Authors/Thomas Aquinas/physics/L8/lect10

Lecture 10 In that which moves itself, one part moves and the other is moved

Latin	English
	Lecture 10 In that which moves itself, one part moves and the other is moved.
lib. 8 l. 10 n. 1 Postquam philosophus ostendit quod in mobilibus et in moventibus non proceditur in infinitum, sed est devenire ad aliquod primum, quod vel est immobile, vel est seipsum movens; hic ostendit quod etiamsi perveniatur ad primum quod est seipsum movens, quod nihilominus oportet devenire ad primum quod est immobile. Et dividitur in partes tres: in prima ostendit quod movens seipsum dividitur in duas partes, quarum una movet et alia movetur; in secunda ostendit quomodo huiusmodi partes se habeant ad invicem, ibi: quoniam autem movet etc.; in tertia concludit ex praemissis quod necesse est devenire ad aliquod primum immobile, ibi: manifestum igitur ex his et cetera. Circa primum duo facit: primo ostendit quod in eo quod movet seipsum, una pars movet et alia movetur, ex hoc quod totum non potest se totum movere; in secunda excludit alios modos, quibus aliquis opinari posset quod esset aliquid movens seipsum, ibi: quod autem non contingat et cetera. Circa primum tria facit: primo proponit quod movens seipsum non totum movet se totum; secundo probat propositum, ibi: totum enim feretur etc., tertio concludit principale intentum, ibi: hoc quidem igitur movet et cetera.	1050. After showing that in mobiles and movers there is no going on to infinity, but that a first is reached with is either immobile or self-moving, the Philosopher now shows that even if a first that moves itself is reached, it is nevertheless necessary to come to a first which is immobile. This treatment is divided into three parts. In the first he shows that what moves itself is divided into two parts, one of which is mover and the other moved; In the second how these parts are mutually related, (L. 11); In the third that it is necessary to come to a first which is immobile, (end of L, 11). About the first he does two things: First he shows that in a thing that moves itself, one part is mover and the other is moved, because a whole cannot move its whole self; Secondly, he rejects other ways in which a thing that moves itself might be thought to do so, at 1054. About the first he does three things: First he proposes that what moves itself does not totally move itself as a whole; Secondly, he proves the proposition, at 1052; Thirdly, he concludes to the main conclusion intended—end of 1053.
lib. 8 l. 10 n. 2 Quia vero totum et pars locum non habent nisi in rebus divisibilibus, ideo ex probatis in sexto concludit primo, quod necesse est omne quod movetur esse divisibile in semper divisibilia: hoc enim est de ratione continui, omne autem quod movetur est continuum, si per se movetur (per accidens enim moveri aliquod indivisibile non est impossibile, ut punctum aut albedinem). Et hoc ostensum est prius in sexto huius: omnia enim quae ante hunc octavum dixit, vocat universalia naturae, quia in hoc octavo ea quae supra de motu in communi dixerat, incipit applicare ad res. Sic ergo cum id quod movetur sit divisibile, potest in omni quod movetur inveniri totum et pars. Si ergo sit aliquid quod moveat seipsum, erit in eo accipere totum et partem: sed totum non poterit movere seipsum totum (quod est penitus movere ipsum seipsum).	1051. Because whole and part have no place except in things that are divisible, Aristotle, therefore, from what he had proved in Book VI, concludes first that whatever is moved is necessarily divisible into parts that are always further divisible—for this pertains to the very notion of a continuum. Now, whatever is being moved is a continuum, if it is being moved per se (for it is not impossible for an indivisible, for example, a point or whiteness, to be moved per accidens). And this was shown previously in Book VI: for all the statements made prior to Book VIII he calls universals of nature, because in Book VIII he begins to apply to things the statements he previously made about motion in common. Accordingly, since what is moved is divisible, a whole and a part can be found in everything that is being moved. If, therefore, there is anything that moves itself, we shall be able to take a whole and a part in it; but a whole cannot move its whole self, i.e., in its entirety move itself.
lib. 8 l. 10 n. 3 Deinde cum dicit: totum enim feretur etc., probat propositum duabus rationibus: quarum prima talis est. Moventis seipsum simul et semel est unus motus numero: si igitur hoc modo aliquid moveat seipsum quod totum moveat totum, sequetur quod unum et idem erit movens et motum secundum unum et eundem motum, sive sit loci mutatio sive alteratio. Et hoc videtur inconveniens: quia movens et motum habent oppositionem ad invicem; opposita autem non possunt inesse eidem secundum idem. Non est ergo possibile quod secundum eundem motum sit aliquid idem movens et motum. Cum enim aliquid simul movet et movetur, alius est motus secundum quem movet, et alius secundum quem movetur; sicut cum baculus motus a manu movet lapidem, alius numero est motus baculi et motus lapidis. Sic ergo sequetur ulterius quod aliquis docebit et docebitur simul secundum unum et idem scibile; et similiter quod aliquis sanabit et sanabitur secundum unam et eandem numero sanitatem.	1052. Then at (820 257 b2) he proves his proposition with two arguments, the first of which is this: The motion of a thing that moves itself at one time and in one motion is numerically one; if, therefore, a thing should move itself in such a way that the whole moves the whole, it will follow that one and the same will be mover and moved with respect to one and the same motion, whether it be local motion or alteration. But this is seen to be impossible: for mover and moved are mutually opposite, and opposites cannot exist in the same thing with respect to the same. It is therefore not possible that some same thing be mover and moved with respect to the same motion. For when something is at once moving and being moved, the motion according to which it moves is different from the one according to which it is being moved, as when a stick, moved by the hand, moves a stone, the motion of the stick is numerically different from the motion of the stone. Accordingly, it will follow further that someone will be both teaching and be taught at the same time with respect to one and the same knowable thing, and, similarly, that someone will heal and be healed with respect to one and the same numerical health.
lib. 8 l. 10 n. 4 Secundam rationem ponit ibi: amplius determinatum est etc.; quae talis est. Determinatum est in tertio, quod id quod movetur est mobile, scilicet in potentia existens: quia quod movetur, inquantum est in potentia et non in actu movetur: ex hoc enim movetur aliquid, quod cum sit in potentia, tendit in actum. Nec tamen id quod movetur, est ita in potentia ut nullo modo sit in actu; quia ipse motus est quidam actus mobilis inquantum movetur: sed est actus imperfectus, quia est actus eius inquantum est adhuc in potentia. Sed illud quod movet, iam est in actu: non enim reducitur quod est in potentia in actum, nisi per id quod est actu; hoc autem est movens: sicut calefacit calidum, et generat illud quod habet speciem generativam, sicut hominem generat quod habet speciem humanam, et sic de aliis. Si ergo totum moveat se totum, sequitur quod idem secundum idem simul est calidum et non calidum; quia inquantum est movens erit actu calidum, inquantum est motum erit calidum in potentia. Et similiter est in omnibus aliis, in quibus movens est univocum, idest conveniens in nomine et ratione cum moto; sicut cum calidum facit calidum, et homo generat hominem. Et hoc ideo dicit, quia sunt quaedam agentia non univoca, quae scilicet non conveniunt in nomine et ratione cum suis effectibus, sicut sol generat hominem. In quibus tamen agentibus, etsi non sit species effectus secundum eandem rationem, est tamen quodam modo altiori et universaliori. Et sic universaliter verum est quod movens est quodam modo in actu secundum id secundum quod mobile est in potentia. Si igitur totum moveat se secundum totum, sequitur quod idem sit simul actu et potentia; quod est impossibile. Ex hoc ergo concludit principale intentum, quod moventis seipsum una pars movet et alia movetur.	1053. He gives the second argument at (821 257 b6) which is this: It has been determined in Book III that what is being moved is a mobile, i.e., something existing in a state of potency, since what is being moved is being moved precisely because it is in potency and not in act, for a thing is considered to be in motion when, being in potency, it is tending toward act. However, that which is being moved is not in potency in such a way that it is in no wise in act, because the very motion is a kind of act of the mobile precisely as being moved; but it is an imperfect act, being the act of the mobile inasmuch as it is still in potency. But what causes motion is already in act, for what is in potency is not reduced to act except by something in act, namely, the mover; for example, the hot causes heat and that generates which has the form to be generated, as one who has the human form generates a man, and so on for other things. If, therefore, the whole moves its whole self, it follows that the same thing is, with respect to the same, at once hot and not hot, because, insofar as it moves, it will be hot in act; insofar as it is moved, it will be hot in potency. The same is true in all other cases in which the mover is univocal, i.e., agreeing in name and species with the thing moved, as when the hot makes the hot and a man generates a man. And he says this because there are some agents which are not univocal and which do not agree in name and notion with their effects, as the sun generates a man. In such agents, nevertheless, even though they do not possess the form of the effect according to the same notion, they do so in a higher and more universal sense. Consequently, it is universally true that the mover is somehow actually what the mobile is potentially. If, therefore, the whole moves its whole self, it follows that the same thing is at once in potency and in act—which is impossible. From this he concludes (822 257 b10) the main proposition that, with respect to a thing that moves itself, one part is mover and the other part moved.
lib. 8 l. 10 n. 5 Deinde cum dicit: quod autem non contingat etc., excludit quosdam modos, quos aliquis posset existimare in motu moventis seipsum. Et primo ostendit quod moventis seipsum non movetur utraque pars ab altera; secundo ostendit quod pars moventis seipsum non movet seipsam, ibi: at vero neque ipsius primo seipsum et cetera. Circa primum duo facit: primo proponit quod intendit; secundo probat propositum, ibi: neque enim erit et cetera. Dicit ergo primo, manifestum esse ex iis quae sequuntur, quod non contingit aliquid movere seipsum, hoc modo quod utraque pars eius moveatur a residua; sicut si ab moveat seipsum, quod a moveat b, et b moveat a.	1054. Then at (823 257 b13) he rejects certain ways that someone might suppose to take place in the motion of a thing that moves itself. First he shows that with respect to a thing that moves itself, both parts are not moved by each other; Secondly, that with respect to a thing which moves itself, one part does not move itself, at 1059. About the first he does two things: First he proposes what he intends; Secondly, he proves his proposition, at 1055.. He says therefore First (823 257 b13) that it is clear from what follows that a thing can not move itself in such a way that each part is moved by the other; for example, if AB moves itself, that A move B, and B move A.
lib. 8 l. 10 n. 6 Deinde cum dicit: neque enim erit primum etc., probat propositum quatuor rationibus. Et est attendendum, quod ad hanc conclusionem resumit rationes supra positas ad ostendendum quod non omne movens movetur ab alio. Unde ex praemissis abbreviate hic colligit quatuor rationes. Quarum primam sumit ex prima ratione, quam supra posuit duplici ordine, ad ostendendum quod non proceditur in infinitum in hoc quod semper aliquid ab alio moveatur, propter hoc quod non esset aliquod primum movens, quo remoto removerentur sequentia. Unde et hic primo praemittit idem inconveniens. Dicit enim quod si in primo moto quod ponitur movens seipsum, utraque pars ab altera reciproce moveatur, sequetur quod non sit aliquod primum movens. Et hoc ideo, quia sicut supra dictum est, movens prius est magis causa movendi et magis movet, quam posterius movens. Et hoc ideo supra probabatur, quia dupliciter aliquid movet. Uno enim modo movet aliquid ex eo quod movetur ab alio, sicut baculus movet lapidem eo quod movetur a manu; et hoc est secundum movens: alio modo movet aliquid ex eo quod movetur ex seipso, sicut homo movet; et haec est dispositio primi moventis. Illud autem quod movet non eo quod movetur ab alio, magis est remotum ab ultimo quod movetur, et magis proximum primo moventi, quam medium, quod scilicet movet eo quod ab alio movetur. Debet ergo haec ratio sic formari. Si totius moventis seipsum utraque pars movet aliam reciproce, non magis movet una quam alia: sed primum movens magis movet quam secundum: ergo neutra earum erit primum movens. Quod est inconveniens: quia sic sequeretur quod illud quod movetur ex seipso, non esset propinquius primo principio motus (quod nullum sequitur esse), quam id quod movetur ab alio; cum tamen supra sit ostensum, quod movens seipsum sit primum in genere mobilium. Non ergo hoc est verum quod moventis seipsum utraque pars per aliam moveatur.	1055. Then at (824 257 b15) he proves the proposition with four arguments. And it should be noted that for this conclusion he re-uses the reasons previously used to show that not every mover is being moved by another. Hence from the foregoing he here collects four abridged arguments. The first of these he takes from the first argument presented above in a double (i.e., ascending and descending) order to show that the process of something else being moved by another does not go on always, ad infinitum, because then there would be no first mover—from whose non-existence would follow the non-existence of all coming after it. Hence in this place too, the Philosopher premises the same unacceptable outcome. For he says that if, in the first thing moved which is supposed as moving itself, both parts are reciprocally being moved by each other, it will follow that there is no first mover. This follows because, as was said above, the prior mover is more the cause of motion, and moves more, than the subsequent mover. And this was proved above on the ground that something causes motion in two ways. In one way, something moves by being moved by another, as a stick moves a stone, because it is being moved by the hand, and this is a second mover. In another way, something moves by being moved of itself, as a man moves, and this is a condition of a first mover. Now what causes motion independently of being moved by another is farther removed from the last thing moved, and nearer to the first mover, than an intermediate which causes motion as being moved by another. This argument should be formulated in the following way: If both parts of a thing that moves itself move each other reciprocally, one is no more the cause of motion than the other. But the first mover is more a cause of motion than a second mover; therefore, neither of the parts will be a first mover. Now this is unacceptable, since it would then follow that what is moved of itself would be no nearer to the first principle of motion (whose existence would thereby be rejected) than what is moved by another, whereas it was proved above that a mover that moves itself is first in the genus of mobiles. Therefore, it is not true that both parts of a thing that moves itself are moved by each other.
lib. 8 l. 10 n. 7 Deinde cum dicit: amplius, non necesse est etc., sumit duas rationes ad idem, ex una ratione quam supra posuerat ad ostendendum quod non omne movens movetur, ita quod moveri conveniat moventi per accidens. In qua quidem ratione supra duas conclusiones intulit: primam scilicet quod movens contingit et non moveri; alteram quod motus non sit aeternus: et secundum has duas conclusiones, duas hic rationes format. Primo enim dicit quod non necesse est movens moveri nisi a seipso secundum accidens: et est sensus quod nisi accipiatur primum movens moveri a seipso, non erit etiam necesse quod movens primum moveatur secundum accidens; sicut quidam posuerunt quod omne movens movetur, et tamen hoc est ei per accidens. Cum ergo ponitur quod moventis seipsum pars quae movet, e contra aequaliter movetur ab altera, hoc non erit nisi per accidens. Sed sicut supra accipiebamus, quod est per accidens contingit non esse: ergo contingit illam partem quae movet, non moveri. Sic ergo remanet quod moventis seipsum una pars movetur, et alia movet et non movetur.	1056. Then at (825 257 b20) he presents two arguments for the same taken from one he used above when he showed that not every mover is being moved, in the sense that being moved is found per accidens in the mover. In this argument he drew two conclusions above, namely, first, that a mover can happen not to be moved, and secondly, that motion is not eternal. In the light of these two conclusions he now forms two arguments. For he says first of all “it is not necessary for a mover to be moved except by itself according to accident,” the sense of this being that unless the first mover be taken as being moved by itself, it will not also be necessary that the first mover be moved according to an accidents as some posited that every mover is being moved but that its being moved is in it per accidens. When therefore it is supposed that of a thing which moves itself, the part causing motion is equally being moved by the other, this will be only per accidens. But as we conceded above, whatever is per accidens is able not to be; therefore, it is possible for the part which causes motion, not to be moved. Thus, therefore, it remains that of a thing that moves itself one part is moved, and the other causes motion and is not moved.
lib. 8 l. 10 n. 8 Deinde cum dicit: amplius, non necesse est etc., ponit aliam rationem correspondentem secundae conclusioni, quam supra intulerat, scilicet quod sequitur motum non semper esse. Hic autem converso ordine sic arguit. Si necesse est motum semper esse, non necesse est movens cum movet e contrario moveri; sed necesse est quod vel movens sit immobile, vel quod ipsum moveatur a seipso. Huius autem conditionalis ratio ex supra posita ratione apparet. Quia si movens non movet nisi moveatur; et tamen non inest ei moveri nisi per accidens; sequitur quod contingat ipsum non moveri; ergo per consequens neque movere, et sic non erit motus. Sed motum supra ostenderat esse sempiternum: ergo non necesse est movens, cum movet, contra moveri. Et ita non est verum, quod utraque pars moventis seipsum moveatur ab altera.	1057. Then at (826 257 b23) he gives another argument corresponding to the second conclusion that he inferred above, namely, that it follows that motion does not always exist, Here, however, he argues in reverse order. If it is necessary that motion always exist, it is not necessary that a mover, when it causes motion, be moved, but it is necessary that the mover be either immobile or that it be moved by itself. The reason for this conditional is apparent from an argument given above. For if a mover does not cause motion unless it is being moved, and if being moved is only in it per accidens, it follows that it can happen not to be moved. Consequently, it can happen also not to cause motion, and as a result, there will be no motion. But motion was proved to be eternal. Therefore, it is not necessary for a mover to be moved, when it is causing motion, Consequently, it is not true that each part of a thing that moves itself is moved by the other.
lib. 8 l. 10 n. 9 Deinde cum dicit: amplius, si movet motum etc., ponit quartam rationem, quae sumitur ex ratione quam supra posuit ad ostendendum quod non inest per se moventi quod moveatur: quia sequeretur quod esset devenire in hoc, quod movens eodem motu moveretur quo movet, ut supra expositum est. Et ideo hic abbreviando hanc rationem, dicit quod si utraque pars ab altera moveatur, sequetur quod secundum eundem motum movet et movetur: unde sequitur quod calefaciens calefiat, quod est impossibile. Ideo autem sequitur, si moventis seipsum utraque pars ab alia moveatur, quod secundum eundem motum aliquid movet et movetur; quia moventis seipsum est unus motus, et secundum illum oportebit quod pars quae movet moveatur.	1058. Then at (827 257 b25) he presents the fourth argument, which is taken from the argument previously given to prove that it is not essential to a mover that it be moved, because it would follow that we must come to this, that a mover would be being moved by the same motion which it is causing, as explained above. And now abridging this argument he says that, if each part is being moved by the other, it will follow that it causes motion and is being moved with respect to the same motion. Hence, it follows that the heater is heated—which is impossible. Now, the reason why it follows that the same thing is causing motion and being moved with respect to the same motion, when it is posited that each part of a thing which moves itself is moved by the other is that there is in the thing that moves itself just one motion, and it is according to that motion that the part causing motion will itself have to be moved.
lib. 8 l. 10 n. 10 Deinde cum dicit: at vero neque etc., excludit alium modum, scilicet quod moventis seipsum pars seipsam non movet. Et primo proponit quod intendit; secundo probat propositum, ibi: totum enim si movetur et cetera. Dicit ergo primo, quod si accipiatur aliquid quod est primo movens seipsum, non potest dici neque quod una pars eius seipsam moveat, neque quod plures, ita quod quaelibet earum seipsam moveat.	1059. Then at (828 257 b26) he excludes another way, namely, the supposition that the part of a thing which moves itself does not move itself. First he proposes what he intends; Secondly, he proves his proposition, at 1060. He says therefore first that if something that is first moving itself be assumed, it cannot be said either that one part of it moves itself or that a number of parts do so, in such a way that each of them moves itself.
lib. 8 l. 10 n. 11 Deinde cum dicit: totum enim si movetur ipsum etc., probat propositum duabus rationibus: quarum prima talis est. Si totum movetur ipsum a seipso, aut hoc conveniet ei ratione suae partis quae movetur a seipsa, aut ratione totius. Si conveniat ei ratione suae partis, ergo illa pars erit primum seipsum movens, quia illa pars separata a toto movebit seipsam: sed totum iam non erit movens seipsum primum, ut ponebatur. Si vero dicatur quod totum movet seipsum ratione totius, ergo quod aliquae partes moveant seipsas, hoc non erit nisi per accidens. Quod autem est per accidens, non est necessarium: ergo in primo movente seipsum maxime oportet accipere quod partes non moveantur a seipsis. Totius ergo primi moventis seipsum, una pars movebit cum sit immobilis, alia movebitur. Istis enim solum duobus modis possibile esset quod pars movens moveretur, scilicet aut quod moveretur a parte altera quam movet, aut quod moveret seipsam. Unde attendendum est quod Aristoteles, excludendo hos duos modos, intendit concludere quod pars movens in movente seipsum, sit immobilis; non autem quod movens seipsum dividatur in duas partes, quarum una sit movens, et alia mota: hoc enim sufficienter conclusum est per id quod primo ostendit, quod totum non movet seipsum totum. Et sic patet quod non fuit necessarium Aristoteli inducere divisionem quinque membrorum, ut quidam dixerunt: quorum unum membrum sit, quod totum moveat totum; secundum quod totum moveat partem; tertium quod pars moveat totum; quartum quod duae partes vicissim se moveant; quintum quod una pars sit movens et alia mota. Si enim totum non movet totum, per eandem rationem sequitur quod totum non moveat partem, nec pars totum: quia utrobique sequeretur quod aliqua pars mota moveret seipsam. Unde hoc quod totum non movet totum, sufficit ad concludendum quod una pars sit movens et alia mota: sed ad concludendum quod pars movens non moveatur, probat duo alia, scilicet quod pars movens non moveatur a mota, et quod non moveatur a seipsa.	1060. Then at (829 257 b28) he proves this with two arguments, the first of which is that if the whole is being moved by itself, this belongs to it either by reason of a part that is being moved by itself or by reason of the whole. If it belongs to it by reason of its part, then that part will be a first mover that moves itself, because that part separated from the whole will move itself, but then the whole will no longer be a first mover of itself, as was supposed. But if it be said that the whole moves itself by reason of the whole, then it will be only per accidens that some parts move themselves. But what is per accidens is not necessary. Therefore in the mover that first moves itself, it is most important to presume that the parts are not moved by themselves, Therefore, one part of the first mover that moves itself will cause motion, since it is immobile, and the other will be moved. For those are the only two ways in which it is possible that a part which causes motion could be moved, namely, either because that part would be moved by another part which it moves, or because that part would move itself. Hence it should be noticed that Aristotle in excluding these two ways intends to conclude that in a thing which moves itself, the part which causes motion is immobile, but not that what moves itself is divided into two parts, one of which causes motion and the other is moved; for this had been sufficiently concluded, when he first proved that the whole does not move itself as a whole. Accordingly, it is clear that it was not necessary that Aristotle introduce a division of five members, as some claimed: one member of which is that the whole moves the whole; the second that the whole moves a part; the third that a part moves the whole; the fourth that two parts mutually move one another; the fifth that one part is a mover and the other moved. For if the whole does not move the whole, it follows for the same reason that the whole does not move the part, nor the part the whole; because in either case it would follows that a moved part would be moving itself. Hence the fact that the whole does not move the whole suffices for concluding that one part is a mover and the other is moved. But in order to conclude that the part which causes motion is not moved, he proves two other things, namely, that the part causing motion is not moved by a moved part, and that it is not moved by itself.
lib. 8 l. 10 n. 12 Et ad hoc secundum probandum inducit secundam rationem ibi: amplius si tota etc.: quae talis est. Si detur quod pars movens moventis seipsum, ipsa tota seipsam moveat, sequitur per supra probata, quod ipsius partis iterum una pars moveat et alia moveatur: iam enim ostensum est supra quod totum non movet seipsum aliter, nisi per hoc quod una pars eius movet et alia movetur. Sit ergo pars movens moventis seipsum, ab: per rationem ergo praemissam sequitur quod una pars eius sit movens, scilicet a, et alia mota, scilicet b. Si ergo ab moveat tota se totam, ut tu ponis, sequitur quod idem moveatur a duobus motoribus, scilicet a toto, quod est ab, et a parte, quae est a; quod est impossibile. Relinquitur ergo quod pars movens in movente seipsum, est omnino immobilis.	1061. And to prove this last point he presents a second argument (830 258 a3): If it be granted that the motion-causing part of a thing that moves itself moves itself as a whole, it follows through what was proved above that a part of that part causes motion and the other part is moved. For it has been already proved above that a whole does not move itself in any other way than by one of its parts causing motion and the other being moved, So, let AB be the motion-causing part of a thing that moves itself; then by the previous argument it follows that one part of it is a mover, namely A, and the other part, namely B, is moved. Therefore, if AB as a whole moves itself as a whole, as you say, it follows that the same thing would be moved by two movers, namely, by the whole AB and by the part A—which is impossible. It remains, therefore, that the motion-causing part of a thing which moves itself is entirely immobile,