Disputationes metaphysicae

1. We have said that it pertains to the efficacy of the first cause to conserve all things in being; it follows that we declare whether this is proper to it, and consequently we shall explain the common division of causes into those on which effects depend only in becoming, or also in being conserved. And we shall investigate the root of this diversity, namely, whether it is sufficient that the cause be univocal or equivocal, or, if this is not enough, what it is.

The sense of the question is expounded

2. By various titles one thing can depend on another in its conservation.—First of all, however, it must be noted from St. Thomas, I, q. 104, aa. 1 and 2, that one thing can be understood to be conserved by another in various ways, namely, per se or per accidens. Those things are said to conserve a thing per accidens which protect it from contraries, either by resisting them or by removing them. And in this way it is certain that God conserves one creature by means of another; for an angel can easily conserve a man by turning away a stone, fire, etc.; about which there is no question, because this is not so much conservation as another local change, or alteration, upon which it follows by accident that a thing which already was is not corrupted, and so is conserved. But conservation per se can be subdivided; for one is direct and immediate, which consists in the persevering influx of the very being which was communicated through production; but the other is only mediate or remote conservation, which consists in the influx of some dispositions or forms which are necessary in order that the thing be conserved in being. And St. Thomas above, ad 1, seems to call the former principal conservation, but the latter secondary. Of this latter mode of conservation, then, there is no question, because it is certain that in this way some creatures are conserved by others; for so Aristotle said, XII Metaph., text 34, that the heaven and the sun by their divine motion conserve these lower things. And the reason is that this mode of conservation consists only in the production of some qualities or forms. Hence, just as one creature acts on another, so too it can act on qualities consonant with its nature, by which it may be fittingly conserved.

3. Where two things are to be considered: one is that conservation is properly said of that which is through efficiency, as we are now speaking of it, but is yet extended to the other genera of causes, especially the material and formal, in which way the form is conserved by matter, and matter in its way by the form, and the composite by material dispositions. For this reason, then, matter can be said to be conserved by means of secondary causes, because, although they do not inflow being into it mediately, yet they induce into it forms by means of which it is conserved. And by similar reason he who produces connatural dispositions will be said to conserve the subject, in which way the sun conserves living things by fostering their natural heat. The other thing to be observed is that conservation is sometimes attributed to the individual, sometimes to the species, in which way the species is said to be conserved through the continuous generation of individuals, which is also improper conservation, for it is rather a succession of generations. Hence neither is the discourse about this, because it is established that these generations take place by means of secondary causes. The discourse, then, is of most proper conservation through the direct and immediate continuous influx of being itself in the same singular thing.

Resolution of the question

4. I say, then, first: no created substance depends in being conserved as to its substantial being on a created cause. Capreolus noted this, In II, dist. 1, q. 2, a. 3, ad 4 against the third conclusion, from St. Thomas, q. 5 De Potent., a. 1, ad 7. And it can be shown thus by induction and reason; for in incorruptible things which are made through creation the matter is most clear, as St. Thomas noted, III, q. 13, a. 2, because the conservation of these things takes place through the same persevering action by which they are created. Likewise, because that action by which they are conserved is not from matter, because either the things which are conserved through it do not have matter, but are simple, or, if they have it, such influx is at the same time terminated immediately at the being of the matter itself; and therefore, by the reason by which the creation of these things is proper to God Himself, by the same also their conservation. Which is also true of the prime matter of generable things; for of the conservation which is through the form we have already said that it is mediate and improper. Especially if it is true that the form does not concur properly and a priori to the conservation of matter, but only a posteriori and as it were dispositively, as was touched upon in the foregoing.

5. Moreover, corruptible substances in the first place do not depend in being conserved on created immaterial substances; for these cannot per se effect the eduction of forms from the potency of matter; therefore neither conservation; for the reason of conservation is the same. Likewise they do not depend in being conserved on univocal generators, as is established by experience. And the reason is that they receive their forms perfectly according to species. Likewise, because otherwise one individual of one species according to its being would say an essential or at least connatural relation of dependence in its very being on another individual of the same species, and so either one would have to proceed to infinity, or one would necessarily have to stop in some one or some which would not be conserved in a connatural mode; but both are plainly false, as is established. Again, neither on an equivocal generator, if that too is a generated substance, as is also established by experience; for, although a horse generates a mule, the thing generated does not depend in being conserved on the generator. And in these and similar cases perhaps the reason is that these generations are in some way per accidens, and therefore the effect by reason of its being does not say intrinsic dependence on such cause, but only by reason of such becoming. Another general reason we shall treat at once.

6. The reason of St. Thomas for the conclusion is explained.—Finally these generable substances can be compared to the heavenly and incorruptible composite substances. And so some think that lower substances depend in being conserved on the heaven, which Fonseca indicates without proof as likely, c. 2, q. 9, sect. 2, bk. V Metaph. But St. Thomas denies it above. He gives, however, a rather obscure reason in these words: The action of a corporeal agent does not extend beyond motion, and therefore it is an instrument of the first agent in the eduction of forms from potency into act, which is through motion; but not in their conservation, except inasmuch as through some motion dispositions are retained in matter, by which the matter becomes proper to the form. For thus through the motion of the heavenly bodies lower things are conserved in being. Which reason can be explained in two ways: first, that corporeal agents do not attain the eduction of forms immediately but only dispositively, and therefore cannot be the proper cause of conservation. But this sense is against the principles of St. Thomas and against his mind in that place. For according to that sense the form would depend in conservation in the same way as in eduction on the heavenly body, which however St. Thomas denies. But then it remains difficult why, in that instrumental mode in which a corporeal agent by means of motion is the cause of the eduction of a substantial form, it cannot also be the cause of its conservation. The second sense, then, seems to be that the heaven, because it does not act on the lower except by means of accidents, attains the effecting of the substantial form only instrumentally, and therefore has this efficiency only as long as the previous alteration lasts, because the instrument acts towards the effect of the principal agent only with its own action preceding; when, therefore, the motion of alteration ceases, the action of the heaven about the substance itself ceases. But things of this kind are conserved when the alteration ceases, although they are not generated except by means of it; and therefore they do not depend in being conserved on the heaven as they depend in becoming.

7. And in this sense this reason is probable, and can be declared and confirmed further in this way, because a created substance does not effect another except by means of accidents as instruments; but no substance by its nature depends in its being and being conserved on the efficiency of accidents; indeed universally no effect nobler than the instrument seems per se to depend in being conserved on the action of the instrument, granted that sometimes it depends in becoming, because such agent is not apt to effect such effect except by means of the instrument; as, although the intelligible species is made by means of the phantasm as instrument, it does not depend on it in being conserved, and so of others. And the reason seems to be that the relation to a less noble instrument cannot be founded in the intrinsic nature and need of the effect itself, but at most in the nature or will of the agent, because either it is not sufficient or does not will to act without such instrument. Hence the distinction of St. Thomas, as explained by us above, of the cause of becoming only or also of being itself, fits excellently here. For whenever a cause by means of an imperfect instrument acts a perfect effect, it is the cause of its becoming, not of its being, because it is not likely that such effect by virtue of its being absolutely considered demands such cause in order to be, but at most in order to be made by such genus of production. And therefore such effect never depends on such cause in being conserved. Since, then, the heaven effects no lower substance except in this way, namely through accidents, which are less noble instruments than the substantial effects, therefore, although these substances are sometimes made by the heavens, they do not depend on them in being conserved.

8. Which can be shown thirdly in this way, because the elements, according to their substances, do not depend in being conserved on the heavens; therefore neither can mixed bodies so depend; therefore no corruptible substances so depend on the heaven, because these are only either simple or mixed. The antecedent is proved, both by experience, for fire or water, per se speaking, is equally conserved in the absence or presence of the sun, and however the influence of the heaven is changed; and from the origin, because the heavens and the elements were equally created first; hence the elements per se and by their nature do not depend in becoming on the heaven, but either are first made through creation, or afterwards one is apt to generate another like itself; therefore neither do they depend in being conserved. But the first consequence is proved by parity of reasoning, or even a fortiori, because the forms of mixed bodies are more perfect and of themselves equally permanent. Which experience also confirms, because, although gold is generated by the sun, it is conserved without the presence or actual influence of the sun, and so of others. No substance, therefore, is found which immediately and directly depends in its being on another created substance. Nor do I find a reason which even probably persuades the opposite, which must be answered.

9. Which accidents depend in being conserved on their causes, which not.—I say secondly: accidents do not always depend in being conserved on their causes, even equivocal ones. In univocal causes, indeed, the matter is manifest, both by experience and by the reason made above, which universally proves that an effect never depends on a univocal cause, or one of the same notion, in being, but only in becoming. Of an effect made by an equivocal cause, however, it is evident in heat made by the sun; for it remains when its influx ceases, and the same holds of the other primary qualities which are made by the moon and the other stars. The reason, however, we shall at once inquire.

10. I say thirdly: some accidents depend in becoming and in being conserved on created equivocal causes. This conclusion too is established by experience; for so light depends on the sun or another luminous thing, the intentional species of the external senses on the objects, vital acts on the powers, and universally motion on something actually moving. And so it comes about that only these effects do not depend on God alone in being conserved. I say, however, on God alone, because they also depend on Him immediately in being conserved; for, in the way in which every operation of a creature is also immediately from God, as we shall say below, this conservation too which is made through a creature is also immediately from God; for the reason is the same, since this conservation is a certain operation or efficiency. And so in this there is no difficulty.

11. But there is great difficulty in giving the reason of this dependence; for it is not sufficiently given from the fact that the cause is equivocal and the effect imperfectly participates the power of the cause; for it is established from the preceding assertion that this reason does not suffice in other equivocal effects. Hence it is also difficult to assign a reason why some equivocal effects of created causes do not depend on others in being conserved, but others do depend. Which difficulty St. Thomas touched upon, I, q. 84, a. 1, where he tacitly asks why water heated retains heat when the action of fire ceases, but air does not retain light when the action of the sun ceases. And he only answers: Because the matter of water is receptive of the heat of fire according to the same notion in which it is in fire; but air is not receptive of light according to the same notion in which it is in the sun. This reason, however, does not seem sufficient, because the argument can be turned round; for light caused by fire in the air is not conserved when the action of fire ceases, but heat caused by the sun is conserved; and yet air is receptive of light according to the same notion in which it is in fire, and is not receptive of heat according to the same notion in which it is in the sun. Next I ask what it is for some quality to be received in the patient according to the same notion in which it is in the agent; for it can have two senses: the former is that to be received according to the same notion is the same as to be of the same species; and so the reason does not conclude, both because the heat made by the sun is not of the same species, and also because it is probable that air is receptive of light according to the same notion in which it is in the sun; especially according to the same St. Thomas, who in I, q. 67, a. 3, proves from this that the light of the sun is not a substantial form, because in the air it is an accident. Which reason would not be efficacious unless he supposed that the light of the air and the light of the sun are of the same notion.

12. The other sense is that for a quality to be received according to the same notion is the same as to be produced in the patient conjoined to the same radical principle, that is, to the same substantial form as it was in the agent; which sense St. Thomas rather indicates, when he says: Air is not apt to receive light according to the same notion according to which it is in the sun, and expounds: So, namely, that it receive the form of the sun, which is the principle of light; whence he concludes: And therefore, because it does not have root in the air, the light at once ceases when the action of the sun ceases. And he explains the same sense more in the said q. 67, a. 3, ad 1, where he says that the quality follows the substantial form, and therefore, as the subject is disposed to the reception of the substantial form, so it is disposed to the reception and retention of the quality. Hence he concludes that, if together with the quality the substantial form is received, then it is received firmly and without dependence in being conserved on the created agent; but if it is received imperfectly, that is, by disposing and preparing the matter for such form, then it is also conserved for some time when the action of the agent ceases, yet is easily thrown off; but if the quality is neither received with the form nor disposes to the form, it does not remain at all when the action of the extrinsic agent ceases. From this sense, then, such a reason is concluded; for because heat, whether produced by fire or by the sun, always disposes to the form of fire, therefore it does not wholly depend in being conserved on such agent; but the light of the air formally and of itself does not dispose to any substantial form, whether it is made by the sun or by fire; for air illuminated by anything, if it were not heated, would not be disposed to the form of fire, and therefore it wholly depends in being conserved.

13. But neither does that discourse, explained in this way, seem efficacious. First, because it is not universal; for the act of knowledge depends in becoming and being conserved on the agent, but the habit does not so depend; but neither disposes to a substantial form. Next, intelligible species made by the agent intellect do not depend in being conserved on it, and yet they do not dispose to a substantial form. Moreover, figure, heat, and other similar qualities do not dispose to a substantial form and are permanent qualities, which do not depend on some cause conserving them effectively. Finally, whether a quality disposes to a form or does not dispose seems irrelevant to its depending in being conserved on its agent.

14. Why motion depends on the agent in being conserved.—Others, then, think that the reason must be given only from the intrinsic nature of such qualities or effects, because namely they are such as essentially or connaturally to include dependence on such cause. Which reason needs explanation, lest the whole matter seem to be referred back to the occult nature of the thing, which is not so much to give a reason as to confess one's ignorance of it. For it is true that this dependence is founded on some special condition or nature of such effects; and I think it does not come in all from the same root, but according to the nature of each effect the reason of such dependence is to be sought in it. Thus in motion the reason is easily given why it always depends on an actual agent, because namely its being is not so much being as becoming; since, therefore, becoming cannot be without acting, so neither motion without a mover. And this reason proves of every dependence as such; for that is either a certain becoming or is conservation itself. And therefore by itself it depends essentially or intrinsically on the agent, and such dependence on such agent.

15. Why immanent acts.—And hence too the reason is easily given of immanent acts, if, as many hold, they are only actions and not qualities; for every action by itself is essential dependence on the agent. But because every action has its terminus, and every dependence is the dependence of something, therefore, as we more truly suppose, these acts are certain qualities dependent on their powers. And the reason is excellently given from the nature of such qualities; for they are essentially vital acts, which in order to inform demand a faculty inflowing into them; hence, because naturally they cannot be except by actually informing their proximate and intrinsic principle, therefore also naturally they cannot be unless they are actually from it. Which reason ceases in habits, and besides habits imitate powers; for they are with them principles of acting, and are given to dispose and help the powers themselves; and therefore by their nature they are permanent and independent of the actual efficiency of the powers themselves.

16. Which intentional species depend in being conserved on agents, which not.—Of intentional species, however, the reason cannot be given from their general nature, since we see some depend in being conserved on their proximate agents, but others not at all. And therefore the reason can be given either from the final cause, because some were instituted for knowing only in the presence of the objects, but others to be retained in memory; or further, from these diverse ends it can be understood that the species of the external senses are very imperfect, and are as it were conjoined instruments of their objects, and therefore by their nature depend on their action in being and being conserved; but other species, either sensible or intelligible, are of a more perfect notion, and therefore more independent.

17. The same question is treated of physical qualities.—Of other physical qualities, however, of which alone St. Thomas seems to have spoken in the places cited, his reasons are probable; for these qualities either dispose to the form or follow it. Those which dispose, because by their nature they precede the form, can therefore at least in remiss being precede such form, and consequently can also remain without it; but those which follow the form cannot be unless either they flow intrinsically from it or depend on an agent actually having such form. We can add, moreover, another general reason, that qualities of one species never depend in being conserved on qualities of the same species, on account of the reason made above about univocal causes. And therefore it is very probable that light and the light of the sun differ in species. But a quality which is sometimes made by another superior one distinct in species is sometimes such that, per se speaking, it can be made by another of the same species. And then, although sometimes it is made by the superior quality, it does not depend on it in being conserved. Because, since by its nature it does not demand emanation from that superior cause in order to be, there is no reason why it should depend on it in being conserved, although it is made by it, according to the doctrine given in sect. 1, in explaining the reason for doubting. And hence it is that heat, although it is made by the action of the sun, is conserved without its action, because it is apt to be made by another heat. But when a quality is such that in an extraneous subject it can never be made naturally except by a superior quality existing in a connatural mode in a superior agent, then it is a sign that it depends on the agent in being conserved, because, just as absolutely it needs that emanation in order to be, so it requires a similar influx in order to remain in being; and therefore light in the air is not conserved without the presence of the sun or of another thing which agrees with the sun in the nature of light. And Cajetan indicated this reason, although in other words, defending the reason of St. Thomas, I, q. 104, a. 1, last doubt, and it can be applied to all effects, both substantial and accidental.

The first incidental doubt

18. But two difficulties still remain: the former is that every quality depends on some proximate agent in becoming and being conserved; hence also in heat, when the action of fire ceases, God applies another action by which by Himself alone He conserves such heat, as we said above, which action is such that it is equivalent to the action which the fire had with the common concurrence of God; hence per se that action would be sufficient to produce that heat, if it were not produced, because through it alone God gives being to such heat as the sufficient cause of that being. Whenever, therefore, the action of the proximate cause ceases, the effect cannot be conserved unless God supplies the activity of such cause; therefore either every effect depends in being conserved on its proximate cause, or none, because, if in every proximate cause God wills to supply its absence, the effect will never depend in being conserved on such cause. Or finally a reason must be given why God in some effects so behaves that, the proximate causes ceasing, He Himself continues (so to speak) their conservation, but in others not. Or why the nature of the thing demands this, that one effect be said to depend on its proximate cause in being conserved, and not another.

19. It is unravelled.—To this difficulty it can be answered by denying that, in order to conserve without fire the heat produced by fire, God applies so great efficacy as would suffice to produce heat without fire if it were applied from the beginning, but that only that force which God applies to concur with fire suffices afterwards to conserve the heat produced through fire. And because similar efficacy would not suffice to conserve without the sun the light produced by the sun, therefore an excellent reason is given why, fire being removed, God continues (so to speak) the conservative concurrence of heat, but, the sun being removed, does not continue the conservative concurrence of light. For if, the proximate agent being removed, it were always necessary that God apply greater force, no reason could be given why that greater activity is due to the effect, or certainly why it is due rather more to one than to another; just as we rightly understand why the rational soul is conserved by God separated from the body, but not the soul of a horse, because namely the same activity of God which suffices to conserve the rational soul united to the body suffices to conserve it separated, which is not so in the soul of a horse. But if, to conserve the rational soul outside the body, it were necessary that God apply a greater concurrence by which He would supply the lack of the conjoined body, no reason could be given why such greater concurrence were due to the rational soul, or why it were not also due to the soul of a horse; for that too God could conserve outside the body by applying greater concurrence.

20. This reply, however, neither takes a true foundation nor satisfies even from it. For first it seems impossible that God by His power alone conserve a form in matter, whether it be heat or any other material form, and yet that there not intervene there a total dependence or action per se sufficient to give being to such form, if from the beginning and other things being equal it were to be induced into such matter. For, as has been shown, conservative action is not per se distinct from productive; but that action in the notion of conservation is total and integral, and from sufficient power; therefore it is per se sufficient for the production of that form, if it were not supposed produced. Likewise, because heat, for example, cannot have or retain being unless given by an intrinsic cause sufficient to give such being and operating as such. And as to this the reason is the same of the first instant in which being is received and of any other in which it is conserved, as is evident from the discourse made in sect. 1. But as long as the form is conserved, it retains its whole being; therefore it receives it from some cause as per se sufficient to give such being; but it receives it for that instant from God alone in the notion of efficient, for we suppose that it is effectively conserved by Him alone; therefore God then acts as a cause per se sufficient and total, no longer only in the genus of first cause, as when He concurred with the heating fire, but simply in the genus of efficient cause, even proximate; therefore He applies greater efficacy to such conservation than to the production which took place by means of fire.

21. Add that the prior concurrence and action, at least in the production of the whole heat, took place successively, but the conservation perseveres whole at once by way of indivisible action; it takes place, therefore, in another mode and from greater efficacy. Finally, if in heat we admitted that it is conserved by God alone without greater concurrence than He applied with fire, why could not light be conserved in the same way in the absence of the sun through equal concurrence? Or, if it can, why is this not due to it as to heat? The same difficulty, therefore, remains, even the other principle being admitted. And the reason which has been given in that opinion will have place also if we suppose (what is true) that God conserves each thing through its integral and total activity, in the sense expounded, when He conserves it by Himself alone.

22. The reason of the difference, then, which is demanded in that difficulty, is to be taken from the principle laid down in sect. 1, that sometimes an effect flows from its cause by reason of its being absolutely and precisely considered, but sometimes only by reason of such becoming, which becoming, however, is not adequate to such being, either simply or according to the connatural order. When, then, an effect flows from its secondary cause in the former way, then it does not demand to be conserved by God in the absence of its cause. But when it flows in the latter way, conservation is due by reason of the being itself already received, because, since such being per se does not say order to another cause, it connaturally demands to be conserved by any, even by the first, to which it pertains to conserve whatever has been made according to the connatural mode. But it is otherwise when the order to the proximate cause is wholly per se by virtue of such being; for then to change that order would not be connatural, nor could it be due to a thing having such being. Hence heat (and the same holds of any similar form) does not demand to be made and to receive being from another heat, or another similar proximate agent, by reason of its being precisely considered, because no form which can per se be made by a univocal agent says per se dependence on another by virtue of its being, as was also proved above; but only as to becoming does this dependence intervene from the order of natural causes, which does not extend to the conservation of all things. And therefore heat of itself is indifferent to being conserved by any universal agent; and this is due to it by virtue of its being, after it has once received it. But light is such a form as by virtue of its being demands emanation from light as connatural to itself, hence it cannot be produced by a univocal agent; and therefore without any emanation it is not naturally due to it to be conserved by a superior cause alone. And in every other similar quality depending in being conserved on a proximate agent, some natural property will be found from which one may conjecture that such form by virtue of its being demands emanation from such proximate cause, as was declared above and is most evident in vital acts. And in every material form (that we may by this answer a certain example to the contrary posited above) such a mode of entity is found that by its nature it demands an efficient cause as operating from a presupposed subject, and therefore it does not demand to be conserved by God outside a subject. Which is otherwise in the rational soul, which in order to receive being does not demand action from a subject, and therefore separation from the body does not prevent it from naturally demanding to be conserved; that example, therefore, is not similar, and so the whole proposed difficulty seems to have been satisfied.

Another doubt to be noted

23. The second difficulty is whether between the dependence of an effect in becoming only and in being conserved simply there is some middle dependence, according to which the form remains indeed for some time when the action of the agent ceases, yet gradually fails and finally wholly perishes, if the action of the agent is not repeated. For St. Thomas in the places cited seems so to think of accidental forms which dispose to substantial forms and, before they reach the perfect grade in which they are conjoined to their forms, the action of the agent desists: For then (says St. Thomas) the quality remains for some time, but not always, as is evident in heated water, which returns to its nature. And he gives the reason according to the principles declared above, because an accidental form of this kind is conserved by reason of the substantial form; if, then, the action reaches as far as the production of the substantial form, the disposition will be conserved simply and always; but if the action remains only begun, the disposition can be conserved for some time, but not always. A second example can be of habits, which do not so depend in being conserved on acts that they at once perish when the act ceases; but, according to the opinion of some, they so depend that through the sole cessation from acts they are gradually diminished, and, if it is great, wholly corrupted. A third, and to me more difficult, example is of the impetus impressed on a stone thrown upwards; for it does not cease to be as soon as the activity of the thrower ceases, as is established per se; for it is impressed for this, that it may remain for some time after the contact of the impeller; and yet afterwards it gradually ceases of itself to be without any contrary action of an agent, and finally is consumed.

24. It is explained.—Nevertheless this mode of dependence is to me most difficult to understand, because, when the action of the agent ceases, the dependence of the effect on it ceases, because action and dependence are the same, and differ only in the respects connoted, as has often been said; therefore, if, the dependence being taken away, the thing made still remains in its being even for one instant, so far as concerns the force of the lack of such dependence, it will remain perpetually, if it is not destroyed from elsewhere. The consequence is evident, because there is no greater reason of one instant than of any time. Which I declare secondly thus; for if, when the action of the agent ceases, the form made is conserved for some time, then for that time that form no longer receives being from that agent by which it had been made; therefore it is necessary that it be conserved for that time through another action of a superior agent per se sufficient to inflow that being, according to what was just said in the immediate difficulty; therefore by virtue of that action, per se speaking, it will be conserved for any time whatever, nor can a reason be given why that action of the superior agent should of itself cease. Thirdly, even if someone imagines that that other conservative action, per se speaking, ought to cease, no reason can be given why it should cease by parts or gradually, because this is nothing else than that that form be corrupted successively; but of this succession no natural cause can be given. For, just as a form is not made successively as to intensity except when it is made by one contrary with the resistance of the other, so it does not cease successively except when it is corrupted through the action of a contrary agent, itself resisting; but when it is corrupted through the cessation of the acting cause, it ceases in proportion to such cessation; if, then, the agent has wholly ceased from its action about the whole form and all its grades, how can it cease successively? Or why will one grade cease before another, since the action of the agent has equally ceased in all? But if some succession is to be, the prior grades ought to cease first, because the action of the agent had ceased about them first, if it had produced them successively; but this cannot take place, since the prior are the foundation of the posterior.

25. These reasons, then, seem to convince that there is no middle between the cause in becoming only or wholly in being; for if the cause is such that, its action ceasing, the effect cannot subsist even for a moment, it is the proper cause of the effect in being and being conserved; but if the cause is such that, its action ceasing, the effect can subsist for a moment, it can also always, so far as concerns the force of such cause; and therefore it is only the cause of becoming itself. And so those two members are distinguished by immediate contradictory opposition, in which no middle can be found.

26. By what the heat left in water after the action of fire is corrupted.—Whether a habit is diminished by the cessation of the act.—Of the examples adduced to the contrary, however, the first two are very easy. For heat in water, when the action of fire ceases, is corrupted through positive action by its contrary, itself resisting, and therefore perishes gradually. But if we imagined either that in the water the natural emanation of cold from its form were impeded, or that heat as six, for example, were produced in a neutral subject, from which there would be no contrary action, when the action of fire ceased that heat would always remain in the same subject, nor would it of itself cease to be; for, although it is an imperfect disposition to the form of fire, yet, because simply it does not depend on it in being conserved, it could so always remain, if it were not corrupted from elsewhere. The second example too assumes something false; for through the sole cessation of the act a habit is not per se corrupted or diminished, but only by contrary causes which intervene on that occasion, as St. Thomas declared, I-II, q. 54, a. 3, where in the solution ad 1 he declares that heat ceases in no other way through the cessation of the heater, and tacitly expounds what we cited from I.

27. What is the cause of the diminution of impetus in projectiles.—The third example is certainly difficult, for experience itself seems to teach that that impulse is gradually diminished, because thence it comes about that the motion of the projectile is also gradually remitted and languishes. But from elsewhere the action of a contrary agent by which it is corrupted does not appear. For it would be either the intrinsic form or the gravity of the projectile, and this not, because neither is gravity active of another quality, nor is it itself intensified by emanation, as cold in water, because gravity had not been remitted by the impression of the impetus. Or it would be remitted by the medium resisting and impelling in the contrary direction, and this too cannot be said, both because before the projectile begins to be impelled in the contrary direction the impetus begins to be remitted, and also because, if one impetus were not corrupted except by a contrary, the stone could not throw off from itself all impetus; it is necessary, therefore, that it be taken away by pure privation. Wherefore many deny what this difficulty supposes, namely, that impetus is a quality impressed on the projectile, but say that it is only the contact of the thrower as it were continued through the parts of the medium, as Aristotle seems to have taught at the end of the Physics. Nor are others lacking who think that the very gravity of the projectile is the instrument which the thrower uses by means of contact to impel where he wills. But to me these too are uncertain, because I scarcely understand that motion without an impressed quality, as the philosophers now more frequently teach. Of the mode of corruption of that quality, however, the very philosophers who posit it say nothing, nor do I find anything which satisfies me. We can only say that, although impetus is not corrupted through the proper action of a contrary, yet it ceases after the manner of those qualities which are so corrupted, because it ceases with the contrary resisting or opposing. Thus, because that quality is in a contrary subject, resisting its activity, on account of which alone that quality is impressed by way of instrument, therefore it does not demand to be always conserved there, and because otherwise the subject always resists it and its action, the nature of such thing demands that its conservation gradually cease. Yet this is not on account of a middle dependence on its agent, but on account of the peculiar nature and institution of such quality.