Caput 12 Chapter 12 De opinione dicentium quod Deum esse demonstrari non potest sed sola fide tenetur Of the opinion of those who say that the existence of God cannot be proved and that it is held by faith alone Est autem quaedam aliorum opinio praedictae positioni contraria, per quam etiam inutilis redderetur conatus probare intendentium Deum esse. Dicunt enim quod Deum esse non potest per rationem inveniri, sed per solam viam fidei et revelationis est acceptum. The position that we have taken is also assailed by the opinion of certain others, by which the efforts of those who endeavor to prove that there is a God would again be rendered futile. For they say that it is impossible by means of the reason to discover that God exists, and that this knowledge is acquired solely by means of faith and revelation. Ad hoc autem dicendum moti sunt quidam propter debilitatem rationum quas aliqui inducebant ad probandum Deum esse. In making this assertion some were moved by the weakness of the arguments which certain people employed to prove the existence of God. Posset tamen hic error fulcimentum aliquod falso sibi assumere ex quorundam philosophorum dictis, qui ostendunt in Deo idem esse essentiam et esse, scilicet id quod respondetur ad quid est, et ad quaestionem an est. Via autem rationis perveniri non potest ut sciatur de Deo quid est. Unde nec ratione videtur posse demonstrari an Deus sit. Possibly, however, this error might falsely seek support from the statements of certain philosophers, who show that in God essence and existence are the same, namely, that which answers to the question, ‘What is he?’ and that which answers to the question, ‘Is he?’ Now it is impossible by the process of reason to acquire the knowledge of what God is. Therefore, it seems likewise impossible to prove by reason whether God is. Item. Si principium ad demonstrandum an est, secundum artem Philosophi, oportet accipere quid significet nomen; ratio vero significata per nomen est definitio, secundum Philosophum, in IV Metaph.; nulla remanebit via ad demonstrandum Deum esse, remota divinae essentiae vel quidditatis cognitione. Again. If, as required by the system of the Philosopher (2 Posterior Analytics 9, 1) in order to prove whether a thing is we must take as principle the signification of its name, and since according to the Philosopher, the signification of a name is its definition (4 Metaphysics 3, 3, 4) there will remain no means of proving the existence of God, seeing that we lack knowledge of the divine essence or quiddity. Item. Si demonstrationis principia a sensu cognitionis originem sumunt, ut in posterioribus ostenditur, ea quae omnem sensum et sensibilia excedunt, videntur indemonstrabilia esse. Huiusmodi autem est Deum esse. Est igitur indemonstrabile. Again. If the principles of demonstration become known to us originally through the senses, as is proved in the Posterior Analytics 1, 18, those things which transcend all sense and sensible objects are seemingly indemonstrable. Now such is the existence of God. Therefore, it cannot be demonstrated. Huius autem sententiae falsitas nobis ostenditur, tum ex demonstrationis arte, quae ex effectibus causas concludere docet. Tum ex ipso scientiarum ordine. Nam, si non sit aliqua scibilis substantia supra substantiam sensibilem, non erit aliqua scientia supra naturalem, ut dicitur in IV Metaph. Tum ex philosophorum studio, qui Deum esse demonstrare conati sunt. Tum etiam apostolica veritate asserente, Rom. 1:20: invisibilia Dei per ea quae facta sunt intellecta conspiciuntur. The falseness of this opinion is shown to us first by the art of demonstration, which teaches us to conclude causes from effects. Second, by the order itself of sciences: for if no substance above sensible substance can be an object of science, there will be no science above physics, as stated in 4 Metaphysics 3, 7, 9. Third, by the efforts of the philosophers who have endeavored to prove the existence of God. Fourth, by the apostolic truth, which asserts that the invisible things of God are clearly seen, being understood by the things that are made (Rom 1:20). Nec hoc debet movere, quod in Deo idem est essentia et esse, ut prima ratio proponebat. Nam hoc intelligitur de esse quo Deus in seipso subsistit, quod nobis quale sit ignotum est, sicut eius essentia. Non autem intelligitur de esse quod significat compositionem intellectus. Sic enim esse Deum sub demonstratione cadit, dum ex rationibus demonstrativis mens nostra inducitur huiusmodi propositionem de Deo formare qua exprimat Deum esse. Nor should we be moved by the consideration that in God essence and existence are the same, as the first argument contended. For this is to be understood of the existence by which God subsists in himself, of which we are ignorant as to what kind of a thing it is, even as we are ignorant of his essence. But it is not to be understood of that existence which is signified by the composition of the mind. For in this way it is possible to prove the existence of God, when our mind is led by demonstrative arguments to form a proposition stating that God is. In rationibus autem quibus demonstratur Deum esse, non oportet assumi pro medio divinam essentiam sive quidditatem, ut secunda ratio proponebat: sed loco quidditatis accipitur pro medio effectus, sicut accidit in demonstrationibus quia; et ex huiusmodi effectu sumitur ratio huius nominis Deus. Nam omnia divina nomina imponuntur vel ex remotione effectuum divinorum ab ipso, vel ex aliqua habitudine Dei ad suos effectus. Now, in those arguments by which we prove the existence of God, it is not necessary that the divine essence or quiddity be employed as the middle term, as the second argument supposed, but instead of the quiddity we take his effects as middle term, as is the case in a posteriori reasoning. From these effects we take the signification of this word ‘God’. For all the divine names are taken either from the remoteness of God’s effects from himself, or from some relationship between God and his effects. Patet etiam ex hoc quod, etsi Deus sensibilia omnia et sensum excedat, eius tamen effectus, ex quibus demonstratio sumitur ad probandum Deum esse, sensibiles sunt. Et sic nostrae cognitionis origo in sensu est etiam de his quae sensum excedunt. It is also evident from the fact that, although God transcends all sensibles and senses, his effects, from which we take the proof that God exists, are sensible objects. Hence our knowledge, even of things which transcend the senses, originates from the senses. Caput 13 Chapter 13 Rationes ad probandum Deum esse Arguments in proof of God’s existence Ostenso igitur quod non est vanum niti ad demonstrandum Deum esse, procedamus ad ponendum rationes quibus tam philosophi quam doctores Catholici Deum esse probaverunt. Having shown, then, that endeavoring to prove the existence of God is not futile, we may proceed to set forth the reasons by which both philosophers and Catholic doctors have proved that there is a God. Primo autem ponemus rationes quibus Aristoteles procedit ad probandum Deum esse. Qui hoc probare intendit ex parte motus duabus viis. In the first place, we shall give the arguments by which Aristotle sets out to prove God’s existence. He aims at proving this from movement in two ways. Quarum prima talis est: omne quod movetur, ab alio movetur. Patet autem sensu aliquid moveri, ut puta solem. Ergo alio movente movetur. Aut ergo illud movens movetur, aut non. Si non movetur, ergo habemus propositum, quod necesse est ponere aliquod movens immobile. Et hoc dicimus Deum. Si autem movetur, ergo ab alio movente movetur. Aut ergo est procedere in infinitum: aut est devenire ad aliquod movens immobile. Sed non est procedere in infinitum. Ergo necesse est ponere aliquod primum movens immobile. The first way is as follows (7 Physics 1). Whatever is in motion is moved by another. Now, it is clear to the sense that something is in motion, e.g., the sun. Therefore, it is in motion by something else moving it. Now that which moves it is itself either moved or not. If it is not moved, then the point is proved that we must postulate an immovable mover, and this we call God. If, however, it be moved, it is moved by another mover. Either, therefore, we must proceed to infinity, or we must come to an immovable mover. But it is not possible to proceed to infinity. Therefore, it is necessary to postulate an immovable mover. In hac autem probatione sunt duae propositiones probandae: scilicet, quod omne motum movetur ab alio; et quod in moventibus et motis non sit procedere in infinitum. This argument contains two propositions that need to be proved, namely, that whatever is in motion is moved by another, and that it is not possible to proceed to infinity in movers and things moved. Quorum primum probat Philosophus tribus modis. Primo, sic. Si aliquid movet seipsum, oportet quod in se habeat principium motus sui: alias, manifeste ab alio moveretur. Oportet etiam quod sit primo motum: scilicet quod moveatur ratione sui ipsius, et non ratione suae partis, sicut movetur animal per motum pedis; sic enim totum non moveretur a se, sed sua pars, et una pars ab alia. Oportet etiam ipsum esse divisibile, et habere partes: cum omne quod movetur sit divisibile, ut probatur in VI Physic. The first of these is proved by the Philosopher in three ways. First, thus. If a thing moves itself, it must have the principle of its movement in itself; otherwise, it would clearly be moved by another. It also must be moved primarily, that is, it must be moved by reason of itself and not by reason of its part (as an animal is moved by the movement of its foot). For in the latter way not the whole but the part would be moved by itself, and one part by another. It also must be divisible and have parts, since whatever is moved is divisible, as is proved in 6 Physics 4. His suppositis sic arguit. Hoc quod a seipso ponitur moveri, est primo motum. Ergo ad quietem unius partis eius, sequitur quies totius. Si enim, quiescente una parte, alia pars eius moveretur, tunc ipsum totum non esset primo motum, sed pars eius quae movetur alia quiescente. Nihil autem quod quiescit quiescente alio, movetur a seipso: cuius enim quies ad quietem sequitur alterius, oportet quod motus ad motum alterius sequatur; et sic non movetur a seipso. Ergo hoc quod ponebatur a seipso moveri, non movetur a seipso. Necesse est ergo omne quod movetur, ab alio moveri. These things being supposed, he argues as follows. That which is stated to be moved by itself is moved primarily. Therefore, if one of its parts is at rest, it follows that the whole is at rest. For if, while one part is at rest, another of its parts were in motion, the whole itself would not be moved primarily, but its part which is in motion while another is at rest. Now nothing that is at rest while another is at rest is moved by itself: for that which is at rest as a result of another thing being at rest must be in motion as a result of the other’s motion. And hence it is not moved by itself. Hence that which was stated to be moved by itself is not moved by itself. Therefore, whatever is in motion must be moved by another. Nec obviat huic rationi quod forte aliquis posset dicere quod eius quod ponitur movere seipsum, pars non potest quiescere; et iterum quod partis non est quiescere vel moveri nisi per accidens; ut Avicenna calumniatur. Quia vis rationis in hoc consistit, quod, si aliquid seipsum moveat primo et per se, non ratione partium, oportet quod suum moveri non dependeat ab aliquo; moveri autem ipsius divisibilis, sicut et eius esse, dependet a partibus; et sic non potest seipsum movere primo et per se. Non requiritur ergo ad veritatem conclusionis inductae quod supponatur partem moventis seipsum quiescere quasi quoddam verum absolute: sed oportet hanc conditionalem esse veram, quod, si quiesceret pars, quod quiesceret totum. Quae quidem potest esse vera etiam si antecedens sit impossibile: sicut ista conditionalis est vera, si homo est asinus, est irrationalis. Nor is this argument negated by what might be said: supposing a thing moves itself, it is impossible for a part of it to be at rest. Nor again by the statement that to be at rest or in motion does not belong to a part except accidentally, as Avicenna quibbles (2 Suffic. 1). For the force of the argument lies in this, that if a thing moves itself primarily and of itself, not by reason of its parts, it follows that its being moved does not depend on anything; whereas with a divisible thing, being moved depends on its parts, as does its existence, so that it cannot move itself primarily and of itself. Therefore, the truth of the conclusion drawn does not require that we suppose as an absolute truth that a part of that which moves itself is at rest, but that this conditional statement be true: if a part were at rest, the whole would be at rest. Which statement can be true even if the antecedent be false, even as this conditional proposition is true: if a man is an ass, then he is irrational. Secundo, probat per inductionem, sic. Omne quod movetur per accidens, non movetur a seipso. Movetur enim ad motum alterius. Similiter neque quod movetur per violentiam: ut manifestum est. Neque quae moventur per naturam ut ex se mota, sicut animalia, quae constat ab anima moveri. Nec iterum quae moventur per naturam ut gravia et levia. Quia haec moventur a generante et removente prohibens. Omne autem quod movetur, vel movetur per se, vel per accidens. Et si per se, vel per violentiam, vel per naturam. Et hoc, vel motum ex se, ut animal; vel non motum ex se, ut grave et leve. Ergo omne quod movetur, ab alio movetur. Second, he proves it by induction in this way (8 Physics 4). A thing is not moved by itself if it is moved accidentally, since its motion is occasioned by the motion of something else. Nor again if it is moved by force, as is manifest. Nor if it is moved by its nature, like those things whose movement proceeds from themselves, such as animals, which clearly are moved by their souls. Nor if it is moved by nature, as heavy and light things are, since these are moved by their generating cause and by that which removes the obstacle to their movement. Now, all things that are in motion are moved either in themselves or accidentally; and if in themselves, either by force or by nature; and if the latter, either by something in them, as in the case of animals, or not by something in them, as in the case of heavy and light bodies. Therefore, whatever is in motion is moved by another. Tertio, probat sic. Nihil idem est simul actu et potentia respectu eiusdem. Sed omne quod movetur, inquantum huiusmodi, est in potentia: quia motus est actus existentis in potentia secundum quod huiusmodi. Omne autem quod movet est in actu, inquantum huiusmodi: quia nihil agit nisi secundum quod est in actu. Ergo nihil est respectu eiusdem motus movens et motum. Et sic nihil movet seipsum. Third (8 Physics 5, 8), he proves his point thus. Nothing is at the same time in act and in potency in respect of the same thing. Now whatever is in motion, as such, is in potency, because motion is the act of that which is in potency, as such (3 Physics 1, 6). In contrast, whatever moves, as such, is in act, for nothing acts except insofar as it is in act. Therefore, nothing is both mover and moved in respect of the same movement. Hence nothing moves itself. Sciendum autem quod Plato qui posuit omne movens moveri, communius accepit nomen motus quam Aristoteles. Aristoteles enim proprie accepit motum secundum quod est actus existentis in potentia secundum quod huiusmodi: qualiter non est nisi divisibilium et corporum, ut probatur in VI Physic. Secundum Platonem autem movens seipsum non est corpus: accipiebat enim motum pro qualibet operatione, ita quod intelligere et opinari sit quoddam moveri; quem etiam modum loquendi Aristoteles tangit in III de anima. Secundum hoc ergo dicebat primum movens seipsum movere quod intelligit se et vult vel amat se. Quod in aliquo non repugnat rationibus Aristotelis: nihil enim differt devenire ad aliquod primum quod moveat se, secundum Platonem; et devenire ad primum quod omnino sit immobile, secundum Aristotelem. We must observe, however, that Plato (Phoedrus 24). who asserted that every mover is moved, employed the term ‘movement’ in a more general sense than Aristotle. For Aristotle took movement in its strict sense, for the act of a thing that is in potency as such, in which sense it applies only to divisible things and bodies, as is proved in 6 Physics. But, according to Plato, that which moves itself is not a body: for he took movement for any operation, so that to understand or to think is a kind of movement, to which manner of speaking Aristotle alludes in 3 De Anima 7. In this sense, then, he said that the first mover moves itself, inasmuch as it understands, desires, and loves itself. This, in a certain respect, is not in contradiction with the arguments of Aristotle; for it makes no difference whether with Plato we come to a first mover that moves itself, or with Aristotle to something first which is altogether immovable. Aliam autem propositionem, scilicet quod in moventibus et motis non sit procedere in infinitum, probat tribus rationibus. He proves the other proposition (namely, that it is impossible to proceed to infinity in movers and things moved) by three arguments. Quarum prima talis est. Si in motoribus et motis proceditur in infinitum, oportet omnia huiusmodi infinita corpora esse: quia omne quod movetur est divisibile et corpus, ut probatur in VI Physic. Omne autem corpus quod movet motum, simul dum movet movetur. Ergo omnia ista infinita simul moventur dum unum eorum movetur. Sed unum eorum, cum sit finitum, movetur tempore finito. Ergo omnia illa infinita moventur tempore finito. Hoc autem est impossibile. Ergo impossibile est quod in motoribus et motis procedatur in infinitum. The first (7 Physics) of these is as follows. If one were to proceed to infinity in movers and things moved, all this infinite number of things would necessarily be bodies, since whatever is moved is divisible and corporeal, as is proved in 6 Physics. Now every body that moves through being moved is moved at the same time as it moves. Therefore, all this infinite number of things are moved at the same time as one of them is moved. But one of them, since it is finite, is moved in a finite time. Therefore, all this infinite number of things are moved in a finite time. But this is impossible. Therefore, it is impossible to proceed to infinity in movers and things moved. Quod autem sit impossibile quod infinita praedicta moveantur tempore finito, sic probat. Movens et motum oportet simul esse: ut probat inducendo in singulis speciebus motus. Sed corpora non possunt simul esse nisi per continuitatem vel contiguationem. Cum ergo omnia praedicta moventia et mota sint corpora, ut probatum est, oportet quod sint quasi unum mobile per continuationem vel contiguationem. Et sic unum infinitum movetur tempore finito. Quod est impossibile, ut probatur in VI physicorum. That it is impossible for the aforesaid infinite number of things to be moved in a finite time, he proves thus (7 Physics 1, 2). Mover and moved must be simultaneous, as he proves by induction from each species of movement. But bodies cannot be simultaneous except by continuity or contact. Therefore, since all the aforesaid movers and things moved are bodies, as proved, they must be as one movable thing through their continuity or contact. And thus one infinite thing would be moved in a finite time, which is shown to be impossible in 6 Physics 7. Secunda ratio ad idem probandum talis est. In moventibus et motis ordinatis, quorum scilicet unum per ordinem ab alio movetur, hoc necesse est inveniri, quod, remoto primo movente vel cessante a motione, nullum aliorum movebit neque movebitur: quia primum est causa movendi omnibus aliis. Sed si sint moventia et mota per ordinem in infinitum, non erit aliquod primum movens, sed omnia erunt quasi media moventia. Ergo nullum aliorum poterit moveri. Et sic nihil movebitur in mundo. The second argument (8 Physics 5) in proof of the same statement is as follows. In an ordinate series of movers and things moved—namely, where throughout the series one is moved by the other—we must find that if the first mover be taken away or cease to move, none of the others will move or be moved, because the first is the cause of movement in all the others. Now if an ordinate series of movers and things moved proceed to infinity, there will be no first mover, but all will be like intermediate movers. Therefore, it will be impossible for any of them to be moved: and thus nothing in the world will be moved. Tertia probatio in idem redit, nisi quod est ordine transmutato, incipiendo scilicet a superiori. Et est talis. Id quod movet instrumentaliter, non potest movere nisi sit aliquid quod principaliter moveat. Sed si in infinitum procedatur in moventibus et motis, omnia erunt quasi instrumentaliter moventia, quia ponentur sicut moventia mota, nihil autem erit sicut principale movens. Ergo nihil movebitur. The third argument (8 Physics 5) amounts to the same, except that it proceeds in the reverse order, namely, by beginning from above. It is as follows. That which moves instrumentally cannot move unless there be something that moves principally. But if we proceed to infinity in movers and things moved, they will all be like instrumental movers, because they will be alleged to be moved movers, and there will be nothing by way of principal mover. Therefore, nothing will be moved. Et sic patet probatio utriusque propositionis quae supponebatur in prima demonstrationis via, qua probat Aristoteles esse primum motorem immobilem. We have thus clearly proved both statements which were supposed in the first process of demonstration by which Aristotle proved the existence of a first immovable mover. Secunda via talis est. Si omne movens movetur, aut haec propositio est vera per se, aut per accidens. Si per accidens, ergo non est necessaria: quod enim est per accidens verum, non est necessarium. Contingens est ergo nullum movens moveri. Sed si movens non movetur, non movet: ut adversarius dicit. Ergo contingens est nihil moveri: nam, si nihil movet, nihil movetur. Hoc autem habet Aristoteles pro impossibili, quod scilicet aliquando nullus motus sit. Ergo primum non fuit contingens: quia ex falso contingenti non sequitur falsum impossibile. Et sic haec propositio, omne movens ab alio movetur, non fuit per accidens vera. The second way (8 Physics 5) is as follows. If every mover is moved, this statement is true either in itself or accidentally. If accidentally, it follows that it is not necessary: for that which is accidentally true is not necessary. Therefore, it is a contingent proposition that no mover is moved. But if a mover be not moved, it does not move, as the opponent asserts. Therefore, it is contingent that nothing is moved, since, if nothing moves, nothing is moved. Now Aristotle holds this to be impossible (8 Physics 1), namely, that at any time there be no movement. Therefore, the first proposition was not contingent, because a false impossibility does not follow from a false contingency. And therefore this proposition, ‘every mover is moved by another,’ was not accidentally true. Item, si aliqua duo sunt coniuncta per accidens in aliquo; et unum illorum invenitur sine altero, probabile est quod alterum absque illo inveniri possit: sicut, si album et musicum inveniuntur in Socrate, et in Platone invenitur musicum absque albo, probabile est quod in aliquo alio possit inveniri album absque musico. Si igitur movens et motum coniunguntur in aliquo per accidens, motum autem invenitur in aliquo absque eo quod moveat, probabile est quod movens inveniatur absque eo quod moveatur. Nec contra hoc potest ferri instantia de duobus quorum unum ab altero dependet: quia haec non coniunguntur per se, sed per accidens. Again, if any two things are found accidentally united in a certain subject, and one of them is to be found without the other, it is probable that the latter can be found without the former: thus if ‘white’ and ‘musical’ are found in Socrates, and ‘musical’ without ‘white’ is found in Plato, it is probable that ‘white’ could be found without ‘musical’ in some subject. Accordingly, if mover and moved be united together in some subject accidentally, and it be found that a certain thing is moved without its being a mover, it is probable that a mover is to be found that is not moved. Nor can one urge against this the case of two things, one of which depends on the other; because those in question are united not per se but accidentally. Si autem praedicta propositio est vera per se, similiter sequitur impossibile vel inconveniens. Quia vel oportet quod movens moveatur eadem specie motus qua movet, vel alia. Si eadem, ergo oportebit quod alterans alteretur, et ulterius quod sanans sanetur, et quod docens doceatur, et secundum eandem scientiam. Hoc autem est impossibile: nam docentem necesse est habere scientiam, addiscentem vero necesse est non habere; et sic idem habebitur ab eodem et non habebitur, quod est impossibile. Si autem secundum aliam speciem motus movetur, ita scilicet quod alterans moveatur secundum locum, et movens secundum locum augeatur, et sic de aliis; cum sint finita genera et species motus, sequetur quod non sit abire in infinitum. Et sic erit aliquod primum movens quod non movetur ab alio. Nisi forte aliquis dicat quod fiat reflexio hoc modo quod, completis omnibus generibus et speciebus motus, iterum oporteat redire ad primam: ut, si movens secundum locum alteretur et alterans augeatur, iterum augens moveatur secundum locum. Sed ex hoc sequetur idem quod prius: scilicet quod id quod movet secundum aliquam speciem motus, secundum eandem moveatur, licet non immediate sed mediate. If, however, the aforesaid proposition is true in itself, again there follows something impossible or unfitting. For the mover must be moved either by the same kind of movement or by another kind. If by the same kind, it follows that whatever causes alteration must itself be altered, and furthermore that the healer must be healed, that the teacher must be taught, and in respect of the same science. But this is impossible: for the teacher must have science, while the learner must not have it, and thus one thing will be both possessed and not possessed by the same person, which is impossible. And if it be moved by another kind of movement—namely, so that what causes alteration be moved in respect of place, and that which moves in respect of place be increased, and so on—it will follow that we cannot go on indefinitely, since the genera and species of movement are finite in number. And thus there will be some first mover that is not moved by another. Unless someone happens to say that a recurrence takes place in this way: when all the genera and species of movement have been exhausted, a return must be made to the first. For instance, if that which moves in respect of place be altered, and that which causes alteration be increased, then again that which is increased be moved in respect of place. But the consequence of this will be the same as before, namely, that which moves by one kind of movement is itself moved by the same kind, although mediately and not immediately. Ergo relinquitur quod oportet ponere aliquod primum quod non movetur ab alio exteriori. It remains, therefore, that we must postulate some first mover that is not moved by anything outside itself. Quia vero, hoc habito quod sit primum movens quod non movetur ab alio exteriori, non sequitur quod sit penitus immobile, ideo ulterius procedit Aristoteles, dicendo quod hoc potest esse dupliciter. Uno modo, ita quod illud primum sit penitus immobile. Quo posito, habetur propositum: scilicet, quod sit aliquod primum movens immobile. Alio modo, quod illud primum moveatur a seipso. Et hoc videtur probabile: quia quod est per se, semper est prius eo quod est per aliud; unde et in motis primum motum rationabile est per seipsum moveri, non ab alio. Since, however, it does not follow that a first mover that is not moved by anything outside itself is absolutely immovable, Aristotle proceeds further, saying that this may happen in two ways. First, so that this first mover is absolutely immovable. And if this is granted, our point is established, namely, that there is a first immovable mover. Second, that this first mover is moved by itself. And this seems probable, because what is of itself is always prior to what is of another. Hence it is likewise logical in things moved that what is moved first is moved by itself and not by another. Sed, hoc dato, iterum idem sequitur. Non enim potest dici quod movens seipsum totum moveatur a toto: quia sic sequerentur praedicta inconvenientia, scilicet quod aliquis simul doceret et doceretur, et similiter in aliis motibus; et iterum quod aliquid simul esset in potentia et actu, nam movens, inquantum huiusmodi, est actu, motum vero in potentia. Relinquitur igitur quod una pars eius est movens tantum et altera mota. Et sic habetur idem quod prius: scilicet quod aliquid sit movens immobile. But, if this be granted, the same consequence follows (8 Physics). For it cannot be said that the whole of what moves itself is moved by its whole self, because then the absurd consequences mentioned above would follow, namely, that a person might teach and be taught at the same time, and in like manner as to other kinds of movement. And again, a thing would be at the same time in act and in potency, since a mover, as such, is in act, while that which is moved is in potency. It remains, therefore, that one part thereof is mover only, and the other part moved. And thus we have the same conclusion as before, namely, that there is something that moves and is itself immovable. Non autem potest dici quod utraque pars moveatur, ita quod una ab altera; neque quod una pars moveat seipsam et moveat alteram; neque quod totum moveat partem; neque quod pars moveat totum: quia sequerentur praemissa inconvenientia, scilicet quod aliquid simul moveret et moveretur secundum eandem speciem motus; et quod simul esset in potentia et actu; et ulterius quod totum non esset primo movens se, sed ratione partis. Relinquitur ergo quod moventis seipsum oportet unam partem esse immobilem et moventem aliam partem. And it cannot be said that both parts are moved, so that one is moved by the other; nor that one part moves both itself and the other; nor that the whole moves a part; nor that part moves the whole, since the above absurdities would follow—namely, that something would both move and be moved by the same kind of movement, and that it would be at the same time in potency and in act, and (finally) that the whole would move itself not primarily, but by reason of its part. It remains, therefore, that in whatever moves itself, one part must be immovable, and must move the other part.