Authors/Thomas Aquinas/physics/L8/lect7

Lecture 7 Universally, whatever is moved is moved by another

Latin	English
	Lecture 7 Universally, whatever is moved is moved by another
lib. 8 l. 7 n. 1 Postquam philosophus suam intentionem manifestavit, hic incipit prosequi suam intentionem: scilicet non omnia quandoque moveri et quandoque quiescere; sed aliquid esse omnino immobile, aliquid autem quod semper movetur. Dividitur autem ista pars in duas: in prima ostendit primum movens esse immobile; in secunda ostendit primum mobile semper moveri, ibi: at vero si aliquod est et cetera. Prima pars dividitur in duas: in prima ostendit primum movens esse immobile ex ordine moventium et mobilium; in secunda ex sempiternitate motus, ibi: et iterum considerans et cetera. Prima pars dividitur in partes duas: in prima ostendit primum movens esse immobile; in secunda ostendit ipsum esse perpetuum, ibi: quoniam autem oportet et cetera. Circa primum duo facit: primo ostendit quoddam quod est necessarium ad probationem sequentium, scilicet quod omne quod movetur ab alio moveatur; secundo ostendit propositum, ibi: hoc autem dupliciter et cetera. Ostenderat siquidem supra in principio septimi, omne quod movetur ab alio moveri, ratione communi accepta ex parte ipsius motus: sed quia incepit applicare motum ad res mobiles, illud quod supra universaliter est ostensum, hic ostendit universaliter verificari in omnibus mobilibus et moventibus. Unde prima pars dividitur in partes duas: in prima ponit divisionem moventium et mobilium; in secunda manifestat propositum in singulis, ibi: et maxime moveri et cetera. Circa primum duo facit: primo dividit moventia et mobilia; secundo manifestat positam divisionem, ibi: quod enim ipsum a seipso et cetera.	1021. After revealing his aim, the Philosopher now begins to execute it, namely, to establish that not all things are sometimes in motion and sometimes at rest, but that something is entirely immobile, and something always in motion. The treatment is divided into two parts. In the first he shows that the first mover is immobile; In the second that the first mobile is always being moved, (L. 13). The first part is divided into two sections: In the first he shows the immobility of the first mover from the order of movers and mobiles; In the second, from the eternity of motion, (L. 13). The first is divided into two parts: In the first he shows that the first mover is immobile; In the second that the first mover is eternal, (L. 12). About the first he does two things: First he shows that to prove what follows depends on showing that whatever is moved is moved by another; Secondly, he shows the proposition, (L. 9). He had indeed showed above, in the beginning of Book VII, that whatever is moved is moved by another, by a generic argument based on motion itself, but because he has now begun to apply motion to mobile things, he here shows that what was previously proved in a universal way is verified universally in all mobiles and movers. Hence the first part is divided into two parts: In the first he gives a division of movers and mobiles; In the second he explains his proposition in individual cases, at 1024. About the first he does two things: First he divides movers and mobiles; Secondly, he explains the division, at 1023.
lib. 8 l. 7 n. 2 Primo ergo ponit tres divisiones moventium et mobilium. Quarum prima est, quod moventium et mobilium quaedam movent seu moventur per accidens, quaedam autem per se. Et accipit hic per accidens large, secundum quod comprehendit sub se etiam quod est secundum partem. Unde exponens quod dixerat per accidens, subdit quod per accidens moveri aut movere dicitur dupliciter. Primo quidem dicuntur movere per accidens, quaecumque movere dicuntur ex eo quod insunt aliquibus moventibus; sicut cum dicitur musicum sanare, quia is cui inest musicum, sanat: et similiter dicuntur moveri per accidens, ex eo quod insunt iis quae moventur, vel sicut locatum in loco, prout dicimus hominem moveri quia navis movetur in qua est; vel sicut accidens in subiecto, prout dicimus album moveri quia corpus movetur. Alio modo dicuntur aliqua movere vel moveri per accidens, quia movent aut moventur secundum partem; sicut homo dicitur percutere aut percuti, quia manus percutitur aut percutit. Per se autem dicuntur moveri aut movere, per remotionem duorum praedictorum: quia scilicet nec dicuntur movere aut moveri ex eo quod sint in aliis quae movent aut moveantur; neque ex eo quod aliqua pars ipsorum moveat aut moveatur. Omissis igitur iis quae movent et moventur per accidens, subdividit ea quae moventur per se. Primo quidem, quia eorum quae moventur per se, alia moventur a seipsis, sicut animalia, alia vero ab aliis, sicut inanimata. Tertiam divisionem ponit, quia alia moventur secundum naturam, alia extra naturam.	1022. He gives therefore First (790 254 b7) three divisions of movers and mobiles. The first of these is that among movers and mobiles some move or are moved per accidens, and some per se. And he takes “per accidens” in a wide sense include what moves or is moved with respect to a part. Hence in explaining what he means by “per accidens, he adds that things cause motion or are moved per accidens in two ways. (1) Whatever things are said to cause motion by virtue of being present in things which move are said to cause it per accidens, as when it is said that a musician causes health, because a knowledge of music is present in the one who heals; and likewise things are said to be moved per accidens either on account of existing in what is being moved in the way that an object in place exists in a place, e.g., when we say that a man is being moved, because the ship on which he is is being moved, or on account of being an accident in a subjects as when we say that the white is being moved, because a body is being moved. (2) In another way, things are said to move or to be moved per accidens, because they move or are moved with respect to a part, as a man is said to strike or be struck, because his hand strikes or is struck. But when these two per accidens ways of causing motion or being moved are eliminated, things are said to move or to be moved per se, i.e., when they are not said to cause motion or be moved by virtue of being in the cause of motion or in what is being moved, or because some part of them causes motion or is moved. Therefore, leaving out what causes motion or is moved per accidens, he subdivides things that are moved per se into those which are moved by themselves, as are animals, and those moved by others, as are the non-living. He gives a third division, namely, that some things are moved according to nature and some not according to nature.
lib. 8 l. 7 n. 3 Deinde cum dicit: quod enim ipsum etc., manifestat qualiter inveniatur secundum naturam et extra naturam in iis quae moventur a seipsis, et quae moventur ab alio. Et primo dicit de iis quae moventur a seipsis (sicut sunt animalia, quae movent seipsa), quod moventur secundum naturam. Quod probat per hoc quod moventur a principio intrinseco: illa autem dicimus a natura moveri, quorum principium motus in ipsis est. Unde manifestum est quod motus animalis, quo movet seipsum, si comparetur ad totum animal, est naturalis: quia est ab anima, quae est natura et forma animalis. Sed si comparetur ad corpus, contingit huiusmodi motum esse et naturalem et extra naturam: hoc enim considerandum erit secundum differentiam motus et elementi ex quo constat animal. Si enim animal constat ex elemento gravi praedominanti, sicut corpus humanum, et moveatur sursum, erit motus violentus quantum ad corpus: si vero moveatur deorsum, erit motus corpori naturalis. Si autem essent aliqua animalia corpore aerea, ut quidam Platonici posuerunt, de illis esset e contrario dicendum. Secundo manifestat qualiter inveniatur motus violentus et naturalis in iis quae moventur ab alio. Et dicit quod horum quaedam moventur secundum naturam, ut ignis sursum et terra deorsum: quaedam vero extra naturam, ut terra sursum et ignis deorsum, qui est motus violentus. Tertio ponit alium modum innaturalis motus in animalibus: secundum scilicet quod multoties partes animalium moventur extra naturam, si considerentur rationes et modi naturalis motus in partibus animalium; sicut homo brachia flectit ad anterius, tibias autem ad posterius; canes vero et equi et huiusmodi animalia anteriores pedes ad posterius, posteriores vero ad anterius. Si autem fiat motus in animalibus per contrarium, erit motus violentus et extra naturam.	1023. Then at (791 254 b14) he explains how to discern what is according to nature and what is not according to nature, both in things that are moved by themselves and in things that are moved by something else. First, with respect to things that are moved by themselves—such as are animals, which move themselves—he says that they are moved according to nature. And he proves this on the ground that they are moved by an intrinsic principle, and since things whose principle of motion is within are said to be moved by nature, it follows that an animal’s motion, by which it moves itself, if it is compared to the whole animal, is natural, because that motion proceeds from the soul which is the nature and form of the animal. But if it be compared to the body, an animal’s motion may be both natural and not according to nature. The difference depends on the type of motion and on the element of which the animal is composed. For if an animal consists of a predominant heavy element, as does the human body, and it is moved upwards, such a movement would be compulsory with respect to the body; but if it is moved downward, it will be a movement that is natural to the body. However, if there were animals whose bodies were composed of air, as Platonists held, then the contrary would be true. Secondly, he explains how to discern compulsory and natural motions in things that are moved by another. Of these, some, he says, are moved according to nature, as fire upward and earth downward; others are moved outside their nature, as earth upward and fire downward, which is a compulsory motion. Thirdly, he mentions another type of unnatural motion in animals, namely, those in which the parts of animals are moved in an unnatural way, their positions and the character of the motion being abnormal. For example, a man’s arms bend (at the elbow) facing forward, while his legs bend (at the knee) facing backward; but dogs and horses and the like, bend the forelegs facing backward and the hind legs facing forward. If motions contrary to these are made, they will be compulsory and not according to nature.
lib. 8 l. 7 n. 4 Deinde cum dicit: et maxime moveri etc., probat omne quod movetur, ab alio moveri. Et primo ostendit in quibus sit manifestum; secundo ostendit de iis in quibus est dubium, ibi: maxime autem dubitatur et cetera. Relictis autem iis quae moventur per accidens, quia ipsa non moventur, sed dicuntur moveri ex eo quod quaedam alia moventur: inter ea quae per se moventur, maxime in his quae moventur per violentiam et extra naturam, manifestum est quod id quod movetur, ab alio movetur. Manifestum est enim quod ea quae per violentiam moventur, ab alio moventur, ex ipsa violenti definitione. Est enim violentum, ut dicitur in III Ethicorum, cuius principium est extra, nil conferente vim passo. Post ista vero quae moventur per violentiam, manifestum est quod id quod movetur ab alio movetur, in iis quae moventur secundum naturam a seipsis, sicut animalia dicuntur seipsa movere. In iis enim manifestum est quod aliquid ab alio movetur: sed dubium potest esse quomodo oporteat accipere in ipsis movens et quod movetur. Quantum enim ex primo aspectu apparet, et secundum quod multis videtur, sicut in navibus et in aliis artificialibus quae non sunt secundum naturam, diversum est quod movet ab eo quod movetur, sic et in animalibus: videtur enim quod hoc modo se habeat anima quae movet, ad corpus quod movetur, sicut nauta ad navim, ut dicitur in II de anima. Et per hunc modum videtur quod totum animal seipsum moveat, inquantum una pars eius aliam movet. Utrum autem se habeat anima ad corpus sicut nauta ad navim, in libro de anima inquirendum relinquit. Quod autem sic aliquid dicatur seipsum movere, inquantum una pars eius movet et alia movetur, in sequentibus ostendetur.	1024. Then at (792 254 b24) he proves that everything that is moved is moved by another. First he manifests it in cases that are evident; Secondly, in cases about which there is doubt, at 1025. Leaving aside things that are moved per accidens, because such things are not moved but are merely said to be moved when other things are moved, and confining ourselves to those which are moved per se, it is clear, especially in things moved by compulsion and outside their nature, that what is moved is moved by another. For in the case of things moved by compulsion, it is clear from the very definition of compulsion that they are moved by another. For compulsion, as is said in Ethics III, is that whose principle is from without, with the thing suffering it contributing nothing. After things that are moved by compulsion, it is clear that what is moved is moved by another if we consider things moved by themselves according to nature, as animals are said to move themselves. For in animals it is clear that something is being moved by something else—but there might yet be a question as to how to distinguish in them the mover and what is being moved. For at first glance it appears to many that what is true with respect to ships and other artifacts which do not exist according to nature, namely, that the part which causes motion is diverse from the part which is moved, applies to animals, for it seems that the soul which causes motion is related to its body which is moved, as the mariner is related to the ship, as is said in On the Soul II. In this way it seems that the whole animal moves itself insofar as one part moves another. But whether the soul is related to the body as a mariner to a ship he leaves to be investigated in his treatise On the Soul. However, the fact that a thing is said to move itself, insofar as one part thereof moves and another is moved, will be shown later.
lib. 8 l. 7 n. 5 Deinde cum dicit: maxime autem dubitatur etc., manifestat propositum in iis in quibus est magis dubium. Et circa hoc tria facit: primo ponit in quibus sit magis dubium omne quod movetur ab alio moveri, quia scilicet in gravibus et levibus, cum secundum naturam moventur; secundo ostendit quod huiusmodi non movent seipsa, ibi: et namque ipsa a seipsis etc.; tertio ostendit a quo moveantur, ibi: sed accidit et haec et cetera. Dicit ergo primo, quod ex quo maxime manifestum est quod movetur ab alio moveri, in iis quae moventur per violentiam, et post haec in iis quae movent seipsa; maxime videtur dubium in residuo membro ultimae divisionis, scilicet in his quae non movent seipsa, et tamen moventur naturaliter. Ultimam autem divisionem dicit istam, scilicet quod eorum quae moventur non a seipsis sed ab alio, quaedam moventur extra naturam, quaedam vero e contrario moventur secundum naturam. Et in istis dubium est a quo moveantur: sicut sunt gravia et levia, quae quidem in contraria loca moventur per violentiam, sed in propria secundum naturam, leve scilicet sursum, grave vero deorsum; sed a quo moveantur non est manifestum cum moventur secundum naturam, sicut est manifestum cum moventur extra naturam.	1025. Then at (793 254 b33) he explains his proposition in regard to things in which it is more doubtful. About this he does three things. First he sets down those things in which it is more doubtful that whatever is moved is moved by another, namely, in the heavy and the light, when they are moved according to nature. Secondly, he shows that they do not move themselves, at 1026; Thirdly, he shows by what they are moved, (L. 8). He says therefore First (793 254 b33) that, since it is in things moved by compulsion, and after them in things which move themselves, that it is especially evident that whatever is being moved is moved by another, the greatest doubt appears to be in the remaining member of the last division, namely, in things that do not move themselves, but yet are moved naturally. The “last” division to which he refers is that in which he divided things that are moved not by themselves but by another into those that are moved contrary to nature, and those that are moved according to nature. In these latter there is doubt as to what moves them: for example, heavy and light objects are moved to their proper places according to nature—i.e., the light upwards and the heavy downwards—and into contrary places by compulsion; but the source of their motion when they are moved according to nature is not clear, as it is when they are moved contrary to nature.
lib. 8 l. 7 n. 6 Deinde cum dicit: et namque ipsa a seipsis etc., probat quod huiusmodi non movent seipsa, quatuor rationibus. Quarum prima est, quod movere seipsum pertinet ad rationem vitae, et est proprie animatorum: motu enim et sensu discernimus animatum ab inanimato, ut dicitur in I de anima. Manifestum est autem haec non esse viva, seu animata. Non ergo movent seipsa.	1026. Then at (794 255 a5) he proves with four arguments that these things do not move themselves. The first of which is that to move itself pertains to the notion of life and is peculiar to living things; for it is through motions and sensations that we distinguish the animate from the inanimate, as is said in On the Soul I. But it is manifest that the heavy and light as such are not alive, or animate. Therefore, they do not move themselves.
lib. 8 l. 7 n. 7 Secunda ratio ponitur ibi: et facere stare etc.: quae talis est. Quaecumque movent seipsa, possunt etiam sibi esse causa quietis; sicut videmus quod animalia per suum appetitum moventur et stant. Si ergo gravia et levia moverent seipsa motu naturali, possent facere stare seipsa; sicut si aliquis est sibi causa ambulandi, est etiam sibi causa non ambulandi. Hoc autem videmus esse falsum: quia huiusmodi non quiescunt extra propria loca, nisi propter aliquam causam extrinsecam prohibentem motum ipsorum. Ergo non movent seipsa. Sed quia posset aliquis dicere quod huiusmodi, etsi non sint sibi causa standi extra propria loca, sunt tamen sibi causa standi in propriis locis, subiungit tertiam rationem ibi: quare si in ipso est etc.: quae talis est. Irrationabile est dicere, quod illa quae movent seipsa, moveantur solum a seipsis secundum unum motum, et non pluribus motibus: quia quod movet seipsum, non habet motum determinatum ab alio, sed ipsum sibi determinat motum; et quandoque determinat sibi hunc motum, et quandoque alium. Unde est in potestate eius quod movet seipsum quod determinet sibi hunc vel illum motum. Si ergo gravia et levia moverent seipsa, sequeretur quod si in potestate ignis esset quod moveretur sursum, quod in potestate eius esset quod moveretur deorsum; quod nunquam videmus accidere, nisi ex causa extrinseca. Non igitur movent seipsa. Est autem sciendum, quod istae duae rationes sunt probabiles secundum ea quae apparent de moventibus seipsa quae sunt apud nos, quae quandoque inveniuntur moveri hoc motu, quandoque alio, quandoque etiam quiescere. Unde non dixit impossibile est, sed irrationabile; quo modo loquendi in probabilibus uti consuevit. Ostendet enim inferius, quod si aliquid est movens seipsum, in quo movens est omnino immobile, quod illud semper movetur, et uno motu: sed tamen hoc non posset dici in gravibus et levibus, in quibus non est aliquid quod non moveatur per se vel per accidens, cum etiam generentur et corrumpantur.	1027. The second argument is given at (795 255 a7); Things that move themselves can cause themselves to stop, as we see that animals are moved and stop by reason of their appetite, Therefore, if heavy and light things moved themselves with a natural motion, they could cause themselves to stop, in the way that a person who is the cause of his walking is so also of his ceasing to walk. But we see that this is false, because the heavy and the light do not stop outside their proper places, unless some external cause intervenes to halt their motion. Therefore, they do not move themselves. But because someone could say that although such things are not the cause of their own stopping outside their proper places, yet they are the cause of stopping in their proper places, he adds a third argument at (796 255 a9): it is unreasonable to say that things which move themselves are so moved according to one motion alone and not by many, because what moves itself does not have its motion determined by another but determines its own motion for itself, so that at one time it determines this motion and at another time that one. Hence it is in the power of what moves itself to determine for itself this or that motion. Therefore, if heavy and light things moved themselves, it would follow that if it were in the power of fire to be moved upward, it would also be in its power to be moved downward, which is something we never see occurring, unless from an extrinsic cause. Therefore, they do not move themselves. It should be recognized that these two arguments are probable in respect to what appears in things among us that move themselves, which are found at one time to be moved with this motion and at another time with that motion, and at another time to be at rest. Hence he does not say, “It is impossible,” but “It is unreasonable,” which is his manner of speaking when he talks of what is probable. For he will show later that if something is moving itself and it is an entirely immobile mover, that it is always being moved and with one motion. Yet that could not be said in regard to heavy and light things, in which there is nothing that is not moved either per se or per accidens, and they are also generated and cease to be.
lib. 8 l. 7 n. 8 Quartam rationem ponit ibi: amplius quomodo etc.: quae talis est. Nullum continuum movet seipsum: gravia autem et levia sunt continua: ergo nihil horum movet seipsum. Quod autem nullum continuum seipsum moveat, sic probat. Quia movens ad motum se habet, sicut agens ad patiens: cum autem agens sit contrarium patienti, necesse est quod dividatur id quod est aptum natum agere, ab eo quod est aptum natum pati: secundum ergo quod aliqua sunt non contacta ad invicem, sed sunt omnino unum et continuum et quantitate et forma, secundum hoc non possunt pati ab invicem. Sic ergo sequitur quod nullum continuum moveat seipsum, sed necesse est quod movens dividatur ab eo quod movetur; sicut apparet cum res inanimatae moventur ab animatis, ut lapis a manu. Unde et in animalibus quae movent seipsa, est magis quaedam colligatio partium, quam perfecta continuatio: sic enim una pars potest moveri ab alia, quod non invenitur in gravibus et levibus.	1028. He gives the fourth argument at (797 255 a13): No continuum moves itself. But heavy and light bodies are continua. Therefore neither of these moves itself. That no continuum moves itself he proves in the following manner: The mover is related to the moved as agent to patient. But since the agent is contrary to the patient, that which is apt to act must be divided from what is apt to be acted upon, Now, to the extent that things are not in mutual contact but are completely one and continuous in quantity and form, to that extent they can not be acted upon by one another, In this way, therefore, it follows that no continuum moves itself, but the mover must be divided from what is moved, as is evident when non-living things are moved by living things, as is a stone by the hand, Hence, too, in animals that move themselves, there is rather a connection of parts than a perfect continuity (for which reason one part can be moved by another), a situation that is not verified in the light and the heavy.