Disputationes metaphysicae

1. This question is treated ex professo by Aristotle, concerning physical motions, in VII Phys., c. 2; yet the question is more universal and properly metaphysical, for it embraces every efficient cause. Hence it is commonly treated by theologians both of God, I, q. 8, and In I, dist. 37, and of angels, I, q. 52, and In I, dist. 37, and In II, dist. 2; we, however, are dealing here with finite causes, for of God we shall speak later. The question, however, is treated of transient action by which one thing acts on another; for in immanent action, and whenever a thing acts on itself per se primo, that is, according to the same part, it is clear that the agent cannot be distant from the patient; but when one supposit acts on another, or the same supposit through one part on another, they can either be immediately near, or some body, or part of a body, or some space can be interposed between them. And there is no doubt among philosophers that an efficient cause can act on a distant thing through a near one; but the difficulty is, when the cause acts proximately and immediately through the power which it has in itself, and not through another which it diffuses, whether it must immediately touch by its quantity or presence that thing on which it acts, or whether it can act immediately on it even though it is distant in space. With which difficulty another is conjoined, namely, when the cause acts through a near, undistant thing, how through the near it attains the distant.

The first opinion is reported and founded

2. There are, then, two celebrated opinions on this matter. The first is that the efficient cause can act on a distant patient, and so immediate nearness is not required, but only that it be within a certain sphere of activity; for there is no doubt that a finite power has a certain terminus in space or distance which it can attain, because, as is established by experience, a thing acts more strongly on what is near than on what is distant. Greater power, therefore, is required for acting on a distant thing; since, therefore, the power is finite, it also has in this a limited sphere, in which all agree; yet within it, this opinion says, the agent can immediately effect in a distant patient. Avicenna holds the same, in his book On the Soul, sect. 4, c. 4, citing Hippocrates for the same opinion. Likewise Alexander of Aphrodisias, I Metaph., comm. 18; Scotus, In I, dist. 37, and there Ockham, and Gabriel, Bassolis, Mayronis, and other Scotists. Although Scotus confesses of physical causes that they never act on a distant thing through one form or quality without acting on what is near through another, although it is not necessary that they attain the near and the remote through the same one; whether this is said consistently we shall see later.

3. The preceding opinion is founded on various experiences.—This opinion is proved, however, by an induction made through all the genera of actions. First, in substantial generation: the sun generates in the earth various mixed bodies, such as minerals, or also animals which are generated from putrefaction; but that action must flow immediately from the substantial form of the sun, for the accidents diffused through the medium either do not attain substantial generation or do not suffice for it.

4. Secondly, in the motion of alteration there seem to be certain things which alter a distant thing without altering the near one. The first example commonly adduced is of the imagination, which is said to have efficacy to induce a new quality by altering a distant member or another thing, as Avicenna hands down above from Hippocrates. The second example is of the fascination of the eye; for the eye sometimes harms by altering a distant thing, as experience bears witness of the eyes of some women, as Aristotle too notes, sect. 20, Problem 34; Alexander, bk. II of the Problems, at 50; Albert, bk. XXII De Animal., c. 5; Marsilio Ficino, bk. XIII On the Immortality of the Soul, c. 4; and of the basilisk Isidore affirms, bk. XII of the Etymologies, c. 4, that it kills serpents by its smell, slays a man by its look, and harms flying birds although they are far distant. Pliny reports almost similar things, bk. VIII of the History, c. 31, where he attributes the same power to the catoblepas, that it kills a man who sees its eyes; and in c. 22 he similarly says that the sight of wolves is harmful and for the moment takes away a man's voice. The third example can be of the torpedo fish, which numbs the hands of fishermen from afar; and Aristotle, bk. IX of the History, c. 37, says: The torpedo fish affects those it seeks with the faculty of numbing which it has in itself, and so it catches them and feeds on them, and for this it hides itself in sand and mud. Which is a sign that it does not act through the medium; and in the same place he reports other similar experiences. Pliny reports the same, bk. XXXII, c. 1, where he expressly says that the torpedo does this from a distance and from afar, even if it is not touched by a spear or rod. Let the fourth example be of a certain herb named aproxis, whose root catches fire from afar, as Pliny reports, bk. XXIV, c. 17, where he reports the same of naphtha, a certain kind of bitumen, of which the same Pliny speaks, bk. II, c. 108. Fifthly, it often happens that a distant thing is more vehemently altered than a near one; therefore it is a sign that the agent by its own force acts immediately on the distant thing; for through a quality which is remiss in the medium it could not effect a more intense quality in the extreme. The antecedent is evident from many experiences; for fire heats the water existing in a cauldron more vehemently than the bottom of the cauldron, and makes oil placed on paper boil much more vehemently than the paper, and heats tow at some little distance so much more intensely than the intermediate air that sometimes it inflames it; and the sun heats a mirror or the earth more vehemently than the intermediate air. Nor is it to be wondered that an agent sometimes acts more on a distant thing than on a near one, if the disposition of the patient is unequal. And this very thing is confirmed by other examples; for the sun illuminates more clearly those parts of the air which it reaches or regards through a window by a straight line than those which are to the side or at an oblique line; therefore it is a sign that it does not illuminate those which are directly opposite only through the parts of the intermediate air, but immediately through itself. The consequence is evident, because with respect to the parts of the intermediate air the other parts of the air, whether they are directly opposite the sun or only to the side, are equally near and equally applied; if, therefore, the illumination of the remote parts takes place only by means of the near part, the remote parts which are equally neighbouring to the nearer will be equally illuminated, even if they have a diverse aspect with respect to the sun; for that part, so far as concerns itself, acts equally towards every part near to it. A similar experience is of the hand or another thing exposed to fire or the sun through the window of a furnace, for example, which feels a more vehement heat when directly exposed to the fire than when placed to the side, even if with respect to the intermediate air it is equally near; therefore it is a sign that the fire immediately attains the distant hand if it is directly opposed through an unimpeded medium. A sign of which also is that if something is interposed or the window of the furnace is closed, the vehement sensation of heat which came from the action of the fire suddenly ceases, and yet the medium still retains all the heat which it had conceived; therefore it is a sign that the action came immediately from the fire, and not only from the medium.

5. Thirdly, experiences are principally brought concerning local motion, which takes place in various ways from a corporeal mover (for of the incorporeal I shall speak below), namely, by pushing, pulling, carrying and rolling. And concerning pushing, the experiences of projectiles are commonly brought, and of heavy and light things, whose motions are reduced to pushing, as St. Thomas notes, VII Phys., c. 2. But they are of no weight; for the proximate instrumental principle of that motion is not only near, but even existing in the mobile; but that impulse is either communicated by generation—whether this requires nearness has already been proposed—or is impressed by some quantitative contact; for a corporeal mover cannot of itself immediately push a mobile except by touching it; but what is impressed through that contact, or what impulse is, is not to be declared in this place; it is treated, however, by Aristotle, bk. IV Phys., c. 8, and VIII Phys., last ch., and III De Caelo, c. 2. And hence too it is established that rolling, since it includes pushing, requires the same nearness that pushing requires. Of carrying, however, it is known per se that it requires contact, since what is carried is moved as it were per accidens with the motion of the carrier. Only in pulling, therefore, are examples brought in favour of the said opinion. The first is of the magnet drawing distant iron to itself. The second can be of amber lifting straws. The third, almost of the same notion, is what is commonly brought about the fish remora, otherwise echeneis, which holds back a passing ship, as Aristotle reports, bk. II of the History, c. 14; Pliny, bk. IX of the History, c. 25.

6. Fourthly, an induction is made in the actions of the powers of the soul; for the phantasy existing in the brain immediately moves the appetite which is in the heart, and the appetite immediately moves the hands or feet. Similarly the external sense seems by its act to impress a species on the imagination. For it is not likely that something should act through the whole medium, so that, for example, if the foot is heated, the species of heat should continuously ascend as far as the head, where the phantasy or the common sense is.

7. Fifthly, the same induction is made in the action of the intelligences, which can only be twofold, namely, either local motion, whether of a body or of another spirit, or speech, which is only to another intellectual thing. This latter action, then, by the opinion of all, can take place to a distant thing, as is established from St. Thomas, I, q. 89, aa. 7 and 8, and q. 108, a. 4, and q. De Anima, a. 18, ad 13; and it does not take place without some efficiency, because through it the angel to whom another speaks receives the faculty of understanding what before he could not, namely, the free thought of the other; but it does not seem that he can receive a new faculty without something new being made in him. Especially because he not only receives the faculty, but is also aroused to hear; but he cannot be aroused unless something is impressed on him. Hence St. Thomas, I, q. 107, a. 1, ad 3, says thus: As sense is moved by the sensible, so is the intellect by the intelligible; as, therefore, sense is aroused by a sensible sign, so the mind of an angel can be aroused to attend by some intelligible power. As, therefore, a sensible sign does not arouse sense except by impressing something on it, so angelic speech does not arouse the hearer except by impressing something on him, for example, some intelligible species. Hence the same St. Thomas, q. De Anima, a. 20, ad 11, treating of a similar action by which intelligences effect species in the separated soul, says: Since such action is not situational, one need not seek here a medium carrying situationally, but the order of nature operates the same here, indicating that this action does not require nearness, but subordination. For with similar words and similar reasoning he said, in the I, that the speech of an angel is not impeded on account of distance. Of the other action of the intelligence, however, which is local motion, that it too can take place to a distant thing is taught by Durandus, Gabriel, Ockham, Scotus and Hervaeus, In I, dist. 37. And it seems likely from the same foundation, that the angel of itself has no situation nor acts in the manner of a corporeal thing, but through intellect and will; therefore its efficacy does not require situational nearness, but the power of the will. For since it moves only by willing, what need is there that it be substantially present where it wishes to move?

8. A reason for the preceding opinion.—Sixthly, a reason can be formed in this way: because the active power of a creature has some quantity (so to speak) of perfection; therefore it is not likely that it is so limited that it cannot through itself act immediately except on a point or indivisible surface; therefore it can act immediately within some quantified or quantifiable distance; therefore it can also immediately attain the distant parts of that sphere or space. This reason is declared and confirmed, first: for when fire heats water by means of air, it has immediately near to it only the last surface of the air neighbouring it; therefore, according to the opposite opinion, it will act immediately through itself on that alone; indeed it will act on that immediately only through the heat which it has in its last surface; and through the surface it will act on the immediate part, and through the nearer part on the more remote, as it were dividing the action through all the near and remote proportional parts; but this mode of acting seems incredible per se and to have no small drawbacks. First, on account of the reason given, because it seems irrational to confine every power of acting, however great, to the very space in which the agent is, or at most to the last surface contiguous to it; for the power of acting can be greater and less, and its efficacy consists not only in the effect, but also in the mode of acting and in a greater sphere of activity. Likewise, I take the surface of the air nearest the fire and ask on what it acts immediately. It will be said that it acts immediately on the part near it; whence, since none is adequately near according to its whole self, it must consequently be confessed that it has no immediate subject, either indivisible or of definite magnitude, on which it acts immediately as a whole, but that it acts immediately only on the near taken as it were confusedly; but this seems unfitting, namely, that a determinate action, which takes place in an instant, for example, from the heat or light which is in this surface, should not have a determinate subject in which it takes place per se and immediately. Likewise, that mode of acting, as it were enumerating all the proportional parts, acting through these on those, since they are infinite, scarcely appears intelligible, especially in an action which is not extended successively through the subject, but takes place as a whole at once and in an instant, by way of one.

9. Finally it is confirmed, secondly, because from that principle it follows, speaking per se, that natural agents have no sphere of activity nor a terminus in it. The sequel is evident, for if one considers that on which they can act immediately and per se, they have no sphere, but only the surface nearest them. But if one considers that whole on which they can act mediately, attaining the remote through the near, there is no certain sphere nor any terminus of that action; for whatever terminus is designated to which the action intrinsically reaches, through it it will be able to proceed further, because in that terminus there is some power of acting; therefore that power will do something on what is near it. I say, however, speaking per se; for from the resistance of the patient it can happen that the power reaches that terminus so weak that it cannot overcome the resistance of the next part, either per se or in the power of the most distant agent; but this is accidental, on account of resistance. Although that too is most difficult to explain, namely, how a quality received in the medium can, in the power of the remote agent, overcome the resistance of the part nearest it, which it could not overcome per se and by its own power, if the remote agent does nothing per se immediately on the remote resisting part, but only through the power received in the nearer part. But of this later; now, however, the argument presses, speaking per se, and with resistance removed from the medium. And thus it comes about that the sun could in an instant illuminate the air to infinity, which is plainly false, because now it illuminates the near part of the air more than the remote, as is evident in a lamp; therefore, if the action is extended too far, it will at last be finished. Add that the reason for this effect too could not be given; for why does a lamp illuminate a remote part less than a near one, if it does not illuminate the former, like the latter, per se immediately? But from this head the reason is excellently given; for since the power is finite, it does not equally overcome a thing neighbouring it and a distant one, and therefore greater nearness contributes to greater perfection of action; but if it acts on the remote only through the near, it will communicate to the remote part all the intensity of quality which it communicates to the near, because that quality is active of what is like itself, and the remote part is capable of it and is immediately near to the nearest part; it is a sign, therefore, that the action does not take place in that way, but that the agent through itself immediately attains the whole sphere.

The second opinion is reported and declared

10. The second principal opinion is that in every efficient cause it is a condition necessary for acting that it be near and undistant from that thing on which it first and immediately acts; so that, if both, namely the agent and the patient, are quantified, they are contiguous, and the action begins from the last surface in which they touch each other, and so contact of power always presupposes quantitative contact; but if the agent is spiritual, it is near in a proportional way according to substantial presence. This is the opinion of Aristotle, VII Phys., c. 2, and I De Generat., c. 6, which St. Thomas defends everywhere, especially I, q. 8, a. 1, and III Cont. Gent., c. 68, in which places Cajetan, Ferrariensis and other Thomists; Capreolus, In I, dist. 37; and there Durandus, q. 1. And Richard signifies the same, a. 2, q. 1; Albert and others suppose the same when they infer His presence from the operation of God. The same Albert, VII Phys., tract. I, c. 4, where the Commentator, Aphrodisias and others commonly. The holy Fathers too favour this opinion, indeed even sacred Scripture, when they signify that even in God Himself immediate presence is rightly gathered from immediate operation. Of which argument we shall speak at length later, treating of the immensity of God. This opinion, however, is not proved by Aristotle by any reason, but by induction and experience alone, which is sufficiently known to the senses, so far as it can be from frequent sensible effects. The induction, however, will be perfect if we show that it never happens that natural action takes place otherwise, or at least that it cannot be persuaded by any experiment; but this will be established by the solution of the objections. And thus the argument is concluded; for the mode of acting common to all natural agents is founded on some intrinsic and natural necessity; but this mode is through immediate contact and nearness; therefore it is a sign that this is a necessary condition for every natural agent in order that it be able to act.

11. Various reasons for the necessity of the presence of the agent to the patient.—The reason for this necessity, however, is given by some as follows: just as a thing cannot pass from place to place except through the medium, so the action of the agent cannot be transmitted immediately to a distant thing unless it first attains the medium, and through it as it were continuously reaches the distant thing. But this reason in my view is inefficacious, because the action does not pass numerically the same to the distant thing through the medium as the numerically same body passes to the extreme place through the medium; hence it is not rightly said that the action passes to the extreme, but that it is educed by the power of the agent from the potency of the distant subject; in which, by virtue of that reason or likeness, no repugnance appears.

12. Others take the reason from the limitation of the finite agent, which on account of the defect of its power needs the presence of the patient in order to act. And this reason can be confirmed, because if the agent could act on a distant thing, by the same reason it could act at any distance whatever; for if it does not need action on the medium, what does it matter whether the patient is more or less distant? But in the first place the authors of this opinion, and especially St. Thomas, do not limit it to finite agents, but require this condition also in God; therefore it does not arise from the limitation of power. Next, from the limitation of power there seems at most to arise a limited sphere. But why should so great a limitation, to the proximate and immediate patient, be inferred from any limitation of power whatever, if the notion of efficient as such does not require that condition? Especially because not every power is equally limited, as we argued above. And for the same reason the inference made in the confirmation does not appear efficacious; for those who deny that that supreme nearness is simply necessary for action do not deny that it is useful in order that the agent act in the best way; indeed they even assert that it is necessary in order that it act with its whole power and as much as it can; and hence they think it arises that, other things being equal, natural agents act uniformly-difformly through spaces; and so nothing follows of what is inferred in that confirmation. For without doubt it is established from the very terms that it belongs to greater power to overcome a distant thing than a near one; and in the same proportion it will belong to greater power to overcome a thing more distant than less, just as it belongs to greater power to throw a stone to a more distant place. Hence Capreolus above, to the eighth argument, says that the reason for this is not to be taken from some imperfection or order of the acting and receiving power, but from the fact that the agent is in a certain way the act of the patient itself and the patient is in a certain way in potency to the agent; but act and potency of their notion demand to be undistant, so that, namely, they may exercise between themselves the notion of act and potency. Which reason, although it does not suffice to convince a perverse intellect, yet, sufficient experience of the thing being supposed, seems to me to touch more nearly and indicate more the proper cause of this necessity. In order, however, that we may declare this matter more fully and defend the opinion of Aristotle, it is necessary to explain the modes of nearness and distance and the various modes of acting through the near on the distant.

Resolution of the question

13. Various modes of distance and undistance of the agent from the patient.—It must be noted, then, that the patient can be distant from the agent because between them there lies a wholly empty space, which, although it does not happen naturally, yet they could be so understood, and it is necessary to say how they would then behave in action, because it will contribute not a little to explaining the matter. Secondly, the patient can be distant from the agent with some intermediate space interposed, not empty, but full of such a body that the agent could do nothing on it. Thirdly, it can be understood that the agent does something on the medium, yet not through the same power, as if it acts on the air through light, but on the earth through the substantial form. Fourthly and finally, it can be understood that the distant patient is conjoined to the agent through a medium on which the agent also operates, and through the same power. But this itself can be understood to happen in various ways. First, that the remote agent immediately brings action only on the patient near it, and through the quality impressed on that the action takes place on the remote patient, so that the relation per se and immediate of that action, as it is in the remote patient, is only to the power or quality impressed in the nearest part, but to the agent itself only remotely and inasmuch as it gives or conserves that power. Secondly, it can be understood that the agent acts on the remote by means of the power conferred on the nearest part, at the same time and actually inflowing with it into the remote part, so that it can neither attain the remote without it and through it, nor does that power alone, although conserved there, suffice for the action which takes place in the remote part without the actual influx of the agent itself. Thirdly, it can be understood that the action of the agent is diffused of necessity to the remote through the near, not by necessity of the causality of the near part of the patient upon the remote part, but only by necessity of order (so to speak); which necessity can arise either on the part of the agent, which by its nature determines for itself this mode of acting as it were through an uninterrupted line, or on the part of the patient, which, applied to a natural agent, necessarily suffers in the near part before the remote.

First assertion

14. With a vacuum lying between, there is no action on a distant thing.—Why all bodies abhor a vacuum.—First, then, it must be said that the efficient cause can do nothing on a distant patient if an empty space is interposed. This assertion is commonly received, so that not even the authors of the first opinion seem to deny it; for Scotus, even if he admits some generative action from distant matter, says nevertheless that some other action must be diffused through the medium, although he confesses this only of natural agents. This assertion cannot, however, be proved by positive experience (so to speak), because such a vacuum has never been given between bodies; it can, however, be proved by negative experience (so to speak) and by the providence of universal nature, or rather of its author, who so founded things and placed in them such a propensity or motion that they wholly avoid a vacuum, even if it is necessary to desert their proper places. Of which the chief reason seems to have been that some bodies might be able to exercise their actions through others, and distant bodies through intermediate ones participate in the influx of others, and especially of the heavenly bodies. Which Aristotle not obscurely signified, text 1 of the Meteorology, saying: It is necessary that it (that is, the lower world) be in a certain manner (that is, through the intermediate elements) nearest to the highest revolutions of the heaven, so that its whole faculty may be constituted and ruled from there. Nor will he satisfy who says that nature did not abhor a vacuum and so solicitously procure the contiguity of bodies on account of simple necessity, but only on account of greater convenience and utility. Both because so great a solicitude of nature indicates a greater necessity, and also because, if it were true that natural agents could attain a distant thing without a medium, it would often be more useful for action to have no real medium interposed, because the sphere would be more free and the power of the agent less occupied about it, according to what will be said at once.

15. Secondly, it can be proved by another experience which, although it is taken from a wholly opposite thing, yet seems to have the same root, namely, that if the space interposed between agent and patient is filled with some body which interrupts the action of the agent, the action on the distant patient is wholly impeded, even if otherwise it is constituted within the sphere of activity of the agent; therefore by the same reason, if the medium were wholly empty, the action of the agent could not pass to the distant patient, because the action would be interrupted no less by the vacuum than by that plenum. It can be answered that that interposed body impedes the action on further bodies not because it interrupts the action of the agent, but because the whole power of the agent is occupied (so to speak) about that body, whence it comes about that its sphere is terminated there. For they say that the sphere is not always the same, or of the same magnitude or distance, but according to the capacity or resistance of the medium. For it can happen that a body a foot long, on account of its density, resists more than a large rare body, and therefore finishes and terminates in itself the sphere of the agent. But although this reply can have some appearance of truth when the interposed body truly has the notion of a patient, in overcoming and (so to speak) penetrating which the power of the agent is occupied, yet, when the interposed body is wholly incapable of such action, so that the power of the agent is in no way applied to it according to that action, how can it detain it or resist the agent so that it does not effect on further bodies? An example is in the sun illuminating, whose action is impeded by an opaque body interposed in a window, which is incapable of light and does not resist illumination of itself positively, but negatively through incapacity; in which way also a vacuum can be said to resist, although from diverse principles; therefore the illuminative power of the sun is not occupied as it were in striving and acting about that body, but only does not act on it, as neither does it act on a vacuum; therefore that body impedes the passage (so to speak) of that action in no other way than by interrupting its continuation and as it were its line or ray; therefore an equal impediment will arise from an interposed vacuum. And this experience seems to me very efficacious for proving the conclusion laid down; of its reason, however, we shall speak below.

Second assertion

16. What it cannot effect on a full medium, it will not effect on a distant patient.—Hence it is said secondly: when the patient is distant from the agent through an interposed real medium, the agent can effect nothing on the distant patient if it cannot also act on the whole medium. It is manifestly evident from what has been said. First, because, if the interposed medium were not necessary to sustain and as it were carry the action of the agent, that medium would be related wholly per accidens to the action; it would therefore be irrelevant whether that medium were real or empty. Secondly, the experience of the interposed dense body proves this, which impedes the further passage of the action only because it is incapable of the action of the agent. Thirdly, because the reason which we gathered from the vacuum was only that in it the action of the agent is interrupted, and this was a sufficient impediment to action; but this same interruption intervenes when the medium nearest the agent is not capable of its action or influence; therefore. And thus we see that the sun does not illuminate the earth except by illuminating all the intermediate bodies; but if sometimes the moon is interposed, which the sun cannot penetrate with its light, the action of illuminating does not attain the earth.

Third assertion

17. By the power by which something acts on a distant thing, it must also act on the medium.—I say thirdly: in order that the agent may effect on a distant patient, it is not enough that it act on the medium through another, wholly distinct power or action; but it is necessary that, through the same or a subordinated power by which it acts on the distant thing, it begin to act on the medium near it and diffuse the action or influence through the whole of it as far as the distant patient. This assertion is directly against Scotus and others; it is proved, however, from what has been said, because in order that the agent act on a distant thing, it is necessary that prior in time or nature it act on the near and continuously on the whole medium; therefore it is necessary that that continued action flow in some way from one and the same power of the agent. The consequence is evident, because if there are two powers and two actions flow from them, there are formally two agents there, although materially it is one by reason of one supposit or subject; therefore it is not enough that it act on the proximate through one power in order that through another it may act on the distant. The consequence is proved, because those actions are related only concomitantly, and one cannot be said to be continued through the other and to take place without interruption. As, for example, although fire can act through heat and dryness, in order that it may act through heat on a distant patient it is not enough that it act through dryness on the near medium, because this is per accidens to the action of heat as such; it is necessary, therefore, that it act through heat on the near, because that is per se necessary for the continuation of the action. Indeed, although it can happen that the action of one power is necessary on the part of the patient in order that the action of another power may reach it—as, for example, if the action and disposition of dryness were necessary for the action of heat—it would not be enough that one power act beforehand, disposing, in order that the other might act immediately on the distant doing nothing on the near; because that disposition is merely material, and it is irrelevant that it comes from another concomitant power in the same subject, because through this the action of the other power does not take place continuously through the whole medium; which, however, has been shown by the two preceding conclusions to be necessary for the action.

18. A note.—Two things, however, are to be observed. One is that, when we say the action must be from one power, the sense is not that that power must be one form or one entity, but that it must be the adequate principle of one action, even if it coalesces from several forms, whether acting equally or subordinated. The other thing to be observed is that, when we say that the action on the near and the remote must be as it were one by continuation, it is not to be understood of rigorous and physical continuation, such as there is in illumination if the medium is continuous; but it is enough if there is continuation according to a certain subordination and causality. For it is not necessary, when the agent operates as far as some distance, that in the whole of it it produce a quality of the same notion; for in a body near it it can effect a certain quality, and in a more remote one a diverse one; as the sun, for example, produces only light in the heavenly bodies which it has below it; but in the air down to the earth it produces heat together with light; but in the earth, according to its depth, it does not produce light, but heat only, and by means of heat it effects other forms. The same may be considered in the other stars, which have proper influences, which they diffuse as far as the recesses of the earth, yet they do not do the same in all intermediate bodies, but in each they operate, according to its capacity, what is proportioned to its disposition. Then, therefore, since the qualities or termini produced in diverse bodies are distinct, the efficiency cannot be diffused by way of one continuous action; it is necessary, however, that through the quality produced in the neighbouring body it produce another in the remote, and through that similarly in the more remote, and in this way the action is said to be continued through subordination and causality. For since it is necessary that the action take place continuously by way of one, as was shown in the assertions, and continuation in the same species of action or quality is not necessary, it is necessary that it be through the emanation of one from another; otherwise the action which takes place on the distant will have no connection with the action which takes place on the near, but both these actions will be related wholly per accidens; which the reason given in the third assertion proves cannot happen.

Fourth assertion

19. Some agent can act immediately on an extended space and all its parts.—I say fourthly: although it is necessary that the efficient cause be near and undistant from the patient on which it first acts, yet it is not certain that it always acts through the near on the distant as through an instrument or power of acting; but it is probable that it sometimes acts on some whole patient immediately through its own proper power; and similarly, when it acts through the near as through an instrument on the distant, it is not necessary that it act through it as through an instrument separated in causing, but as through a conjoined one, so that together with the power diffused through the medium the agent itself inflows immediately by one and the same action. The first part is the very conclusion of Aristotle and the common opinion which we defend, and besides his induction it is manifestly proved from the preceding assertions and their proofs, by which it was shown that the agent cannot diffuse its action as far as a distant thing except by way of one uninterrupted action; therefore it is necessary that the action begin from a wholly neighbouring and undistant patient; otherwise it would from the beginning be begun interrupted. And this is not a little confirmed by some experiences in which we see that the agent per se intends action only on the remote, and nevertheless does not exercise it except through the medium, although that action, as it takes place in the medium, is altogether useless, except that it at least serves for this, that through it the action may be carried to the distant patient in which the agent has the effect per se intended; for example, the visible object does not diffuse species to the eye except through the medium. Of which there are some evident signs. One is of the mirror in which reflection of species takes place, which also takes place in water; but it could not take place unless species were multiplied as far as those bodies. Another is that according to the disposition of the medium the species are either disturbed or conveniently carried. Likewise, there is that touched upon above, that, for whatever reason some part of the medium is incapable of species, the action is impeded from reaching the eye. But this action of the species per se and from the intention of nature is wholly ordered to the eye, because in that alone can the species have the effect for which they were instituted; such action of the species in the medium would therefore be useless unless it were necessary in order that through it the action might reach the distant eye; therefore it is a sign that such action takes place on account of this necessity. And the same judgment is to be passed on every similar action, even if it is not known by such certain experiments.

20. An inference from all that has been said.—From all these, then, I gather that the natural mode of acting of the efficient cause is as it were through a continued line of its action from the near to the distant. And this ought to be a sufficient reason for the conclusion, the experiences adduced being supposed, even if another reason were lacking, namely, that this cause determines for itself from its nature such a mode of acting. For we often judge so of the natures of things from what we experience, even if we are not able to give a further reason for that natural condition. As, for example, the object of sight multiplies species only in a straight line, but the object of hearing also in an oblique one, and enters through any pores whatever, as is established by experience, from which we rightly gather that this is the natural mode of acting of such objects; of which the sufficient reason is that such a property follows the nature of each sense. We try, however, to investigate some reason for this nature when we say that sound is a certain quality following motion and imitating its nature, and therefore can enter by any ways whatever, while colour acts in a more quiet and subtle way, and therefore diffuses species only by a straight way. Thus, then, in the present case, if we wish to investigate some reason or conjecture of that natural condition of agents, certainly that which was touched upon by Capreolus is not to be despised; for every act requires conjunction with the potency in order to exercise its causality upon it; as, therefore, in a formal act intimate union is required, so an efficient act requires at least undistance, not on account of imperfection, but rather on account of the perfection which the notion of act or actuation includes. Or if this is to be referred to some imperfection, it is to be taken on the part of the effect, which, since it is dependent on its cause, demands conjunction and undistance from it in order to be able to flow from it, as a stream requires conjunction with its source in order to flow from it. In which too a certain latitude can be considered according to the various perfections of causes; for corporeal causes and effects cannot according to their whole selves be immediately present or undistant to one another, and therefore they are brought near at least according to their extremes. Created spiritual things, however, are conjoined or present according to their whole selves to the effect or patient, although it is not always necessary that they be intimately present to the whole patient and to all its parts; for they can be present to one part and through it act on the whole, in which way the intelligence moving the heaven is thought to be in the East. But God, wherever He acts, is present whole and in the whole, not only from immensity, but also from the perfection of acting, as we shall see below in its place. I said, however, that this mode of acting, beginning the action from an undistant patient, is connatural to the efficient, because we are not now disputing whether God can supernaturally change this mode of acting. We believe, however, that this is not repugnant to divine instruments, even if it cannot be connatural to any created agent; of which matter I have spoken in tome I of the III Part, disp. 31, sect. 7.

21. And hence it can further be understood that from the necessary nearness between patient and agent it is not at once inferred that it is also necessary that the agent act through the near part of the medium on the remote as through an instrument; for it will be enough if it acts through it as through a medium necessary for the continuation of the action, or in order that the action take place without interruption, because neither the experiences nor the reasons so far adduced prove more. Wherefore, when the action through the medium varies in the proximate and the remote patient according to various qualities and termini of action, then certainly it seems necessary that the power diffused in the near medium be the instrument for acting on the remote, as we said just now, because otherwise there would be no continuation or per se subordination between those actions. But when the action is wholly of the same notion in the near and the remote part of the medium, it does not seem per se necessary, at least by virtue of the nearness necessary between patient and agent, that the near part be the instrument for acting on the remote; because that action per se has its continuity and integrity, which is necessary from the natural mode of operating of such a cause, as we have shown. I said, so far as concerns the force of the necessary nearness; for if the quality diffused through the medium is active of what is like itself, it follows from the nature of the thing that, existing in the near part, it can help to act on the remote, either by way of instrument or by way of partial agent; this, however, can be as it were per accidens and only concomitant to the action of the first agent.

22. Wherefore, if it happened that the quality diffused through the medium were not active of what is like itself, then it would not be necessary that the nearest part be an instrument, but only a medium for the action. Whether this ever so happens is not certain to me; yet I do not see a repugnance by virtue of that condition necessary for acting which we are now treating, namely, nearness. And an example could be in the object of sight, for it seems so to multiply species through the medium as far as the sense that the species received in the diaphanous medium is not effective of what is like itself; which seems to be proved from the fact that beyond a certain distance the object cannot effect a species of itself, which would not happen if the species received in the medium effected what is like itself. Which argument was touched upon among the foundations of the first opinion, and in the replies we shall see how efficacious it is. Another example can be of the impetus which is impressed on a thrown stone; for the contact of the thrower is only in one part of the stone, and yet the impetus is not received in that part alone, but in the whole thrown body; nor does the part of the impetus impressed on one part effect another like it in the neighbouring part, both because impulse is not effective of another impulse, but of local motion only, just as gravity is not effective of gravity, but of local motion; and also because impulse is not impressed except by strong contact; but one part cannot in this way touch another continuous with it; it seems likely, therefore, that impetus is impressed on the whole mobile and all its parts immediately by the thrower, by means of contact in only one part of it. Whatever be the case, however, about special examples, yet, speaking in general, in order to save that axiom about the necessary nearness between the agent and the first patient, we are not compelled to say that the efficiency of one part of the patient on another is necessary. Whether, however, some experiences or reasons sufficiently show that that efficiency does not always intervene, or is not per se necessary, we shall see in treating the arguments of the first opinion.

23. The parts of the medium nearer the agent do not act on the remote ones without its help.—Finally, on this too depends in part the last part of the assertion; for even if the nearest parts of the medium act on the remote ones, it seems to be proved by experiment that they do not act by the power received in themselves alone, nor are they wholly destitute of the actual influx of the first agent; otherwise the action of the same medium would not be so vehement in some parts and so remiss in others equally near to it, but unequally applied with respect to the first agent; which is to be examined more closely in the solutions of the arguments. Now, however, we say only that from this nearness and condition necessary for acting which we are now treating it does not follow that the agent acts on the distant part only through the power received in the nearest part as through an instrument as it were separated in causing, that is, acting per se alone without the actual influx of the principal agent: both because neither is this necessary in order that the patient be absolutely near to the agent, from which the action may flow continuously and without interruption; and also because then from the agent itself and the power received in the medium there is as it were composed one integral agent which touches the other part, and therefore can act on it through its whole power. Which I declare by this likeness: for when fire heats the air near it, it does not act on it through the heat alone which it has in the last surface by which it touches the air, nor through some neighbouring part alone, even if it be imagined of any quantity whatever, which can only be determined merely gratuitously; it acts, therefore, immediately through the whole heat which it has in itself and in all its parts (for I suppose all are within the sphere of activity), and yet not all the parts of the acting fire are immediately near to the air suffering; but because from all of them there coalesces one agent which through its terminus is contiguous to the air suffering, that is enough for all those parts to inflow immediately into the patient by way of one integral agent. And it would be the same if two fires, discontinuous between themselves, were applied to the same part of the patient, so that from both together one action would flow by way of one integral agent; therefore similarly it can be understood that the agent conjoined to the first part of the patient, already affected with its quality, acts by way of one and inflows into the further patient, whether they concur as two partial agents or as principal and instrumental agent. But all these things will be more elucidated in the replies to the first opinion.

Solutions of the arguments

24. What agent is present to substantial generation.—To the first experience, then, concerning substantial generation, the common reply is that the accidents which are proximately present effect substantial generation in the power of the substantial form, although that is distant. Which reply has the difficulty touched upon in sect. 3, because, although accidents can be instruments for effecting substance, they cannot be sufficient principles if they are separated as to causality. And therefore, if the substantial form, far distant, can in no way actually inflow with the accidental power into substantial generation, it cannot through accidents alone be a sufficient principle of such generation. Wherefore it can probably be said that that instrumental power diffused from the heaven as far as the place of the earth in which substantial generation takes place does not act as a separated power, but as conjoined in causality, and that the form of the heaven actually inflows with it, if otherwise the effect does not exceed in perfection the very form of the heaven. Nor does it follow from this that the heaven acts immediately on a distant thing, because it does not act except as conjoined to its power diffused through the medium as far as the distant patient. You will say: the form of the heaven and the accidental power of the same heaven are diverse powers of acting; but the whole preceding alteration was produced by the heaven by means of the accidental power only; therefore that does not suffice for the form of the heaven to be able afterwards to inflow by means of its substantial form into the substantial generation of another. I answer that the form and the accidental power of the heaven itself are not two powers only concomitantly and as it were per accidens conjoined, but are subordinated as principal and instrumental principle; and therefore, although the substantial form attains the generation which takes place in a distant place, it does not act formally and properly on a distant thing, because it is conjoined by means of its power. And this will be easier and clearer if one holds that the substantial form of the heaven concurs per se as principal principle not only to the eduction of the substantial form, but also to the preceding alteration, which we said above is probable. But if perhaps this does not please someone, it must necessarily be said that the heaven concurs to these generations only instrumentally through the accidental power diffused through the medium, but is helped to accomplish these generations by some superior agent.

On the alteration of the body by the imagination

25. To the second, about alteration, the assumption is denied, namely, that some cause alters a distant thing without altering the near. And to the first example, about the imagination, it is answered that the discourse is either of the body of the animal itself whose phantasy it is, or of another's. Speaking of another's body, I deny that the phantasy of another has the power of altering it; nor has any probable experiment been brought so far which shows it; nor is it likely by force of reason, because the act of imagination is immanent, and there is no source from which it should have the power of naturally altering another's body. But if the discourse is of the proper body of the animal itself which operates by imagination, it must be said that the imagination does not move the body except by means of the sensitive appetite, at whose motion the humours and vital spirits are aroused, by means of which the body is altered; but the motion of the appetite by the imagination is not an alteration, but a certain vital affection, of which I shall speak below. The appetite, however, since it is in the heart, which is the principle of the animal's motion and of the vital spirits, can easily arouse such motion or alteration, doing nothing immediately on a distant thing, but by means of near parts; although in that motion too a special reason intervenes, because it takes place through the natural sympathy of powers rooted in the same soul, as will be said below and more at length.

On fascination

26. To the second example, there are those who deny that power of fascination. But there is no reason why we should deny an experience confirmed by philosophers and physicians and received almost by common sense. We confess, therefore, that fascination happens naturally; its mode, however, St. Thomas declares, I, q. 117, a. 3, ad 2, and III Cont. Gent., c. 103. And in the first place it must be said that fascination does not take place by the very act of seeing as the principle by which alteration takes place in another, because an immanent act, as we said above of the act of imagination, is not per se active upon anything. Next, it must be said that that alteration takes place from some poisonous quality existing in the eye, or in the internal disposition, complexion or humours of the body, which is communicated to the vital spirits, which are stirred by the imagination and attention of the mind and reach the eyes. Again, hence it comes about that by means of those spirits the nearest air is infected and the alteration reaches to a certain distance, and so harms another although he is some little distance away. And perhaps sometimes it happens that the infected spirits themselves are sent forth as far as that person on whom the gaze is directly fixed, and so harm more easily and more vehemently; and Aristotle signifies above that fascination sometimes takes place by the corrupted breath itself transmitted as far as another person. In these ways, then, fascination can take place naturally without immediate action on a distant thing. I omit (what St. Thomas noted above) that sometimes harm of this kind happens from the malice of demons, who by a hidden pact cooperate to inflict harm of this kind. St. Thomas also notes there that this alteration happens more easily in infants and children, because on account of their tender body they more easily suffer any external impression. More about action of this kind can be read in Pliny, bk. VII, c. 2, and bk. XXXIII, c. 10; Abulensis, paradox 4, c. 16; Richard, Quodl. III, q. 12. The same, due proportion being kept, must be said of any harm whatever which is inflicted by venomous animals, either by sight or by smell. And the same holds of the third example, of the torpedo, of which Pliny expressly says that it affects the limbs by the odour and a certain breath of its body; it does not, therefore, act immediately on a distant thing, but either by altering the medium or also by breathing out some noxious vapour. Nor does it matter that it is said to hide under sand or mud, because it is not necessary that we understand it to lie wholly hidden under the earth, so as not to leave either its head or mouth open for harming.

Whether an agent can act more intensely on the distant than on the near

27. Why the bottom of a cauldron is colder than the boiling water placed over it.—In the fourth and fifth examples it must be declared whether, and for what reason, it happens that the agent acts more vehemently on a distant thing than on the near medium, and whether then that more vehement alteration takes place immediately on the distant thing without the cooperation of the medium. And indeed Aristotle, sect. 24 of the Problems, qq. 5 and 8, notes that when water is heated in a vessel, at the beginning of the heating, while the water is still cold, the bottom of the vessel is felt hotter; but afterwards, when the water is boiling so that it burns the hand, the bottom of the vessel is more temperate, so that it can be held by the hand. He assigns the reason, however, that at the beginning of the action, while the water is cold, the whole heat is shut up in the bottom of the vessel and not permitted to ascend; but when the water is now hotter, the heat is as it were permitted to breathe and ascend, and thence it comes about that the bottom of the cauldron is tempered. For which cause he says in the same place that baths are hotter in winter than in summer. And thence it consequently comes about that, as the action proceeds and the water is excessively heated and rarefied by heating, the hotter parts ascend upward and the thicker and colder descend downward and cling to the bottom of the vessel and temper it, and therefore it is reckoned less hot. Here, however, by the name of heat is not to be understood the quality or accident of heat alone; for this can neither ascend nor descend, nor be detained so as not to ascend, except by reason of its subject; but the hot exhalations or vapours which are aroused by the action of the fire are to be understood. For that ascent or descent cannot be declared only metaphorically, that is, that heat is said to be impeded from ascending only because the patient resists the heating's proceeding further towards the upper part. For in this sense the reason would be of no weight, namely, that the bottom of the cauldron is hotter at the beginning because then the heat is impeded from ascending further; for that the action proceeds further per se in no way prevents that lower part from remaining equally hot, as is known per se. It must therefore be understood properly of some hot exhalations, which, while they are detained by reason of the nearest body, namely cold and dense, make the heat of that part both greater and more vehemently felt; but when, the nearest body being heated and consequently rarefied, they are permitted to ascend, less heat is felt in that lowest part; especially since in the pores where those exhalations were, colder parts of the water succeed in their place, which, as they are heavier, so they naturally descend more, and from that head too that heat is tempered more.

28. From this reason of the Philosopher so expounded, however, it is easily understood that from this experience it is not had that the agent acts more intensely on the distant than on the near except by transmitting some proportioned agent which proximately effects that intensity. For in the said example, when at the beginning of the action the bottom of the vessel grows excessively hot, this comes from the neighbouring fire and from the fiery or hot exhalations enclosed in the very pores of the bottom; but when, as the action proceeds, the upper parts of the water seem hotter, this comes not only from the remote fire, although its action helps much, but also from the hotter vapours ascending and penetrating the water itself, and for this cause it heats it more vehemently. Add that the water itself, while it begins to be heated more near the bottom of the vessel, at once ascends, having become lighter; while that which was above, heavier and colder, descends; and so it comes about that the more distant part of the water is hotter, not because, being so distant, it has been more heated, but because it was before near and there more heated. But never is that part of the water which sits nearest the bottom of the vessel more vehemently heated than the vessel itself or its bottom, through which the action is transmitted, except perhaps at the end of the action, when the water is now wholly overcome, so that it happens that it is all exhaled and corrupted. Which comes from the fact that by reason of its moisture it is more easily changed into air or into some imperfect mixed body. Likewise, because, since it is less dense than the vessel, the hot ascending vapours or exhalations more easily penetrate it. It also helps if there is any surrounding air. And thus the whole action and its intensity always takes place through some medium.

29. Why paper is less hot than oil placed on it.—Why tow is inflamed while the air lying between it and the fire is not inflamed.—In the same way it must be said of the similar experiences adduced above, namely, of the oil which seems to grow hot more vehemently than the paper by means of which it is heated. For the oil, as soon as it begins to be heated, is also easily rarefied and penetrated by the ascending vapours, and itself too, made subtler and lighter, at once ascends; while the thicker and moister parts descend; and so the same happens in this example as in the former. Of the tow, however, that it is inflamed through the interposed air while the air itself is not inflamed, is not so manifest by experience; for perhaps the air is inflamed first, although it is not so perceived by sense as in the tow, on account of the latter's density. And the same can be said to the example of the root of the herb aproxis and of the bitumen naphtha.

30. An objection is answered.—It could, however, be answered otherwise, admitting what is assumed in the argument, that remote matter is sometimes inflamed while the near is not, and saying that this comes from the disposition of the matter without a more intense action of the fire on the remote than on the near. Which will easily be declared if we suppose that it is not necessary that in some matter supreme heat precede in order that it be inflamed, but that it suffices that intense heat precede in that grade with which the form of the tow, for example, cannot be conserved, and, if sufficient dryness is joined to it, it sufficiently disposes for the introduction of the form of fire. Thus, then, it can happen that the intermediate air is hot as seven and is not inflamed for defect of dryness, while the tow, as soon as it reaches that grade, is inflamed; and so the action of the heating fire was never more intense in the remote matter than in the near, but had another effect on account of another disposition of the patient. You will say: in that instant in which that matter is inflamed, it is already hot as eight. I answer: if it is so (for it is not certain of the first instant), yet this does not come from the action of the distant fire alone, but is by natural resultance from the form already conceived. Which resultance, if no resistance remains in the matter, takes place in a moment; and so it must be said to take place if we suppose that all accidents perish in corruption. If, however, some grade of the contrary quality can remain, some succession will intervene, yet most brief and imperceptible, because the resistance is least and the activity great. But what of the action of the substantial form itself, which takes place in the distant matter, not in the medium? It is commonly said to take place by natural resultance, sufficient disposition being supposed, or to be produced by the accidental dispositions existing there, in the power of the substance. We, however, must answer, according to the first assertion, either that the form of fire together with its power can reach there and at the same time inflow into the eduction of that form, or certainly, if the substantial form does not have this power, that it is necessary that that concurrence be supplied by some superior cause; just as, when it happens that some thing is so heated by motion that it is inflamed, the introduction of that form is attributed to some universal cause.

31. Another way of explaining the experiments adduced.—Another way of answering these experiences can be by admitting that the agent can make some quality more intense in a distant patient than in a near one, yet not by acting immediately on the distant thing, but through the medium. This mode of action, however, can be conceived in two ways. First, so that the medium does not serve as an instrumental or partial co-efficient for acting on the remote, at least as to that grade of greater intensity which is made in the remote part. This way of speaking, however, is not sufficiently consistent with the opinion we defend; for it plainly follows that that action, inasmuch as it is intensification in such a grade, is produced by the remote agent immediately on the distant patient without any action about the medium or through the medium; because the remiss action which takes place in the near medium per se does not contribute to, nor is continued with, the action on the distant thing, except at most up to a like grade; therefore that greater intensity which is produced in the distant thing is an immediate action on it without a medium. Just as, if the whole medium and the distant patient were first hot as four without the action of fire, and afterwards the applied fire immediately intensified that heat in the distant patient and not in the medium, without doubt that action would be immediate on the distant thing; therefore the same will hold even if the heat as four was produced by the same fire. In another way, therefore, it can be understood that the agent, through the power impressed in the medium, effects a more intense quality in the remote patient than in the medium itself, on account of greater capacity or disposition and less resistance. This power, however, can sometimes be a quality of a diverse notion from the other which is intensified, and then the matter is not difficult; as in the example given above of the mirror and the air heated by the sun, because that heating takes place by means of light, it can happen that, by means of the light of the air as power of acting, the sun heats more vehemently the distant mirror or another similar thing than the near air, on account of the greater capacity and disposition of the patient; and in this I see no repugnance. For as an acting cause through diffused power can have some effect on the remote which it does not have on the near, as all concede, and notably St. Thomas, In II, dist. 15, q. 1, a. 2, ad 6, and the Commentator, IX Phys., and bk. II De Caelo, com. 34, so with greater reason it can alter the remote part more intensely than the near. In another way, finally, it can be understood that this takes place through a quality of the same notion; as, for example, that the sun, through air remissly illuminated, illuminates a distant mirror more intensely, so that the light of the intermediate air, even if it is in itself more remiss, concurs as conjoined to the first agent, either instrumentally or partially, to effecting the light in the mirror, even as to the greater grade of intensity. And this mode is harder to believe, because it supposes that a remiss quality, at least as conjoined to the prior agent, can concur to the intensification of a quality of the same species in that grade in which it is unlike it and exceeded by it; whether this can happen we shall examine in the following section, where we shall say more about that example of the mirror and its reflected action.

Why the agent operates more efficaciously in a straight line

32. To the other experiences which are brought in confirmation of that second argument, I answer that they quite probably persuade the second part of the last assertion. Nor does any other probable reply or evasion occur to me; for I do not see why the presence of the sun in a straight line with respect to this part of the remote air conduces to its greater illumination, except because the sun itself inflows into it together with the air nearer to it; but into another part of the air, not so directly opposite, but to the side, for example, of the window, it cannot so inflow, even if with respect to the medium itself that part is equally near. Someone will perhaps say that the light received in the medium acts in the power of the sun on that part of the air which lies in a straight line opposite the sun, but on another falling to the side acts only by its own power, and therefore illuminates that part more than this. But this is both said merely gratuitously and voluntarily, and it cannot be understood what thing underlies those words, nor in what that difference consists, if the sun itself actually inflows through itself into neither of those parts. For, this being supposed, what is to act in the power of another except to act as a power diffused from it and taking its place? But that power received in the medium is one and the same; therefore with respect to any part of the medium whatever it acts as a power diffused from the sun and in its stead; therefore it acts equally in the power of the sun. Nor can it be explained what that situational position (so to speak), or presence of the sun, contributes such that for that cause it is said to act in the power of the sun on one part and not on another, if by reason of that application the sun itself does not inflow more per se.

33. Which finally I confirm and declare thus: for when an accident acts in the power of another without its actual influx, if such an accident is conserved without that other in whose power it is said to act, it can have the same action. This is evident in gravity or impetus moving in the power of the generator or the impressor, and the same holds of the heat of water, if heat is said to heat in the power of fire; indeed, those too who say that supreme heat effects in the said way the form of fire in the power of fire without another actual influx of it consequently say that heat separated, equally as conjoined to fire, can in the power of fire effect the form of another fire. Thus in the present case, if the light received in the part of the air nearer the sun effects light in another part in the said way in the power of the sun, then if that light were conserved in one part, the sun being taken out of the way, it would illuminate in the same way the same part which it now illuminates. But the consequent is plainly false, both because otherwise even now it would equally illuminate the part of the air neighbouring it which is not opposite the sun, because the sun is not more, nor so, absent now from that part as it would be absent from the other if it were wholly removed; and also because in fire and heat the opposite is established by experiment, as was proposed in the same confirmation we are treating. Therefore it seems necessarily to be said that the sun actually inflows with the nearest part of the medium to illuminate another directly opposite it, but cannot equally inflow into another part existing at the side, even if it is equally near to the intermediate air itself, and that thence it comes about that those parts are not equally illuminated or heated.

On the action of the magnet and similar things

34. In the third argument, concerning local motion, the first and chief experience is of the magnet; of which, as of many other experiments which we treat here, the Conimbricenses learnedly gather much, bk. VII Phys., c. 2, q. 1. Briefly, however, so far as concerns the present matter, we admit that that attraction is effectively produced by the magnet. For Alexander, bk. II of the Natural Questions, c. 3, thought that iron is not drawn by the magnet except as by an end, and that it moves itself to the magnet by an internal and innate power, as it were by natural weight. This, however, Albert rejects, II Metaph., tract. III, c. 6; St. Thomas, VII Phys., lect. 3, text 10; and Galen, bk. III On the Natural Faculties, last ch. First, because natural motion from an intrinsic power takes place from any distance whatever, as is evident in earth and fire; but iron does not tend to the magnet from any distance whatever, but from a certain and definite one; therefore it does not tend to it, but is drawn. Secondly, because iron is not moved to the magnet unless they exist in due proportion of quantity; for a mass of iron will not be drawn by a small magnet; therefore this is on account of action, which does not follow from a proportion of lesser inequality. Thirdly, because it is said to be established by experience that if a magnet is anointed with goat's blood or the juice of garlic or onion, it cannot draw iron; therefore this is because its attractive power is thereby weakened.

35. It must be added, next, that the magnet impresses on the iron some motive quality by which it draws it to itself. So all authors teach; for just as projection takes place through an impressed quality, so also does drawing; there is, however, a difference, because impulse is impressed by immediate quantitative contact, but not this attractive quality; and the reason is that they were instituted by nature for contrary effects. For by impulse the mobile is separated from the mover which touches it; but by drawing the mobile is drawn towards the mover, or even until it touches it. Moreover, this attraction of the magnet is such that it not only draws iron per se to itself, but also communicates to the iron itself a participation of its power; for the iron attracted draws other iron to itself, and that draws another, so that as it were a chain is made of them, as Augustine reports, XXI De Civit., c. 4, and as we too have sometimes experienced; this, therefore, is an open sign that the magnet impresses on the iron a quality which has both the power of moving the iron itself and of effecting another like one by which the iron draws to itself.

36. Finally it must be added, in order that we may answer the argument proposed, that the magnet does not impress that quality on the iron except through the medium, namely, by altering it as far as the iron; for although this alteration of the medium is not perceived by sensible experiment, yet, since it can easily take place, we gather from other experiments and reasons that in that alteration too the natural mode of acting of the efficient cause is observed. Nor does it stand in the way that the medium itself is not drawn to the magnet; because it is not necessary that the quality diffused through the medium have the same effect in the medium which it has in the distant patient; as was said above, on account of the diverse disposition of the patient it happens that the power diffused through the medium effects in a distant body a new quality, or an intensification of quality, which it does not make in the medium itself. Thus, then, it can happen in the present case, either that the quality diffused through the medium is not of the same notion as that which is impressed on the iron itself, or certainly that, although it is in itself of the same species, it does not have the same effect of drawing in the medium which it has in the iron, on account of the peculiar proportion or disposition of the iron.

37. Only another experience can stand in the way, by which it is established that the magnet changes iron even with a dense medium interposed, as is also perceived by experiment and as Augustine reports above, saying that, iron being placed on silver and a magnet beneath, the iron is moved with the motion of the magnet, with a most rapid course and recourse, as the magnet is moved by someone, the silver (he says) in between suffering nothing. For it does not seem likely that the magnet could alter and penetrate the whole of so dense a medium. But nevertheless, when Augustine says the silver suffers nothing, he plainly understands it of that sensible passion, such as was the motion and agitation of the iron; of invisible alteration, however, Augustine disputes nothing there. Nor is it so difficult to believe that the magnet penetrates the intermediate body by its alteration, either because it is porous, as wood is, or because it has little depth, as perhaps was that silver of which Augustine makes mention; just as the heavenly influences too penetrate even the densest bodies and at a great distance, on account of their great power of acting. For this power of the magnet is thought to be a certain participation of a heavenly property, as St. Thomas says, q. 5 De Verit., a. 10, ad 5; q. unica De Anima, a. 1. Perhaps it can also happen that that action, although it does not penetrate the whole dense body, by the intervention of the surrounding air reaches continuously as far as the iron. And in the same way judgment is to be passed of amber lifting straws, and the same holds of quicksilver drawing particles of gold, and of any other similar thing, or a medicinal root or herb, which has the power of drawing something or also of expelling.

38. How the remora holds back a ship.—As regards the holding back of the echeneis, however, although otherwise it is a wonderful effect of nature, it is most difficult to explain by what power so small an animal can retard so vehement a mass; yet in the present case it brings in no difficulty, for Pliny expressly says that it does this with no labour of its own, not by holding back or in any other way than by adhering; it does nothing, therefore, on a distant thing. What it impresses on the ship in order to detain it Scaliger treats at length against Cardano, exercit. 218, and against him the Conimbricenses above, a. 5. I, however, think the matter most hidden, and one which must necessarily be reduced to some power of a superior notion, which has such and so great a force for resisting the impulse of the ship that it cannot be weakened by it. Whether this is done by this animal impressing on the ship some quality weakening the force of that impetus, or only by adhering by a power innate to it, as a man holds a proportioned stone so that it does not fall, or finally whether this fish has such power of stopping itself and as it were adhering to its place that it cannot be snatched away or dislodged even by what impels the ship, is uncertain to me. In whichever of these ways it happens, however, there is no doubt that it comes from a wonderful and hidden power, helped perhaps by some special and connatural heavenly influence. Indeed Ambrose adds, bk. V Hexaem., c. 10, at the end, imitating Basil, hom. VII Hexaem., that by the gift and power of the Creator so small an animal received so great a power.

On the action of the phantasy and similar things

39. In solving the fourth difficulty those labour who think that the knowledge existing in the phantasy concurs effectively by its own physical influx to the act of the appetite. Hence some place both powers either in the brain or in the heart, so that they may be neighbours and able to act on each other, although the truer doctrine holds that the phantasy is in the brain and the appetite in the heart, as is to be shown more at length elsewhere. Others say that I know not what qualities are diffused from the brain, by means of the act of the phantasy, as far as the heart in order to change the appetite. But this is like a fiction, because those qualities are neither species of the object nor of the very act of the phantasy—for they would be useless, since the appetite cannot use species—nor can they be some qualities as it were carrying to the appetitive power the knowledge of the object which is in the phantasy; because the appetitive power itself never perceives that knowledge; nor can the knowledge of one power be manifested to another, either formally or objectively, except by means of another species or knowledge of itself. Others finally, convinced by the argument, confess that the knowledge existing in the brain inflows by immediate action, through its own efficiency, into the appetite. Nor do they think this unfitting, because those two faculties are conjoined in the same soul, which is the principal principle of that action; for just as a principal power can cooperate with its instrumental power, even if this is diffused as far as a distant place, so conversely some instrumental power will be able to cooperate with the principal power, even in a distant place, if the principal power itself is diffused as far as that, provided that in that part too, where the action takes place, there is another instrument more proper and proportioned to such action. Which reply, that first foundation being supposed, is among the rest less improbable, and is commonly applied to divine instruments, that they can attain immediately to distant things because the principal power is present there. Absolutely, however (whatever be the case about miraculous actions), it does not satisfy, because efficiency is now admitted from some form or quality or act which leaps across to a distant thing as it were by a jump, without continuous action through the medium.

40. And therefore we shall more easily escape these straits by denying that knowledge concurs actively to the act of the appetite, but only as a condition representing the object, which being posited, the appetite effects its act through the natural sympathy of these powers. And to this the rooting of those faculties in the same soul contributes excellently; for it, or the supposit through it, is what principally operates and uses these faculties; and therefore, while through one it perceives an object fitting to itself, through another it desires it; not indeed because through one it effects in the other, but because from the object apprehended through one it is aroused to operate through the other; which arousing is not by real and effective change, but by metaphorical or final change, and therefore does not require local nearness, but animal nearness, so to speak. And the same must be said proportionally of the appetite and the motive power; for although it could be said that every motion begins from the heart and proceeds by means of the spirits and nerves as far as the part in which the motion is exercised or appears, yet, as concerns the present matter, the application of the motive power by the appetite is not through the proper and physical action of one power on another, but through the subordination of the powers in the same soul; in which way also the intellect and senses are applied to operating by the will and appetite; of which more at length the philosophers in the books On the Soul, and the theologians in the I-II. Of the efficiency of the sensible species in the internal senses, by means of the external, however, there is another and far diverse reason; for here proper efficiency truly intervenes, which must take place through the medium, as the visible species are said to tend from the eye as far as the common sense through the optic nerve; for this action of such species is not properly vital or immanent, but is proceeding from an extrinsic thing by means of those instruments, and therefore it is properly diffused through the medium, like other natural actions.

On the action of a spiritual thing on a body

41. So far we have spoken of corporeal agents and patients among themselves; in the fifth argument, however, the action of spiritual things on bodies and among themselves is treated. And as to the first part, concerning the action of spirits on bodies, speaking consistently, it must be said that the immediate nearness of the intelligence to the body is necessary in order that it can move it locally; for I suppose that a created spirit can exercise no other action on a body, which I shall show below in disputing about the intelligences. Hence, if an angel, in order to move a body, can impress impetus by means of another body which it does not move locally, then indeed for moving some body locally it will suffice for it to be present by immediacy of power; yet it will be necessary that by immediacy of supposit it be present to the body in which it first began to impress that power. If, however (which I think more probable), the angel cannot impress that power through intermediate bodies not moved, it will be necessary that the moving angel be proximately present by immediacy of supposit to that body which it immediately moves. And in this way the philosophers say that each intelligence moving the heaven is present to that orb which it moves. Thus too theologians say that angels are present by supposit to those bodies which they assume and in which they appear. And whenever Scripture says that an angel moves or carries some man, it signifies there that the angel is substantially present, or is moved with the thing which it moves. Which would not be necessary unless the angel had to be present where it moves. And St. Thomas plainly supposes this, I, qq. 52 and 53, and 55, a. 2, ad 3, and q. 113, a. 6, ad 3, and more clearly in the places to be cited below.

42. Nor does it stand in the way that a spiritual thing does not have situation; for it has a substantial and real defined presence, according to which it must be conjoined to the patient when it acts on it. Nor do I now dispute whether operation is the reason of that presence, which some theologians seem to assert, or, conversely, whether that presence according to itself is prior or even independent of operation, which more affirm and which seems to me more probable; but I assert that substantial presence is necessary for operation, which St. Thomas perhaps called spiritual touch upon a body, q. 6 De Potentia, a. 7, ad 12; and more openly, q. 16 De Malo, a. 1, ad 15, he says that an angel does not act immediately on any body distant from it, and brings Damascene saying: Where an angel is, there it operates. Who is to be seen in bk. I De Fide, cc. 16 and 17, and bk. III, c. 2.

43. Nor does it stand in the way that the angel moves through intellect and will, because, as I shall say below in its place, it does not move through these powers as proximately eliciting the motion, but by directing and applying the executive power, which must be conjoined to the patient. Which reply St. Thomas intimates in the place just cited from De Potentia; for when he had objected in argument 12 that mover and moved must be together, but that the angel is not together with the body from the fact that it wills it to be moved, he answers: The command of an angel requires the execution of power; whence there must be a certain spiritual touch upon the body which it moves; and Quodl. VI, a. 2, ad 2, which was similar, The command of an angel requires the execution of power. And it is declared further, because, if the efficacy in moving were to be weighed from the mode in which the will attains its object, just as the will of an angel can indifferently will the near and the distant however far, so with the same efficacy it could move a near body and a distant one at any distance whatever; but the consequent is plainly absurd, because, since it has a finite power, it is not likely that it can operate equally on a thing however distant, but that it has a terminus in the sphere of its activity. As, therefore, the motive power is compared otherwise to its subject than the will to its object, so also in the absolute condition of nearness and distance; for the moving power acts really and transiently on the subject which it moves, and therefore it must be really undistant from it; but it is otherwise with the will as it is concerned with an object on which it does not really act nor which it changes.

On the action of spirits among themselves

44. The other part of that argument concerned the action of one angel on another or on a separated soul, which action too can be either speech or local motion. Of the latter the reason is the same as of the motion of a body; nor do I see a reason for a difference which could be assigned. Hence St. Thomas, in the place just cited, says generally that the substance of an angel must be conjoined to the things which it moves; for he did not say bodies, but things, in order to indicate that the doctrine is general. I suppose, however, that the discourse is of when one angel moves another truly and physically, effecting motion in it; for if it moves only morally by command, it requires only that presence which suffices for command, of which the reason is the same as of speech, for command takes place by speech.

45. How angels speak with one another.—Of the speech of one angel to another, however, we cannot speak here ex professo, for it is a theological matter and difficult to explain; speaking generally, however, one may proceed in it in one of two ways. One is that the speaking angel does nothing on the one to whom it speaks; and thus the reply in the present case is easy, because the angel to whom another speaks is not compared to it as subject or patient to agent, but only as object to immanent act; and therefore it is no wonder that speech can be immediately to an angel however distant. According to this way of speaking, however, it must be answered to the argument made that the speech of one and the arousing of the other do not take place by transient action from one to the other, but as it were by a certain natural sympathy; because, while one angel wills that the other perceive its act or concept, at once the other uses the species which it had of that act or concept in order to attend to the speaker. Nor do I see in what other way that opinion could be explained; but at once there appears from this how great a difficulty there is in it, namely, that faculties rooted in diverse essences or substances should have among themselves a natural sympathy and connection and concomitance in acting, not causal,¹ but infallible and per se, without action of one on the other. To which difficulty another is added: if the angel has innate species of the other's acts, why can it not behold them as soon as they exist, if it wishes, even if the other does not arouse it and as it were apply it by its ordination or will? Again there is added the difficulty about the illumination by which one angel not only speaks to, but also teaches another; for which, even if that sympathy is admitted, it does not seem to suffice. Finally, whatever be the case about speech taken strictly, the difficulty can be extended to every action of an intelligible species; for it is probable that one angel, inasmuch as it is an actually intelligible object, can, so far as concerns itself, impress a species of itself or of its acts on another angel, if this one lacks such a species. And whatever be the case about angels among themselves, with respect to the soul which is separated from the body this is more received; such action being posited, therefore, the difficulty remains intact, if it is not impeded by distance.

46. Another way of speaking, therefore, can be by admitting some intellectual action of one spirit on another through the real affection of some intelligible species, or of some intensification or modification of it. Which being supposed, the touched difficulty can still be answered in two ways. First, by excepting this action from the general rule handed down. Which way St. Thomas intimates in the cited question De Anima, and in Quodl. VI, a. 10. And he signifies the reason in both places, because the same thing is order in angels as situation in bodies, and therefore purely intellectual action does not depend on situation or medium, but on the order of nature. And in I, q. 107, a. 4, he adds that the operation of the intellect abstracts from place and time, and therefore the speech which takes place through it is not impeded on account of distance. And this can be confirmed, for it seems incredible that one angel cannot speak to another unless they are undistant in supposit and substance, for that action cannot be carried through the medium. This opinion, however, in truth seems less consistent with all that has been said, because it greatly weakens the principle laid down and its whole reason. Likewise, although in angels there is no situation, there is yet substantial presence; therefore the difference assigned is none for excluding the necessity of this presence for the said action; otherwise neither would undistance between angels be necessary in order that one might locally move or detain another. Likewise, according to that reason, God by virtue of the action by which He creates or illuminates an angel would not be intimately present in it through essence, but only by reason of immensity; which is against St. Thomas and the truer doctrine, as we shall see below. The sequel is evident, because God too acts on an angel as spirit on spirit; therefore the reason is the same of Him. On account of these things, therefore, the last way of speaking will be probable, that for this action too, and for angelic speech, if it requires that action, undistance is necessary. Between which opinions I leave the judgment to others as to which is simply more probable; I assert only that this third is more consistent with the matter we are now treating, unless the first is chosen, whose difficulties it is most difficult to satisfy.

On the sphere of activity

47. The last difficulty proposed in the sixth argument is most easily solved from the second and third parts of the last assertion, which it probably persuades, while against the earlier assertions it proves nothing. For although we grant that each agent has a natural sphere of activity of a certain magnitude, on which it can act per se and by its own power and action, it does not follow that it can act immediately on the remote part of that sphere without acting on the near, because it cannot act except by continued action, beginning it from a patient near and undistant to it, and continuously diffusing it through the whole sphere; for every efficient cause determines this mode of acting for itself. Nor is it unfitting that all causes, even if they are unequal in power, equally determine for themselves this nearness of the patient, because this does not come only from the limitation or imperfection of the power, but from the nature of this causality; but the limitation of the sphere comes from the limitation of the power, and so according to the inequality of power the sphere too will be unequal, if other things are equal. That argument does, however, seem rightly to prove that natural agents are not limited to acting per se and through their own proper power on the last surface alone of the body contiguous to them, but within some certain space, which they can attain by their power, even if, by a possible or impossible supposition, one part of the medium does not act on another; which we asserted in the last conclusion.

48. That argument does not prove, however (although it seems also to tend to this), that that mode of acting through the near part on the remote through the whole space is impossible, so that, however we divide the remote part from the near by proportional parts, and indeed the nearest surface from the rest of the magnitude, the effect can always proceed actively to the remote through the near; because in this mode of acting no repugnance is involved, since the quality received in the medium, or in any part of the medium, or in the surface, can be active, and the patient is also apt to receive such a quality, and the remote part is in due proportion with respect to the nearer so that it can suffer from it; because the action proceeds uniformly-difformly from the beginning of the sphere to the end; therefore all things necessary can concur for the action always to take place through the near on the remote. For the infinity of proportional parts cannot stand in the way, because a similar infinity is in the succession of action. We do not, therefore, assert that this mode is impossible; but we assert, first, that it is not necessary in order that every agent require nearness and undistance of the patient on which it first acts. Nor yet that it suffices for defining the sphere of activity of the agent per se by virtue of the quantity and limitation of its power. We assert, next, that even when the action proceeds in that way through the near part on the remote, it does not take place from one part on another in such a way that the agent does not at the same time and actually act with all within the sphere of its activity, and therefore the action on the remote part through the near is more efficacious than if the near part alone acted on the remote through the power received in itself. And both of these were asserted in the last conclusion, and seem to be sufficiently proved from all that has been said and what is contained in that last difficulty.