Jacques Maritain Center: Thomistic Institute

Nature as a Metaphysical Object

Lawrence Dewan, o.p.

General Considerations

A paper on nature as a metaphysical object(1) is, as we shall see, a paper on essence.(2) Is there anything more to say about essence? Essence had a difficult time in the 20th century, when the insistence was decidedly on existence. It might be wise to begin with a reminder of essence's right to "equal time". Since there are actually metaphysicians "out there" who think of essence as a mere limit on actual existence, or as a metaphysical item only needed to make possible the existence of creatures, beings other than the supreme being,(3) perhaps the best recommendation of essence we can provide is its status in the case of God. Suffice to say, then, that while in God the subsisting thing, the essence, and the act of being are one simple identical item, nevertheless that simple item verifies what is proper to each: inasmuch as God is not in another, he is a subsisting thing; inasmuch as he has whatness, he is an essence; and inasmuch as he is, actually, he is the act of being.(4) Indeed, what we call "essence" in creatures exists by priority in God, and exists there in a higher way: essence is most truly essence in God.(5)

The word "nature" has many meanings. Aristotle presented a whole series of meanings of "phusis" in Metaph. 5.(6) Boethius also had occasion to leave us a set of meanings of "natura", the most relevant Latin term.(7) Thomas Aquinas recounted several times the findings of these authors, sometimes offering personal reflections on them.(8)

Aristotle begins with the generation or birth of living things as a meaning; in Thomas's Latin, "natura" in that meaning is equated with "nativitas".(9) Aristotle subsequently moves to the principles, within things, of such an event, and to the principle of a thing's other changes or movements.(10) The word is extended in use even to the essence of changeable things. Lastly, by what Aristotle describes as a "metaphor", the word is applied to all ousia.(11) It is with this last "metaphorical" use of the word that I will be concerned. Lest the word "metaphor" lead one to think of this use as negligible, let us recall Thomas's treatment of the word "light" [lux]. Is it said properly or metaphorically(12) as applied to spiritual things? Well, if you consider the word as regards its first imposition, it is indeed metaphorically applied to spiritual things; however, if you consider its subsequent history in the mouths of speakers ["secundum usum loquentium"], it is said properly as applied to spiritual things.(13) I would say that the same is true of the use of "nature" as applied to the essence of all beings.

Aristotle is, of course, reporting on actual Greek usage. One has an impressive use of "phusis" placed by Plato on the lips of the youthful Socrates in the dialogue Parmenides. Socrates speaks of the Forms of things as "patterns fixed in nature"[paradeigmata hestanai en té phusei], where "nature" clearly means the realm of the unchangeable, i.e. true being.(14) In fact, the relation of this area of vocabulary to the expression of being is striking. Thus, the English word "be" is cognate with the Greek "phusis", and stems from the Sanskrit "bhu", meaning "to become", i.e. to arrive at the terminus of generation.(15)

Again, Plato, in the Cratylus, writes :

[Socrates] … [things] must be supposed to have their own proper and permanent essence [ousian]; they are not in relation to us, or influenced by us, fluctuating according to our fancy, but they are independent, and maintain to their own essence the relation prescribed by nature [héper pephuken].(16)


[Socrates] Are not actions a class of being [ti eidos tôn ontôn]?… Then the actions also are done according to their proper nature [kata tén autôn phusin], and not according to our opinion of them?(17)

Clearly, in this metaphysical discussion, what a thing is "as to nature" is contrasted with the mere being in human opinion.

My aim, then, in this paper, is to consider to some extent Thomas's use of this notion of nature as an object found universally, but analogically. What texts come to mind? Their great variety is already suggested by the variety of topics proposed by speakers for this week's proceedings. Certainly, texts include those on natural intellectual knowledge; on natural love in intellectual creatures; on nature and will in God; on the distinction between natural being and intentional being; on such a question as "is death natural?", etc. The point is to see what special task this notion of "nature" as applied universally performs. Why is it needed? Obviously, I can only hope to stimulate interest in so wide a topic.

But what is a "metaphysical outlook"? We might begin to answer that by recalling Aristotle's characterization of the science which seeks the first causes as the science of being as being. As Thomas reads him, Aristotle tells us that a cause must be the cause of some nature, and that the highest cause must be the cause of the nature of being.(18) Thus, to engage in metaphysics, one must grasp the beings themselves which we experience as exhibiting the sort of unity we mean by "a nature".(19) It will not be a specific nature or a generic nature. It will, nevertheless, have a unity which can well be described as "natural".(20)

In order to so view reality, we do not start with the "biggest picture". We start with the relevant sort of unity, but exhibited more locally. Thus, in CM 4, Thomas explains the Aristotelian conception of the unity of the field of metaphysics by means of a presentation of being in four modes or measures. In presenting four "modes of being", Thomas begins with the weakest, the least, and moves towards the strongest. The four are (1) negations and privations, (2) generations and corruptions and movements, (3) inhering accidents, and (4) substances. Here is his presentation:

One should know that the aforementioned [by Aristotle] modes of being [modi essendi] can be reduced to four. For one of them, which is the weakest, "is" only in the mind, namely negation and privation; we say they "are" in the mind, because the mind treats them as though they were some sort of beings, when it affirms or negates something in their regard. (The difference between negation and privation will be explained later.)

Another mode is close to the first as regards weakness, according to which generation and corruption and movement are called "beings". The reason [they are weak] is that they have, mixed in, something of negation and privation. Thus, it is said in [Aristotle's] Physics, bk. 3, that movement is imperfect actuality.

Now, in third place those items are called ["beings"] that have no admixture of not-being, and yet still have weak being, because they "are", not by themselves, but in another, the way qualities, quantities, and properties of substances "are".

But it is the fourth kind which is the most perfect, namely that which has being in nature [esse in natura] [i.e. not merely in the mind], and without an admixture of privation, and has solid and firm being, as existing by virtue of itself, the way substances "are".

And to this, as to what is first and principal, all the others are referred back. Thus, qualities and quantities are said to "be", inasmuch as they have "being-in" substances; movements and generations [are said to "be"] inasmuch as they tend towards substance, or to one of the others [i.e. quality or quantity]; and privations and negations [are said to "be"], inasmuch as they remove something pertaining to the other three modes.(21)

It is this kind of "sizing up" of what we immediately experience which constitutes the metaphysical outlook.(22)

Thomas obviously considers that reality is constituted with a unity along the lines suggested by this fourfold presentation. Thus, in other texts we see that substances themselves are presented to us in modes or levels or intensities of being. Thus, in ST 1.12.4, on whether any created intellect can by its own natural powers see the divine essence, Thomas establishes the premise that:

… the knowing [performed] by any knower is in keeping with the mode of its [the knower's] nature.

And he continues:

Therefore, if the mode of being of any known thing exceeds the mode of the nature of the knower, necessarily the knowledge of that thing is beyond the nature of that knower.

And we are then presented with the hierarchy:

Now, there are many modes of being.

Some things are, whose nature does not have being save in this individual matter; and of this mode are all corporeal things.

But some things are, whose natures are subsistent by themselves, not in some matter; which nevertheless are not their own being, but are [things] having being: and of this mode are incorporeal substances, which we call "angels".

Of God alone the proper mode of being is that he be his own being subsisting.(23)

Clearly, this is a vision which has to be built up, and we see many signs of the process of building in various places. However, one thing is especially clear: that in the presentation of the hierarchy as a hierarchy of being as being, the importance of cognition, and particularly intellectual cognition, as constituting a principle of division, is most evident. The reason for this is the ineluctable role of ontology in the explanation of cognition. Aristotle's mot that the soul, through sense and intellect, is in a way all things suggests that there is a difference from the viewpoint of being itself, as between the thing which has intellect and the thing which does not. Thus, Thomas, in explaining why the rational creature is a subject of divine providence in a special way, says:

It is evident that all parts are ordered towards the perfection of the whole: for the whole is not for the sake of the parts, but the parts are for the sake of the whole. But intellectual natures [naturae intellectuales] have a greater affinity with the whole than [do] other natures [aliae naturae]: for each intellectual substance is in a way all things, inasmuch as through its intellect it is inclusive of being in its entirety [totius entis comprehensiva est]; whereas any other substance has a merely particular participation in being [particularem solam entis participationem habet]. Thus, fittingly, the others are provided for by God for the sake of the intellectual substances.(24)

Both levels of substance have being, but one has it in a more complete and so meaningful way. Accordingly, it occurs to me that a consideration of the presentation of this mode of nature will serve to stimulate interest in nature as a metaphysical object.

Among the various presentations by Thomas of the meanings of the word "natura", the foregoing texts put me in mind of one which contains an especially illuminating specification. In the De ente et essentia, commenting on the use of "nature" to mean the essence of a thing, Thomas says:

[Essence] by another name is also called "nature", taking "nature" according to the first way of those four which Boethius presents in the book On the Two Natures: according as every item which can be grasped by intellect in any way is called a "nature": for a thing is intelligible only through its definition and essence; and thus also the Philosopher says in Metaphysics 5 that every substance(25) is a nature. Nevertheless, the word "nature" taken in this way seems to signify the essence of the thing according as it has an order towards the proper operation of the thing, since no thing is bereft of a proper operation.(26)

It is this conception of essence as ordered to the thing's proper operation(27) which will be the key to my approach here today.

We should reflect on the idea of a proper operation, and, indeed, on the conception of operation. Obviously, it pertains to the move from a consideration of "nature" as naming the proper principles of physical things, as presented in Aristotle's Physics 2.1, to what is meant by "nature" as said of every essence. The Aristotelian definition in Phys. 2 speaks of a principle of movement or change. As Boethius says in this connection: "every body has its proper movement".(28) Thomas, I might add, relates the doctrine that "nothing is without its proper operation" to St. John Damascene.(29) Now, consider the following argument from an objector to the view that life pertains to God:

Some things are said to "live", inasmuch as they move themselves… But to be moved does not befit God. Therefore, neither does "to live".

Thomas answers:

… as is said in Metaph. 9, action is twofold: one which goes forth into external matter, as to heat and to cut; the other, which remains within the agent, as to understand, to sense, and to will. The difference between the two is as follows: that the first [sort of] action is not the perfection of the agent which brings the movement about, but rather [is the perfection] of the very thing moved; whereas the second [sort of] action is the perfection of the agent. Hence, because movement is the act of the moveable thing, the second [sort of] act, inasmuch as it is the act of the one performing the operation, is called its "movement", on the basis of this likeness, that just as movement is the act of the moveable, so this sort of action is the act of the agent: though, admittedly, movement is the act of the imperfect, i.e. of that which exists in potency, whereas this sort of action is the act of the perfect, i.e. of that which exists in act, as is said in De anima 3. Therefore, in this mode in which understanding is a movement, that which understands itself is said to move itself. And in this way also, Plato held that God moves himself, not in the way that movement is the act of the imperfect.(30)

This sort of extension of the vocabulary of "movement" to operation in general helps to explain the movement of thought from "nature" in the Phys. 2 sense to "nature" in the sense of essence as ordered towards its proper operation. Thomas, commenting on the text of Aristotle's De anima 3 referred to above, stresses the difference between sensation and physical motion [a motu physico, line 32]; sensation, along with intellection and volition, is properly called an "operation".(31)

The term "act", also, is used for both movement and operation, as is clear from the above. Movement is the act of a thing in potency, whereas operation is the act of a thing in act.(32) Indeed, Thomas will, in a metaphysical context, use the vocabulary of "operation" and "action" for the movement or change proper to the physical thing. Thus, we read:

… the bodies of those things whose being is in [the domain of] change imitate incorruptible bodies in this respect, that they always act; thus, for example, fire, which just in virtue of itself always heats, and earth, which just in virtue of itself always performs its proper and natural operations. And this indeed is the case because they have movement and their own proper operation just in virtue of themselves, and within them, inasmuch as their forms are the principles of such movements and actions.(33)

We must also recall the doctrine of the importance for a thing of its proper operation. We remember the text:

… it is evident that operation is the ultimate act of the one performing the operation: hence, it is called "second act" by the Philosopher in De anima 2 [412a23]: for the thing having form can be merely potentially operating, as for example, the scientist is potentially considering. And thus it is that in other things "each thing is said to be for the sake of its operation", as is said in De caelo 2 [286a8].(34)

An especially good general picture of the nature and its order towards both being and operation is provided in the ST discussion of the Trinity; speaking of the equality of magnitude which obtains among the three Persons in God, Thomas says:

The magnitude of God is nothing else but the perfection of his very nature.(35)

In the question's first article, an objector is introduced to argue that there can be no equality in God because there is no quantity. And to this, Thomas provides the following reply:

... quantity is twofold. One is called "quantity of mass" or "dimensive quantity", which is found in corporeal things only, and so has no place in the Divine Persons. But the other is "quantity of power" [quantitas virtutis], which is caught sight of in connection with the perfection of some nature or form. It is this [latter] quantity which is signified when something is said to be "more" or "less" warm, inasmuch as it is more perfect or less perfect as regards such a quality.(36) Such quantity of power [quantitas virtualis] is seen first of all at its root, that is, in the very perfection of the form or nature, and thus one speaks of "spiritual greatness" [magnitudo spiritualis], as one speaks of heat as "great" because of its intensity and perfection. And thus Augustine says in De trin. 6, that "in those things which are 'great', not by reason of their mass, that is 'greater' which is 'better'"; for the more perfect is what one calls "better".

Secondly, however, quantity of power [quantitas virtualis] is seen in the effects of form. And the first effect of form is being, for every thing has being in accordance with its form. The second effect is operation, for every agent acts by virtue [per] of its form. Thus, quantity of power is seen as regards being and as regards operation; as regards being, inasmuch as those things which are of a more perfect nature have a greater duration; and as regards operation, inasmuch as those things which are of a more perfect nature, are more powerful as regards action…(37)

While we see these considerations applied, in the above quotation, to any particular nature, thus making being [esse] the effect of the nature, ultimately Thomas regularly takes the case of what is most formal of all, namely being itself.(38) Thus, he will speak of God, presented as being itself, subsisting by itself, as possessed of the entire perfection of being. We see this in a text such as the following:

... God is being itself, subsisting by itself [ipsum esse per se subsistens]: hence it is necessary that the total perfection of being [totam perfectionem essendi] be contained in him. For it is evident that if something warm does not have the total perfection of the warm, this is because warmth is not participated in according to its perfect character [perfectam rationem]; but if warmth were subsisting by itself, there could not be lacking to it anything of the power of warmth. Hence, since God is being subsisting, nothing of the perfection of being can be lacking to him. But the perfections of all things pertain to the perfection of being: for it is according to this that some [particular] things are called "perfect", viz. that they have being in some measure [aliquo modo esse habent]. Hence, it follows that the perfection of no thing is lacking to God.(39)

This text, showing what I would call the "Fourth Way" viewpoint, is absolutely typical of Thomas's metaphysical overview, for the whole of his career. It is a vision wherein being itself is considered as a nature.(40)

More Particularly: The Nature of the Human Soul

The presentation of the human soul in ST 1.75-89 affords us the opportunity to watch Thomas contemplate a nature precisely as a nature. In the prologue to q. 75, in the midst of the treatise on the divine work of distinction,(41) we arrive at the consideration of the human being, a composite of spiritual and corporeal substance. However, after dividing the presentation into consideration of [1] the nature of man and [2] the production of man, it is immediately noted that it belongs to the theologian to consider the nature of man as regards man's soul. The body enters into the discussion only as regards its relation to the soul. Thus, qq. 75-89 are on the essence of the human soul. Thomas finds in pseudo-Dionysius's On the Celestial Hierarchy the approach he requires for this study, a three-step approach suitable to the study of spiritual substances, in terms of essence, power, and operation.(42) Philosophically, this is clearly an exercise in metaphysics.(43)

Thomas has considerable confidence in the quality of his knowledge of the human soul. In discussing the limitations of our knowledge of God and angels, he raises the question whether our intellect through knowledge of material things can come to understand the immaterial substances. An objector argues in favour of such understanding:

The human soul is in the genus of immaterial substances. But it can be understood by us through its act, by which it understands material things. Therefore, also other immaterial substances can be understood by us through their effects on material things.

Thomas, however, replies:

… the human soul understands itself through its own act of understanding, which is its proper act, perfectly demonstrating its power and its nature. But neither through this, nor through other things which are found in material things, can the power and nature of the immaterial substances be perfectly known; because such [effects] do not adequately measure up to their powers.(44)

While qq. 75-89 are rich in materials relevant to our topic, q. 77, located between the discussion of the essence of the soul in itself and the discussion of the operation of understanding, is an ideal focal-point for seeing the essence ordered towards operation, i.e. the nature. The first issue is the very distinction between essence and power. As Thomas himself points out, not everyone sees the need to make this distinction.(45) The single article here depends on a three-step presentation already given in treating of the angels, viz. 1.54.1-3. Thomas there begins by distinguishing between the substance of the angel (and of any creature) and its act of understanding (or any operation); he next shows the necessity to distinguish between the angel's act of being and its act of understanding (indeed, between any creaturely act of being and any operation); and lastly he argues that the essence of the angel (or of any creature) cannot be identified with its operative power.

Of these three articles, the most important and enlightening is the second, distinguishing between the act of being and the act of understanding. Thomas recalls the distinction between actions which remain in the agent, such as to sense, to understand, and to will, and actions which project forth and influence something else, such as to heat and to cut. The problem is not here with these latter, since they are not easily confused with the substance or the act of being of the agent. However, "I think" and "I am" might be confused, and so the basis of distinction is the object of the operation: to understand and to will have an infinite object, viz. all things, whereas the creaturely act of being is finite.(46)

As I said, 1.77.1 is based on 1.54.1-3, and concludes that in no creature can there be identity between essence and operative power. 1.77.2 presents the rationale for the multiplicity of powers of the human soul. The point is that the multiplicity of powers pertains to the place of man and human soul in the hierarchy of reality. Man belongs in the upper echelon of reality inasmuch as he can attain to "the universal and perfect good", i.e. to beatitude. However, among things so endowed, he is at the lowest level, and so needs many kinds of operation to do so.

1.77.3 explains how one distinguishes one operative power from another, i.e. on the basis of the objects of the operation. One notes here how important it is that the distinctions are rather evident in the realm of the external senses, thus providing a model for the discussion of the more immaterial powers.

With 1.77.4 we come to what more directly concerns us at present. Is there an order among the powers of the human soul? Without this vision of order, we would have little conception of the unity of the source, i.e. of the soul as a nature. That this is so is brought out in 77.6, where the first objection against the powers flowing from the essence of the soul is the simplicity of the soul versus the multiplicity of powers:

From one simple item diverse items do not proceed. But the essence of the soul is one and simple. Since, therefore, the powers of the soul are many and diverse, they cannot proceed from its essence.

And Thomas replies:

It is to be said that from one simple item many can naturally proceed in some order. And, again, because of the multiplicity of recipients. Thus, therefore, from the one essence of the soul many and diverse powers proceed, for one reason, because of the order of the powers, for another, because of the diversity of corporeal organs.(47)

This means that, in order to have a decent conception of the order of the essence towards the powers and operations, i.e. of the essence as a nature, one must consider the order of the powers, already presented in a. 4.

We might note in a. 4, first of all, the sort of thing we have in the sed contra, recalling that Aristotle had compared the powers of the soul to the sequence of geometrical figures. The idea that one must proceed from one to many by virtue of an order is linked to the coherence of the procession, its per se character. Obviously one can associate a merely chaotic variety of accidental entities with a substance, but they are not per se associates if they do not have something to do with the very unity of the substance.(48) Thus, Thomas begins precisely on this point:

It is to be said that since the soul is one, while the powers are many, and it is by some order that there is procession from something one to a multiplicity, it is necessary that there be order among the powers of the soul.

He then specifies:

Now, a threefold order is seen among them. Two of them are considered as to the dependence of one power on another; the third is taken from the order of [their] objects.

But the dependence of one power on another can be taken in two ways: in one way, according to the order of nature,(49) inasmuch as the more perfect are prior to the less perfect; in the other way, according to the order of generation and time, inasmuch as from the imperfect one comes to the perfect.

Therefore, according to the first order of powers, the intellective powers are prior to the sensitive powers: hence, they direct them and dominate them. And, similarly, in this order the sensitive powers are prior to the powers of the nutritive soul.

But according to the second order, the converse is the case. For the nutritive powers of the soul are prior, on the pathway of generation, to the sensitive powers: hence, they prepare the body for the actions of the latter [powers]. And it is similar for the sensitive powers relative to the intellective powers.

But as regards the third order, some sensitive powers are ordered among themselves, viz. sight, hearing, and smell. For the visible is naturally prior, because it is common to superior and inferior bodies. And audible sound is brought about in air, which is naturally prior to the mixture of the elements, which odor follows upon.

Notice here the following objection and reply. The second objector says:

… The powers of the soul relate to their objects and to the soul itself. But based on the soul there is no order among them, because the soul is one. Similarly also, based on the objects, which are diverse and altogether disparate, as is clear in the case of color and sound. Therefore, there is no order among the powers of the soul.

Thomas replies:

It is to be said that this order of the powers of the soul has its base in the soul, which according to a certain order stands related to the diverse acts, even though it is one as to its essence; and also, as based on the objects; and also as based on the acts, as was said.(50)

The third reply here notes that in the case of the first two sorts of order, the operation of one power depends on the operation of another.

Obviously, here in 1.77.4 we are close to the vision of human unity itself, inasmuch as we see this order in the multiplicity.

1.77.5 asks whether all the powers are in the soul as in a subject. Here we have the distinction between the intellect and will, on the one hand, viz. the powers which have no corporeal organ, and all the other powers which do have an organ. The latter have as their subject the composite of soul and body, the former the soul alone. However, it is noted already, all the powers have the soul as their principle(51)

It is aa. 6 and 7 of q. 77 which most concern us here. Do the powers flow from the essence of the soul? Does one power flow from another? If we are to see the essence of the soul as a nature, i.e. as ordered towards its proper operation, this doctrine is central.

In a. 6, the sed contra sends us to Aristotle's Metaphysics 7, that the subject is introduced into the very definition of the proper accident.(52) The idea is that the powers of the soul are its natural properties, and thus are caused by the soul.

The body of the article could not be more metaphysical. It consists mainly in a distinction between the role of the substantial form and that of the accidental form (where the accidental form is a proper accident of the substance). It begins:

It is to be said that the substantial form and the accidental form partly agree and partly differ. They agree in this, that each is act, and in function of each something is in some measure in act.

But they differ in two respects. Firstly, because the substantial form brings about being, unqualifiedly, and its subject is a being in potency only. The accidental form, on the other hand, does not bring about being, unqualifiedly; but rather, being such, or so much, or in some relation; for its subject is a being in act. Hence, it is clear that actuality [actualitas] is found by priority in the substantial form rather than in its subject; and because what is first is cause in every order, the substantial form causes being in act in its subject. But, conversely, actuality is found by priority in the subject of the accidental form rather than in the accidental form; hence, the actuality of the accidental form is caused by the actuality of the subject. And this takes place in such a way that the subject, inasmuch as it is in potency, is receptive of the accidental form; while inasmuch as it is in act, it is productive of it. - And I say this regarding the proper and essential [per se] accident; for relative to the extraneous accident, the subject is merely receptive; an extrinsic agent is productive of such an accident

But, secondly, the substantial and accidental forms differ, because since the less principal is for the sake of the more principal, matter is for the sake of the substantial form; but, conversely, the accidental form is for the sake of the completion of the subject.

All this is said subsequent to a. 5, in which we saw that some powers, viz. the intellect and the will, have the soul itself as their subject. Thus, Thomas now briefly makes his point:

But it is evident from things already said [1.77.5] that the subject of the powers of the soul is either the soul alone, which can be the subject of an accident inasmuch as it has something of potentiality, as was said above [1.77.1.ad 6; 1.75.5.ad 4]; or else the composite. But the composite is in act through the soul. Hence, it is manifest that all the powers of the soul, whether their subject is the soul alone or the composite, flow from the essence of the soul as from a principle; because it was just said that the accident is caused by the subject according as it is in act, and is received in it inasmuch as it is in potency.

This concludes the body of the article. The basic idea is that the substantial form as such is source of actuality for the accidental forms.

The doctrine of the powers flowing from the essence of the soul is thus based on the priority as to actuality of the subject of the accidental form over the accidental form itself; which in turn is based on the priority of substance and hence substantial form over accident. It is the fundamental doctrine of being which is in play.(53)

Let us move quickly on to a. 7, on the flow of one power from another. The body of the article begins:

It is to be said that in those things which proceed in a natural order from something one, just as the first is the cause of all, so also that which is closer to the first is in some measure [quodammodo] the cause of those which are more remote.

But it has been shown above [1.77.4] that among the powers of the soul there is manifold order. And so one power of the soul proceeds from the essence of the soul through the mediation of another. [470a19-27]

Having made this general point, Thomas now looks at the situation more closely. We read:

But because the essence of the soul compares to the powers both [1] as active and final principle and also [2] as receptive principle, either separately by itself or together with the body; and the agent and the end is more perfect, whereas the receptive principle, as such, is less perfect; the consequence is that the powers of the soul which are prior according to the order of perfection and of nature are the principles of the others in the mode of end and active principle: for we see that sense is for the sake of intellect, not the converse; moreover, sense is a lesser [deficiens] participation in intellect; hence, according to natural origin it is in some measure [quodammodo] from intellect, as the imperfect from the perfect.

But in function of the pathway [viam] of the receptive principle, conversely, the imperfect powers have the role of principles with respect to the others; just as the soul, inasmuch as it has the sensitive power, is considered as a subject and a sort of material with respect to the intellect; and for that reason, the more imperfect powers are prior on the pathway of generation: for animal is generated prior to man.(54)

The comparison with the soul, as having a conception in terms of the sequence of types of soul, is to be noted here. The nobility of the soul is seen in its being the single principle of the variety of powers.(55)

This is the entire body of the article. My point is, as always, that the order of causal flow of the powers pertains to the doctrine of the unity of source, and so to the vision of the essence of the soul as a nature, a nature with a certain proper perfection.

Before concluding, I wish to add a few points which complete the picture. Thomas takes on the complex task of presenting the essence of the soul as source of all the powers of man. I will focus for the moment on the soul as source and subject of the two spiritual powers, the intellect and the will. In terms of what we have seen, it is clear that one of these powers flows from the other, and in fact, the will flows from the intellect, the less perfect from the more perfect. This is the significance of the articles in which Thomas makes the comparison of the one power to the other, e.g. ST 1.82.3. We might note one objection and reply in that context, one which harmonizes very much with what we have seen. The objector, arguing for the greater nobility of the will, says:

Natural things are found to proceed from the imperfect to the perfect. And this also is apparent among the powers of the soul: the process is from sense to intellect, which is more noble. But the natural process is from the act of the intellect to the act of the will. Therefore, the will is a more perfect and more noble power than the intellect.

To which Thomas replies:

It is to be said that that which is prior as to generation and time is more imperfect: because in one and the same thing potency temporally precedes act and imperfection perfection. But that which is prior, unqualifiedly, and as regards the order of nature, is more perfect: for thus act is prior to potency. And it is in this way that intellect is prior to will, as the motive principle [motivum] to the mobile item, and as the active to the passive: for the understood good moves the will.(56)

We note that the sequence here is not temporal, but rather one of the imperfect following upon the perfect. The act of the will which follows upon that of the intellect can very well be simultaneous with that of the intellect.(57)

We should note how Thomas conceives of the "flow" of powers from the essence of the soul, and of one power from another. In 1.77.6.ad 3, the objector argues:

… "Emanation" names a sort of movement. But nothing is moved by itself, as is proved in Physics, book 7 [241b24], save perhaps by reason of a part: as an animal is said to be moved by itself, because one of its parts is the mover and another is the moved. Nor, also, is the soul moved, as is proved in De anima 1 [408a34]. Therefore, it is not the case that the soul causes in itself its own powers.

I.e. this whole idea of the flow of the powers, which have their seat in the essence, from the essence itself, doesn't make sense: one identical thing would be both mover and moved. And Thomas replies:

It is to be said that the emanation of the proper accidents from the subject is not by virtue of any change [transmutationem]; but rather by a natural following forth [naturalem resultationem]: the way in which from one item another naturally [naturaliter] results: as, for example, color from light.(58)

Here, the idea is that light and color are given together in one same instant, but that color is able to affect the transparent medium (e.g. the air around the colored body) only with the aid of light (color being a participation of light by the body limiting the transparent medium).(59)

One would have eventually to discuss the outmoded character of this example. I had at first thought that our best examples of what Thomas means are such sequences as arm and hand, or eye and socket muscles. We find in things a natural order of forms, without which a thing which is one would be incomplete. However, that is more a case of final causality than of productive causality. We might better resort to something more intellectual. When one already knows the major premise and one comes to see the minor in its role as minor, at the same moment one sees the conclusion. The conclusion is an effect of the premise, a natural sequel.(60)

We see something of the importance of the doctrine of emanation of powers from soul and power from power when, speaking later of how the intellect knows the act of the will and the will itself, Thomas first of all faces an objector who argues that the intellect, being an entirely different power than the will, the act of the will is not in the intellect and so is not known by the intellect. Thomas replies:

… the argument would work if the will and the intellect, just as they are diverse powers, so also they differed as to subject: for thus what is in the will would be absent from the intellect. Now, however, since both are rooted in the one substance of the soul, and one of them is in some measure [quodammodo] the principle of the other, the consequence is that what is in the will is also in some measure in the intellect.(61)

So also, explaining what Augustine meant by saying that the affections of the soul are known through certain "notiones", Thomas says:

… the affections of the soul are not in the intellect merely through likeness, as bodies are; nor through presence as in a subject, as [in the case of] the arts; but rather as the result [or: sequel] in the principle [sicut principiatum in principio] in which one has the notion [notio] of the result…(62)

Lastly, we should note a problem: if the power cannot be identical with the essence of the soul because, it would seem, of the very nobility of the object of the power (at least in the case of intellect and will), how can the essence itself still be seen as the source of the power? Can the greater come from the lesser? A manifestation of this problem is seen in the particular case of the agent intellect. Thomas teaches that the agent intellect is a power of the human soul. The argument for this point in the ST is not simple. Thomas first teaches that there must be, above the human intellect, a higher intellect on which it depends, and from which it obtains the power [virtus] to understand. That this is a power within the soul itself, participated from the higher mind, Thomas concludes both on general principles and in view of our own actual experience.

However, one of the objections runs:

If the agent intellect is something belonging to the soul, it must be some power…. But every power flows from the essence of the soul. Therefore, it would follow that the agent intellect would proceed from the essence of the soul. And thus it would not be in the soul by participation from some higher intellect; which is unacceptable. Therefore, …

Thomas answers:

… since the essence of the soul is immaterial, created by the supreme intellect, nothing stands in the way of the power which is participated from the supreme intellect, [the power] by which it abstracts from matter, proceeding from its essence, just as the other powers.(63)

We see that, for an adequate conception of the essence of the soul as a nature, i.e. as ordered to operation, and in particular to the intellectual operation, it must be seen as itself flowing from the divine creative cause.

This falls in with the picture we were given in 1.77.6: the property relates to the essence both as in potency relative to the essence and as act relative to the essence. As act relative to the essence's potency, it indicates the need for something above the essence of the soul. This is in accord with the need for completion which the soul (and every creature) has. It is to this situation Thomas refers when explaining later how supernatural grace can be a quality of the soul. A most important ontological remark is found in the reply to an objection. Substance, it is objected, is nobler than quality, and grace is nobler than the nature of the soul. Thus, it cannot be its quality. Thomas replies:

It is to be said that every substance either is the very nature of the thing of which it is the substance, or else is a part of the nature (in which way the matter or the substantial form is called "substance"). And because grace is above human nature, it cannot be that it is the substance or the substantial form: rather, it is an accidental form of the soul itself. For that which is in God substantially is brought to be accidentally in the soul participating the divine goodness: as is clear in the case of science. Therefore, in accord with that, because the soul imperfectly participates the divine goodness, the very participation in the divine goodness which is grace has being in a more imperfect mode in the soul than [the mode of being by which] the soul subsists in itself. Nevertheless, it is more noble than the nature of the soul, inasmuch as it is an expression or participation of the divine goodness, though not as to the mode of being [non autem quantum ad modum essendi].(64)

This is true even of a natural virtue such as theoretical science, which is a participation in beatitude.(65) The mode of being is accidental, but the sort of participation in the divine goodness is so noble that it cannot be substantial in creatures.

To complete this picture of the divine agent above the human soul, let us look now at ST 2-2.2.3. It asks whether believing something beyond natural reason is necessary for salvation. It uses the vision of the natural cosmic hierarchy as a basis for a conception of the relation of the human mind to God. We read:

In all ordered natures it is found that two things concur for the perfection of the lower nature: one which is according to its proper movement; the other which is according to the movement of the superior nature.

For example, water, according to its proper movement is moved towards the center [of the universe], but according to the movement of the moon it is moved about the center as regard flowing and flowing back; similarly, also, the spheres of the planets are moved by their proper movements from west to east, but by the movement of the first sphere from east to west.

Now, only the created rational nature has immediate order to God. Because the other creatures do not attain to anything universal, but only to something particular, participating the divine goodness either as to being only, as inanimate things, or also in living and knowing singulars, as plants and animals; but the rational nature, inasmuch as it knows the universal intelligibility of being and the good [universalem boni et entis rationem], has an immediate order to the universal principle of being [ad universale essendi principium].

Therefore, the perfection of the rational creature does not consist merely in that which befits it according to its own nature, but in that also which is attributed to it from some supernatural participation of divine goodness. Hence, earlier it was said that the ultimate beatitude of man consists in some supernatural vision of God.(66)

Thomas goes on to explain the role of faith in the attainment of this beatitude. My primary point in citing this text is not the general doctrine of hierarchy of natures, where the examples are in obvious need of updating; nor am I concerned for the moment with the need for faith; rather, I underline the view of the rational nature as such, as immediately under the divine influence.(67)

There should be no hesitation in seeing here a metaphysical conception of nature. Thus, Thomas speaks of the divine nature as the "higher nature":

It is to be said that because the nature of man depends on a higher nature, natural knowledge does not suffice for his perfection, but some supernatural [knowledge] is required…(68)


My aim today has been to recall how all-embracing and important is the conception of nature as essence ordered towards operation. After indicating the presence of this notion in the very conception of metaphysics as a science, I have focused on a particularly prominent case, the essence of the human soul as exhibiting such an order.

1. By "a metaphysical object" I mean what is a proper target of attention of the science of metaphysics; thus, in ST 1.11.3.ad 2, Thomas, speaking of the "one" which is interchangeable with "a being", calls it "quoddam metaphysicum", in contrast to the "one" which is the principle of number; this latter, he says, is "de genere mathematicorum". In CM 5.5 (808), he carefully explains how "natura", as said of all substance, pertains to first philosophy, just as does "substance", taken in all its universality.

At the outset of his Commentary on the Nicomachean Ethics Thomas lists among the orders with which reason has to do, the order of natural things. He says:

There is a certain order which reason does not make, but only considers: such as is the order of natural things [ordo rerum naturalium]. [In Eth. 1.1 (#1).]

And he goes on to list the diverse sciences which relate to the various orders mentioned. As regards the order of natural things, he says:

… to natural philosophy it pertains to consider the order of things which human reason considers but does not make: we are taking "natural philosophy" as including within it also metaphysics [ita quod sub naturali philosophia comprehendamus et metaphysicam]. [In Eth. 1.1 (#2).]

2. ST 1.60.1 (ed. Ottawa, 362b5-7):

… nature is prior to intellect, for the nature of each thing is its essence.

3. In his book Introduction à la philosophie chrétienne, Paris, 1960: Vrin, looking for the basis for the possibility of having beings other than God himself, Étienne Gilson tells us:

The difficulties to be surmounted are particularly serious in a theology like this one, where the first Cause transcends the order of essence. Indeed, it is a matter of understanding how essences can emanate from the being in which no distinctive essence is added to the esse to form a composition with it? This way of posing the question should, besides, suffice to allow us to see in what direction the answer must be sought. If one located God in the order of essence, even at its summit, it would become extremely difficult, not to say impossible, to find outside of God a place for the world of creatures… But we begin here with the notion of a God entirely transcending the order of essences, which includes the totality of creatures, whence one can infer that no problem of addition or subtraction will arise as between him and the being he creates. [170-171; my italics and caps; the question-mark is Gilson's]

And towards the end of the meditation, he tells us:

The property of essence [Le propre de l'Essence] , finite mode of participating in being, is to render possible the existence of a natura rerum which is neither nothing nor God [198, my italics and small caps].

Thus, it is clear that the word "essence", for Gilson, means properly a finite participation in being.

Of course, one can say that God transcends the entire order of being, as including both essence and existence; but that is obviously not what Gilson had in mind; cf. Thomas, Expositio libri Peryermenias 1.14 (ed. Leonine, t. 1*1, Rome\Paris, 1989: Commissio Leonina\Vrin, lines 438-442):

... the divine will is to be understood as standing outside the order of beings [ut extra ordinem entium existens], as a cause pouring forth being in its entirety [totum ens] and all its differences. Now, the possible and the necessary are differences of being...

In another late text, ST 3.75.4 (2943a18-19), we have:

... his [i.e. God's] action extends to the entire nature of being [ad totam naturam entis]...

This is in the context of the discussion of the change involved in the sacrament of the Eucharist. In the ad 3, there, God is called the author of ens, and the nature is also termed "entitas", "entity".

4. In SCG 4.11 (ed. Pera #3472-3473).we read:

... those things which in creatures are divided are unqualifiedly one in God: thus, for example, in the creature essence and being [esse] are other; and in some [creatures] that which subsists in its own essence is also other than its essence or nature: for this man is neither his own humanity nor his being [esse]; but God is his essence and his being.

And though these in God are one in the truest way, nevertheless in God there is whatever pertains to the intelligible role [ratio] of the subsisting thing, or of the essence, or of the being [esse]; for it belongs to him not to be in another, inasmuch as he is subsisting; to be a what [esse quid], inasmuch as he is essence; and being in act [esse in actu], by reason of being itself [ipsius esse].

5. Cf. De ente et essentia c. 1 (ed. Leonine, lines 53-63. My italics.):

... But because "ens" is said absolutely and primarily of substances, and posteriorly and in a somewhat qualified sense of accidents, thus it is that essentia also properly and truly is in substances, but in accidents it is in a certain measure and in a qualified sense. But of substances, some are simple and some are composite, and in both there is essentia; but in the simple in a truer and more noble degree [ueriori et nobiliori modo], inasmuch as they also have more noble esse; for they are the cause of those which are composite, at least [this is true of] the first simple substance which is God.

6. Aristotle, Metaphysics 5.4 (1014b16-1015a19).

7. Boethius, Contra Eutychen et Nestorium, c. 1. Cf. The Theological Tractates, with an English translation by H. F. Stewart and E.K. Rand, London and New York, 1918 [reprint 1926]: Heinemann and Putnam [Loeb Classics].

8. E.g. ST 1.29.1.ad 4; also 3.2.1.

9. Thomas, CM 5.5. (808).

10. Here we have the meaning which will be given primacy in both the Metaphysics and the Physics. In Physics 2.1 (192b21-23), nature is a cause or principle of being moved and of being at rest, being within firstly and by virtue of itself and not by accompaniment. This is primarily the substantial form, secondarily the matter (193b3-8). In the Metaphysics, it is ultimately the form [ousia, which Thomas, CM 5.5 (826), interprets as form here] of things having a principle of movement within themselves as themselves (1015a13-15). - The importance of the notion of substance for this conception cannot be too strongly underlined; selfhood or a primary "within" depends on the notion of substance, since among the modes of unity, identity or selfhood is the mode proper to substance as substance; cf. CM 4.2 (#561) and 10.4 (#2002-#2005).

11. Aristotle, Metaph. 5.4 (1015a11-13); cf. Thomas, CM 5.5 (823).

12. For Thomas's explanation of the difference between things said metaphorically and things said properly, cf. ST 1.13.3.ad 1 and ad 3.

13. ST 1.67.1.

14. Plato, Parmenides 132D.

15. Cf. Concise Oxford Dictionary, London, 1964 [fifth edition]: Oxford University Press, concerning "be".

16. Plato, Cratylus 386d-e [transl. Benjamin Jowett].

17. Cratylus 387a.

18. As Thomas, CM 4.1 (533), on Aristotle at 1003a26-32, paraphrases:

… Every principle is the essential principle and cause of some nature. But we seek the first principles and the highest causes… therefore, they are the essential cause of some nature. But of no other nature than that of being…. Italics mine]

In ST 1.45.5.ad 1 (288b35-38), Thomas qualifies his use of the term "natura" for the field of reality as falling under the cause of being as such:

… sicut hic homo participat humanam naturam, ita quodcumque ens creatum participat, ut ita dixerim, naturam essendi; quia solus Deus est suum esse…

[… as this man participates human nature, so also each created being whatsoever participates, if I may so speak, the nature of being, because God alone is his own being…]

19. I will cite an early text along these lines, Commentary on the Sentences (ed. Mandonnet, pp. 12-13), part of the prehistory of the Fourth Way (ST 1.2.3); Thomas is aiming to show that there must be one and only one unqualifiedly first principle:

... This is apparent ... from the very nature of things [ex ipsa rerum natura]. For there is found in all things the nature of entity [natura entitatis], in some [as] more noble [magis nobilis], and in some less [minus]; in such fashion, nevertheless, that the natures of the very things themselves are not that very being itself [hoc ipsum esse] which they have: otherwise being [esse] would be [part] of the notion of every quiddity whatsoever, which is false, since the quiddity of anything whatsoever can be understood even when one is not understanding concerning it that it is. Therefore, it is necessary that they have being [esse] from another, and it is necessary to come to something whose nature is its very being [cujus natura est ipsum suum esse]; otherwise one would proceed to infinity; and this is that which gives being [esse] to all; nor can it be anything else but one, since the nature of entity [natura entitatis] is of one intelligibility [unius rationis] in all, according to analogy [secundum analogiam]: for unity in the caused requires unity in the proper [per se] cause. This is the route taken by Avicenna in his Metaphysics 8.

Here, then, the unity of the first principle is concluded to from the unity of the hierarchy of acts of being, a unity described as the "nature of entity".

20. We might recall ST 1-2.10.1.ad 3, concerning whether the human will is moved towards anything naturally. The objector argues that nature is determined to something one, but that the will relates to opposites; thus, it has no natural movement. Thomas replies:

It is to be said that to a nature something one always corresponds, [but] something proportionate to the nature. For to the generic nature [naturae… in genere] there corresponds something generically one [unum in genere]; and to the specific nature there corresponds something specifically one; while to the individuated nature there corresponds one individual something. Therefore, since the will is a certain immaterial power, just as is the intellect, there corresponds to it naturally some one common thing, viz. the good; just as to the intellect there corresponds some one common thing, viz. the true, or that-which-is [ens], or the what-it-is [quod quid est]. Still, under the good, taken universally [sub bono… communi], many particular goods are contained, to none of which is the will determined.

The point of the reply is that there is a unity proper to the altogether universal intelligibles.

21. CM 4.1 (Cathala #540-543). - We note the use here of "being in nature", as contrasted with being in the mind.

22. This is an approach mainly in terms of being as divided by the categories, though the inclusion of change shows that being as divided by act and potency is also in play; change is "imperfect actuality" [actus imperfectus]. Thomas teaches that the approach in terms of act and potency is wider than that in terms of the categories; the latter is about perfect being, while the form includes even the imperfect: CM 5.9 (889).

23. ST 1.12.4 (64b13-23). In this article, we seem to have the use of the word "nature" very much in the sense of "essence as ordered towards operation". One might even say that the act of being of the thing is being viewed as a quasi-movement caused by the essence. Cf. ST 1-2.10.1.ad 1, where the act of being [esse] is called "motus proprius naturae" (unless "motus" there should read "modus"???). Cf. also ST 1.42.1.ad 1, where the form or nature is seen as having two effects, the act of being and the operation. Thus, the notion of magnitude of perfection is applied even to the divine nature. - For a remarkable presentation of ontological hierarchy of substances, cf. SCG 3.20 (especially paras. 1-4), on how things imitate the divine goodness.

24. SCG 3.112 (#2860).

25. Here, "substance" is translating Aristotle's "ousia", and clearly means essence; cf. on the variety of meanings of the Latin "substantia", Thomas, De potentia 9.1.

26. EE c. 1, lines 36-49:

Hoc etiam alio nomine natura dicitur, accipiendo naturam secundum primum modum illorum quatuor quod Boetius in libro De duabus naturis assignat: secundum scilicet quod natura dicitur omne illud quod intellectu quoquo modo capi potest, non enim res est intelligibilis nisi per diffinitionem et essentiam suam; et sic etiam Philosophus dicit in V Methaphisice quod omnis substantia est natura. Tamen nomen nature hoc modo sumpte uidetur significare essentiam rei secundum quod habet ordinem ad propriam operationem rei, cum nulla res propria operatione destituatur..

Thus, here Thomas relates this general usage of "nature" to the first meaning proposed by Boethius:

Natura est earum rerum quae, cum sint, quoquomodo intellectu capi possunt. [De persona et duabus naturis c. 1 (PL 64, 1431 B)]

(This is not the meaning from Boethius used in other presentations of "nature" as bearing upon essence, and notably not the meaning used in presenting Boethius in CM 5.)

The statement that no thing is without its proper operation is presented in DV 19.1.sed contra 1as coming from St. John Damascene's De fide orthodoxa 2.23. Cf. Saint John Damascene, De fide orthodoxa, Versions of Burgundio and Cerbanus, edited by Eligius M. Buytaert, O.F.M., St. Bonaventure, N.Y., 1955: Franciscan Institute, cap. 37, pp. 142-143:

… Operatio enim est naturalis uniuscuiusque substantiae virtus et motus. Et rursus, operatio est naturalis omnis substantiae innatus motus… Impossibile enim substantiam expertem esse naturali operatione. [lines 1-10, in part]

27. Cf. ST 1.42.3.ad 4:

… "natura" quodammodo importat rationem principii, non autem "essentia"…

28. The work of Boethius to which Thomas regularly refers as "Liber de duabus naturis" is usually presented under the title Contra Eutychen et Nestorium. It can be found in Boethius, The Theological Tractates, with an English translation by H. F. Stewart and E.K. Rand, London and New York, 1918 [reprint 1926]: Heinemann and Putnam [Loeb Classics]. Boethius in his chapter 1 presents the meanings of the term "natura". He begins with the widest meaning and only comes in the end to the meaning given in Aristotle's Physics 2. We read:

Quod si naturae nomen relictis incorporeis substantiis ad corporales usque contrahitur, ut corporeae tantum substantiae naturam habere uideantur, sicut Aristoteles ceterique et eiusmodi et multimodae philosophiae sectatores putant, definiemus eam, ut hi etiam qui naturam non nisi in corporibus esse posuerunt. Est autem eius definitio hoc modo: "natura est motus principium per se non per accidens". Quod "motus principium" dixi hoc est, quoniam corpus omne habet proprium motum, ut ignis sursum, terra deorsum. Item quod "per se principium motus" naturam esse proposui et non "per accidens", tale est, quoniam lectum quoque ligneum deorsum ferri necesse est, sed non [?] deorsum per accidens fertur. Idcirco enim quia lignum est, quod est terra, pondere et grauitate deducitur. Non enim quia lectus est, deorsum cadit, sed quia terra est, id est quia terrae contigit, ut lectus esset; unde fit ut lignum naturaliter esse dicamus, lectum uero artificialiter.

29. Cf. above, note 26.

30. ST 1.18.3.obj. 1 and ad 1.

31. In De anima 3.6 [Leonine lines 8-36], commenting on De anima 3.7 (431a6).

32. For the three modes of act, viz. form, operation, and imperfect act (which includes the movement of the mobile thing), cf. Aristotle, Metaph. 9.6 (1048b6-17) as commented upon by Thomas at CM 9.5 (1828-1831). For the origin of the vocabulary of "act" for the discussion of being, as coming from the vocabulary of movement, cf. Aristotle, Metaph. 9.3 (1047a30-b2) as commented upon in CM 9.3 (1805-1806).

33. CM 9.9 (1880), paraphrasing Aristotle, Metaph. 9.8 (1050b28-30). The Latin of the cited passage runs:

… corpora eorum, quorum esse est in transmutatione, imitantur corpora incorruptibilia in eo, quod semper agunt; sicut ignis, qui secundum se semper calefacit, et terra quae secundum se semper facit operationes proprias et naturales. Et hoc ideo est, quia habent motum et operationem suam propriam secundum se, et in eis, inquantum scilicet formae eorum sunt principia talium motuum et actionum.

34. ST 1-2.3.2 (ed. Ottawa, 727b28-36):

Manifestum est autem quod operatio est ultimus actus operantis; unde et actus secundus a Philosopho nominatur, in II De anima; nam habens formam potest esse in potentia operans, sicut sciens est in potentia considerans. Et inde est quod in aliis rebus "res unaquaeque dicitur esse propter suam operationem", ut dicitur in II De caelo.

In his In Aristotelis De caelo et mundo expositio 2.4 (334 [5]), Thomas says:

… [Aristotle here says] that each thing which has a proper operation is for the sake of its operation [propter suam operationem]: for anything whatsoever has appetite for its own perfection, as for its goal [suum finem]; and the operation is the ultimate perfection of the thing (or at least the product of the operation, in those things in which there is some product besides the operation, as is said in Ethics 1 [1094a3-7]); for it is said in De anima 2 [412a23] that form is first act, while operation is second act, as the perfection and the end of the one operating. And this is true both in corporeal things and in spiritual things, for example in the habits of the soul; and both in natural things and in artificial things.

But [Aristotle] says "which has a work" because of those things which are against nature, as are monstrosities; they do not have any work, taken precisely as such, but rather they have a deficiency as regards the operative power, as is evident in the case of those which are born lame or blind: for lameness is not an end intended by nature, for the sake of which it brings about the birth of the lame animal; but rather this happens aside from the intention of nature, from the deficiency of the natural principles.

35. ST 1.42.4 (268a24-25).

36. Here, the text says: "in tali caliditate", i.e. "in such warmth", but I am conjecturing "in tali qualitate", i.e. "in such a quality".

37. ST 1.42.1.ad 1.

38. ST 1.7.1 (37a43-44), and 1.4.1.ad 3.

39. ST 1.4.2.

40. Cf. above, nn. 18 and 19; also ST 1.14.6 (97b43-51):

… the proper nature of each thing has solidity [consistit] inasmuch as it participates the divine perfection in some measure. But God would not perfectly know himself if he did not know in whatever measure his perfection is participable by others; nor would he know the very nature of being [ipsam naturam essendi] if he did not know all the modes of being.

41. Cf. ST 1.44.prologue (qq. 47-102 are on the divine work of distinguishing created things, one from another); 1.48.prologue (qq. 50-102 are on the distinguishing of the spiritual and the corporeal creature).

42. ST 1.75.prologue; and cf. 1.77.1.sed contra.

43. Notice the discussion of the limits of physics relative to metaphysics, as found in CP 2.4 (Maggiolo ed., #175 [10]), concerning Aristotle at 2.2 (194b13-15). We read:

Hence, the consideration of the physicist which is concerning forms extends right up to the rational soul. But how it is with forms totally separate from matter, and what they are, or even how it is with this form, i.e. the rational soul, according as it is separable and able to exist without the body, and what it is as separable in virtue of its essence: to determine all this pertains to primary philosophy. Cf. ST 1.76.1.ad 1.

44. ST 1.88.2.obj. 3 and ad 3. The Latin of the reply reads:

… anima humana intelligit seipsam per suum intelligere, quod est actus proprius eius, perfecte demonstrans virtutem eius et naturam. Sed neque per hoc neque per alia quae in rebus materialibus inveniuntur, perfecte cognosci potest immaterialium substantiarum virtus et natura; quia huiusmodi non adaequant earum virtutes.

45. ST 1.77.1 (463b6).

46. ST 1.54.2.

47. ST 1.77.6.ad 1.

48. Cf. 1.76.4.ad 3:

… in matter there are considered diverse grades of perfection, viz. being, living, sensing, understanding. But always the following supervening one is more perfect that the previous one. Therefore, the form which gives merely the first grade of perfection to matter is most imperfect; but the form which gives the first and the second and the third, and so on, is most perfect; and nevertheless, it is immediately [united] to the matter.

And cf. also ST 1.76.5.ad 3:

It is to be said that the parts of the animal, as the eye, the hand, the flesh, and the bone, and such, are not in a species; but rather [it is] the whole [which is in a species]; and so it cannot be said, properly speaking, that they are of diverse species, but rather that they are of diverse dispositions. And this suits the intellective soul, which though it is one as to its essence, nevertheless because of its own perfection is many as to power; and therefore for the sake of the diverse operations it requires diverse dispositions in the parts of the body to which it is united. And for this reason we see that the diversity of parts is greater in the perfect animals than in the imperfect, and in these latter than in plants.

49. On the natural order in being, cf. CM 5.13 (950-953), concerning Aristotle, Metaph. 5.11 (1019a2-14).

50. ST 1.77.4.ad 2.

51. This doctrine will affect the reply in the last article of q. 77, viz. a. 8, as to whether the powers remain in the soul when it is separated from the body. Only the intellect and will remain actually, though the others remain as in their source [virtute]. Notice ST 1.77.8.ad 2: the powers having the composite as subject are not natural properties of the soul alone, but are properties of the composite.

52. The footnote in the Ottawa ed. sends us to Metaph. 7.4 (1029b30), but I would say that 7.4 and 5 (1030a17-1031a14); cf. CM 7.4.

53. On the ontology of substance and accident, cf. SCG 4.14 (para. "Quamvis autem in Deo…"):

… in us relations have dependent being [esse], because their being is other than the being of the substance: hence, they have a mode of being proper [to them] in function of their own proper character [rationem], just as is the case with the other accidents. Indeed, because all accidents are certain forms added to the substance, and caused by the principles of the substance, it is necessary that their being be added on, over the being of the substance, and depending on it [the being of the substance]; and the being of each of them is prior or posterior inasmuch as the accidental form, as regards its proper character, is closer to substance or more perfect. For which reason, a relation really added to the substance has the last and most imperfect being: last, because not only does it presuppose the being of the substance, but also the being of other accidents from which the relation is caused: as, for example, one in quantity causes equality, and one in quality likeness; but most imperfect, because the proper character of relation consists in the fact that it is towards another: hence, its proper being, which it adds to the substance, depends not only on the being of the substance, but also on the being of something external.

54. ST 1.77.7.

55. Cf. ST 1.76.3 (454b28-56).

56. ST 1.82.3.ad 2.

57. Cf. e.g. DV 29.8 [Leonine lines 212-ff.].

58. ST1.77.6.ad 3; this is explicitly applied to the flow of one power from another in 1.77.7ad 1.

59. Cf. In De anima 2.14 (Leonine lines 342-387, especially lines 373-380 as follows):

… it is to be said that the power of color in acting is imperfect, as compared to the power of light: for color is nothing else but a light in some measure obscured by being mixed with the opaque body; hence it does not have the power to render the medium in that disposition by which it is rendered receptive of color; which pure light can do.

60. Cf. De substantiis separatis, c. 9 [Leonine lines 180-234] (Lescoe tr., p. 63): what is brought into being by change must have being after not being, whereas in the mode of production which is by simple emanation or influence the effect or result can be understood as always having being. Thomas sees the sort of thing he has in mind best exemplified for us humans, not in corporeal causes and effects, but rather in "intellectual things which are at a greater remove from motion". Thus, he points out that the truth of the principles is the cause of the truth which is in the conclusions, which conclusions are always true; he introduces Aristotle on necessary things which have a cause of their necessity: Metaph. 5.6 (1015b9) and Phys. 8.3 (252a32-b6).

61. ST 1.87.4.ad 1. - On the natural sequence: substance, intellect, will, cf. my paper, "The Real Distinction between Intellect and Will", Angelicum 57 (1980), 557-593.

62. ST 1.87.4.ad 3.

63. ST 1.79.4.ad 5.

64. ST 1-2.110.2.ad 2.

65. ST 1-2.66.3.ad 1.

66. ST 2-2.2.3 [1415b41-1416a25].

67. This was also seen in the fact that the human soul can only come into existence by being itself created, unlike other substantial forms (ST 1.90.1-3); and in the fact that it is God who, as supreme in the order of immateriality, is the source of the intellective power (ST 1.105.3).

68. ST 2-2.2.3.ad 1.