Si enim esset idem simpliciter secundum rationem, tunc, sicut motus est actus aeris inquantum est aes in potentia, ita esset actus aeris inquantum est aes. Sed non est idem secundum rationem aes et potentia aeris. Et hoc manifestum est in potentia contrariorum; quia posse sanari et posse laborare, idest infirmari, non est idem secundum rationem: ratio enim potentiae sumitur ex actu. Unde, si posse sanari et posse infirmari esset idem secundum rationem, sequeretur, quod idem esset infirmari et sanari, quod est impossibile. Sic igitur non est eadem potentia ad utrumque contrariorum secundum rationem potentiae, sed est eadem subiecto; idem enim est subiectum quod potest esse sanum et languens; sive illud subiectum sit quicumque humorum in corpore animalis, sive sanguis, qui est naturalior et magis proprius vitae et animalium nutrimento, possit esse causa sanitatis et aegritudinis. Quia ergo posse sanari et posse infirmari non est idem secundum rationem, manifestum est quod neutrum horum est idem secundum rationem cum suo subiecto; quia quae uni et eidem per se sunt eadem, sibiinvicem sunt eadem per se. Quia ergo non est idem secundum rationem aes, et aes in potentia ad statuam, sicut neque color et visibile, quod est potens videri, ideo necessarium fuit quod in definitione motus, dicto quod est actus existentis in potentia, adderetur, inquantum huiusmodi.	2296. And by the phrase (977). Then he explains a phrase which was given in the definition of motion, namely, insofar as it is such, or inasmuch as it i’s of this kind. With a view to making this clear he says that bronze is in potentiality to being a statue, and thus the subject bronze and bronze in potentiality to being a statue are the same, although they are not the same in their meaning; for the concept of bronze as bronze and that of bronze insofar as it has some potentiality are different; and this is what he means when he says that to be bronze and to be some potentiality are not the same. For if they were the same in their meaning, then just as motion is an actuality of bronze insofar as it is bronze in potentiality, in a similar way motion would be the actuality of bronze insofar as it is bronze. But bronze and the potentiality of bronze do not have the same meaning. This is evident in the case of the potentiality for contraries, because the potentiality “of being healed and that of being ill” do not have the same meaning; for the concept of a potentiality is derived from that of the actuality. Hence, if the potentiality of being healed and that of being ill were the same in meaning, it would follow that being healed and being ill are the same. But this is impossible. Therefore the potentiality for each of two contraries is not the same in meaning, although it is the same in subject. For it is the same subject which can be healed or be ill; and whether that subject is any one at all of the humors in the animal’s body, or the blood, which is more natural and proper to the life and nourishment of the animal, it can be a cause of its being healed or being ill. Since, then, the potentiality of being healed and that of being ill are not the same in meaning, it is evident that neither of these is the same as its subject in meaning, because any two things which are essentially the same as some third thing are themselves essentially the same. Hence, since bronze and bronze in potentiality to being a statue are not the same in meaning, just as color and the visible object are not the same, the phrase insofar as it is such must be added to the statement that motion is the actualization of what is potential.
lib. 11 l. 9 n. 9 Deinde cum dicit quod quidem exponit id quod ponitur in definitione motus tamquam genus; dicens manifestum esse quod hoc sit motus, quia dico motus tunc est, quia tunc accidit moveri quando hic, idest actu existentis in potentia fuerit actu, et neque prius neque posterius. Manifestum est enim quod unumquodque mobilium contingit aliquando esse actu, aliquando non. Sicut aedificabile inquantum aedificabile, quandoque est in potentia, et quandoque est in actu. Dicit autem quod aedificabile inquantum aedificabile, quia materia domus est ad duo in potentia; scilicet ad formam domus et ad hoc quod aedificetur. Et quod ad utrumque contingit esse quandoque in potentia quandoque in actu. Sed potentia quae est in materia domus ad hoc quod aedificetur, significatur in hoc quod dicitur aedificabile. Tunc ergo aedificabile inquantum aedificabile fit actu, quando aedificatur. Et sic aedificatio est actus aedificabilis, inquantum aedificabile.	2297. That motion is this (978). Then he explains the term which was given as the genus in the definition of motion. That motion is this is evident, he says, because the said motion then exists “when it” (the actuality of what is potential) “is actual in this way,” and neither before nor after. For obviously every movable thing can be at one time in a state of actualization and at another not; for the buildable as buildable at one time is in a state of potentiality and at another time is in a state of actualization. He says “the buildable as buildable” because the matter of a house is in potentiality to two things, namely, to the form of a house, and to the process of being built. And it is possible for it at one time to be in a state of potentiality to both and at another to be in a state of actuality. But the potentiality which the matter of a house has for being built is signified by the term buildable. Therefore the buildable as buildable becomes actual when it is being built; and thus the process of building is the actuality of the buildable as buildable.
lib. 11 l. 9 n. 10 Quod sic probat: quia materia domus non est in potentia nisi ad duos actus; scilicet ad aedificationem domus et ad formam. Aedificabile autem significat quamdam potentiam in materia domus existentem. Oportet igitur, cum omni potentiae respondeat aliquis actus, quod potentiae significatae per hoc quod dico aedificabile, respondeat alter duorum actuum; scilicet vel forma domus, vel aedificatio. Sed non est actus aedificabilis inquantum aedificabile forma domus; quia adveniente forma domus non est adhuc aedificabile, sed est iam aedificatum. Sed aedificabile est actu, quando aedificatur actu. Necesse est igitur quod aedificare sit actus aedificabilis. Aedificare autem est quidam motus; et sic motus est actus aedificabilis. Et eadem ratio est de omnibus aliis motibus. Unde manifestum est quod motus est actus existentis in potentia.	2298. He proves this as follows: the matter of a house is in potentiality to only two actualities, namely, the act of building the house and the form of the house. But the term buildable signifies a potentiality belonging to the matter of the house. Therefore, since there is some actuality corresponding to every potentiality, the potentiality signified by the term buildable must correspond to one of these two actualities, namely, either to the form of the house or to the act of building. But the form of the house is not the actuality of the buildable as buildable, because when the form of the house develops, the house is no longer buildable but is already built. But the buildable is in a state of actuality when the house is actually being built. Therefore the act of building must be the actuality of the buildable. Now the act of building is a kind of motion; and thus motion is the actuality of the buildable. The same explanation holds for all other motions. It is evident, then, that motion is the actuality of what is potential.
lib. 11 l. 9 n. 11 Deinde cum dicit quod autem probat definitionem positam esse bene assignatam. Et primo ponit probationem in generali; dicens quod manifestum est motum esse bene definitum, ex his quae alii dixerunt de motu definientes ipsum. Et iterum ex eo quod non potest de facili aliter definiri. Non enim potest poni in alio genere nisi in genere actus.	2299. That this account (979). Then he proves that the definition given is a good one. First, he gives a general proof. He says that it is evident that this definition of motion is a good one if we consider what others have said about motion when they defined it; and also because it cannot easily be defined in a different way. For it cannot be put in any other class than in that of actuality.
lib. 11 l. 9 n. 12 Secundo ibi, palam autem ponit ea quae alii dixerunt de motu, dicens quod quidam dixerunt motum esse alteritatem, et quidam inaequalitatem, et quidam non ens. Forte ideo quia illud quod movetur recedit ab eo quod prius erat, et dum movetur semper alio et alio modo se habet, et magis appropinquat ad terminum.	2300. This is evident (980). Second, he states what others have said about motion. He says that some have said that motion is otherness, others inequality, and others non-being. And perhaps they spoke of it thus because the thing being moved gradually loses its initial state, and so long as it is being moved it is always in different states and comes closer to its goal.
lib. 11 l. 9 n. 13 Tertio ibi, quorum nullum ostendit praedictas definitiones non esse convenientes. Neque enim conveniunt motui ex parte subiecti, quod movetur. Si enim motus esset non ens, vel inaequalitas, vel alteritas, sequeretur quod omne non ens, vel alterum, vel inaequale moveretur: sed nullum horum necesse est moveri: non est igitur motus quod dictum est. Idem etiam apparet ex parte terminorum motus, qui sunt terminus a quo, et terminus ad quem. Non enim magis est motus ad non ens vel inaequalitatem, vel alteritatem, quam ad opposita horum; neque magis est motus ex his, quam ex oppositis. Contingit enim moveri ex non ente ad ens, et e converso; et de alteritate ad similitudinem, et de inaequalitate ad aequalitatem et e converso.	2301. However, no one (981). Third, he shows that the definitions given above are not suitable ones; for they do not fit motion so far as its subject is concerned, i.e., the thing moved. For if motion were non-being or inequality or otherness, it would follow that every non-being or whatever is other or unequal is moved, but it is not necessary that any of these should be moved. Hence motion is not as they have described it to be. The same thing is also apparent with regard to the termini of motion, which are the limits from which and to which there is motion. For motion is not to non-being or inequality or otherness rather than to their opposites, nor is motion from these rather than from their opposites. For there can be motion from nonbeing to being and vice versa, and from otherness to likeness, and from inequality to equality and vice versa.
lib. 11 l. 9 n. 14 Quarto ibi, causa autem ostendit quare praedicto modo definierunt motum; dicens quod ista est causa quare posuerunt motum in praedicta quasi genera, quia motus videtur esse aliquid indeterminatum, et illa sunt indeterminata quae sunt privativa. Et ideo motum posuerunt quasi privationem quamdam.	2302. The reason (982). Fourth, he shows why some defined motion in the foregoing way. He says that the reason why they put motion in the above-mentioned class is that motion seems to be something indefinite, and things which are privative are indefinite. Hence they assumed that motion is a kind of privation.
lib. 11 l. 9 n. 15 Et sciendum quod, sicut in primo huius dictum est, Pythagorici posuerunt duos ordines: in quorum uno quem dicebant ordinem bonorum, posuerunt illa quae videbantur perfectionem habere, sicut lucem, dextrum, masculum, quietem et huiusmodi. In alio autem ordine quem sub malo constituebant, posuerunt tenebras, sinistrum, feminam, motum et huiusmodi. Et omnia huiusmodi dicebant esse indeterminata et privativa, quia nullum istorum videbatur significare neque hoc, idest substantiam, neque tale, idest qualitatem, neque aliquod aliud praedicamentorum.	2303. It should also be noted, as has been pointed out in Book I (60:C 127) of this work, that the Pythagoreans posited two orders of things, and in one of these, which they called the order of good things, they placed things which seem to be perfect, for example, light, right, male, rest, and the like; and in the other order, which they listed under evil, they placed darkness, left, female, motion and the like. And they said that all such things are indefinite and privative because no one of them seems to signify “either a this,” i.e., substance, “or such,” i.e., quality, or any of the other categories.
lib. 11 l. 9 n. 16 Quinto ibi, cur autem dicit causam, quare motus inter indeterminata ponatur: et dicit, quod causa huius est, quia motus neque poterat poni in genere potentiae, neque in genere actus. Si enim esset in genere potentiae, sequeretur quod quicquid est in potentia ad aliquid, puta ad esse quantum, moveretur ad illam quantitatem: sed hoc non est necessarium, quia etiam antequam incipiat aliquid moveri ad quantitatem, est in potentia ad quantitatem illam. Neque etiam movetur quando iam actu est quantum secundum illam quantitatem, ad quam erat in potentia; sed tunc iam terminatus est motus.	2304. The reason why (983). Fifth, he points out why motion is placed in the class of the indefinite. The reason for this, he says, is that motion can be placed neither in the class of the potential nor in that of the actual; for if it were placed in the class of the potential, it would follow that whatever is in potentiality to something, for example, to have some quantity, would be moved to that quantity. But this is not necessary, because, before a thing begins to be moved to some quantity, it is in potentiality to that quantity. Moreover, it is not being moved when it already actually has that quantity to which it was in potentiality, but the motion has then already been terminated.
lib. 11 l. 9 n. 17 Sed oportet, quod motus sit actus quidam, ut supra probatum est: sed est actus imperfectus. Et huius causa est, quia illud cuius est actus, est imperfectum, et hoc est ens possibile sive ens potentia. Si enim esset actus perfectus, tolleret totam potentiam, quae est in materia ad aliquid determinatum. Unde actus perfecti non sunt actus existentis in potentia, sed existentis in actu. Motus autem ita est existentis in potentia, quod non tollit ab eo potentiam. Quamdiu enim est motus, remanet potentia in mobili ad id quod intendit per motum. Sed solum potentia quae erat ad moveri tollitur per motum; et tamen non totaliter; quia id quod movetur, adhuc in potentia est ad moveri, quia omne quod movetur, movebitur, propter divisionem motus continui, ut probatur in sexto physicorum. Unde relinquitur, quod motus est actus existentis in potentia: et sic est actus imperfectus et imperfecti.	2305. But motion must be a kind of actuality, as has been proved above (975:C 2294), although it is an imperfect one. The reason for this is that the thing of which it is the actuality is imperfect, and this is a possible or potential being; for if it were a perfect actuality, the whole potentiality for some definite actuality which is in the matter would be eliminated. Hence perfect actualities are not actualities of something in potentiality but of something in actuality. But motion belongs to something that is in potentiality, because it does not eliminate the potentiality of that thing. For so long as there is motion, the potentiality for that to which it tends by its motion remains in the thing moved. But only the previous potentiality for being moved is eliminated, though not completely; for what is being moved is still in potentiality to motion, because everything which is being moved will be moved, because of the division of continuous motion, as is proved in Book VI of the Physics. It follows, then, that motion is the actuality of what is potential; and thus it is an imperfect actuality and the actuality of something imperfect.
lib. 11 l. 9 n. 18 Et propter hoc difficile est accipere quid sit motus. Videtur enim quod aut necesse sit ponere motum in genere privationis, sicut patet ex praemissis definitionibus, aut in genere potentiae, aut in genere actus simplicis et perfecti; quorum nullum contingit esse motum. Unde relinquitur quod motus sit id quod dictum est; scilicet actus; et quod non dicatur actus perfectus. Quod quidem difficile est videre, sed tamen contingens est esse, quia hoc posito nullum sequitur inconveniens.	2306. It is because of this that it is difficult to grasp what motion is; for it seems necessary to place motion either in the class of privation, as is evident from the definitions given above, or in the class of potentiality, or in that of simple and complete actuality—none of which may be moved. It follows, then, that motion is as we have described it to be, namely, an actuality, and that it is not called a perfect actuality. This is difficult to grasp, although it can nevertheless be true, because when this is admitted nothing untenable follows.
lib. 11 l. 9 n. 19 Quidam autem definierunt dicentes, quod motus est exitus de potentia in actum, non subito. Sed erraverunt; quia necesse est quod in definitione exitus ponatur motus, cum sit species motus. Et similiter in definitione eius quod est subito, ponitur tempus; et in definitione temporis motus.	2307. Some have defined motion by saying that it is the gradual passage from potentiality to actuality. But they erred, because motion must be given in the definition of a passage, since it is a kind of motion. Similarly, time is placed in the definition of the gradual, and motion in the definition of time.
lib. 11 l. 9 n. 20 Deinde cum dicit et quod est ostendit in quo sit motus; et primo ostendit quod in mobili: quia omnis actus est in eo cuius est actus. Sed motus est actus mobilis a movente causatus. Unde relinquitur quod sit in mobili. Et quod sit actus mobilis, ex superioribus patet.	2308. That motion belongs (984). Then he explains what the subject of motion is. First, he shows that it is the thing moved; because every actuality is found in the thing whose actuality it is. But motion is the actuality of the movable by what is capable of causing motion. Hence it follows that motion is found in the movable or thing moved; and that it is the actualization of this is clear from the above discussion.
lib. 11 l. 9 n. 21 Secundo ibi, et motivi actus ostendit qualiter se habeat motus ad movens: et proponit duo: scilicet quod motus est actus motivi: et quod non est alius motus qui est actus motivi, et qui est mobilis: oportet enim motum esse actum amborum.	2309. And the actuality (985). Second, he shows how motion is related to a mover; and he gives two points, namely, that motion is the actuality of what is capable of causing motion, and that the actuality of the thing capable of causing motion and that of the thing moved do not differ; for motion must be the actuality of both.
lib. 11 l. 9 n. 22 Tertio ibi, et motivum primum eorum duorum probat: scilicet quod motus sit motivi actus. Illud enim actus est alicuius, quo fit actu. Sed motivum dicitur ex eo quod est potens movere; movens autem in operari, idest in eo quod est esse actu; et ita, cum movens dicatur propter motum, motus erit actus motivi.	2310. And a thing is capable (986). Third, he proves the first of these two points, namely, that motion is the actuality of what is capable of causing motion. For the actuality of a thing is that by which it becomes actual. But a thing is said to be capable of causing motion because of its power of moving, and it is said to be a mover because of its activity, i.e., because it is actual. Hence, since a thing is said to be a mover because of motion, motion will be the actuality of what is capable of causing motion.
lib. 11 l. 9 n. 23 Quarto ibi, sed est activum probat secundum propositorum: scilicet quod unus motus sit actus motivi et mobilis, hoc modo. Dictum est enim quod motus est actus motivi inquantum facit motum. Est autem mobilis inquantum fit in eo motus: sed motivum facit illum motum qui est in mobili et non alium. Et hoc quod est dicit quod movens est activum mobilis. Unde relinquitur quod unus motus sit actus et moventis et mobilis.	2311. But it is (987). Fourth, he proves the second of these points, namely, that the actuality of what is capable of causing motion and the actuality of what is capable of being moved are one and the same motion. He does this as follows: it has been stated that motion is the actuality of what is capable of causing motion inasmuch as it causes motion; and a thing is said to be movable inasmuch as motion is caused in it; but the thing capable of causing motion causes that motion which is found in the thing moved and not a different one. This is what he means when he says that it is on what is movable that the mover is capable of acting. It follows, then, that the actuality of the mover and that of the thing moved are one and the same motion.
lib. 11 l. 9 n. 24 Quinto ibi, quemadmodum eadem manifestat hoc per exempla: et dicit quod una est distantia duorum ad unum et unius ad duo. Sed differt ratione. Propter quod diversimode significatur: scilicet per duplum et dimidium. Similiter una est via ad ascendendum et descendendum, sed differt ratione. Et propter hoc dicuntur hi ascendentes et illi descendentes. Et ita est de movente et moto. Nam unus motus secundum substantiam est actus utriusque, sed differt ratione. Est enim actus moventis ut a quo, mobilis autem ut in quo; et non actus mobilis ut a quo, neque moventis ut in quo. Et ideo actus moventis dicitur actio, mobilis vero passio.	2312. And it is one (988). Fifth, he clarifies this by an example. He says that the distance from one to two and from two to one are the same, although they differ conceptually; and for this reason the distance is signified differently, namely, by the terms double and half. Similarly, the path of an ascent and that of a descent are one, but they differ conceptually; and for this reason some are called ascenders and others descenders. The same applies to a mover and to the thing moved; for the actuality of both is essentially one motion, although they differ conceptually. For the actuality of a mover functions as that from which motion comes, whereas the actuality of the thing moved functions as that in which motion occurs. And the actuality of the thing moved is not that from which motion comes, nor is the actuality of the mover that in which motion occurs. Hence the actuality of the thing causing motion is called action, and that of the thing moved is called undergoing or suffering.
lib. 11 l. 9 n. 25 Sed si actio et passio sunt idem secundum substantiam, videtur quod non sint diversa praedicamenta. Sed sciendum quod praedicamenta diversificantur secundum diversos modos praedicandi. Unde idem, secundum quod diversimode de diversis praedicatur, ad diversa praedicamenta pertinet. Locus enim, secundum quod praedicatur de locante, pertinet ad genus quantitatis. Secundum autem quod praedicatur denominative de locato, constituit praedicamentum ubi. Similiter motus, secundum quod praedicatur de subiecto in quo est, constituit praedicamentum passionis. Secundum autem quod praedicatur de eo a quo est, constituit praedicamentum actionis.	2313. But if action and undergoing are essentially the same thing, it seems that they should not be different categories. However, it should be borne in mind that the categories are distinguished on the basis of a different way of predicating; and thus inasmuch as the same term is differently predicated of different things, it belongs to different categories; for inasmuch as place is predicated of a thing that locates, it belongs to the genus of quantity, but inasmuch as it is predicated denominatively of the located thing it constitutes the category where. Similarly, inasmuch as motion is predicated of the subject in which it is found, it constitutes the category of undergoing; but inasmuch as it is predicated of that from which it comes, it constitutes the category of action.