Authors/Thomas Aquinas/physics/L3/lect4

Lecture 4 Action and passion are the same motion

Latin	English
	Lecture 4 Action and passion are the same motion
lib. 3 l. 4 n. 1 Postquam philosophus definivit motum, hic ostendit cuius actus sit motus, utrum scilicet mobilis vel moventis. Et potest dici quod hic ponit aliam definitionem motus, quae se habet ad praemissam ut materialis ad formalem, et conclusio ad principium. Et haec est definitio: motus est actus mobilis inquantum est mobile. Haec enim definitio concluditur ex praemissa. Quia enim motus est actus existentis in potentia inquantum huiusmodi; existens autem in potentia inquantum huiusmodi, est mobile, non autem movens, quia movens inquantum huiusmodi est ens in actu; sequitur quod motus sit actus mobilis inquantum huiusmodi.	297. After defining motion, the Philosopher now shows whose act motion is, i.e., whether it is the act of the mobile or of the mover. Also it may be said that he gives another definition of notion which is related to the previous one as material to formal and as a conclusion to its principle. And this is the definition: motion is “the act of the mobile inasmuch as it is mobile.” This definition is a conclusion from the previous one. For since motion is “the act of a thing existing in potency inasmuch as it is in potency,” and since that which exists in potency as such is the mobile and not the mover (for the mover as such is in act), it follows that motion is an act of the mobile as such.
lib. 3 l. 4 n. 2 Circa hoc ergo tria facit: primo ostendit quod motus est actus mobilis; secundo quomodo se habet motus ad moventem, ibi: motivi autem actus etc.; tertio movet dubitationem, ibi: habet autem defectum et cetera. Circa primum duo facit: primo ponit definitionem motus, scilicet quod motus est actus mobilis; secundo ex hoc declarat quoddam quod poterat esse dubium, ibi: et dubium autem et cetera. Circa primum tria facit: primo investigat definitionem motus; secundo concludit eam, ibi: unde motus etc.; tertio manifestat eam, ibi: accidit autem et cetera. Ad investigandum autem definitionem motus, praemittit quod moveri etiam accidit moventi. Et circa hoc duo facit: primo probat quod omne movens movetur; secundo ostendit unde accidat ei moveri, ibi: ad hoc enim agere et cetera.	298. In regard to the main question he does three things: First he shows that motion is an act of the mobile; Secondly, he shows how motion is related to the mover, at 303; Thirdly, he raises a difficulty, at 308. About the first he does two things: He posits a definition of motion, namely, that motion is an act of the mobile; He clears up a doubt, at 303. In regard to (1) he does three things: He investigates the definition of motion: He concludes to the definition, at 302; He explains it, at 302 bis. In investigating the definition he shows that “to be moved” even occurs to the mover. In regard to this he does two things: He shows that every mover is being moved; He shows why that happens, at 301.
lib. 3 l. 4 n. 3 Quod autem movens moveatur, ostendit ex duobus. Primo: quidem quia omne quod prius est in potentia et postea in actu, quodammodo movetur; movens autem invenitur prius esse movens in potentia et postea movens in actu; movens ergo huiusmodi movetur. Et hoc est quod dicit, quod omne movens, cum ita se habeat quod quandoque sit in potentia mobile, idest ad movendum, movetur, sicut dictum est: hoc enim ex dictis apparet. Dictum est enim quod motus est actus existentis in potentia; et hoc contingit in omni movente naturali; unde dictum est supra quod omne movens physicum movetur.	299. He shows in two ways that the mover is moved. This is so first of all because anything that is previously in potency and then in act is somehow being moved. But movers are found that are previously movers in potency and afterwards movers in act; therefore they are moved. He states, therefore, that every mover, since it is such that it is in potency to being a mover, is likewise moved. This is clear from what has been already said, for it was said that motion is an act of a thing existing in potency and this occurs in every natural mover; that is why it was said above that every physical mover is moved.
lib. 3 l. 4 n. 4 Secundo, ibi: et cuius immobilitas etc., ostendit idem alio modo. Cuicumque sua immobilitas est eius quies, huic inest motus; quies enim et motus, cum sint opposita, habent fieri circa idem: sed moventis immobilitas, idest cessatio a movendo, dicitur quies; dicuntur enim quaedam quiescere, quando cessant agere: omne igitur tale movens, scilicet cuius immobilitas est quies, movetur.	300. Secondly [206 202 a4] he brings out the same point in another way: Whatsoever’s immobility is its rest is capable of motion; for rest and motion, since they are opposites, happen to the same. But the immobility of a mover, i.e., its ceasing from moving, is called rest; for there are things which said to rest when they cease to act. Therefore every such mover, i.e., one whose immobility is rest, is moved.
lib. 3 l. 4 n. 5 Deinde cum dicit: ad hoc enim agere etc., ostendit unde accidat moventi quod moveatur. Non enim accidit ei ex hoc quod movet, sed ex hoc quod movet tangendo: quia movere est agere ad hoc quod aliquid moveatur; id autem quod sic a movente patitur, movetur. Sed hoc quod est agere facit tactu; nam corpora tangendo agunt: unde sequitur quod et simul patiatur, quia quod tangit, patitur. Sed hoc intelligendum est quando est mutuus tactus scilicet quod aliquid tangit et tangitur, ut contingit in his quae communicant in materia, quorum utrumque ab altero patitur dum se tangunt. Corpora autem caelestia, quia non communicant cum corporibus inferioribus in materia, sic agunt in ea quod non patiuntur ab eis, et tangunt et non tanguntur, ut dicitur in I de Gen.	301. Then [207 202 a5] he shows why it happens that a mover is moved. For it does not happen precisely because it is a mover but because it is such by touching; because to move is to act in order to cause something to be moved and what is so acted upon by the mover is moved. But whatever acts does so by touching, for bodies act by touching; hence it follows that what acts is at the same time acted upon, because that which touches is acted upon. However, this must be understood of those cases where there is mutual touching; namely, when the thing touching is also touched, as happens in things which are material, where both of the things are acted upon when they touch one another. But heavenly bodies, because they do not have material like the lower bodies, so act on them that they are not acted upon in return and they touch without being touched as is stated in De Generatione I (l.18).
lib. 3 l. 4 n. 6 Deinde cum dicit: unde motus actus mobilis est etc., ponit definitionem motus, concludens ex praedictis quod quamvis movens moveatur, motus tamen non est actus moventis, sed mobilis secundum quod est mobile. Et hoc consequenter manifestat per hoc quod moveri accidit moventi, et non per se ei competit: unde si aliquid secundum hoc movetur, secundum quod actus eius est motus, sequitur quod motus non sit actus moventis, sed mobilis, non quidem inquantum est movens, sed inquantum est mobile. Quod autem moveri accidat moventi, manifestat per id quod supra dictum est: hoc enim, scilicet actus mobilis qui est motus, accidit ex contactu moventis: ex quo sequitur quod simul dum agit patiatur, et sic moveri competit moventi per accidens. Quod autem non competat ei per se manifestat per hoc, quod semper aliqua forma videtur movens esse, sicut forma quae est in genere substantiae, in transmutatione quae est secundum substantiam; et forma quae est in genere qualitatis, in alteratione; et forma quae est in genere quantitatis, in augmento et diminutione. Huiusmodi enim formae sunt causae et principia motuum, cum omne agens moveat secundum formam. Omne enim agens agit inquantum est actu, sicut actu homo facit ex homine in potentia hominem actu: unde, cum unumquodque sit actu per formam, sequitur quod forma sit principium movens. Et sic movere competit alicui inquantum habet formam, per quam est in actu. Unde, cum motus sit actus existentis in potentia, ut supra dictum est, sequitur quod motus non sit alicuius inquantum est movens, sed inquantum est mobile: et ideo in definitione motus positum est, quod est actus mobilis inquantum est mobile.	302. Then [208 202 a7] he posits a definition of motion concluding from the aforesaid that although the mover is moved, motion nevertheless is not an act of the mover but of the mobile inasmuch as it is mobile. He shows this subsequently by the fact that “to be moved” is accidental to the mover and does not belong essentially to it. Whence, if something is moved precisely inasmuch as its act is motion it follows that motion is an act not of the mover but of the mobile, not, indeed, insofar as it is a mover but insofar as it is a mobile. That “to be moved” is accidental to the mover is clear from what was pointed out in the earlier part of this lecture; for the act of the mobile which is motion happens from its contact with the mover; from which it follows that at the same time that it is acting it is acted upon and thus “to be moved” is accidental to the mover. That “to be moved” does not belong essentially to the mover is clear from the fact that some form is always seen to be the mover—as the form which is in the genus of substance is the mover in substantial change, and a form in the genus of quality is the mover in alteration, and a form in the genus of quantity in growth and decrease. Forms of this type are the causes and principles of motions, since every agent moves according to its form. For every agent acts inasmuch it is actual—as an actual man makes an actual man of man in potency. Hence, since it is through its form that a thing is actual it follows that form is the moving principle. Thus “to move” belongs to a thing inasmuch as it has a form through which it is actual. Wherefore, since motion. is the act of a thing existing in potency, as said above (l.2, no.285), it follows that motion belongs to a thing not insofar as it is a mover but insofar as it is mobile. For that reason the definition says that motion is an act of the mobile inasmuch as it is mobile.
lib. 3 l. 4 n. 7 Deinde cum dicit: et dubium autem etc., manifestat quoddam dubium ex praedictis. Solet enim esse dubium apud quosdam, utrum motus sit in movente aut in mobili. Sed hoc dubium declaratur ex praemissis. Manifestum est enim quod actus cuiuslibet est in eo cuius est actus: et sic manifestum est quod actus motus est in mobili, cum sit actus mobilis, causatus tamen in eo a movente.	303. Then [209 202 a13] he shows a difficulty that arises from the aforesaid. For some wonder whether motion is in the mover or in the mobile. But this doubt is solved from what went before. For it is clear that an act of anything is in that thing of which it is the act. Thus, it is plain that the act of motion is in the mobile, since it is an act of the mobile, although caused in it by the mover.
lib. 3 l. 4 n. 8 Deinde cum dicit: motivi autem actus etc., ostendit quomodo se habeat motus ad movens. Et primo proponit quod intendit, dicens quod actus motivi non est alius ab actu mobilis. Unde, cum motus sit actus mobilis, est etiam quodammodo actus motivi.	304. Then [210 202 a15] he shows how motion and mover are related. And first of all he proposes his intention, saying that the act of the mover is not distinct from the act of the mobile. Hence since motion is an act of the mobile it is somehow also an act of the mover.
lib. 3 l. 4 n. 9 Secundo ibi: oportet quidem enim etc., manifestat propositum. Et circa hoc tria facit: primo ostendit quod moventis est aliquis actus, sicut et mobilis. Quidquid enim dicitur secundum potentiam et actum, habet aliquem actum sibi competentem: sed sicut in eo quod movetur dicitur mobile secundum potentiam inquantum potest moveri, motum autem secundum actum inquantum actu movetur; ita ex parte moventis motivum dicitur secundum potentiam, inquantum scilicet potest movere, motus autem in ipso agere, idest in quantum agit actu. Oportet igitur utrique, scilicet moventi et mobili, competere quendam actum.	305. Secondly [211 202 a17] he explains this. And in regard to this he does three things. First he shows that there is an act of the mover as well as of the mobile. For whatever is described according to potency and act has some act competent to it. Now just as that which is moved is called “mobile” in potency since it is capable of being moved, and is called “moved” according to act inasmuch it is actually being moved, so on the part of the mover, a mover is described “potential mover” inasmuch as it is able to move, and “moves” in the act inasmuch as it actually acts. Therefore some act is competent to both, i.e., to mover and to mobile.
lib. 3 l. 4 n. 10 Secundo ibi: sed est activum mobilis etc., ostendit quod idem sit actus moventis et moti. Movens enim dicitur inquantum aliquid agit, motum autem inquantum patitur; sed idem est quod movens agendo causat, et quod motum patiendo recipit. Et hoc est quod dicit, quod movens est activum mobilis, idest actum mobilis causat. Quare oportet unum actum esse utriusque, scilicet moventis et moti: idem enim est quod est a movente ut a causa agente, et quod est in moto ut in patiente et recipiente.	306. Secondly [212 202 a17] he shows that the act of the mover and of the mobile is the same act. For something is called “mover” inasmuch as it acts and “moved” inasmuch as it is being acted upon. But what the mover causes by acting and what the moved receives is being acted upon are one and the same. thing. And this is what he means when he says that the mover actualizes the mobile, i.e., causes the act of the mobile. Wherefore, they must both, namely, mover and moved, have the same act; for what is from the mover as agent cause is the same as what is in the moved as patient and receiver.
lib. 3 l. 4 n. 11 Tertio ibi: sicut idem spatium etc., manifestat hoc per exempla. Eadem enim distantia est unius ad duo et duorum ad unum secundum rem, sed differunt secundum rationem; quia secundum quod incipimus comparationem a duobus procedendo ad unum, dicitur duplum, e contrario vero dicitur dimidium. Et similiter idem est spatium ascendentis et descendentis; sed secundum diversitatem principii et termini, vocatur ascensio vel descensio. Et similiter est in movente, et moto. Nam motus secundum quod procedit a movente in mobile, est actus moventis; secundum autem quod est in mobili a movente, est actus mobilis.	307. Thirdly [213 202 a18] he illustrates this by an example. For the distance from one to two is the same as that from two to one, but they differ according to conception; for in relating two to one we have “double,” but in relating one to two we have “one-half.” The same thing is true of the distance covered by one ascending and by one descending, but by reason of the diversity of starting point and term, one is called “ascent” and one “descent.” A parallel case is true of the mover and of the thing moved. For motion, inasmuch as it proceeds from the mover into the mobile, is an act of the mover, but inasmuch as it is in the mobile from the mover, it is an act of the mobile.