Authors/Thomas Aquinas/physics/L5/lect8

Lecture 8 Contrariety of motions

Latin	English
	Lecture 8 Contrariety of motions
lib. 5 l. 8 n. 1 Postquam philosophus determinavit de unitate et diversitate motus, hic determinat de contrarietate motuum, quae est quaedam diversitatis species, ut patet in X Metaphys. Et dividitur in partes duas: primo ostendit qualiter accipienda est contrarietas in motu, et etiam in quiete; in secunda movet quasdam quaestiones circa contrarietatem praedictam, ibi: dubitabit autem aliquis et cetera. Circa primum duo facit: primo determinat de contrarietate motus; secundo de contrarietate quietis, ibi: quoniam autem motui et cetera. Circa primum tria facit: primo distinguit diversos modos, secundum quos videri posset quod acciperetur contrarietas in motu; secundo removet quosdam illorum, ibi: est autem qui est etc.; tertio assignat verum modum contrarietatis in motu et mutatione, ibi: quoniam autem differt et cetera.	715. After discussing unity and diversity of motions, the Philosopher now discusses contrariety of motions, which is a kind of diversity, as is evident from Book I of Metaphysics. His treatment is divided into two parts: In the first he shows how to understand contrariety in motion and in rest; In the second he raises some questions about such contrariety, at 742. About the first he does two things: First he settles the problem of contrariety of motion; Secondly, about contrariety of states of rest, at 727. About the first he does three things: First he distinguishes diverse ways according to which contrariety of motion might be taken; Secondly, he rejects some of these ways, at 717; Thirdly, he assigns the true way in which motions and changes are contrary, at 722.
lib. 5 l. 8 n. 2 Dicit ergo primo, quod post praedicta determinandum est qualis sit motus contrarius alicui motui; et eodem modo determinandum est de mansione, idest de contrarietate quietis ad motum, et quietis ad quietem. Sed in hoc tractatu hoc primo faciendum est, quod debemus distinguere modos, secundum quos universaliter accipi potest ratio contrarietatis in motibus. Et distinguit quinque modos. Quorum primus est, ut ratio contrarietatis in motibus accipiatur secundum accessum ad aliquem terminum, et recessum ab eodem. Et hoc est quod dicit: utrum contrarius motus sit qui est ex eodem, ei qui est in idem, ut qui est ex sanitate, ei qui est in sanitatem: secundum quam rationem generatio et corruptio videntur esse contraria, quia generatio est motus ad esse, corruptio autem est motus ab esse. Secundus modus est, ut ratio contrarietatis motuum accipiatur secundum contrarietatem terminorum, a quibus incipit motus. Et hoc est quod dicit: aut qui est ex contrariis, ut qui est ex sanitate, ei qui est ex aegritudine. Tertius modus est, ut contrarietas motuum accipiatur secundum contrarietatem terminorum, ad quos terminatur motus. Et hoc est quod dicit: aut qui est in contraria, ut qui est in sanitatem, ei qui est in aegritudinem. Quartus modus est, ut accipiatur motuum contrarietas secundum contrarietatem termini a quo, ad terminum ad quem. Et hoc est quod dicit: aut qui est ex contrario, ei qui est in contrarium, ut qui est ex sanitate, ei qui est in aegritudinem. Quintus modus est secundum contrarietatem ex parte utrorumque terminorum. Et hoc est quod dicit: aut qui est ex contrario in contrarium, ei qui est ex contrario in contrarium, ut qui est ex sanitate in aegritudinem, ei qui est ex aegritudine in sanitatem. Necesse est enim quod contrarietas motuum accipiatur aut secundum unum horum modorum, aut secundum plures: quia non contingit secundum aliquam aliam rationem contraponere motum motui.	716. He says therefore first (530 229 a7) that it is now time to decide how one motion is contrary to another, as well as how rest is contrary to motion and rest to rest. But in this treatment we must first distinguish the ways according to which the idea of contrariety in motions can be taken universally. And he distinguishes five ways. The first of which is that one idea of contrariety in motions is based on one motion approaching a definite terminus and another departing from the name terminus. And this is what he says: “...whether contrary motions are motions respectively from and to the same thing, e.g., a motion from health and a motion to health”. According to this, generation and ceasing-to-be seem to be contrary, because generation is a motion to being, and ceasing-to-be from being. The second way is that the idea of contrariety of motions is based on contrariety of the termini from which the motions begin. And this is what he says: “...or motions respectively from contraries, e.g., a motion from health and one from sickness”. The third way is that contrariety of motions is based on the contrariety of the goals at which they are terminated. And this is what he says: “...or motions respectively to contraries, e.g., a motion to health and a motion to sickness”. The fourth way is to take contrariety of motions according to the contrariety existing between the start of one and the goal of the other. This is what he says: “...or motions respectively one from a contrary and the other to a contrary, e.g., a motion from health and one to sickness”. The fifth way is based upon contrariety on the part of both termini of each motion. This is what he says: “...or motions respectively from a contrary to its opposite and from the latter to the former, e.g., a motion from health to sickness and a motion from sickness to health”. Now contrariety among motions is necessarily based either on one of these five ways or on more than one, for there is no other possible way of one motion being contrary to another.
lib. 5 l. 8 n. 3 Deinde cum dicit: est autem qui est ex contrario etc., excludit duos praedictorum modorum. Et primo quartum, qui accipiebatur secundum contrarietatem termini a quo, ad terminum ad quem; secundo secundum modum, qui est secundum contrarietatem terminorum, ex quibus incipit motus, ibi: neque qui est ex contrario etc.; tertio concludit quomodo se habeant duo modi reliqui ad invicem, ibi: relinquitur igitur et cetera. Dicit ergo primo, quod motus qui est ex uno contrario, non potest dici contrarius ei qui est in aliud contrarium, ut si diceretur quod motus qui est ex sanitate, sit contrarius motui qui est in aegritudinem. Idem enim non est sibi ipsi contrarium: sed motus qui est ex sanitate, motui qui est in aegritudinem, est unus et idem subiecto, sed non est idem esse ipsis, idest differunt ratione, eo modo quo non est idem secundum rationem moveri a sanitate, et moveri in aegritudinem; quia unus importat habitudinem motus ad terminum a quo, alius autem habitudinem eiusdem motus ad terminum ad quem. Non est igitur accipienda contrarietas motus secundum contrarietatem unius termini ad alium.	717. Then at (531 229 a16) he rejects two of these five: First of all the fourth, which based contrariety on the opposition between the start of one and the goal of the other; Secondly, the second, which based contrariety on the opposition between the start of one and the start of the other, at 716. Thirdly, he concludes how two of the remaining ways are related, at 721. He says therefore first (531 229 a16) that a motion which begins at one contrary cannot be called contrary to a motion that tends to the opposite contrary, so as to say that a change from health is contrary to a change to sickness. For nothing is contrary to itself; but a motion from health is one and the same as a motion to sickness, although they differ in thought inasmuch as a change from health is not the same idea as a change to sickness—for one stresses the starting point and the other the goal of the same notion. Consequently, contrariety of motion must not be taken from the viewpoint of the contrariety existing between the start of one and the end of the other.
lib. 5 l. 8 n. 4 Deinde cum dicit: neque qui est ex contrario etc., ostendit quod contrarietas motuum non est accipienda secundum contrarietatem terminorum ex quibus incipit motus. Et hoc tribus rationibus, quarum prima talis est. Duo motus qui in idem tendunt, non sunt contrarii: sed duo motus ex contrariis recedentes, possunt in unum et idem tendere; simul enim accidit mutari, idest aequaliter, ex contrario in contrarium aut in medium, ut postea dicetur; et sic ex utroque contrario contingit in unum medium mutari. Non ergo motus propter hoc sunt contrarii, quia a contrariis incipiunt moveri.	718. Then at (532 229 a20) he shows that contrariety must not be taken from the contrariety existing between the two starting points of two motions: and this for three reasons, of which the first is the following. Two motions that tend to the same goal are not contrary; but two motions that start from contraries can tend to one and the same goal, for a motion can go either to a contrary or to what is intermediate between the contraries, as will be said later. Thus two motions that start from contraries could terminate at the same intermediate. Consequently, motions are not contrary just because they start at terms that are contrary.
lib. 5 l. 8 n. 5 Secundam rationem ponit ibi: sed magis in contrarium mutari etc.; quae talis est. Ex illo accipienda est ratio contrarietatis in motu, quod magis facit motum esse contrarium: sed contrarietas terminorum ad quos motus terminatur, magis videtur esse causa contrarietatis motuum, quam contrarietas terminorum a quibus incipit motus; quia cum dico motus incipere a contrariis terminis, dico remotionem contrarietatis; cum vero dico motus accedere ad contraria, dico acceptionem contrarietatis: ergo non accipitur contrarietas motuum secundum terminum a quo tantum.	719. He gives the second reason at (533 229 a22), which is this. The idea of contrariety in motion must be based on that which more evidently makes the motion contrary, but contrariety between goals at which motions end seems to be a greater cause of contrariety in motions than is contrariety between termini at which motions start. For when I say that motions begin at contrary terms, I am stressing the removal of contrariety, but when I say that motions are approaching contrary goals, I am stressing the receiving of contrariety. Therefore, contrariety of motions is not based solely on the termini at which they start.
lib. 5 l. 8 n. 6 Tertiam rationem ponit ibi: et dicitur autem unusquisque etc.; quae talis est. Ab eo a quo aliquid recipit nomen et speciem, recipit etiam contrarietatem, cum contrarietas sit differentia secundum formam, ut patet in X Metaphys. Sed unusquisque motus magis dicitur, idest denominatur, et speciem recipit a termino in quem, quam a termino ex quo, sicut sanatio dicitur motus in sanitatem, et aegritudo motus in aegritudinem; et hoc etiam supra dictum est. Magis ergo accipienda est contrarietas motuum secundum terminum in quem, quam secundum terminum a quo. Et sic idem quod prius.	720. He gives the third reason at (534 229 a25) and it is this. Things receive contrariety from that from which they take their name and species, for contrariety is a difference based on form, as in clear in Book X of Metaphysics. But every motion gets its name and species from the goal more than from the starting point, as healing is a motion to health and getting sick is a motion to sickness. This point was mentioned before. Therefore, contrariety of motions is taken rather from the goal than from the terminus at which they start. Thus our conclusion is the same as before.
lib. 5 l. 8 n. 7 Deinde cum dicit: relinquitur igitur etc., concludit quod, remotis duobus modis secundum contrarietatem terminorum acceptis, relinquuntur duo alii, scilicet tertius et quintus: quorum unus est secundum solam contrarietatem terminorum ad quos, quem tangit cum dicit qui est in contraria; alius qui est secundum contrarietatem utrorumque terminorum, quem tangit cum dicit et qui est in contraria ex contrariis. Primus autem modus non accipiebatur secundum contrarietatem aliquam terminorum, sed secundum accessum et recessum ab eodem termino. Concludit autem ulterius, quod forte hi duo modi residui sunt idem subiecto, quia illi motus qui sunt in contraria, sunt etiam ex contrariis: sed forte secundum rationem non sunt idem, propter diversas habitudines motus ad terminos, ut supra dictum est. Et exemplificat quod motus qui est in sanitatem, ei qui est ex aegritudine est idem subiecto, sed non ratione. Et similiter qui est ex sanitate, ei qui est in aegritudinem.	721. Then at (535 229 a27) he concludes that having rejected the two ways that were based on the contrariety of termini, there remain two other ways, namely, the third and the fifth. Of these, one is based solely on the contrariety of goals and the other on the contrariety of both sets of termini. Way #1 was not based on any contrariety of termini but on approach and departure from the same terminus. He further concludes that perhaps these two remaining ways are really the same, because motions that tend to contrary goals also start at contraries; but perhaps they are not the same in conception, on account of the various relationships that exist between motions and their termini, as was said above. For example, a motion to health is really the same as a motion from sickness, but they differ in conception. The same is true for a motion from health and a motion to sickness.
lib. 5 l. 8 n. 8 Deinde cum dicit: quoniam autem differt etc., ostendit quomodo accipiatur contrarietas in motu. Et primo secundum quod motus est ad contrarium; secundo prout motus est ad medium, ibi: qui autem ad medium et cetera. Circa primum duo facit: primo ostendit quid facit contrarietatem in motibus; secundo quid in mutationibus, ibi: qui autem est in contrarium et cetera. Circa primum duo facit: primo ostendit propositum syllogismo; secundo inductione, ibi: manifestum est autem et cetera. Ponit autem primo talem rationem. Contrarietas aliquorum accipitur secundum propriam speciem et rationem ipsorum: sed propria ratio specifica motus est, quod sit quaedam mutatio a quodam subiecto affirmato in quoddam subiectum affirmatum, habens duos terminos (in quo differt a mutatione, quae non semper habet duos terminos affirmatos): ergo relinquitur quod ad contrarietatem motus requiritur contrarietas ex parte utrorumque terminorum; ut scilicet proprie dicatur motus contrarius, qui est ex contrario in contrarium, ei qui est ex contrario in contrarium, sicut qui est ex sanitate in aegritudinem, ei qui est ex aegritudine in sanitatem.	722. Then at (536 229 a30) he explains how to take contrariety in motion. First, when the motion tends toward a contrary; Secondly, when it tends toward the intermediate, at 726. About the first he does two things: First he explains what makes for contrariety in motions; Secondly, in changes, at 724. About the first he does two things: First he explains his proposition with a syllogism; Secondly, by induction, at 723. As to the first, he gives this reason at (536 229 a30): The contrariety of things is based on their specific nature and definition. But the specific definition of motion is that it is a change which takes place from a definite affirmed subject to a definite affirmed subject and that two termini are involved—on this point, motion differs from change, which does not always require two affirmed termini. Therefore, we are left with the fact that for contrariety of motion there must be contrariety on the side of both termini. In other words, a motion which goes from contrary to contrary is, strictly speaking, contrary to one that is from contrary to contrary; for example, one that is from health to sickness is contrary to one from sickness to health.
lib. 5 l. 8 n. 9 Deinde cum dicit: manifestum est autem etc., manifestat idem per inductionem. Et primo in alteratione corporali: quia aegrotare est contrarium ei quod est sanari, quorum primus est motus a sanitate in aegritudinem, alius vero ab aegritudine in sanitatem. Hoc etiam patet in alterationibus animae: quia ei quod est addiscere, contrarium est decipi, non ab ipso, sed ab alio. Hi enim motus sunt in contraria ex contrariis; quia addiscere est motus ab ignorantia ad scientiam, decipi autem a scientia ad ignorantiam. Quare autem addit non per ipsum, ostendit subdens, quia sicut in scientia contingit quod aliquis per seipsum acquirat eam, et hoc vocatur invenire; quandoque vero non per seipsum sed ab alio, et hoc vocatur addiscere; ita contingit quod aliquando aliquis decipitur a seipso, aliquando ab alio; et hoc proprie opponitur ei quod est addiscere. Et hoc etiam apparet in motu locali: quia motus sursum est contrarius ei qui est deorsum, quae sunt contraria secundum longitudinem; et motus qui est ad dextrum, est contrarius ei qui est ad sinistrum, quae sunt contraria secundum latitudinem; et motus qui est ante, est contrarius ei qui est retro, quae sunt contraria secundum altitudinem. Sed considerandum est quod hic loquitur de istis differentiis positionum, scilicet de longitudine, latitudine et altitudine, secundum quod sunt in homine: quia sursum et deorsum considerantur secundum longitudinem hominis: dextrum autem et sinistrum secundum latitudinem eius; ante et retro secundum grossitiem eius, quae dicitur altitudo vel profunditas. Item considerandum est quod secundum sursum et deorsum invenitur contrarietas etiam in motibus naturalibus: sed secundum dextrum et sinistrum, ante et retro, invenitur contrarietas in motibus, non secundum naturam, sed secundum motum qui est ab anima, quae movet in has contrarias partes.	723. Then at (537 229 b2) he proves the same by induction. And first of all in bodily alterations: for to fall ill is contrary to getting well. In these two examples the first is from health to sickness and the other from sickness to health. This is also evident in changes that occur in the soul: for to learn is contrary to being led into error (not by oneself but by another). These two motions are also from contraries to contraries, because learning is a motion from ignorance to knowledge, and being deceived is from knowledge to ignorance. He says “not by oneself”, because just as, in the case of knowledge, it is possible for a person to acquire it by himself (and this is called “discovery) or with someone’s help (and this is called “learning”), so also it can happen that a person is led into error sometimes by himself and sometimes by another. It is the latter that is properly opposed to learning. Continuing, we take an example from local motion: for an upward motion is contrary to a downward (and these are contraries in respect of length); a motion to the right is contrary to one to the left (and these are contrary in respect of breadth); and a motion to the fore is contrary to one to the rear (and these are contrary in respect of depth). But notice that Aristotle is here speaking of differences of position as they apply to man: for up and down are measured in respect to man’s length; left and right in respect to his breadth; fore and after in respect to his thickness, which is called height or depth. Moreover, it should be noted that even in natural motions, there is a contrariety based on up and down; but in regard to right and left, or fore and aft, the contrariety is not according to nature but according to motions that originate from the soul, which has motions toward these contrary directions.
lib. 5 l. 8 n. 10 Deinde cum dicit: qui autem est in contrarium etc., ostendit qualiter sit contrarietas in mutationibus. Et primo ostendit quomodo accipiatur contrarietas mutationum in rebus, in quibus invenitur contrarietas; secundo quomodo accipiatur in rebus, in quibus non est contrarietas, ibi: quibus autem non est contrarium et cetera. Dicit ergo primo, quod si accipiatur contrarietas solum ex parte termini ad quem, ut dicatur contrarius qui est in contrarium, hoc non facit contrarietatem motus sed mutationis, quae est generatio et corruptio; sicut fieri album et fieri nigrum contraria sunt. Nec oportet quod contrarietas harum generationum attendatur secundum contrarietatem termini a quo; quia in generatione terminus a quo non est aliquid affirmatum, sed aliquid negatum; fit enim album ex non albo, non autem ex aliquo affirmato. Non enim mutatio de subiecto in subiectum est mutatio, sed motus.	724. Then at (538 229 b10) he shows how there is contrariety in changes. First he explains how to take contrariety of change in things in which contrariety is found; Secondly, how to take it in things in which there is no contrariety, at 725. He says therefore first (538 229 b10) that if contrariety is taken merely from the goal so that what tends to a contrary is said to be contrary, such a process does not make for contrariety of motion, but of change, which is generation and ceasing-to-be, as becoming white and becoming black are contrary. Now the contrariety of these instances of generation is not based on the contrariety of starting point; because in generation the starting point is not something affirmed but something negated, for the white comes to be from the non-white and not from something affirmed. For a change from subject to subject is not change but motion.
lib. 5 l. 8 n. 11 Deinde cum dicit: quibus autem non est contrarium etc., ostendit quod in illis, in quibus non est contrarietas, sicut in substantiis et aliis huiusmodi, accipitur contrarietas mutationum secundum accessum et recessum ab eodem termino. Et hoc est quod dicit, quod in illis in quibus non est contrarium, accipitur contrarietas mutationis ex eo quod est recessus ab ipso, et quod est accessus in ipsum idem; sicut accessus ad formam ignis, quod pertinet ad generationem ignis, et recessus ab eadem forma, quod pertinet ad eius corruptionem, sunt contraria. Unde generatio contraria est corruptioni, et quaecumque remotio cuicumque acceptioni. Sed huiusmodi non sunt motus, sed mutationes. Patet ergo quod ex quinque modis supra positis, duo, scilicet secundus et quartus, ad nihil utiles sunt; unus autem convenit ad contrarietatem motuum; duo autem congruunt ad contrarietatem mutationum.	725. Then at (539 229 b11) he shows that in things in which there is no contrariety, for example, in substances and the like, contrariety of change is based on approach and departure from the same terminus, as accession to the form of fire, which pertains to the generation of fire, and receding from the same form, which pertains to its ceasing-to-be, are contraries. Hence generation is contrary to ceasing-to-be and any loss is contrary to any gain, But these are changes, not motions. It is evident, therefore, that of the five ways listed above, the second and fourth are of no use; one of the remaining is suitable for knowing contrariety of motions, and the other two are suitable for contrariety of changes.
lib. 5 l. 8 n. 12 Deinde cum dicit: qui autem ad medium etc., determinat de contrarietate motus ex parte medii. Et dicit quod in quibuscumque contrariis invenitur medium, motus qui terminantur ad medium, hoc modo ponendi sunt esse contrarii, sicut illi qui terminantur ad contraria: quia motus utitur medio sicut contrario, ita quod ex medio contingit mutari in utrumque contrariorum. Sicut ex fusco, quod est medium inter album et nigrum, hoc modo mutatur in album, ac si mutaretur ex nigro in album; et e converso ex albo sic mutatur aliquid in fuscum, ac si mutaretur in nigrum; et ex nigro sic mutatur in fuscum, ac si mutaretur in album: quia fuscum, cum sit medium ad utrumque extremorum, dicitur utrumque; quia in comparatione albi est nigrum, et in comparatione nigri est album, ut supra dictum est. Ultimo autem concludit quod principaliter intendit, scilicet quod motus sit contrarius motui secundum contrarietatem utrorumque extremorum.	726. Then at (540 229 b14) he decides about contrariety of motion from the viewpoint of the intermediate between contraries. And he says that wherever a pair of contraries admit of an intermediate, motions to that intermediate must be held to be somehow motions to one or other of the contraries, for the intermediate serves as a contrary for the purposes of motion, no matter in which direction the change may be. For example, grey in a motion from grey to white takes the place of black as starting point, but in a motion from white to grey, it takes the place of black as goal. For the middle is, in a sense, opposed to either of the extremes, as has been said above. Finally, he concludes what he mainly intended; namely, that motions are contrary to one another, only when one is a motion from a contrary to the opposite contrary and the other is a motion from the latter to the former.