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Dr. John Finley: “The Extraordinary Unity of the Human Being”

Posted: October 7, 2016


by Dr. John Finley
Assistant Professor of Philosophy
Kenrick-Glennon Seminary[1]
September 23, 2016
Part of the 2016-17 St. Vincent de Paul Lecture and Concert Series, endowed by Barbara and Paul Henkels


Socrates made it his mission to get people to self-reflect: to better know their own selves. The entire history of philosophy speaks to a great deal of time delving into the nature of the human being. We are, as Walker Percy says, mysteries to ourselves and in many ways we know more about galaxies light years away than we do about the self with whom we have spent our entire life.[2] As some of the great thinkers of antiquity knew, part of the reason man is so mysterious is that he is both spiritual and material. Because he is somehow spiritual, man alone among animals is able to ask the question, Who and what am I? But because he’s material, he’s unable even to look at himself from the side. This hybrid character of the human being seems to present itself most vividly and frequently in the form of tensions and disharmonies. We seek to live rationally and virtuously, but we often fall prey to lower passions. We wish to create something beautiful, but these hands and eyes just can’t coordinate themselves. Sometimes man’s hybrid identity is the stuff of comedy: the body can manifest itself, against our will, in all sorts of delightfully embarrassing ways. Yet the most forceful reminder we have of our hybridization is decidedly not comic: the inevitable fact of death. We seek to live, but the body can’t live up to our seeking.

Let’s consider for a moment two texts that initiate all TAC students into their 4 yr conversation with the Great Authors: Homer’s Iliad, and Ecclesiastes. Homer and Qoheleth both announce death as a fundamental theme; and remarkably, they both present death in terms of a radical disunity. Recall the opening lines of the Iliad: “Sing, goddess, the rage of Peleus’ son Achilles / and its devastation, which put pains thousandfold upon the / Achaians / hurled in their multitudes to the house of Hades strong souls / of heroes, but gave their bodies to be the delicate feasting / of dogs, of all birds, and the will of Zeus was accomplished.”[3] Achilles’ rage certainly leads to death, but it’s also provoked by this inevitable, awful reality that at some point, wherever our spirits may be, our bodies will rot. Recall too the closing lines of Ecclesiastes: “Remember also your Creator in the days of your youth […] because man goes to his eternal home, and the mourners go about the streets; before the silver cord is snapped, or the golden bowl is broken, or the pitcher is broken at the fountain, or the wheel broken at the cistern, and the dust returns to the earth as it was, and the spirit returns to God who gave it. Vanity of vanities, says the Preacher; all is vanity.”[4] In view of this strange and final separation of spirit and dust, all wordly things are in vain. Death, if nothing else, seems to voice the strange, problematic character of the human being as paradox, as somehow both spiritual and material.

In this light, what a remarkable move Thomas Aquinas makes when he argues for the human being as a profound unity of spirit and matter. Adopting a Platonic insight, Thomas asserts that the individual human soul is a spiritual reality, incorruptible. (It has to be, since it possesses an immaterial power: the power of intellect. We are, after all, capable of understanding. But modifying and transforming the Platonic insight, Thomas grafts it into Aristotelian thought by arguing that the spiritual soul is in fact the very form of the human body. (It has to be, because a thing’s substantial form is what gives it the kind of existence it has and in the human being, to exist is to live and to live as capable of reason. Our substantial form, then, is our life principle and our reason principle, which is to say, our form is the spiritual soul.) Not just a tenuous housing of intellectual principle in physical subject, the human being is a substantial union of the two as form and matter.[5] As such, man is the highest among all natural substances, constituting the unified boundary between the physical and spiritual realms.[6]

Yet we still die, and we die because the human soul and body belong to the most diverse creaturely realms: spirit and matter, the incorruptible and the corruptible. Perhaps man, though the highest of all natural substances, is by that very fact the most fragile in his substantial unity.

In this talk I wish to answer that proposed conclusion with a decided “No.” Just the opposite is true. I’d like to focus on Thomas’s view of man, and show how he actually ups the ante on human unity. He holds that the human being is not just the highest kind of soul/body unity; it is also the most unified soul and body. (And this claim is surprising, I think, given what we’ve said about death.) The first part of my talk argues for the human substance as more unified in comparison with other natural substances. The second part looks to the realm of human action, and specifically the body’s role therein, to find confirmation of our greater unity at the experiential level. In conclusion, I’ll briefly indicate what this argument reveals about human disunity.

I. Human unity at the level of substantial being

Thomas holds that all things, insofar as they exist, are one—undivided in their being.[7] So, to hold that certain things are more one than others is to maintain that certain things are less divisible in themselves than others are. [For example, Thomas proceeds this way in Summa Theologiae I, q. 11. After arguing in a. 3 that God is one, he argues in a. 4 that God is supremely one by invoking the supreme simplicity (uncomposedness, or indivisibility) of God as Subsisting Being Itself. Beneath God, a purely spiritual creature—an angel—is doubly composed. First, its way of being is not the same as its very act of being: this is the essence/existence composition; and second the creature itself is not the same as its activity: this is the substance/accident composition. In turn, physical substances add to this twofold composition a third, that of form and matter: for no physical substance is its essence: I am not humanity.[8] All natural substances, humans included, possess this threefold divisibility: of existence and essence, of substance and accident, of form and matter. Arguing that humans are more unified than other physical substances means showing that in humans, one or more of these three compositions gives rise to a distinctively strong unity.]

          A. Thomas on the superior unity of human beings

Thomas himself speaks to the greater unity of the human being in ScG II, c. 68 [by way of singling out the form/matter composition, which should not be surprising given that this composition uniquely characterizes humans and other physical substances]. After an extensive argument that in humans the spiritual soul is the form of the body, Thomas then states the following, as if in response to a likely supposition:

“Yet something constituted by intellectual substance and corporeal matter is not less one than something constituted by the form of fire and its matter; as it happens, it is more one, since as much as form more transcends matter, so much the more one is that which is brought about from it [form] and matter.”[9]

Thomas contrasts the human situation with that of fire, a safe but illuminating example: the form of fire is certainly inferior, relative to the human form, and fire has a manifest tendency toward dispersion, disunity. We would probably readily, though perhaps vaguely, agree that a human being is more unified than a fire. Still, Thomas’s reasoning here would imply that human unity is greater than the unity of even a higher animal, like a dog or monkey. Thomas spends the remainder of the chapter articulating the diverse levels of form in the physical cosmos, beginning with the lowest substances, then moving upward through plants and animals, showing at each step how form more and more transcends matter, and concluding with the human form, which “exceeds the condition of corporeal matter,” such that it is “not totally comprehended by matter or immersed in it.” As surpassing matter more than all sub-human substantial forms do, the human soul with its matter, Thomas maintains, gives rise to a greater unity than do those lower forms with theirs. So, the argument is simply this: the more a form transcends materiality, the greater the unity constituted by that form and its matter. Since the human form transcends materiality more than all other natural forms—it is spiritual, after all—the human form and its matter make the human substance more unified than any other natural substance.

[Let’s briefly note, by the way, that this argument proceeds by way of examining the natural world and the different levels of form within it. But the same conclusion could be reached through a metaphysical argument at the level of being and its transcendental properties. Specifically, we can recall two principles mentioned earlier in ScG II: first, that things have being and unity in the same way, insofar as unity is a transcendental property of being; and second, that since form is the principle of being in composite substances, form is also the principle of unity.[10] What Thomas invokes here in ScG II, c. 68 is a kind of corollary to the two principles, namely, that as forms become greater, or higher, so do the unities they provide in things.[11] A plant, then, would be more unified than a diamond, an animal more unified than a plant, and a human more unified than an animal, given the human form’s notable superiority as a spiritually subsisting reality. Let’s unpack this hierarchy of natural unities.]

          B. Two grades of natural unity: the continuum and the whole

Now what this conclusion means is not immediately evident. Just how are higher beings in the natural realm less divisible—more unified—than lower ones? Clearly, for example, humans are not less composed of parts than are other composite substances are; in fact, experience suggests just the opposite. Owing to their greater powers (both in kind and in number), higher composite substances are more complex, in terms of parts, than lower ones.[12] Nor are humans less divisible (or destructible) in a sheerly quantitative sort of way. Substances like diamond, for example, could seem to be more unified than a human being just because of diamond’s greater resistance to quantitative division. And diamond, like human being, is a natural substantial unity; both are composed of substantial form and corporeal matter. In all natural substances, as opposed to artifacts, the substantial form is present in the whole and in all the parts: one half of a diamond is no less diamond than the other half, just as my arm is no less human than my head.[13]

Yet a closer look at this example reveals how in comparison with a human being the unity of diamond is far more precarious from the standpoint of the particular reality at hand, e.g., ‘this particular diamond’ in comparison with ‘this human Socrates.” For in homogenous substances like diamonds, a part, presumably all the way down to the specific molecular structure, possesses the form in as perfect a manner as the whole does. That the given instance of diamond exists undividedly (i.e., as unified) and not as a multitude of smaller diamonds results not from anything in the demands of its own nature, but simply from circumstantial forces surrounding it. We can refer to such a unity as that of a continuum.[14] The parts of a given diamond are parts only in the sense of quantitative continuity, or physical contact; in themselves, they could just as well be separate instances of diamond, which is to say that they are parts only accidentally. In turn—and this is the crucial point—the original whole is one only accidentally. Our grammatical usage indicates this distinction: in noticing water or granite on the path we’d tend to refer it not as “a water” but as “a puddle of water,” or simply, “some water”; not “a granite,” but “some granite,” or a piece of granite. The same applies to all inanimate substances, homogeneous as they are.

A greater sort of unity characterizes natural substances that we could call totalities, or wholes.[15] These are living organisms; human beings are the highest kinds. So think here of trees, dogs, humans. Wholes are heterogeneous; their parts are parts essentially, since quantitative separation of a part does not typically entail a new instance of the same substance, and usually entails the part’s decomposition altogether (and sometimes the decomposition of the whole). Likewise, the whole is a whole essentially; its nature demands that it exist with various sorts of parts, arranged in a particular order—generally so as to reach an approximate size—all for the sake of particular activities. Natural wholes possess a discernible completeness in themselves and accomplished by themselves, as manifested in their ability to be sources of appropriate action for their own sakes.[16] Diamonds are complete only by way of some external standard, such as a desired size for a ring.

It follows that the unity between a thing and its nature is greater in wholes than in continuums. In the realm of continuums, the particular instances within the nature have no intrinsic meaning as far as the nature is concerned. Nothing in diamond form or diamond matter requires that ‘this particular diamond’ exist instead of its parts on their own: all the diamond in the universe could exist as one mass just as well as it could exist in millions of pieces. In noting each piece as ‘diamond,’ one could equally note that these are potential parts of the single great diamond whole, or that each is potentially many diamonds through further division into quantitative parts.

By contrast, in the realm of natural wholes, particular instances of the nature are intrinsically meaningful inasmuch as ‘whole’ and ‘part’ are clearly delineated in such substances. In pointing out the numerous instances of the species ‘human being,’ one is decidedly not saying that these are potential parts of some cosmic human whole. The wholes exist right here, in the instances. Similarly, in viewing any instance of human on its own, we see that further divisibility into more instances through sheerly quantitative separation is impossible. The items within the human are parts, simply, and not potential wholes. The natures of higher substances demand the given instances within which, and only within which, the natures can exist.

We can put this very simply. All the substances around us in the natural world are instances of natures: I take a hike by the lake and am aware of it as an instance of water; lying by its banks are instances of granite; standing near it is an instance of oak; I am an instance of human, and so on. But the instance of water is a portion of water; the instance of granite is a piece of granite; these are unities simply as continuums. In contrast, the instance of oak is not necessarily a piece of oak tree, it could be a whole oak tree. My dog is not a piece of retriever, but a whole retriever. I am certainly not a piece of human, but a whole human. Crucial to wholes is that they are in some way complete unto themselves, as we know by seeing their parts working on behalf of the whole.

How does this continuum/whole distinction contribute to understanding Thomas’s claim that the higher form entails a greater substantial unity? Let’s view the continuum/whole distinction through the lens of form’s relation with matter.

C. Two grades of form/matter unity

We can express what’s just been said by distinguishing two kinds of unity between form and matter. In continuums, or non-living substances, the only crucial unity is the unity of form with the appropriate kind of matter: unity1. For example, all that is necessary for water is the compound of two parts hydrogen and one part oxygen, no matter the actual amount. We could have a gallon, or teaspoon, or a whole lake. Whereas in wholes, or living substances, not only is the unity of form with the appropriate kind of matter necessary, but this unity is only and always present as the unity of form with a specific arrangement and amount of matter: unity2.[17] (So a golden retriever will never be shaped like a rhinoceros or a diamond; it will never be fifty feet tall, and so on).[18]

Consequently, non-living substances are divisible in a way that living substances are not, namely, through quantitative division at the level of unity2. If a living substance is divided at the level of unity2, the substance itself is gone, while a non-living substance can undergo such division and be just as present, at least down to the molecular level.[19]

It follows that the indivisibility—the unity—possessed by living substances, which non-living substances lack, is the quantitative indivisibility of the primary substance as the kind of thing it is. If ‘this particular human’ is divided into quantitative parts, both the ‘this’ and the human are gone; while if ‘this particular diamond’ is divided, this ‘this’ departs but diamond remains. You could say that the unity of the whole, of the living substance, is greater in that its unity necessarily encompasses not just form and matter, but also shape and size.

This means that living beings are more easily numbered. What counts as “one” in non-living beings is less clear, given their lack of any intrinsic determination as to how much they are or ought to be.[20]  In this sense, continuums, or non-living substances, are simply continuous quantities, while wholes (living substances), are naturally discrete quantities.

We can see, too, how the greater unity of higher substances does not mean they are less corruptible. On the contrary, their corruption is in some way easier, since the removal of unity2 includes the removal of unity1; that is, if an animal is divided so as to lose its proper shape and amount, it fairly quickly loses its substantial unity of form and matter. By contrast, the removal of unity2 in lower substances allows unity1 to remain intact. After all, unity2 is accidental to non-living substances in the first place. In the natural realm, the less of a unity something is, the fewer are the ways in which the little unity it has can be corrupted. This is because lesser substantial unities involve less complexity, fewer sorts of parts, and fewer orders among those parts.[21]

One can discern, then, two interrelated criteria by which to establish that higher substances are more unified than lower ones. First, higher substances are more whole, meaning that they are more complete, more sufficient unto themselves: their parts are parts essentially and they employ these parts on behalf of themselves. Second, the form of the higher substance is more related to the particular matter in which it exists, since this matter (and not just this kind of matter) is what essentially bears the form and with it makes a whole. This is why, in higher substances, the nature and the particular instance of the nature are more unified, in that the division of a higher substance’s matter entails the removal of both the substance itself and its nature. If human beings are greater metaphysical unities than non-human composites, they ought to be, not less divisible in terms of sheer quantity or corporeality, but less substantially divisible. They will have to be more whole, more sufficient unto themselves, and more characterized by the relation of form to particular matter, which means they will be more united, as particular instances, with their natures.  

D. Hierarchy of form/matter unities.

Let’s return to Thomas’s claim that the higher the form, the greater the unity it and its matter provide. What makes the living substance a greater unity is form’s withdrawal from characterization by the continuum of physical matter. In non-living substances, form itself is “submerged” within bodiliness to the point that it effectively assumes the dispersion—the part-outside-of-part structure—that characterizes the lowest sorts of realities.[22] Form’s transcending of matter is relatively weak here.

Yet higher substances possess a tendency to unification above and beyond part-outside-of-part togetherness. Form in such substances actualizes, organizes and structures matter by way of distinct sorts of parts, which serve the whole. This is the realm of form as soul. While quantitative continuity is still present, matter is brought together in ways beyond the merely contiguous, as is revealed in mutual interaction among the parts for the sake of some end proper to the whole substance. A part is thus not only meaningfully related to parts very different from itself, but even indicates them, as well as the entire whole, from within itself, in the sense that comprehension of the part necessarily entails some grasp of the whole (and various other parts) to which it belongs. (The complexity of the human genome.) It takes a greater principle of unity to pervade not just the whole and homogenous parts, as in diamond, but even parts of different sorts, acting in different ways (plants, animals, and humans).

The general principle here is that the more a form rises above mere bodiliness, whose continuity tends toward indefinite extension, the more of a unity is the substance itself, since its matter is brought more and more into a kind of togetherness marked by wholeness, or completion. Such wholes are plants and animals, especially higher animals.[23] The reason that the higher form entails a greater unity of the substance is precisely that the more a form transcends materiality, the more that form elevates the matter to which it is joined. The higher form, in actualizing its matter, gathers it into a unity higher than the merely continuous—a unity of wholeness, marked by actions that more and more surpass the capacities of sheer bodiliness. Now let’s discuss the nature of this wholeness, as revealed by the human being as most unified among natural wholes.

          E. The human soul: spiritual wholeness

If higher forms recede more and more from the quantitative dispersion characteristic of mere bodiliness, what are they approaching? What is the sort of togetherness into which the parts of matter are drawn so as to constitute a unity beyond the merely continuous? We’ve seen how living substances, as wholes, are greater unities than non-living substances, or continuums. In the realm of living substances, which includes plants, animals, and humans, how do we rank wholeness? Wholes are characterized by being in some way complete, somehow sufficient unto themselves. It makes sense, then, that if we’re going to rank wholes, we’d need to rank them in terms of how complete they are, how self-sufficient they are.

Now as mentioned earlier, the upmost limit among all forms in the natural world is the intellectual human soul, which is to say that immaterial being is what all substantial forms, to greater or lesser degrees, approach. Like other substantial forms, the human soul is composed neither of physical quantitative parts, nor of form and matter. But distinctively, as indicated by its intellectual activity, the human soul is a subsisting reality possessing its own spiritual being.[24] My claim in this section of the talk is that the unity proper to the human soul is a kind of wholeness that surpasses the wholeness proper to non-human substances. Further, (section F, below) to the extent that the human soul’s wholeness embraces the body, the entire human person is more whole, and thus more unified, than non-human substances.

As a subsisting spiritual reality, lacking any integral parts, the soul is indivisible—and thus incorruptible.[25] It possesses the simplicity characteristic of spiritual being, which is a unity different in kind from, and superior to, any physical unity.[26] Its simplicity means that the soul exists in itself, unlike a physical being which, as such, is “spread out,” existing in the dispersion of part-outside-of-part.[27] One could say that the human soul’s unity of simplicity is a kind of wholeness surpassing any physical wholeness, since the soul possesses its being in a complete manner: all together, indivisible, and incorruptible.

Now it’s impossible for us to peer directly at the spiritual soul, much less any spiritual being. We have to get at it by way of its effects or properties, and we have to use some language which is metaphorical. To better capture how the human soul’s wholeness of simplicity relates to physical wholeness, I think it helpful to use the language of “selfhood,” a notion not explicitly present in Thomas’s thought, but certainly not opposed to it. Specifically, degrees of wholeness are proportional to degrees of selfhood. As a spiritual being, Thomas says, the soul is “always actually present to itself” (semper sibi adest actu) simply by way of existing in itself.[28] These phrases refer to nothing other than than the simplicity proper to spiritual being. At the same time, the soul’s existence in itself is the foundation of the intellectual act proper to spiritual being: self-awareness, which entails self-love and self-governance. Thomas refers to this fundamental spiritual act as a “return to self.”[29] The intellectual return to self is a natural consequence of simplicity, of having one’s being all in oneself and not dispersed through physical partition.[30] A being is intellectual, in other words, because it is spiritual, and this spiritual way of being grounds the human soul as a unique kind of whole among other substantial forms. Because the human being possesses a spiritual soul, it will be able to make a true return to self through the intellectual act of self-awareness.

We can thus return to Thomas’s hierarchy of substantial forms and view it from the top down. The unity given by form that substances approach to varying degrees, beginning with homogenous continuums, is the wholeness of selfhood: being a self.[31] Only in the human being, at the upmost limit of all substantial forms, does selfhood truly occur, as indicated by rational self-awareness and self-mastery (which characterize personhood in the first place). This is how the human being, more than any other natural substance, is whole, or complete: for it alone can determine itself. It can possess itself through knowledge and govern itself through free will. Beneath humans, animals present certain kinds of selves, characterized not only through structural and mobile distinction from their surroundings, but fundamentally through the beginnings of self-awareness and self-directedness, in sensation and desire. Still, an animal is less of a self to begin with, compared to a human, inasmuch as the animal lacks any spiritual simplicity. As its entire being is “dispersed” in physicality, even of a very high order, the animal is the last and noblest whole for whom the realm of continuity ultimately proves decisive.[32] Correspondingly, the animal lacks a complete return to self through intellect. Finally, the most rudimentary dimensions of selfhood appear in plant organisms, inasmuch as they at least gather themselves together into intrinsic unities marked off from their surroundings, and take in material that contributes to their preservation.

F. The human body’s participation in the soul’s unity

The spiritual human soul, the highest substantial form, possesses a wholeness and simplicity that transcends the unities given by all non-human forms, and that these forms approach to varying degrees, as they constitute lesser or greater wholes out of the matter they actualize. Yet what of the human person as a whole, including the body? Let us grant that the soul is simple and that it ultimately allows the human being to possess itself through knowledge and love. Yet the human body is not something spiritual; it is physical and highly complex. The human body corrupts, and in this way is separable from the soul. The question, then, is how the soul’s transcendent unity entails a greater unity of the whole human being. If the admittedly superior unity of the soul’s essence is foreign to the body, one can’t claim a corresponding superior unity of the human person.

Thomas anticipates this concern. Earlier we saw that higher natural forms, precisely in their superior transcendence over matter, bring matter into a higher unity. Why should the human be any different? The solution Thomas provides is the crucial insight for the purposes of this talk.  He explains that because the spiritual soul is the subsisting form of the body, the soul’s transcendence over matter, far from implying some separation of the two, means rather the soul’s communication of its own being into the body.[33] (Repeat?) In non-human animals, form and matter participate in the being (esse) of the physical composite, even though this composite has its being through form.[34] In humans, by contrast, the composite is nothing other than matter participating in the form’s own being. Metaphysically, a unique connection exists between form and matter in humans, for the human body shares immediately in the soul’s spiritual being;[35] while in non-human substances, matter does not share in the form’s being, since the form has no being of its own. Rather, in lower substances matter achieves a particular degree of physical actuality, owing to the kind of form it possesses.

Thomas parses out the being of the human person in ScG II, c. 68:  “[f]or the being belongs to corporeal matter as to a recipient and a subject raised to something higher, but it belongs to the intellectual substance as to a principle, and according to a congruity with its proper nature.”[36] The “kind” of existence, or being, that the human body participates in is spiritual, such that in this case corporeal matter is elevated. From the body’s viewpoint, because a thing’s being, or existence, is more intimate to it than anything else and the body participates in the soul’s act of existing, the soul can be considered closer to the body than anything else that might be said of the body, which entails the remarkable fact that spiritual being is more intimate to the human body than is any physical quality.[37] Thomas boldly states that the corporeity—the bodiliness—of a human being is the intellectual soul, which is not actually bodily but possesses bodiliness virtually, as the sun possesses color, or as it belongs to a light body to be raised up.[38] The human way of being a body is only possible through spiritual being; just as the human way of being spiritual essentially entails matter and the physical order.[39]

Human matter, then, as actualized, elevated, and organized by spiritual being, is characterized by the unity of spiritual being; no other body is. As the human body participates in the soul’s being, so it participates in the soul’s unity. Yet it remains only a participation. Here it is crucial to see why the spiritual soul and the body are naturally joined. In one sense, the soul is not a spiritual being joined with the body. For the soul, as Thomas insists, though a spiritual reality (hoc aliquid) in its own right, is not a being of a complete species. On its own it lacks the completion of its nature. What the soul does not possess in its own right is that most fundamental consequence of being, namely, proper activity, which in this case is knowing sensible reality.[40] As Thomas puts it, knowing belongs to the soul in its own right inasmuch as the soul is the principle of the intellectual operation, but inasmuch as the natural object of that operation is sensible being, the body shares (communicat) in knowing.[41] While the simplicity characteristic of spiritual being belongs to the soul, the usual fulfillment of that simplicity—intellectual activity, or “return to self”—naturally occurs for the human soul only on the condition of its union with sensible being, by way of embodiment.

As we noted earlier, the complete unity of spiritual being is the wholeness of simplicity fulfilled in the intellectual return to self. This completeness does not naturally belong to the human soul in its own right, which means that its own spirituality and simplicity are inferior to those of complete spiritual substances (angels). Yet more than a comment on the soul’s spiritual inferiority, this conclusion is an indication of the soul’s essential ordering to embodiment: its natural “part-hood” within the human being. In order for self-return to occur actually, i.e., in self-knowledge and self-governance, the human soul needs sensory contact with physical being, which in turn demands bodiliness. The return to self that characterizes spiritual being is, in human substances, “worked out” through bodiliness and consequent activity. Fully spiritual substances accomplish their own act just in virtue of being spiritual, while the human soul requires a “going outside of itself” in order to return to itself, via the bodily dimension.[42]

Since all substances exist for the sake of their proper activities, the body’s contribution is quite literally essential. Thomas even calls the body the “organ” of the soul, since it is crucial in order for any of the soul’s powers to be actualized in their natural state. In a certain way, then, the body is closer to the soul’s essence than are the various human powers, even those of reason and will.[43] (As Thomas indicates in ST I, the body pertains to the soul’s essence itself, while the powers flow from the essence.) As well, it is not as though the bodily realm serves simply as extrinsic instrument for the intellect’s spiritual act, since what the human intellect naturally targets is the being of physical realities.[44] These are the things we know best and most properly.[45] We should think of the soul as spiritual in order to approach the human being accurately, but in seeing the nature of the soul’s bodily-mitigated spiritual act we finally do best to think of the soul as “human.” 

It is only the human person, body and soul, that realizes what ought to be present in any case of substantial being: existence and natural activity. Since the acts involved here are intellectual, the human person can be seen as a participant in the kind of unity proper to spiritual substances. Yet because the human person realizes these acts through soul and body, the person remains only a participant in this spiritual unity, transcending the unity of solely physical substances, but beneath that of purely spiritual ones. 

Let’s recall the two criteria for higher unity established earlier: (1) something is more unified than something else if it is more whole, more complete, or sufficient unto itself. (2) One natural substance is more unified than another the more it is characterized by form being joined to this particular matter, rather than just a certain kind of matter. In light of these criteria, we can conclude that the human being is a greater unity, metaphysically, than other natural substances. First, the entire human person—soul and body—exists through the one act of spiritual being originating from the soul. As sourced by a spiritual principle of unity and existing for the sake of self-unity in action, the human person more than all other composite substances is characterized by the unity of wholeness: completeness, or selfhood, fully actualized in the return to self that includes self-awareness and self-governance. Second, the human person’s form is distinctly characterized by union with ‘this particular matter,’ inasmuch as a particular human soul essentially communicates its own spiritual existence to ‘this matter,’ and remains oriented to do so for eternity. It is no objection to this conclusion that the human body corrupts, since all lesser bodies are also corruptible. The point is that while a human body, this body participates in a being and unity that transcends lesser substances. [As a corollary, since spiritual being is incorruptible, the individual human is more closely united to its nature than is any lesser substance, which corrupts entirely and in so doing loses its nature altogether.]

II. Human unity at the level of action

Everything I have argued so far has been an attempt to elucidate Thomas’s claim that the human soul/body relation constitutes a greater unity than does the same relation in other natural substances. This claim regards the superior unity of the human person at the deepest metaphysical level: the level of our substance. We might wonder what this superior unity “looks like” or feels like, especially in our spatially distended and remarkably complex bodiliness. What awareness and confirmation of this unity do we encounter in our own living?

First I’ll comment on the connection between bodily complexity and human action; then I’ll show how human action can reveal, or confirm, the greater substantial unity of the human being. In conclusion, I will briefly consider the implications my argument has on human disunity, death, and the Christian life.

          A. Human complexity as serving human action 

The human body may be the most complex physical reality in the universe. As Thomas sees it, this complexity is directly linked to the human soul’s superior capacity for action.[46] Human beings possess greater power than any other composite substance because they possess the greatest kind of power: intellect. In the physical realm, greater power means not only a higher sort of power, but also, as a consequence, greater numbers and kinds of power. We see this in the hierarchy of earthly substances: as we moves from the non-living to the plant to the animal realms we see greater sorts of powers entailing greater diversity of powers. Sensation, for example, targets all of physical reality in principle, and does so by a variety of means, each requiring a distinctive bodily organ, which in turn requires nourishment, structural support, communication systems with the remainder of the organism, and the organism’s ability to respond appropriately to sensory information. The presence of sensation thus entails a degree of complexity and diversity among bodily parts beyond what is required for the presence of nutrition alone. When the highest power, reason, enters the picture the complexity of powers increases, particularly with regard to the internal senses (the workings of the brain).

So the human being among all creatures is the least simple—the most complex—when it comes to the realm of power.[47] The complexity of human bodily systems and of the powers that demand them is not just an index of the various sorts of action that human beings can perform. More than this, as Thomas insists, the human being is a natural unity, such that all of its powers and physical structures exist as ordered to one defining operation: rational activity.[48] As discussed earlier, human bodiliness and all its powers exists in order that the human being might come into its own as intellectually active, by knowing physical beings and pursuing the intelligible goods that they display or indicate.

Thomas remarks that the unity of the human person is confirmed by our observation of an “overflow” (redundantia) of one power into another.[49] This overflow is noteworthy as a sign of the way in which the lower human powers are yet human, and in that sense, rational. For example, I can be looking intently at the words on this page and remain virtually unaware of their actual sensory features, since I am rationally focusing on their meaning. The same happens when I listen closely to what someone is saying. Rationality can so pervade seeing and hearing that it could be hard to know what “mere” seeing and hearing are like. Because one and the same spiritual soul sources all the powers, and because the lower powers serve the higher, we can discern various bodily activities as characterized by, or participating in, properly rational activity.

B. Human action as manifesting our greater substantial unity

Let us turn, then, to human action to see better what it means to say that the body participates in spiritual unity. After briefly explaining the nature of a human action and its essentially bodily dimension, I will show how such action images human unity.

Human action as personal and as bodily. A human action, properly speaking, is an action sourced in conscious, free agency. Now there are some actions that in some way come from us, but in less than human fashion.[50] To illustrate the difference, if I run my fingers through my hair to appear scary while playing with my son, this is a human action; whereas if I absentmindedly do the same thing while thinking about human unity, this action, while rightly attributed to me, cannot lay claim to distinctively human agency. Human persons, thanks to their spiritual powers, are characterized by the ability to act of themselves, deliberately.

Still, a human action, while spiritually informed, is not the act of a spirit. Thomas insists equally on the intellectual act as spiritual, but also on the agent of the intellectual act as the human person, soul and body. The experiential touchstone for his analysis of the human being is the simple fact that I experience myself understanding.[51] The “I” who experiences “myself” as understanding is both body and spirit. Human action, in other words, while specifically differentiated by the dimension of personal agency, essentially possesses a bodily dimension.

Indeed, most actions that constitute our distinctly human lives are identifiable as specific bodily movements: talking, going to work, playing sports, cooking, typing, and so on. While it is possible for human action to occur without a specific bodily descriptor (for example, thinking about what I will do tomorrow, vs. telling someone what I will do tomorrow), even these cases involve a bodily dimension inasmuch as all human thinking is shaped by particular sensory influences, which work best when the body as a whole is running smoothly, free from distraction.[52] Moreover, we think in words, which are first and foremost public, vocal, interpersonal communications. Private thinking, says Robert Sokolowski, is “the derivation from or the rehearsal for a public performance. It is the shadow of what we do in public […] We tend to think of speech as voiced thought (‘thinking out loud’) but we should think of silent thinking as unvoiced speech.”[53] Accordingly, the body’s quiet role in private thought is nearly as important as it is in conversation, wherein the body’s greatest contribution is to employ its whole self in the activity of speaking, which means that much of the body may seem to be inactive. Yet it is hardly the case that in thinking or in speaking the majority of the body assumes a deadweight or extraneous stance. If this were the case, we would notice our bodies acutely on all such occasions. As it is, quite the contrary: we seem to notice our bodies least at such times, and we recognize that it is best for our thinking or speaking if this is so. It is in accord with Thomas’s principles to see in these situations how the body fully realizes itself as human—through participation in intellectual being and activity—precisely when it is least noticed as sheer corporeality.

Human action images the superior wholeness of human embodiment. Since things act as they are, it should be expected that properly human actions possess a unity that resembles the metaphysical unity of soul and body.[54] Speech may be the paradigmatic example of human action, formed by and expressive of rationality, governed through will, yet actualized in the physical realm and generally considered one of the definitive activities distinguishing us from other animals. Like music (the two are often linked across history and cultures) speech is a distinctly human activity characterized by a remarkable degree of physical complexity, temporally distended and yet unified in a way that transcends physicality, encompassing past, present, and future. This unity is an intelligible one.

At its most basic, predication reveals a thing’s identity (being) by articulating the subject in view as unified with one of its aspects—or as not unified. Sense alone, unable to parse out the relation between a subject and its aspect in the first place, cannot accomplish such identification. Thomas refers to speech in this most essential way as a kind of composition, or division. Though articulation itself is necessarily distended, the articulated unity, as such, is not, even if that unity is recognized as tenuous in reality. When I say, “Socrates is standing over there,” we are aware of various physical unities in the situation: Socrates is a kind of physical unity, as is his place. The length of time he will stand in the place is a temporal unity; even the sentence I utter is contained within a particular amount of time. Yet what the sentence asserts is the unity of Socrates with the position he maintains in the place he is in. This unity, as perceived by reason and articulated in words, is itself neither a temporal nor a quantitative amount. It is, rather, an intelligible structure, an order perceived and articulated by thought. As such, it is not fully characterized by physical or temporal extension; it can never be destroyed; it can be communicated to many, translated, and reformulated all while remaining itself. Yet it can only be expressed in and through the sensory, temporal sphere.

Speech thus imitates the structure of the speaker: an intellectual form expressed in physicality, but thereby granting to its physical constituency a remarkable sort of unity. In the realm of mere sensory perception, speech is as similar to other sound as the human person is to other moving, bodily magnitudes. From this viewpoint, the fact that half a million such sounds are woven into the unity that is Anna Karenina strikes us almost as much as the fact that certain proportions of oxygen, carbon, hydrogen, nitrogen, and other elements can unify to become Leo Tolstoy. Our most characteristic activity as rational animals imitates the kind of metaphysical unity that we are.

Also imaging distinctively human unity are all cases of bodily performance: playing a sport or a musical instrument, acting, dancing, observing table manners, pointing, or even standing straight. Within the bodily and temporal continuities that constitute it, a human action as simple as a bow not only expresses some thought; it brings meaning to pass in its very gesture. The bow is thus an integral unity of intelligible meaning and physical, temporal display. In all these cases, through training and practice the performer experiences, or hopes to experience, the body’s relative “disappearance” as sheer bodiliness precisely in the context of rational activity. At the same time, this is for the sake of the body’s “re-appearance” as human: as emanating rational order and unity, for the sake of both performer and observer. Since the greater human unity of soul and body exists in order for properly human action to occur, it should not be surprising that in such action, as in an effect, we discern something of the cause.

Conclusion: The disunified human being

But let us return to the ubiquitous experience of ourselves as disunified. Not only are we subject to physical weakness, injury, sickness and death; we are also fragmented in uniquely human ways, through distraction, frustration, confliction, regret, guilt, and remorse. We are prey to psychological, emotional, mental, and spiritual disturbances. A full account of our experience of disunity would, for Thomas, include some consideration of Original Sin’s inheritance and its effects. Here I simply wish to note two points from the standpoint of philosophical reflection: first, that the human being is potentially the most disunified creature when it comes to powers and actions; and second, that even this disunity points back to the underlying metaphysical unity of spiritual soul and human body.

First. The mere fact that humans are able to experience the sorts of disunities just listed can be explained naturally. Thomas explains that precisely because man is situated as the border of the bodily and the spiritual, he is less simple than any other being at the level of power.[55] As our spirituality is merely in potency to its proper act, and thus dependent upon sensation, the soul in its simplicity originates the whole gamut of powers, those proper to animals as well as those proper to spiritual beings. In proportion to the great complexity of the human being are the many ways it can go wrong.

Of particular significance for human disunity is the fact that we possess apprehension and appetite of two sorts: sensory and intellectual. There is always the possibility that our inclination toward some sensory good will oppose the rational inclination toward something else, and vice versa.[56] Indeed, to some extent our way of being privileges the sensory realm, since these realities are the ones most immediately present to us.[57]

Disunity points back to unity. For Thomas, our experience of sensory/rational conflict reveals disunity at the level of power, to be sure, but also confirms a corresponding unity at the metaphysical level. In defending the substantial union of human soul and body against an objection that cites the conflict between “flesh and spirit,” Thomas responds as follows:

“[the] very fact that the flesh lusts against the spirit indicates the soul’s affinity for its body. For ‘spirit’ means the superior part of the soul by which a human being surpasses other animals … Now the flesh is said to ‘lust’ because those parts of the soul that are united to the flesh desire those thing which are pleasant to the flesh, and sometimes these desires are at war with the spirit.”

In other words, if the sensory and rational powers were not as united as they are, we would not experience the conflict between them as acutely as we do.[58]

Something similar can be said about our experience of the deepest human fissure, death itself. It might be thought that the foregoing account of human unity would maintain death to be simply unnatural, since by nature the soul and body are even more united than any other form/matter union. Yet the argument does not follow: human matter, only participating in spiritual being and unity, does not itself become spiritual. Its decomposition remains a natural possibility.[59] What does follow, it seems to me, is that the human experience of and attitude toward death would be more painfully felt than in the case of other animals. The reason for this suffering is not only that humans, unlike animals, are rationally aware of what is happening; it is also that what happens in human death is more violent than in animal death. Death is less natural in humans than in animals, since the unity it sunders is a greater one.

But death, as we Christians know, doesn’t have the last word. I’ll let my final thoughts here concern Christ, who removes the sting of death, and the life He offers us. In the Summa contra Gentiles IV, while discussing the Incarnation, Thomas states that human soul/body union is the closest analogy we have to the union of Divine Word and Human nature in Jesus Christ.[60] The soul is spiritual and communicates its own being into the body, so that the body might assist the soul in its activity. Analogously, the Divine Word communicates its being into the human nature of Christ so that Divinity might most fittingly accomplish the work of salvation. Of course this is only an analogy—but the thesis of this talk, that the human soul and body constitute the greatest natural unity, contributes nicely to the analogy Thomas gives. And in this light let us consider the role of our souls and bodies in the life that imitates Christ. At times, we rightly mortify our bodies. But this doesn’t have to be just in order to tame lower passions. St. Thomas More speaks of how we all ought to weep over our sins. And for those many of us who aren’t yet able to weep for our sins, we need not despair: our souls and bodies are so united, More says, that we can mortify our bodies in some way, for the sake of Christ, and it will be as though we are weeping for our sins.[61] Indeed, the ultimate mortification, death itself, for the Christian doesn’t have to a sign of man’s disunity. It doesn’t have to warrant the judgment: vanity of vanities. Rather, because our soul and body are so united, when we offer our bodies in death for the sake of Christ, it is as though we are offering our very souls. And it is to reestablish this unity for eternity, in the resurrection of the body, that Christ died and rose. So that having given our life away, we may find it again, in all its unity.


[1] © 2016 John Finley All Rights Reserved.

[2] Lost in the Cosmos (Picador, 1983), pp. 5-8.

[3] Trans. Richmond Lattimore.

[4] Revised Standard Version, Second Catholic Edition.

[5] STh I, q. 75, a. 4; q. 76, a. 1.

[6] ScG II, c. 68.

[7] STh I, q. 11, a. 1.

[8] De ente et essentia, c. 3 (hereafter, De ente); ScG II, cc. 52-54.

[9] “Non autem minus est aliquid unum ex substantia intellectuali et materia corporali quam ex forma ignis et eius materia, sed forte magis: quia quanto forma magis vincit materiam, ex ea et materia efficitur magis unum.” Translations are my own, unless otherwise noted. I translate forte here as “as it happens,” which seems more appropriate, given the context, than James Anderson’s “perhaps.” See Summa Contra Gentiles. Book Two: Creation, Trans. James Anderson (Notre Dame: University of Notre Dame Press, 1975), p. 205. Thomas immediately gives a universal reason for his claim, which makes it unlikely that he would express the claim itself tentatively. This is the only passage I know of in Thomas’s corpus that explicitly affirms human hylomorphic unity as greater than the unity of other composite substances.

[10] Ch. 58

[11] See also ScG I, c. 42, where Thomas invokes the transcendental proportion between being and unity to argue that the more a thing has being, the more it has unity.

[12] ScG II, c. 72; STh I, a. 77, a. 2.

[13] This presence of substantial form in the whole and in all the parts reveals natural beings as greater unities than artifacts, wherein the form of the whole (like a house) only arranges, and does not actualize the parts as such. See STh I, q. 76, a. 8; V Metaphysicam, lect. 7, n. 851; X Metaphys., lect. 1, nn. 1922, 1926. Thomas develops this notion of natural unity into an articulation of substantial form as wholly present in the whole body and in each part. He calls this a totality, or wholeness, of essential perfection, e.g., the wholeness of a substance as possessing its proper form and matter. Such wholeness is distinguished from wholeness of quantity and of power. See Disp. de anima, q. 10; De spir. creat., a. 4; ScG II, c. 72. This essay owes much to Thomas’s discussions in these texts.

[14] V Metaphys., lect. 8, nn. 870-71; X Metaphys., lect. 1, nn. 1922-28; Disp. de anima, a. 10, resp.; De spir. creat., a. 4, resp.

[15] V Metaphys., lect. 8 nn. 870-71. Using Thomas’s geometrical examples, we could say that the living organism (the whole) is more like a circle, which is complete and lacks nothing; while the non-living substance (the continuum) is more like the straight line, which can be extended indefinitely.

[16] The distinction between what I call continuums and wholes is insightfully discussed by Hans Jonas, “Biological foundations of individuality,” in Philosophical essays: from ancient creed to technological man (Englewood Cliffs, N.J.: Prentice Hall, 1974). Jonas emphasizes the self-actualization of living organisms.

[17] De spir. creat., a. 4, resp., ad 9; II De Anima, lect. 8, n. 332. This is not the same as Thomas’s distinction between designated and undesignated matter (De ente, c. 1), which he employs to articulate the difference between a nature considered in itself and in an individual instance.

[18] Notably, as Jonas points out, the metabolic activity central to any living organism preserves ‘this matter’ precisely through constantly replacing the parts of matter over time. See “Biological foundations of individuality.”

[19] Plants and certain animals like worms, as Thomas notes, possess a trace of the homogeneity proper to non-living substances, since various forms of sheerly quantitative division can entail new instances of the same substance. Still, the fact that prior to such division a single soul is at work indicates that the homogeneity present in these organisms is more of a merely potential sort than it is in non-living substances. See De spir. creat., a. 4, ad 19.

[20] Before arguing for God as supremely one, in STh I, q. 11, a. 4, Thomas argues that God is one, i.e., that there is one God, in a. 3. Here Thomas is showing that nothing like continuity or commonness exists in the Divine Nature. The Divine cannot be present in pieces or in instances. Compared to their Creator, all creatures possess something resembling continuity, since they all participate (analogously) in being (esse). They are all instances (analogously) of being (ens). Bodily living creatures, while instances of a kind, are at least not pieces.

[21] See Disp. de anima, q. 8, ad 11.

[22] Ibid., q. 10, resp.; De spir. creat., a. 4, resp.

[23] Thomas would have also considered the heavenly bodies such totalities.

[24] STh I, q. 75, aa. 1, 2, 5; q. 76, a. 1.

[25] Disp. de anima, q. 14, resp.

[26] De spir. creat., a. 4, ad 17; ScG II, c. 49, n. 2.

[27] Quaestiones disputatae de potentia dei, q. 10, a. 5, obj. 6, ad 6 (hereafter, De potentia); STh I, q. 14, a. 2, ad 1.

[28] ScG III, c. 46, n. 2: “Ipsa autem anima semper sibi adest actu, et nunquam in potentia vel in habitu tantum.”

[29] Quaestiones disputatae de veritate, q. 1, a. 9, resp.: “…illa quae sunt perfectissima in entibus, ut substantiae intellectuales, redeunt ad essentiam suam reditione completa: in hoc enim quod cognoscunt aliquid extra se positum, quodammodo extra se procedunt; secundum vero quod cognoscunt se cognoscere, iam ad se redire incipiunt, quia actus cognitionis est medius inter cognoscentem et cognitum. Sed reditus iste completur secundum quod cognoscunt essentias proprias…” (hereafter, De veritate).

[30] De spir. creat., a. 1, ad 12.

[31] Jonas discusses the centrality of selfhood to living organisms in “Biological foundations of individuality.” Also, Jonas, “Is God a Mathematician?” in The Phenomenon of Life: Toward a Philosophical Biology (Northwestern University Press, 1966), pp. 64-98.

[32] One way to see the irrational animal’s subjection to continuity is in its generation, through which the whole being, substantial form and matter, is brought forth by way of physical separation from parents. In human generation, only the material principle is thus divided. See De potentia, q. 3, aa. 9-11.

[33] ScG II, c. 68.

[34] De spir. creat., a. 2, ad 8.

[35] Disp. de anima, q. 9.

[36]“Hoc autem convenienter diceretur si eodem modo illud esse materiae esset sicut est substantiae intellectualis. Non est autem ita. Est enim materiae corporalis ut recipientis et subiecti ad aliquid altius elevati: substantiae autem intellectualis ut principii, et secundum propriae naturae congruentiam.”

[37]“…inter omnia, esse est illud quod immediatius et intimius convenit rebus, ut dicitur in Lib. de causis; unde oportet, cum materia habeat esse actu per formam, quod forma dans esse materiae, ante omnia intelligatur advenire materiae, et immediatius ceteris sibi inesse” (Disp. de anima, q. 9, resp).

[38]“Corpus autem quod est in genere substantiae, habet formam substantialem quae dicitur corporeitas, quae non est tres dimensiones, sed quaecumque forma substantialis ex qua sequuntur in materia tres dimensiones; et haec forma in igne est igneitas, in animali anima sensitiva, et in homine anima intellectiva” (De spir. creat., a. 3, ad 14); “…licet anima non habeat corporeitatem in actu, habet tamen virtute, sicut sol calorem” (ad 16).

[39]Thomas remarks that the human soul gives not simply actual being to the body, but being of a certain sort, namely, life, and life of a certain sort, namely, in an intellectual nature. De spir. creat., a. 11, ad 14. 

[40] Disp. de anima, q. 1, resp., ad 3; q. 8, resp.

[41] “…intelligere est propria operatio animae, si consideretur principium a quo egreditur operatio; non enim egreditur ab anima mediante organo corporali, sicut visio mediante oculo, communicat tamen in ea corpus ex parte obiecti; nam phantasmata, quae sunt obiecta intellectus, sine corporeis organis esse non possunt” (Disp. de anima, q. 1, ad 11).

[42] De veritate, q. 1, a. 9, resp.; q. 8, a. 6, resp.; STh I, q. 55, a. 2, resp.

[43] Disp. de anima, q. 10, ad 1: “Et propter hoc totum corpus, cui respondet principaliter anima ut forma, est organum…”. Thomas sees the intelligibility of the body as metaphysically prior to that of the powers, since the body pertains to the soul’s essence itself, while the powers flow from the essence (STh I, q. 75, proem.)

[44] STh I, q. 84, a. 7, resp.; q. 85, a. 1, resp.

[45] For an excellent discussion of the human intellect’s natural partnership with the physical realm, see Brock, “The Physical Status of the Spiritual Soul.”

[46] Disp. de anima, q. 9, resp.

[47] STh I, q. 77, a. 2.

[48] Disp. de anima, q. 13, ad 7.

[49] Disp. de anima, q. 11, resp.

[50] STh I-II, q. 1, a. 1.

[51] STh I, q. 76, a. 1; Disp. de anima, q. 2; De spir. creat., a. 2.

[52] Ibid., q. 84, aa. 7-8.

[53] Robert Sokolowski, The Phenomenology of the Human Person (Cambridge University Press, 2008), p. 62. Thomas holds that human thought always involves words, though the exterior word, while better known to us, is consequent upon the interior word in the act of understanding itself; see STh I, 85, a. ad 3; De veritate, q. 4, a. 1, resp.; a. 2, ad 4. He comes close to giving a kind of priority to words received from others in DV, q. 11, a. 2, ad 11, while comparing knowledge received through teaching to knowledge acquired directly from things. See also I Peri Hermenias, lect. 2, where Thomas discusses the social dimension of man’s rationality and the priority of vocal over written words.

[54] ScG III, c. 3, n. 6.

[55] STh I, q. 77, a. 2.

[56] STh I-II, q. 9, a. 2.

[57] Ibid.; ScG III, c. 6, n. 8.

[58] See also Disp. de anima, q. 8, ad 7. At the end of the respondeo to q. 11, Thomas notes that one evidence for the unity of vegetative, sensitive, and rational soul is the fact that the operation of one power, when strong, can overwhelm that of another.

[59] Ibid., q. 1, ad 14; q. 8, resp.

[60] Ch. 41.

[61] Dialogue of Comfort against Tribulation.