C. Rejection of the Instance

446. [From authorities] - The first authority is Aristotle Physics 8.4.255b19-31, where, in solving the doubt about heavy and light things, he says that ‘potency is said in many ways, hence it is not evident what a heavy thing is moved by’. Now he distinguishes ‘potency’ into potency for first act and potency for second act (as is plain about potency for knowledge and potency for actual consideration of knowledge), and when applying it to the issue at hand he says that ‘fire is in essential potency to becoming cold, namely insofar as water is generated from it - but when water has been generated, it is in accidental potency to making something cold, unless it be impeded’.

447. Thus too does he himself say about the heavy and light [Physics 8.4.255b8-12]: “For the light comes from the heavy, as water from air; but when it is already light it will at once operate, unless it is prohibited; now the act of a light thing is to be somewhere and to be upwards, but it is prevented when the contrary is present in it.”

Here there is no validity to the exposition that, since it is actually light, it is actually light such that going upwards is the feature of light, because then to say that ‘it is actually light’ is the same as to say ‘because it is actually light, it goes upwards’, which is nothing other than a causal statement. For he says that ‘it will at once operate, unless it is prohibited’, which cannot be understood of the actually light in first act, because the act of a light thing in this way cannot be prohibited or prevented while it is actually such. Likewise, he says that ‘it is prohibited when it is in the contrary place’; but a light thing is not non-light ‘because it is in a contrary place’. Therefore he means this of second act, namely that ‘its act is to be somewhere’ - that is, that its act, which is upwardness, is its operation. Therefore, just as fire when it has heat as first act is truly and effectively disposed toward heating (which is second operation), so also fire actually existing light is effectively disposed to being upwards, or to the second operation whereby it exists upwards.

448. The same in Physics 4.9.217b16-18 about the vacuum, for he says that ‘two contraries accompany the dense and the rare, namely the heavy and light and the hard and soft’ - and when speaking of the contrariety of the heavy and light he says that “according to this contrariety they will be active in motion, but according to hard and soft they will be passive.”     Therefore etc     .

449. And if you say that that is not his intention (although the words sound that way), because when, in On Generation 2.2.329b18-22, he enumerates the active qualities, he excludes the heavy and light from qualities that are truly active and passive - I reply:

I say that by what he says in On Generation 2 he would contradict himself in Physics 8 [n.445] if he did not understand the matter there differently from here; for in Physics 8 he says, the way it is cited on their behalf, that ‘natural things have a principle not of acting but of undergoing’ - but in On Generation 2 he says that “heavy and light are neither active nor passive,” and his proof there is plain.

450. Therefore he is speaking in one way about action and passion in Physics 8 and where discussion about action and passion occurs, and in another way in On Generation 2 and where discussion about generation occurs; for just as in the Physics he is speaking in general and universally about motion while in On Generation he is speaking about motion toward form, so too in Physics 3 he is speaking of action and passion in general and universally - and thus what he says in Physics 8 is true, that ‘they have a principle of undergoing’, namely with respect to local motion; but in the book On Generation he is speaking of action toward form where agent and patient are contraries (which indeed is true of univocal actiona), and these are equivocal at the beginning, and at the end are alike with univocal likeness (in equivocal action the agent is alike in form to the produced thing with equivocal likeness, as he himself concedes in On Generation 1.7.324a34-b1, that some agent does not communicate with the thing that undergoes, as neither does medicine with the healed body).

a.a [Interpolation] wherein agent and patient are dissimilar and contrary at the beginning and similar at the end.

451. Now in this way [sc. by understanding action as motion toward form] he denies in On Generation 2 that heavy and light things are principles of acting or doing and also of undergoing - and this is what the wording of his reason expressly says, that they are ‘not principles of acting on other things nor of suffering from other things’; and therefore they are not principles of producing something according to some substantial form (and of this producing he is there speaking), nor are they principles of suffering from some agent correspondent to such action. But they are passive principles in some way with respect to local motion to a ‘where’, and in some way active principles with respect to the same - both of which he himself expressly says in Physics 8, that they are passive in that ‘natural things have in themselves a principle of undergoing’ [n.445], and that they are active in that he said the operation of a light thing is ‘to be somewhere’ [n.447], as the operation of a knower is to consider [n.446].

452. The authority of the Commentator, On the Heaven 3 Com.28, could also be adduced for this purpose: “In the case of simples,” he says, “mover and moved are the same in idea but different in manner; for a stone moves itself insofar as it is actually heavy, and it is moved insofar as it is potentially in a lower place; for it is found in one way to be actual and in another way to be potential - and the cause of this is that it is composed of matter and form.” But he seems to speak of this variously, for in the same place he seems to mean that a stone ‘moves itself per accidens, by pushing the medium in which it is, as a sailor moves himself by moving the ship on which he is’ - and for this reason his authorities are not much to be relied on.

453. [From reasons] - There are reasons for this conclusion.

The first is of the following sort: every effect has, when it is actually caused, an actual cause (this is plain from Aristotle Physics 2.3.195b17-20 and Metaphysics 5.2.1014a21-23, the chapter on cause: ‘The efficient cause in act and the caused in act are and are not at the same time’; it is also plain - if there were no authority - from manifest reason, because what is not, when it is not, does not bring anything into being); therefore when the descent of a heavy thing is actual, then there is something actually causing it.

454. But this descent is not actual from something that removes an impediment. Nor consequently is it the heavy thing’s relation downwards, ‘because what impels it moves it per se downwards’, for in this respect the heavy thing is as it were the remover of an impediment - and such a mover, according to the Philosopher in Physics 8.4.255b24-27, is as it were a per accidens mover; and there must, in addition to a per accidens mover, be a per se efficient cause, because everything per accidens has to be reduced to something per se.

455. Nor can this per se cause be the center pulling it, because if per impossibile there were nothing heavy in the center but the whole earth were removed from it (and the center remained, as before, under the relation of being the center), the heavy thing would still tend naturally to the center. - What then is pulling it? Is it the ‘where’? Manifestly not because the ‘where’ is not an active form.

456. Nor too is it the influence of the heaven, because to have recourse to a universal cause seems a subterfuge - it is to deny particular effects and particular causes; also the influence of the heaven (as far as concerns itself) is uniform in the whole medium, so there is no reason for it to move one part upwards in the whole medium and another part downwards unless a particular determining agent is posited.

457. Nor can the ‘actual mover’ (when it is actually moving) be posited to be the actual moved heavy thing, because nothing univocally moves itself toward what it possesses - and for this reason motion is something extrinsic to the heavy thing; nor can what generates the heavy thing be the actual mover, because it can at that point not be.Tr. The generator of a heavy thing need no longer exist when the heavy thing is actually in motion downwards, so that the generator cannot be the actual mover of it at that time. ³⁸ Therefore it must be something intrinsic.a

a.a [Interpolation] to the heavy thing, or it must be the heavy thing through something intrinsic to it.

458. It is said that the generator [of the heavy thing] remains virtually in the heavy thing, and that in this way it moves the heavy thing [cf. 1 d.17 n.89]. - On the contrary: it does not remain virtually save as a cause remains in its effect, and what remains thus does not remain in itself but only because it remains in its effect - and then its virtue in respect of the motion pertains to the genus of efficient causality. For if the generator is said to bring something about, and if it does not bring anything about save as it is in act, it must needs bring something about because it brings about what is virtually the efficient cause, and in this way the proposed conclusion still follows.a

a.a [Interpolation from Appendix A] Again, if the generator remains virtually in the heavy thing, then either in its own virtue and or in that of its effect, because acting presupposes being. If it remains only by virtue of its effect, namely the heavy thing, and it is thereby cause of the motion of the heavy thing, then the heavy thing moves itself.

459. Besides, what does not move another save by being first naturally moved by something else [e.g. as a stick does not move a stone save by being first moved by the hand] gets from the same thing the fact that it moves and that it is moved; but a heavy thing that has a light thing tied to it (and whose lightness is not greater than the heavy thing’s heaviness) moves that same light thing by drawing it with itself toward the center - and it only moves because it is moved; therefore it is moved naturally first before it moves. And it is moved by the same thing as that which is tied to it is moved by; but it moves what is tied to it by something else, namely by its heaviness; therefore it moves itself in the same way.

460. A confirmation can be given for this reasoning because, when something has active power with respect to some form, it can cause that form in any passive thing proportioned and proximate to it; but a heavy thing has active power with respect to a ‘where’ downward, just as it does with respect to what it pulls along with it, and it itself -when it is outside the place downward - is receptive of that form, which it lacks, and it is proportionate and proximate to itself; therefore it can cause that form in itself.

461. This can also be sufficiently plain if one considers that rest requires a cause actually causing it just as motion does; for then one should posit a cause naturally causing coevally with a heavy thing the rest of the heavy thing; but there is no such cause causing rest coevally with the heavy thing save the heavy thing, and so the heavy thing is causing with efficient causality - and so it is causing the motion toward that rest, because these two [sc. motion and rest] are from the same cause.

462. Further, a heavy thing - when prevented from moving - removes what is preventing it if its heaviness is superior to the virtue of the impeding or resisting thing; to wit, if it is placed on something continuous [e.g. a wooden plank] and its heaviness is superior to the nature of the continuity, it breaks it and by thus getting rid of the continuity it gets rid of what impedes its going downward. Now this breaking, since it is a forced motion, must have some existing extrinsic cause for it, and to suppose there is any cause other than the heavy thing itself does not seem rational; but the heavy thing does not break the continuous object save because it aims to put itself in the center; therefore it has the putting of itself in the center from the same principle as that from which it has the removing of the impediment.

463. This could also be made clear in another way, because the heavier object moves more quickly, and yet the same generator could generate something heavier and something less heavy, and these two could be at the same distance from the center and under the same influence of the heaven; therefore the difference of motions in them is from something intrinsic to them.

464. Again “natural motion becomes more intense at the end,” according to the Philosopher On the Heaven 1.8.277b5-7, and it would be difficult to assign a cause for this if the efficient cause of this motion were precisely something extrinsic.

465 [Response to the statements of Aristotle] - I reply then to Aristotle, who is adduced for the contrary view [n.445], that he is in my favor (the way I have adduced him [nn.446-448]) - that the heavy thing does effectively move itself, as a knower moves himself effectively to an act of thinking. And I understand this as follows: just as a thing that has a form, which is of a nature to be the principle of some univocal action, can act by that form on what is receptive of the form and proportioned and proximate to it, so too a thing that has a form, which is of a nature to be the principle of some equivocal action, can by it act on what undergoes and is proximate to it; and if the thing itself is receptive of the equivocal action or equivocal effect and lacks it, then it will, by the fact it is itself most proportioned and proximate to itself, not only be able to cause this effect in itself but will supremely cause it. So also is it in the case of the issue at hand, that a stone which is up above is in potency to a ‘where’ down below, but heaviness with respect to that ‘where’ is an active equivocal principle, just as there is only need universally with respect to a ‘where’ to posit an equivocal principle (for a mover moves a movable to a ‘where’ not because the mover is formally in act with respect to that ‘where’, but merely because it is virtually so). Therefore, because the heavy thing is itself receptive of the equivocal effect and lacks it, so it causes that effect in itself first, and causes it in no other thing save by causing it first in itself, such that its causing it is the operation of the heavy thing - as Aristotle says [Physics 8.5.257b9] - the way heating is the operation of a hot thing. But the fact that it causes the effect in itself is accidental to it insofar as it is active (because it is itself receptive with respect to this causing, or with respect to this causability); this could be understood if the heavy thing - while remaining up above -could propel itself, or something else, to the center; no one in that case would then doubt how a heavy object is the principle of descent in something else; and it is not less an active cause now of its own descent.

466. However, because of what the Philosopher says [n.445, that natural things have, in respect of motion, only a principle of receiving and not of acting], I add further that this motion is ‘natural in itself’ not by the fact that it has an active principle in itself, but only by the fact that the movable thing has an intrinsic passive principle naturally inclining it to motion. - This is plain from the definition of nature in Physics 2.1.192b20-23, that it is “a principle of motion in that in which it is per se and not per accidens” (for nothing is a principle of moving for anything save insofar as it is per se in that which is moved; but it is not per se and first in anything that is moved save insofar as it is passive; therefore it is not anything by nature nor a natural principle of anything save because it is a passive principle in the thing moved). This is plain because something is naturally moved for this reason, that it is moved as it is of a nature to be moved.

467. Thus it is in the case of the issue at hand, so that, although here (as in the case of many other things) an active principle is the principle of moving, yet not because of that active principle of moving is it moved naturally, but because of the passive principle because of which it is thus moved. And this is what the Philosopher subjoins (after he has said that “the act of a light thing is to be somewhere, upwards” [n.447]): “And yet,” he says [Physics 8.4.255b13-15], “the question is raised why they [sc. light and heavy things] are moved to their places.” And he says pointedly ‘to their places’, that is, that they are naturally moved to those places, “because they are of a nature to be there,” that is, they have a natural inclination to that ‘where’. And in this way he adds afterwards that “they have only a principle of undergoing and not of doing” [n.445], namely in respect of motion insofar as it is natural - and so, in this solution of this doubt about the motion of heavy things, he says there by the by of the natural principle of this motion, and of the efficient principle of it, that it is only passive.

468. Now Aristotle’s reasons [n.445] do not conclude against me, for the first three (which have the same force) show that the heavy object does not move itself the way what acts by thought moves itself; for an animal could not move itself short of the intended ultimate end - nor even could it direct itself or stop itself - unless it acted by knowledge. And from this is got the Philosopher’s proposed conclusion, that these things [sc. heavy and light things] are not movers first [sc. do not move themselves] - for a first mover moves by knowledge (because “to guide is the mark of the wise man” [Metaphysics 1.2.982a17-18]), as was shown in the third distinction of the first book about the knowledge of God, and in the second distinction of the same book about the being of God [1 d.3 nn.261-268, d.2 nn.76-78].

469. Also, his fourth reason [n. 445] does not draw its conclusion about the continuous precisely as the continuous is some quantum. But it proves it relative to the continuous - namely because the continuous has the same disposition in every part of itself - that a heavy object does not move itself effectively, because there is not one part of it in act able to make another part of it to be in act according to the same quality, in the way he himself states in On Sense and the Sensed Thing [6.447a3-4; n.299 above]. And I concede that in this way an actually existing part of the heavy object does not cause motion to be in another part; but the whole heavy object is in act according to first act, and it causes in itself second act.

470. But if you object, ‘how will Aristotle, if he concede that a heavy object is thus moved effectively by itself (although not by knowledge, nor even because its naturalness is from it insofar as it has an active principle) - how will he get his principal conclusion, that these things [heavy and light things] are necessarily moved by another -which is something he intends principally to prove [n.445]?’ - I say that he gets this conclusion sufficiently from a distinction of power [n.446]. For these things [sc. heavy and light things] do not reduce themselves from second potency [sc. accidental potency, n.446] to act unless they have first been reduced from first potency [sc. essential potency, n.446] to first act, or at least could be reduced to first act; and I assert this of all the elements, which are all - according to him - ungenerable and incorruptible, and yet, because they are of the same nature as their parts are, it is not repugnant for them to be reduced from first potency to first act in just the way their parts are reduced. So it follows that, although the heavy and light thing move themselves from second potency to second act, yet a movable thing is, or is moved, from first potency to first act by something else outside it; for it is not necessary that ‘if everything that is moved is moved by another’, that it is moved by another in the case of every motion - and the first point [sc. everything that is moved is moved by another] is enough for the Philosopher, because thereby deduction is made to something ‘other than all these things’, which something other cannot be moved by another either in one motion or in any motion but it is altogether ‘an unmovable mover’ [Physics 8.5.256a13-258b9].

471. It can also similarly be said that even if heavy and light things are - in the case of this motion - moved effectively by themselves, yet they are not moved as they are by first movers; from the fact too that they do not move by knowledge, the consequence follows that they presuppose something that does move thus by knowledge - and so, although they do effectively move themselves yet they do not do so without being moved by another, although not as they are by a proximate cause.