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On whether Aquinas's ipsum esse is "platonism" (1).

IN SEPTEMBER OF 2002, Oxford University Press published a book by Anthony Kenny entitled Aquinas on Being. In the preface, Kenny declares St. Thomas to be one of the greatest of all philosophers. The book's aim, however, is not to explain this judgment. In fact it is to show that on the topic of being, Thomas "was thoroughly confused." (2) Kenny surveys works spanning Thomas's entire career, finding therein neither a unified nor even a coherent conception of the nature of being. His diagnosis of the confusion is complex, but there is one factor that stands out as the gravest and most pervasive. He calls it "platonism."

Kenny's is not an isolated voice. Indeed, for more than a quarter of a century, the eminent Italian philosopher and student of Aristotle, Enrico Berti, has been raising similar doubts about Thomas's ontology. (3) Berti is less severe than Kenny in his judgments. But his worry is essentially the same: an infection of "platonism."

The complaint, of course, is not simply that (neo)platonic thought is an important source for Thomas's doctrine of being. For some time now, followers of Thomas have been stressing this very fact. They often use it to help explain why Thomas was able, as they say, to "go beyond" the ontology of Aristotle. But what concerns Berti and Kenny is a line of thought that Aristotle himself, associating it with Plato, lays out carefully and vigorously rejects--and that Thomas joins him in rejecting. It is this very line that they find insinuating itself at crucial points in Thomas's own thought on being. So the problem is not just that the line is mistaken (though they clearly think it is). It is also that insofar as he adopts it, Thomas is being incoherent.

It seems to me that Berti's concerns have received far too little attention. (4) Oddly, not even Kenny mentions him. In what follows, I shall refer more to Berti than to Kenny. Berti offers a much fuller analysis of the pertinent Aristotelian doctrines, and this enables him to formulate the issues in a correspondingly sharper way. Here I can address only some of them. I lay these out in sections I and II. My chief aim in the rest of the paper will be to highlight an element in Thomas's ontology that is both very pertinent and, I find, rather neglected by critics and followers alike. This is the connection that Thomas maintains between the nature of being and the differences of things.


Against Plato: being is not a single nature. In book 3 of the Metaphysics, Aristotle presents a list of difficulties that first philosophy needs to address. The 11th difficulty, which he calls "the hardest and the most necessary for knowledge of the truth," is whether being and one constitute the substance and principle of things--the most mental realities--or whether they are only attributes of some other underlying nature. (5) Plato and the Pythagoreans, he says, finding being and one to be the most universal features of things, regarded them as the most essential. Aristotle also indicates that Plato, with his characteristic move of [TEXT NOT REPRODUCIBLE IN ASCII.], isolated these features and posited a Being itself and a One itself existing separately, that is, Ideas of Being and One. (6) Berti calls this the "substantialization" of being and one.

Aristotle, of course, rejects this position. His reasons are several. Among them would be all of his arguments against the possibility that any universal or common feature could be a substance. (7) Others concern the special case of being. Here two points, closely related, stand out.

The first is Aristotle's insistence that if there are many beings, then the substance of them, their essence, cannot be being itself. If it were, then it would be a genus; and this is impossible. The principles by which the species of a genus are divided from each other are their differentiae, and the genus cannot be predicated directly of the differentiae. (8) So if being were a genus, divided by differentiae into many species, then it could not be predicated of the principles dividing it; which is to say, these principles could not be beings. Distinguishing features would not exist. There could not be many beings after all. The differences among beings must also be beings. (9)

The second point also has to do with the multiplicity of the beings. Whether or not being is in the essence of all things, if nonetheless there is one single thing whose essence consists in being itself--an Idea of being--then being must be understood as a single essence. From this it follows that any other thing, considered just in itself or according to its own essence, would not be a being. (10) So again there would be nothing--that is, no beings--to multiply being. Aristotle, in fact, groups Plato with thinkers who, in order to avoid the monism of Parmenides, tried to explain the multiplicity of beings by way of a composition of the nature of being with "something else," that is, some nonbeing. (11) Aristotle's own view is that the substance of each thing is a being (and also one) per se, not by a combination or in virtue of something conjoined to it. This is what he means when he says that "man," "one man," and "existing man" are interchangeable predicates. (12)

So the basic problem with the platonic position is that being is treated as a single essence, univocal. For Aristotle, being must be conceived from the start as diversified. (13) If the multiplicity of things is real, then "being" cannot stand solely for a feature common to all things. It must also be able to stand, immediately, for what is distinctive about each. This is possible only because being does not have an absolute or fully autonomous nature, one that stands entirely on its own. Being is always said of a subject whose essence is not just being itself, and its nature varies in function of what it is said of. (14)

This, Berti insists, does not mean that for Aristotle, "being" signifies nothing by itself. Rather, it would signify nothing, or would be indistinguishable from nonbeing, if it only signified one thing. It signifies many things. This is why it is so rich. (15)


Ipsum esse as univocal. Now, as Berti recognizes, Thomas Aquinas fully agrees with Aristotle's general criticisms of platonic Ideas. Thomas rejects the existence of separate or subsistent versions of the essences of sensible things. Moreover, he does not hold that being pertains to the essence of all things. He takes the point that being cannot be a genus. (16) He also holds that "being," by itself, signifies many things. (17) In fact, he does not fix on the common predicate "being" (ens) and posit this directly as separate. (18) Instead, he isolates the common perfection or determination through which all things are beings, namely, the act of being, esse. He holds this to be outside the essence of all things--save one. This one is God, who is ipsum esse subsistens. All others have esse from Him.

Thomas also sees esse as somehow diversified in things. They have it in various "modes," which are determined according to their diverse essences. Nor is the esse possessed by things the very esse of God. God's esse subsists separately, and hence in a pure and infinite way. The esse of other things is only participated, and it is conditioned and limited in each case, according to the essence of the participant. God is not identical with the esse inhering in all things, esse commune, but is rather its cause--its agent and its exemplar.

Thus there are clear differences between Thomistic esse and the Platonic [TEXT NOT REPRODUCIBLE IN ASCII.] criticized by Aristotle. Nevertheless, Berti is not persuaded that Thomas has fully assimilated the criticism. If he had, he would not posit a single subsistent whose essence is constituted by esse itself. If esse can be the essence of one single thing, then esse itself is one single essence. Even if other things share in it, thereby putting it under a variety of conditions, its own intrinsic signification will remain the same. And if esse is intrinsically the same, then so is ens itself, insofar as it is ens. The diversity of being will not be intrinsic to it, as Aristotle insisted it must be (and as Thomas himself seems to agree that it must be).

As Berti understands it, Thomas's way of placing esse outside the essences of things is not really in line with Aristotle's denial that ens is a genus. If for Aristotle ens is not in the essences of things, this is because it is too intimately tied to each thing's whole essence, too bound up with its full identity, to be merely one essential feature alongside others, as a genus is. The differences are beings too; they exist. But if the nature of ens derives from esse, and if what esse primarily signifies is the essence of a single thing, then the nature of ens will be alien to the essences of other things. It will belong to things only in the manner of something added on. Its intrinsic signification will not embrace the diversity of things.

It is not that Berti entirely rejects the possibility of distinguishing between essence and esse. If the essence of a thing includes potentiality, then it will be distinct from the thing's esse, which is solely its actuality. But the point is that the esse is strictly proportioned to the essence, what we might call a function of it. That is, what a thing's esse is is a function of its essence. For a living thing, "to be" means "to live." For a threshold, it means to have a certain position. There is no third element that is simply "to be," with an independently constituted nature of its own, in which things "participate." (19) What is common to the esse of all things is only a proportionality (which is what Aristotle calls analogy): whatever the esse of a given thing is, it is related to the thing as its actuality. (20)

In short, despite Thomas's own talk of analogy, he would really be making esse something uniform, univocal. (21) He would not be seeing diversity as intrinsic to it, diversity rooted in its immediate connection with the various forms of things. If he were, then he could not "pull esse out" from things and posit one thing that is nothing but esse itself. Kenny puts it vividly:
 Many passages in Aquinas ... suggest that esse is thought of as a
 vast reservoir of liquid that is given particular shape and form by
 being captured in various receptacles. You and I, and the ants and
 the planets, are small buckets of this universal fluid; God is the
 vast, limitless ocean. (22)

This brings us to what is perhaps the most important part of Berti's criticism. In his view, Thomas's ipsum esse is not just un-Aristotelian. It is also incompatible with something even dearer to Thomas than the wisdom of Aristotle: the transcendence of God. If God's essence consists precisely in esse, (23) then it is not something strictly proper to him. It does not belong to him exclusively. (24) That very essence is also present, albeit in diminished "modes," in all creatures. (25) The terms employed to distinguish God from other things seem to indicate only a diversity of conditions of this essence: separate versus inherent, subsistent versus participated, infinite versus finite. They do not display an essential diversity, diversity in what God is. The nature of water is the same, whether it is in the ocean or in a bucket. Kenny draws the final conclusion: Thomas's God is nothing other than the platonic Idea of esse. (26) It is the separate version of the essence common to all the instances of esse. (27)

The importance of the question, then, is evident. Berti also observes its timeliness:
 Contemporary philosophy is particularly sensitive to the existence
 of differences, to the point that it has come to repropose the
 heideggerian conception, replacing the "ontological difference"
 between beings and being--which still always presupposes a univocal
 concept of being and risks subtracting being from the beings, that
 is, from the differences--with the simple differences among the
 beings. In agreement on this position today are existentialism,
 phenomenology, hermeneutics, methodological pluralism, yet without
 realizing that it contains in nuce the foundation of metaphysics,
 that is, the rational demonstration of the transcendence of the
 Absolute. (28)

This is what I propose to examine in the following pages: the role played by the distinguishing features of things--their essences, and especially their differences--in Thomas's ontology. I wish to suggest that they have a constitutive function, not only in the specific natures of the beings, but also in the nature of being, and even in the nature of esse itself. I have arranged the discussion so as to conclude with a consideration of Thomas's understanding of the relation between the nature of esse and the nature of the divinity.


As though constituted through the principles of the essence. It would be otiose here simply to list texts in which Thomas directly expresses agreement with Aristotle's account of being. His professed agreement is itself part of the reason that his own notion of esse as actus essendi is said to involve him in incoherence. However, at least one such text, from his commentary on the Metaphysics, deserves to be recalled. It will serve to introduce some of the terms of the discussion.

The text concerns the passage in which Aristotle says that "one" and "being" add no distinct reality to what they are said of, and that the substance of a thing is one and a being per se, not per accidens. In explaining the first point, Thomas takes the occasion to remark that the name ens is taken from actus essendi. (29) This is already rather striking. If there is any tension between his actus essendi and what Aristotle is saying here, Thomas is completely oblivious to it. (30)

A few lines later, to explain the point that the substance of a thing is one and a being per se, not per accidens, Thomas says that one and being cannot be predicated of a thing "through some ens added to it." This would yield an infinite regress. He then criticizes Avicenna for saying that esse is something added on to a thing's essence. Instead, Thomas says,
 even though the esse of a thing is other than its essence, it
 should not be thought of as something added on, in the manner
 of an accident; but rather, it is as though constituted through
 the principles of the essence. And therefore this name, ens,
 which is taken from esse itself, signifies the same as the name
 which is taken from essence itself [res]. (31)

So we ought not to think of esse as another ens or as a diverse res. It is not an absolute or autonomous nature. Every esse is as though constituted through the principles of an essence. These would presumably be some matter and form, and chiefly some form. So understood, the relation between esse and essence is clearly very tight. For of course the essence itself can also be said to be constituted through those same principles. They are its components. Kenny in fact wonders how, on this account, esse and essence can be said to differ at all. (32)

I take it that part of the answer would be that although the esse is "as though" constituted through the principles of the essence, these are not to be understood as its very components. Thomas's constant teaching is that every esse is something simple. It cannot be composed of matter and form. He must only mean that it is somehow proportioned to the matter and form comprising a thing's essence. However, this would not be sufficient to express the difference between esse and essence in every case in which Thomas holds that they differ: that is, in all creatures. For the essences of some creatures are not composed of matter and form, but are simply forms. So there must also be some more general difference, applying both to material and immaterial creatures. I shall try to bring out such a difference in the next section of the paper.

The Metaphysics commentary is a rather late work of Thomas's. But the way of conceiving esse set forth there is not at all a novelty for him. To cite just one example: in the De potentia, Thomas criticizes Avicenna in the very same way. The esse of a substance is not in the genus of accident. Even if it is not part of the essence, it is the very act of the essence, actus essentiae. (33) In works from every stage of Thomas's career, we find similar formulations of the nature of esse: actus essentiae, actualitas essentiae, actualitasformae, and so on. (34) In the Summa theologiae, he uses such an expression to distinguish esse from action. "An action is properly the actuality of a power (virtutis), as an esse is the actuality of a substance or an essence." (35)

It seems clear then that Thomas would have no objection to the idea that esse is always strictly proportioned to the essence of its subject, as a function thereof: quite the contrary. In relation to our theme, one set of texts in which this idea emerges is especially striking. It is a line of argument that Thomas uses rather frequently in support of the very thesis that esse and essence in things other than God must be distinct. This will be the focus of the next section. I should mention that in presenting this argument, my chief concern is not with whether it serves to show the distinction to be a "real" one. What mainly interests me is the conception of esse involved in it.


Differing according to esse. The argument appears in various versions in different works. I suppose the best known version is that of the Summa theologiae. It is part of the fifth article in the question on God's simplicity (I, q. 3). This article comes immediately after the discussion of the identity, in God, of esse and essence. It concerns whether God is in a genus. Thomas wants to show that the divine nature does not have a definition, a formula composed of genus and differentia. That is, the conception or ratio that properly expresses the divine nature must be perfectly simple.

Thomas gives three arguments to show that God is not in a genus as a species. The first is that the principle of a thing's genus is related to the principle of its differentia as potency to act (36) and that in God there is nothing potential. The second is that since God's essence is His esse, and since a thing's genus signifies its essence, His genus would have to be ens; but ens cannot be a genus, because the differentiae would be outside ens. A non ens cannot be a differentia.

The third argument is the one that interests us. Things that are in a genus, Thomas says, share in the quiddity or essence of the genus; and the genus is predicated of them essentially, in quod quid est. Yet they differ according to esse. The esse of man is not the same as the esse of horse, nor is the esse of this man the same as the esse of that man. Hence, for anything in a genus, esse and quod quid est, or esse and essence, differ. But in God they do not differ. So God is not in a genus, and He has neither genus, nor differentia, nor definition. (37)

It is a difficult argument. However, it has the advantage of distinguishing between essence and esse in a way that applies even to the creatures whose essences are not composed of matter and form--the immaterial creatures, the angels. Thomas holds that the angels constitute a genus divided into species, each with its own differentia. (38) In their case too, we may note, esse is proportioned to essence. An angel's essence, Thomas says, is the "ratio of its whole esse"; it is so insofar as it is "such" an essence (talis essentia), the specific essence that it is, "according to its proper ratio." (39) In the same article, Thomas affirms universally that "the esse of any creature whatsoever is determined to one according to genus and species." (40) So we are dealing with a teaching meant to extend to all created beings. Drawing upon related passages from other works, I understand it as follows. (41)

The first step is that things in a genus share in the quiddity or essence, the "what it is," of the genus. This means that the proper ratio of the genus, its intrinsic intelligible content, is the same in each case. The genus is said univocally of its members. The ratio signified by "animal" is the same when it is said of horses and when it is said of men. Horses and men are animals, and they do not differ with respect to what an animal is. Likewise, Socrates and Plato do not differ with respect to what a man is. Here we can note that although the argument is being used to make a point about things in a genus, Thomas clearly takes it to be applicable also to things in a common species. It applies to any being whose nature has something univocal in common with the nature of some other being. This is explicit in some of the parallel texts. (42)

The next step is that even though esse belongs to all things, they differ with respect to it. How so? Thomas does not spell this out here. But both the logic of the argument and some of the parallel texts leave little doubt about it.

It is not just that things have distinct instances of esse. If man and horse have distinct instances of esse, they also have distinct instances of the nature of animal. They are not the same animal. But the point would be that these instances of the nature of animal are not distinct on account of anything in the very nature of animal. In itself, or according to its own ratio, the nature of animal is entirely one and the same. It is diversified only per accidens, or through association with something extrinsic to its proper ratio; namely, some differentia. By contrast, between diverse instances of esse, the diversity is never solely through association or per accidens. It is intrinsic. Things are diverse "according to" esse. For each thing, there is something which is its esse; but what this something is for one thing differs from what it is for another. The ratio of animal remains the same when said of distinct animals, but the ratio of esse does not. (43) If what esse is were the same for two things, then they would not really be two, but only one: that is, one being (ens). (44)

In effect, then, this argument seems to complement the article's preceding argument, which reasoned that God cannot be in a genus because ens cannot be a genus. (45) Ens is not a genus because it is not diversified solely by something outside its own signification, a differentia. When said of diverse things, its own signification differs. But what it signifies is the esse of whatever it is said of. So the esse of one thing must be intrinsically diverse from that of other things. And, it must be so just insofar as the thing is an ens; which is to say, in every respect. So if something is in a genus, its essence cannot be its esse, because its essence is not in every respect diverse from the essences of other things in the genus. What it is is partly the same as what the others are. But it is not even partly the same ens as the others.

Is Thomas urging us to think of esse as something inconceivable, defying formulation? This would not particularly favor the judgment that it is something diverse in each thing. What he says is that the esse of a man is not the same as that of a horse, and that the esse of this man is not the same as the esse of that. The basic thought, I believe, is that for a horse, to be is to be a horse. For a man, to be is to be a man. (46) For Socrates, it is to be Socrates. Esse is diverse in each case--what it is, its intrinsic ratio, differs--because it is constituted according to diverse essential principles. (47)

If this reading is correct, then the striking thing is that Thomas is using the very proportion between a thing's essence and its esse to show a distinction between them. The distinction is not between the essence of a horse and some alien or absolute nature which is nothing but "esse." It is between the essence of a horse and the act of being a horse. How is the distinction to be understood?

Perhaps some help is afforded by recalling the article's first argument. Genus and differentia stand in a relation of potency and act. In the Metaphysics, Aristotle argues that this is the only way to account for the unity of a true definition. Even though the definition contains many words, what it defines is nonetheless one, and a being, per se. (48) Thomas is presupposing that the genus of a thing does not exist in act on its own, independently of its various species and of their differentiae. The genus has esse only in conjunction with and according to some differentia. (49)

What this means is that in a man, the act of being an animal is the very same thing as the act of being a man, and of being rational. Such an act of being is of course proper to men. But the nature of animal is not proper to men. It also belongs to horses. And in a horse, the act of being an animal is the same as the act of being a horse, and of whatever the differentia of a horse is. So it is at least clear that the nature of animal and an act of being an animal are never quite the same. More generally, no common and univocal feature will be quite the same as an act of being that feature. As Thomas says in the De veritate, man (homo) is not the same as being man (hominem esse), and knowledge (scientia) is not the same as being knowledgeable (esse scientem). (50)

It might seem as though a thing's act of being is nothing other than its differentia or its distinguishing ratio. But this cannot be right either, because even though the thing's act of being is not identical with its genus, it is nonetheless determined according to the genus. (51) For again, the genus is predicated of it in quod est. It is part of the definition expressing the thing's essence, through whose principles the thing's act of being is constituted. Man's act of being, for example, is not only an act of being rational, but also an act of being an animal. It is an act of being a rational animal. To identify his act of being with his differentia would thus lead to absurdity. It would mean that man could be defmed as an animal being a rational animal. (52)

So the esse of a thing cannot be identified either with its genus or with its differentia. It is somehow a function of both. But a serious question still remains. It is similar to the one posed by Kenny. He asked how, if esse is constituted by the principles of the essence--the matter and form--it can be said to differ from the essence, which is also constituted by these same principles. We can likewise ask how, if a thing's esse is to be understood in terms of its genus and differentia, it differs from the thing's whole essence. For the same can be said of the essence itself. Genus and differentia are the parts of the thing's definition, which is the formula expressing the understanding of its essence.

To Kenny's question, I suggested that a plausible answer would be that the esse is not strictly composed of matter and form, as the essence is. Rather, the esse would be something simple, though with a constitution proportioned both to the matter and to the form. The difference then would be that whereas the essence is composite, or has parts, the esse is simple. The answer to our question, I believe, will turn out to be similar to this. However, it will also differ in an important way. Considering this difference will help to formulate it.

The answer cannot quite be that while the esse of a creature is simple, its essence is composed of genus and differentia. The distinction between genus and differentia is not properly a distinction between components or parts of a thing's essence. This is clearest in the case of angels, whose essences are said to be incomposite realities, the essences of pure forms. The only substantial composition in them is that of their essence and their substantial esse. (53) But not even the essence of a corporeal substance is properly composed of genus and differentia. For a corporeal substance has only one substantial form; and this simple form is a principle not only of its differentia but also of all the genera that are predicable of it. It is not in virtue of his matter alone that a man is an animal, or a living organism, or even a body. He is all of these in virtue of the composition of his matter and his one form--the same form in virtue of which he is rational. (54) In other words, the whole constitution of a thing's essence underlies both its genus and its differentia. A sign of this is that both the genus and the differentia are predicated per se of the thing as a whole. (55)

But they signify its essence according to distinct intelligibilities or rationes. This is what genus and differentia properly compose: the whole essential ratio of the thing, its definition. (56) They are distinct intelligible dimensions that the thing essentially instantiates. The distinction reflects our mind's way of getting at a thing's essence, which is by comparing and contrasting it with other things. (57) It is a logical distinction.

However, we should not lose sight of the fact that the ratio which breaks down into genus and differentia is indeed a thing's definition, its essential formula. Genus and differentia are predicated in quod quid est. Each captures a dimension of what the thing is. The essences of things--created things--really lend themselves to this way of understanding. The distinction between genus and differentia in the understanding of creatures is not like the distinction among the meanings of the various names that we can give to God. Our best understanding of God consists of a multiplicity of rationes only because it is a deficient understanding. Although we can give him many true names, and even names that are true of him in virtue of his essence, none of them adequately expresses or represents his essence. Nor do all of them together. (58) None of them quite captures even a dimension of what he is. What he is does not have distinct "dimensions." The ratio that expresses his essence cannot be a definition; it must be utterly simple. Proof of this, Thomas is arguing, is that God's essence is identical with his esse. No esse yields a ratio that breaks down into genus and differentia.

This then seems to be how a creature's esse differs from its essence, according to the present argument. The essence is such that its ratio can be analyzed into parts. It is composed of a number of simpler rationes. Even when the essence is nothing but form, it has distinct intelligible dimensions. There is an indeterminate dimension that belongs also to other kinds of things, the genus; and there is a determining dimension that puts the thing in contrast with those others, the differentia. (59) Of course the thing cannot have one of these dimensions without the other. Both are essential to it. Still, they are quite distinct rationes. The differentia is not in the ratio of the genus; otherwise no member of the genus would be without that differentia.

And the genus is not in the ratio of the differentia, for the reasons given by Aristotle.

The ratio of a thing's esse cannot be analyzed in this way. To be sure, as we have seen, the ratio of its esse is a function of its genus and differentia (and in this it differs from the ratio of the divine esse, which is not such a function). The substantial esse of a man is an act of "being a man," which is to say, "being a rational animal." But although we can also use less complete expressions to refer to it, such as "being rational" or "being an animal," this is not to break it down into genus and differentia. (60) Man's esse does not have a generic dimension that is univocally common to all animals, joined with another, differentiating dimension that makes it proper to man. Even when we call it "being an animal," we must understand this in such a way that what it signifies is proper to man. (61) If something is in a genus, then part of the ratio of what it is is exactly the same as part of the ratio of what some other things are. But the ratio of its being what it is is entirely proper to it.

In short, the essence of something in a genus instantiates many intelligible dimensions, but the ratio of its esse is simpler. And yet it is not simpler in the way that the genus or the differentia are, namely, by being one of those very dimensions. Once more, the esse presupposes and is proportioned to the whole constitution of the essence. Its own ratio is a function of that of the essence, because it is nothing other than the actuality of the essence--of all its dimensions together. (62) I think we can say that the esse is the act proportioned to the unity of the various dimensions of the essence. In the esse, the intelligible dimensions of the essence are as it were perfectly fused, more perfectly than in the essence itself. It is more formal. (63) This does not mean more general, but rather, more concentrated. The esse is the "point" of the essence. Nor is it a mere further specification, just one more dimension. It is expressed by a verb. It is more like the event, or the exercise, of the essence. (Kenny cites a remark by Gilbert Ryle to the effect that existing is something like breathing, only quieter. (64))


God is his act of being. One thing that emerges very clearly in the argument just examined, I believe, is that in distinguishing the essence of a thing from its act of being, Thomas is not thinking of the act of being as something to which no qualifying predicate can be added. The act of being of a man is qualified according to the essence or the form of man. It is an act of being a man. If we need confirmation of this, we may consider another passage from the Summa theologiae, in which Thomas offers a truly fundamental formulation of the principal meaning of "a being" (ens).
 Since "a being" properly bespeaks something's being in act, and act
 properly has order to potency, that according to which something is
 called "a being" unreservedly (simpliciter) is that according to
 which it is first set off from what is merely in potency. But this
 is the substantial esse of each thing. And hence each is called "a
 being" unreservedly in function of its substantial esse. (65)

So esse, in the full sense, means nothing other than the substantial esse of something. For Socrates, to be is the same as to be a man. His beginning or ceasing to be a man is the same as his beginning or ceasing to be simply. It is true that the statement "Socrates is" does not mean the same as the statement "Socrates is a man." The first says that Socrates is in act, "set off from what is merely in potency"; the second says that he actually has human nature. But the point would be that the two statements are true in virtue of one and the same act, which is Socrates' substantial esse. (66) This does not mean that no further esse can be added to him. But what is added will be a merely secondary esse, constituted according to some accident. Thus the passage continues:
 in function of acts added on, something is said to be in a way
 (secundum quid), as "to be white" signifies to be in a way; for
 to be white does not take away being in potency simply, since it
 accrues to a thing that already exists in act. (67)

Besides a thing's substantial act of being, which it has through its substantial form, and the eventual additional acts of being that it acquires through some accidental form, there is no other act of being in the thing. There is no such thing as an act of being that is not constituted according to some form.

Now, Kenny at least is quite clear that Thomas does not think of the esse of creatures as something unqualifiable. (68) Every created being has esse through a form, and its esse can be qualified by a predicate corresponding to its form. But when Thomas speaks of the esse of God, Kenny says, he does indeed seem to introduce an unqualifiable esse. God is esse tantum, esse purum, esse sine additione--ipsum esse. Kenny takes such expressions to mean that God's esse admits no predicate at all. (69) God just is, without being any kind of thing--without form.

Kenny thinks this is absurd. (70) I think he is right. But in my opinion, it is not what Thomas means.

Certainly the argument that God is not in a genus, on account of the identity of his esse with his essence, does not imply that his esse is unqualifiable. (71) It only implies that his esse is not qualified according to some principle distinct from it. It will be an esse that is totally unconditional. Everything in God is identical with his esse. In other words, the argument does not suppose that God's essence is identical with "esse," taken abstractly or by itself. It only supposes the identity of the essence of God with the esse of God--whatever such esse is. Whereas man is other than being man, and knowledge is other than being knowledgeable, God is not other than being God.

This is a crucial point. Kenny in fact grants that if Thomas only means that God is "an" esse itself--not sheer "being itself," but his own being, itself--then he may avoid platonism. (72) What yields platonism is making being itself, taken by itself, a single essence or a single subsistent.

Still, Kenny judges, Thomas at least shows confusion in speaking of God simply as ipsum esse. (73) That God is his own being does not entitle us to say that he is "being itself." Here Kenny introduces some sophisticated considerations from Frege. But as far as Thomas is concerned, it seems to me that we ought to consider something much more elementary. This is that he writes in Latin.

Latin does not have definite and indefinite articles. The one phrase, Socrates est homo, may mean either that Socrates is a man, or that Socrates is the man, or simply that Socrates is man. The context will determine which meaning is intended. So when Thomas writes, Deus est ipsum esse, should we simply take it for granted that he means "God is being itself." Such a translation is already an interpretation--a platonizing one. That God is his esse may well not justify saying that he is "esse itself." But it certainly does justify saying that He is "an" esse itself, "a" very act of being. I think this turns out to be much closer to what Thomas has in mind. (74)

Aside from the grammatical considerations, we should at least take note of the fact that Thomas is very far from denying that God has--or rather is--a form. Earlier in the question on God's simplicity, Thomas says that God is per essentiam suam forma; later in the Summa he says that God maxime est forma simplex. (75) Of course this does not mean that God can be defined. Nor can we grasp his form as it is in itself, in its quiddity. (76) We may grasp the truth that a God exists; but, as Thomas puts it in the Summa contra gentiles, we cannot grasp the esse "by which God subsists in Himself, whose quality--quale sit--is unknown to us, as His essence is." (77) It is clear, however, that the word esse, by itself, does not express what God "consists" in. The esse of God is "qualified" in some way, a way unknown to us. If it is not unknown to God, this is because God does know his essence. According to Thomas, the divine essence is an intelligible form and a species (though of course not a species of a genus); indeed, it is that through which God himself is "specified." (78) And God himself is his own very esse. This is not a formless esse. (79)

God is a subsistent form, identical with his essence. The point of the argument examined above was that if he, or his essence, is also identical with his esse, then he cannot be in a genus. There can be nothing univocal between him and anything else--least of all something called "esse." His esse is wholly proper to him, and everything in him is his proper esse.

At the same time, to be sure, if God is outside all genera, he is also the principle of all genera, and of absolutely everything that in any way is. This follows from the fact that he is his own esse and that there cannot be more than one subsistent that is an esse itself. (80) For
 it therefore results that all things other than God are not their
 esse, but share in esse; and so it is necessary that all things,
 which are diversified according to a diverse participation in
 esse, in such a way that they are more or less perfectly, (81)
 be caused by a first being (ens) which is in a most perfect
 way. (82)

Moreover, if God is the principle, the agent, of all that is, then although there is no genus common to God and the rest, all things must be in some way like him. An agent's effect is always like it. Just insofar as they are beings, Thomas says, creatures are assimilated to God, as to the first and universal principle of esse. (83)

But what we must take care to remember is that if creatures, insofar as they are beings, resemble God, they also differ from him, insofar as they are beings. Being (ens) itself is something diverse in creatures and God. Otherwise it would be like a genus, univocal; and in the final analysis, as Aristotle's arguments show, no being would be really distinct from God.

The likenesses that things have with God, Thomas says in the same place, are never an agreement in something univocal. They constitute neither specific nor even generic unity. They are only "according to some analogy, in the way that esse itself is common to all." As is indicated by this very sequence--species, genus, analogy--Thomas is using the term "analogy" in the Aristotelian sense: a likeness of proportion, a proportionality. (84) It is in this way that we can speak of "the" nature of esse running through all things, as a unit: there is a common proportionality. But analogical community is such that the common feature is itself diverse, intrinsically diverse, in each case. Esse is common to things in such a way that it is also diversified in them. Every esse will be that according to which something is somehow in act, divided somehow from what is in potency. But what being in act consists in is also diverse for each thing. Thomas is saying that in this same way, any characteristic that renders a creature similar to God will also be a characteristic that distinguishes it from him. (85)

And conversely, even the factor that distinguishes the nature of one creature from those of other creatures renders it similar to God. If all things are like God insofar as they are beings, each is also like Him according to what is proper to it, that is, according to its distinctive form. Likeness is "communication in form." Every created form, for instance that of a horse, will have something in common with the divine form. Not something, of course, in its definition; creature and God do not communicate either in species or in genus. "There is not said to be a likeness of the creature to God on account of a communication in form according to the same ratio of genus and species, but only according to an analogy; namely, in the way in which God is a being (ens) essentially, and the others [are beings] by participation." (86) As we saw, for a horse, to be a being means to be a horse; and the horse participates in its being-a-horse in virtue of its form. And thus, if a horse, insofar as it is a being, is like God, then it is also like him insofar as it is a horse.

This brings us to the last point that I wish to highlight it: Thomas's concern to see the very forms of things, and even their differences, as being like God. They are all "contained in His form." This says much, I believe, about Thomas's conception of the nature of being, and about its relation to the nature of God.


The differences of things are in God. In the Summa theologiae, the likeness of all things to God is treated in the third article of the question dedicated to God's perfection, which follows immediately upon the question on the divine simplicity. The identity of essence and esse in God plays an important role in the understanding of his perfection. Thus, in the second article on God's perfection, as though to establish the basis for the third, Thomas seeks to show that all the perfections of things are in God; and the second of the two arguments that he gives turns on the fact that God is esse itself that subsists per se. (87)

The first conclusion that follows from this is that God contains in himself "the whole perfection of esse." To illustrate this, Thomas invites us to imagine a subsistent heat, a pure heat, a heat not received in and conditioned by a subject. Such a heat could not be lacking in any of the perfection--the virtus--of heat. It would be heat at the maximum degree. In the same way, the subsistent esse of God is at the maximum of the perfection, the virtus, of esse. In the words of pseudo-Dionysius, "it precontains (praeaccipit) all esse in itself, in a uniform way (uniformiter)." (88) But if God contains the entire perfection of esse, Thomas continues, then he must contain absolutely all of the perfections in things. For all perfections "pertain to the perfection of esse." Things are perfect just insofar as they have esse in some way.

Now, this last assertion may sound as though esse itself is the only true perfection. But this is not what Thomas means. He also recognizes other perfections, distinct from esse. (89) In a parallel text in the Summa contra gentiles, he gives the example of wisdom. (90) The wisdom of Socrates is not his esse. It is not even his act of being wise. But the wisdom of Socrates is a perfection, because through it, Socrates is wise. His wisdom is a form, according to which his act of being wise is constituted. It "pertains" to his being wise; it is a principle thereof. This is what I wish to stress: if the entire perfection of esse is in God, then, for that very reason, all the various forms of things must also be in him. Every perfection of esse is tied to some form.

In this respect, two of the objections raised in the article are particularly significant. (91) The first is that the perfections of things are many and diverse, whereas God is simple. The second, even stronger, is that the species of things are perfected by their differences, and these are opposites; opposites cannot exist in the same subject. Thomas answers both objections together, very briefly. He does not at all deny that the perfections and differences in things are diverse and even opposed. He simply asserts that items which are diverse and opposed in themselves "preexist" in God as one, without detriment to his simplicity. Thus pseudo-Dionysius likens God to the sun, which precontains all the substances and qualities of sensible things uniformiter, in a single virtus. We might almost call this the thomistic coincidentia oppositorum--though bearing in mind that they are not opposite predicates. Not all perfections are predicable of God, just as not all sensible qualities are predicable of the sun. (92) The many perfections are diverse and opposite effects that preexist in God as in their first cause. He possesses all the power for all perfections, but according to a nature and a "quality" that is proper to him. (93)

The thesis that the differences of things are in God is further developed a little later, in Summa theologiae I, q. 14, a. 6. Here Thomas explains how God knows things other than himself. Everything that God knows, he knows by way of his knowledge of his own nature. He receives no knowledge from outside. For this reason, Thomas tells us, some thinkers held that God only knows other things in a very general way, namely, insofar as they are beings. He would know the nature of being (naturam entis), by knowing himself as principium essendi, the principle of esse. But he would not know the proper natures of things. Thomas rejects this. It would mean a merely confused and general, and so very imperfect, knowledge of things. God must also know each thing in its distinction from the others.

To explain this, Thomas returns to the fact that God contains whatever there is of perfection in creatures. "Not only that in which creatures communicate, namely esse, pertains to perfection; but also the features through which creatures are distinguished from each other, such as life and understanding ... And every form, through which each thing is constituted in its proper species, is a certain perfection." Thomas then explains that God's essence compares to all others as a "perfect act" to the "imperfect acts contained under it." The essence of God possesses "whatever there is of perfection in any other essence, and more besides." To illustrate the idea, Thomas gives the example of how the "sixfold" contains the "threefold."

In this way, through his knowledge of himself, God can know the proper natures of things. For "the proper nature of each thing is constituted according as it shares in some way in the divine perfection. But God would not know Himself perfectly, if He did not know every way in which His perfection can be shared by others." Moreover, Thomas says, "neither would he perfectly know the nature of esse, if He did not know all the modes of esse."

This last affirmation is very striking. The nature of esse cannot be known perfectly unless all its modes are known. These are determined according to the various natures of things. In other words, the natures of things are by no means mere extrinsic receptacles for the "liquid" of esse. Grasping the various natures of things is required for the full understanding of esse itself. We might say: the essences of things are "essential" to esse, indissociable from it. (94) Esse is not diversified by things alien to its own nature--least of all by nonbeings. All the forms of things are perfections, pertaining directly to the perfection of esse.

So we are very far from a conception of esse as something essentially uniform. Even if there is an abstract and common notion of esse, this constitutes only a very imperfect knowledge of it. It only expresses the common proportionality verified in every instance of esse: "the actuality of an essence." The various modes of esse cannot be deduced from it, because the various forms and essences of things cannot be so deduced. (95)


God as the Idea of esse. Now we are in a position to say something about the gravest of the problems raised by Berti, the one regarding the divine transcendence. To recall: according to Aristotle, the nature of esse is not something uniform. It is intrinsically diverse and multiple. Thomas seems to recognize this. But how then can he adopt the assertion of pseudo-Dionysius, according to which a single entity, God, "precontains all esse in himself in a uniform way?" If all esse is contained in a single form or nature, the divine, must not esse itself be understood as something uniform, univocal? And if esse is univocal, then when it is somehow attributed to a creature, will this not amount to attributing the divine nature itself to the creature, in some way?

The answer would be affirmative, I think, if Thomas thought that the divine nature, which is certainly uniform, were simply identical with the nature of esse existing in a separate and subsistent way. But it seems clear that Thomas does not conceive the divine form in this manner. We have just heard him saying that if God did not know the proper natures of things, then he would not know perfectly either himself or the nature of esse. In saying this, Thomas is also distinguishing between the divine nature and the nature of esse.

How can we see that there is a difference between the divine nature (which is identical with the divine esse) and the nature of esse itself?. One consideration that shows this difference particularly clearly, I think, is precisely that the perfection of God contains absolutely all perfections. The perfection of esse itself does not contain all perfections. The forms of things are perfections too, and these are not contained in the perfection of esse. To be sure, they pertain to the perfection of esse; but they remain distinct from it. They are neither reducible to it, nor "derivatives" of it. For they pertain to it, not as effects or results, but as principles. Every esse is constituted according to the principles of an essence. This is why the nature of esse cannot subsist by itself, in separation from the other perfections of things. If God contains all the perfection of esse, he must also contain all other perfections, all forms. And if God contains all perfections, then it is obvious that his own nature cannot be simply identified with any one of them--not even with that of esse.

Likewise, the absolute concept of esse, although somehow embracing the entire perfection of esse, (96) remains distinct from the concepts of other perfections. For this reason, the concept of esse does not succeed in determining the divine nature as it is in itself, that is, according to its quiddity or essence.
 The divine essence is something uncircumscribed, containing in
 itself in a supereminent way whatever can be signified or
 understood by a created intellect. And this cannot in any
 way be represented through a created species, because every
 created form is determined according to some ratio, whether
 of wisdom, or of virtue, or of esse itself, or something of
 this sort. (97)

So in the same way in which the divine form transcends all other forms, it also transcends the nature of esse itself. The entire perfection of esse is inferior to the perfection of God. In other words, esse itself must be related to God as imperfect act to perfect act. The nature of esse is included in the divine nature, as in its cause, but it does not constitute the divine nature. (98)

At the same time, the divine nature is identical with the divine esse. Consequently, not even the divine esse can be identified with the absolute nature of esse. By way of conclusion, I shall try to explain this point a little better.

God contains all the perfection of a horse. This means that He has all the power necessary to produce a horse, as well as to represent it. He is not only its sufficient active principle, but also its perfect exemplar. He is the Idea of a horse. But of course this is an Idea in the thomistic, not platonic, sense. That is, the essence of this Idea--the essence of God--is not the essence of what it is the Idea of--the essence of a horse. If it were, then it could not also contain the perfections of all other things.

But now, Thomas holds that in God there is no distinction between his esse and the other perfections that can be attributed to him. If the nature of God cannot be identified with any particular perfection, neither can it be identified with the mere synthesis of all perfections. For his nature is not a synthesis. It is absolutely simple, even in ratio. Everything in him is his proper esse. This means that his esse itself contains, in its very ratio, not only all the perfection of esse, but also all the other perfections of things. (99) It contains the perfection of life, and of understanding, and of the nature of a horse.

In short, the esse of God is an esse whose nature goes beyond the mere nature of esse. That is, it is certainly an esse, but it is not circumscribed according to the precise ratio of esse, the ratio that distinguishes esse from other perfections. The divine esse includes not only the whole nature of esse, but also all the principles of the nature of esse--all the forms.

Is St. Thomas's God then the Idea of esse? In a sense, yes; but only in the sense in which he is also the Idea of a horse. (100) It is a thomistic Idea, not a platonic Idea. Its essence is not the essence of that of which it is the Idea. If it were, God would not be the Idea of anything whatsoever, because apart from him there could be absolutely nothing.


Pontifical University of the Holy Cross, Rome

Correspondence to: Pontifical University of the Holy Cross; Via dei Farnesi 82, 00186 Rome, Italy.

(1) Revised version of "L'ipsum esse e 'platonismo'?," in Tommaso d'Aquino e l'oggetto della metafisica, ed. S. L. Brock (Rome: Armando, 2004), 193-220.

(2) Anthony Kenny, Aquinas on Being (hereafter "AB") (Oxford: Oxford University Press, 2002), v.

(3) In addition to the works cited in the course of this study, others in which he raises the issue include: Enrico Berti, "Aristotelismo e neoplatonismo nella dottrina tomistica di Dio come ipsum esse," in Enrico Berti, Studi Aristotelici (L'Aquila: Japadre Editore, 1975), 347-52; "Le probleme de la substantialite de l'etre et de l'un dans la Metaphysique, in Etudes sur la Metaphysique d'Aristote, ed. Pierre Aubenque (Paris: Vrin, 1979), 89-129 (French translation of the article cited in n. 6 below); "Il significato del tomismo nel pensiero contemporaneo," Studium 77 (1981): 59-66; "Originarieta dell'idea e ultimita del principio," Giornale di metafisica 7 (1985): 381-97; "Uberwindung della metafisica?," in La metafisica e il problema del suo superamento (Padova: Libreria Gregoriana Editrice, 1985), 9-43, esp. 18-29; "Brentano and Aristotle's Metaphysics," in Whose Aristotle? Whose Aristotelianism?, ed. Robert W. Sharples (Aldershot: Ashgate, 2001), 135-49.

(4) I am aware of only two responses: Antonino Poppi, "Sul problema della sostanzializzazione dell'ente e dell'uno in san Tommaso d'Aquino," in Antonino Poppi, Classicita del pensiero medievale: Anselmo, Bonaventura, Tommaso, Duns Scoto alla prova dell'elenchos (Milano: Vitae pensiero, 1988), 121-49; and Joseph Moreau, "La tradizione aristotelica e l'analogia entis," in Metafore dell'invisibile: Ricerche sull'analogia, ed. G. Santinello (Brescia: Morcelliana, 1984), 93-6. In my opinion these do not address the real core of Berti's criticism, which is that Thomas seems to treat being as a single essence.

(5) Aristotle, Metaphysics 3.4.1001a4-33.See also 3.1.996a4-9; 11.2.1060a36-b6.

(6) See Metaphysics On [TEXT NOT REPRODUCIBLE IN ASCII.], see Enrico Berti, "Il problema della sostanzialita dell'essere e dell'uno nella Metafisica di Aristotele" (hereafter "PS"), in Enrico Berti, Studi Aristotelici (L'Aquila: Japadre Editore, 1975), 183-4. For the most part I shall leave aside the question of the one, since the issue is Thomas's doctrine of being.

(7) See Metaphysics 7.13-16.1038b1-41a5.

(8) Metaphysics 3.3.998b20-27; see 3.4.1001a27-b1. If the genus were predicable of the differentiae, then the name of the genus would appear more than once in the definition of the species, and the differentiae themselves would be either species or individuals; see Aristotle, Topics 6.6.144a36-b3.

(9) "In sum, being is not a genus because, besides expressing what there is that is common to all beings, it also expresses what there is that is diverse, that is, their differences"; Enrico Berti, "L'analogia dell'essere nella tradizione aristotelico-tomistica" (hereafter "AE"), in Metafore dell'invisibile: Ricerche sull'analogia, ed. G. Santinello (Brescia: Morcelliana, 1984), 30 (my translation).

(10) "Being (L'ente) itself, in fact, is a substance having as its essence to be (l'essere) itself; in this way to be is a determinate essence, a single essence, namely the essence of this substance, not a multiplicity of essences. Now, since that which is signified by a term is the essence, if the term 'to be' signifies one sole essence, it must have a single signification. But then everything that is not a being by its essence is a nonbeing"; Berti, PS, 188 (my translation).

(11) In Plato's case, this would be the "Indefinite Dyad." See Enrico Berti, "Multiplicity and Unity of Being in Aristotle" (hereafter "MU"), Proceedings of the Aristotelian Society 101 (2001): 206. Berti refers to Metaphysics 14.2.1089a1-6. We might note that immediately after this passage, Aristotle remarks that being has many senses (1089a7). He seems to be explaining why there is no need to appeal to nonbeing.

(12) Metaphysics 4.2.1003b22-33.

(13) "Consequently being and one ought not to be thought of initially as unitary, and subsequently divided into a plurality of genera. For the same reason, there cannot be a genus, much less a single being, which is nothing but one or being, that is, which realizes in itself the essence of one and being; but there is always just a multiplicity of genera or of beings"; Berti, PS, 190.

(14) See Metaphysics 10.2.1053b9-21. Aristotle compares "being" with terms like "element" and "principle": these do not signify the essence of that which is an element or a principle, but rather we still ask what the element or the principle is: Metaphysics 7.16.1040b16-19.

(15) See Enrico Berti, "L'analogia in Aristotele--interpretazioni recenti e possibili sviluppi" (hereafter "AA"), in Origini e sviluppi dell'analogia. Da Parmenide a S. Tommaso, ed. Giuseppe Casetta (Roma: Edizioni Vallombrosa, 1987), 113.

(16) To cite just one of the many places where he mentions it: "Omne genus differentiis aliquibus diuiditur. Ipsius autem esse non est accipere aliquas differentias; differentie enim non participant genus nisi per accidens, in quantum species constitute per differentias genus participant. Non potest autem esse aliqua differentia que non participat esse, quia non ens nullius est differentia"; Thomas Aquinas, Compendium theologiae (hereafter "CT"), pt 1, ch. 13, in Sancti Thomae Aquinatis doctoris angelici Opera omnia iussu Leonis XIII P.M. edita, vol. 42, cura et studio fratrum praedicatorum (Rome: Commissio Leonina, 1882--), 86. Unless otherwise indicated, all references for works of Thomas are to the Leonine edition.

(17) See Thomas Aquinas, Expositio Peryermeneias (hereafter, "EP") bk. 1, lect. 5 (Leonine ed. 1*1, p. 30, ll. 314-30).

(18) He is explicit about the fact that just as unum and ens cannot be genera, neither can they be a subsistent substance: Thomas Aquinas, In duodecim libros metaphysicorum Aristotelis expositio (hereafter "CM"), ed. Marie-Raymond Cathala and Raymond M. Spiazzi (Turin: Marietti, 1950), bk. 10, lect. 3, [section] 1966.

(19) "Indeed Aristotle could not allow that beings 'participate' in being, understood as an essence diverse from that which is proper to them and as existing by itself, because being for him is not an essence that something can participate in or that can exist by itself, but it is originally a multiplicity of essences existing in diverse ways, each [way of existing] cognate with each [essence]. This is what he means to say, when he affirms that being and one, although each has a diverse signification vis-a-vis the other, add nothing to the signification of what they accompany, such that to say 'man' or 'one man' or 'existing man' is the same"; Berti, PS, 191. See also Berti, AE, 32.

(20) Berti finds proportionality in Aristotle's notion of being, although it is never stated explicitly, "for it is applied to the ontological principles of all beings (the three elements and the four causes) [Metaphysics 13.4.1070a31-32], to their logical principles (non-contradiction and excluded middle) [An. post. 1.10.76a39], to their fundamental opposition (potency and act) [Metaphysics 9.6.1048a37], to the categories of being [Metaphysics 14.6.1093b17-21] and of the good [Eth. Nic. 1.4.1096628]"; Berti, AE, 25. Perhaps we can also add Metaphysics 7.16.1040b16-19; see above, n. 14.

(21) Thomas's general doctrine of analogy is another part of the issue. Berti also finds "platonism" in the so-called analogy of attribution (see especially Berti, AE and AA). This question exceeds the scope of this paper, but below (at n. 84) I offer a few observations in support of the view that Thomas understands the common "nature" of esse as a proportionality. In relation to Berti's criticism, I think a full defense of Thomas's conception of the analogy of being would require showing that this very proportionality can be verified in diverse and ordered ways, secundum magis et minus or per prius et posterius. I mean, not only the things of which the proportionality is predicated, but also the truth of the proportionality itself, must admit such an order.

(22) Kenny, AB, 123. Similarly, "It is almost as if esse were a vast expanse of liquid, portions of which take the shape of the receptacle into which they are poured, so that some esse comes out elephant-shaped, and other esse comes out gadfly-shaped"; Kenny, AB, 72.

(23) Berti speaks of the "scholastic doctrine of God as a being whose essence is constituted by being itself"; Berti, PS, 186, n. 24. Further on I shall suggest that this is not exactly Thomas's teaching.

(24) In this sense being is like what Berti says about unity. "Undoubtedly the principle posited by Aristotle, namely the pure act, is also one, as we have seen, and in this respect it presents affinities with the principle posited by Plato; but what Aristotle now wants to show is that it is not enough to qualify it as one, since unity is not its essence, but it is necessary to say which one it is, or in other words, it is necessary to specify its essence by means of some determination that characterizes it in an exclusive way"; Berti, PS, 201. On the transcendence of God, see also Berti, AE, 32-3.

(25) Berti wonders whether the very idea of "grades" of esse does not imply a univocal notion: "In fact, where there are grades, there seems to be a common essence, participated, precisely, in diverse grades, since difference in grade, rather than being a difference of quality, or in other words of essence, seems to be a difference of quantity. But if there is a single essence, participated in diverse grades, then being has an essence, and so it is univocal, no longer analogical"; Berti, AE, 21. Berti holds that for Aristotle, "when the discussion applies to heterogeneous realities, the adverb mallon [more] does not indicate a more intense grade of the same essence, but rather an essence that possesses the common predicate in a primary way (proteron, in the sense of ontological antecedence, not just chronological)"; Berti, PS, 203, n. 112. He refers to Metaphysics 2.1.

(26) Kenny, AB, 113 and 121. We might also note that so understood, Thomas would be perfectly in line with the neoplatonic commentary on Plato's Parmenides that Pierre Hadot attributes to Porphyry; Pierre Hadot, Porphyre et Victorinus, 2 vol. (Paris: Etudes Augustiniennes, 1968). In this work, the nature of "to be" ([TEXT NOT REPRODUCIBLE IN ASCII.]) is conceived as an actuality distinct from form (ibid., 1:489-90); and the first principle, the One, is presented as a pure "to be," above all form, and even as the Idea itself of "to be" (ibid., 1:132; 2:107). Hadot sees a clear influence of this doctrine in the De hebdomadibus of Boethius, through which it would have passed on to the Middle Ages and Thomas (ibid., 1:490-2). See also David Bradshaw, "Neoplatonic Origins of the Act of Being," The Review of Metaphysics 53 (1999): 383-401.

(27) "Plato conceived being as having only one meaning because he conceived it as a genus, that is to say as an universal predicate expressing only what is common to all things, i.e. only a single aspect of things. This was, in fact, the condition for conceiving it as a separate Form, i.e. Idea. And this was also the condition for conceiving being and one as the essence of a substance, i.e. being itself (ipsum esse subsistens) and one itself (ipsum unum subsistens). In conclusion, if primary substance is the essence of being, being must be understood univocally. If being has an essence, it is this essence. It cannot be many essences. But this is impossible; because we see many things, and their differences are existing and each of them is one. This is the core of Aristotle's criticism of Plato as it is expounded in Metaph. B 4. This criticism ultimately rests on the argument offered in Metaph. B 3, and the view that Being and One cannot be genera"; Berti, MU, 207.

(28) Berti, AE, 30-1.

(29) "Sciendum est enim quod hoc nomen homo, imponitur a quidditate, sive a natura hominis; et hoc nomen res imponitur a quidditate tantum; hoc vero nomen ens, imponitur ab actu essendi: et hoc nomen unum, ab ordine vel indivisione"; CM, bk. 4, lect. 2, [section] 553.

(30) On this see Ralph McInerny, "Do Aristotelian Substances Exist?," Sapientia 54 (1999): 325-38.

(31) "Esse enim rei quamvis sit aliud ab eius essentia, non tamen est intelligendum quod sit aliquod superadditum ad modum accidentis, sed quasi constituitur per principia essentiae. Et ideo hoc nomen ens quod imponitur ab ipso esse, significat idem cum nomine quod imponitur ab ipsa essentia"; CM, bk. 4, lect. 2, [section] 558. Translations of Thomas throughout this paper are mine.

(32) Kenny, AB, 175.

(33) "Esse non dicitur accidens quod sit in genere accidentis, si loquamur de esse substantiae--est enim actus essentiae--sed per quamdam similitudinem: quia non est pars essentiae, sicut nec accidens"; Thomas Aquinas, Quaestiones disputatae de potentia dei (hereafter, "DP"), in S. Thomae Aquinatis Quaestiones disputatae, vol. 2, ed. M. Pession (Turin: Marietti, 1954), q. 5, a. 4, ad 3.

(34) See, for example, Thomas Aquinas, Scriptum super libros Sententiarum (hereafter, "In Sent."), ed. P. Mandonnet and M. Moos (Paris: Lethielleux, 1929-37), bk. 1, d. 4, q. 1, a. 1, ad 2; d. 19, q. 5, a. 1, obj. 1; d. 33, q. 1, a. 1, ad 1; d. 37, q. 1, a. 2; Quaestiones disputatae De veritate (hereafter "DV"), q. 10, a. 1, obj. 3 (Leonine ed., vol. 22); Quaestio disputata De spiritualibus creaturis (hereafter, "DSC"), in S. Thomae Aquinatis Quaestiones disputatae, vol. 2, ed. M. Calcaterra and T. S. Centi (Turin: Marietti, 1954), q. un., a. 11; Summa theologiae (hereafter "STh"), I, q. 54, a. 1; EP, bk. 1, lect. 5 (Leonine ed., vol. 1*1.31, ll. 397-403). See also DP, q. 9, a. 5, ad 19.

(35) "Actio enim est proprie actualitas virtutis; sicut esse est actualitas substantiae vel essentiae"; STh I, q. 54, a. 1. Similarly: "sicut autem ipsum esse est actualitas quaedam essentiae, ita operari est actualitas operativae potentiae seu virtutis"; DSC, q. un., a. 11.

(36) On this point see CM, bk. 8, lect. 2, [section] 1697; STh I, q. 76, a. 3, ad 4.

(37) "Tertio, quia omnia quae sunt in genere uno, communicant in quidditate vel essentia generis, quod praedicatur de eis in eo quod quid est. Differunt autem secundum esse, non enim idem est esse hominis et equi, nec huius hominis et illius hominis. Et sic oportet quod quaecumque sunt in genere, differant in eis esse et quod quid est, idest essentia. Unde manifestum est quod deus non est in genere sicut species. Et ex hoc patet quod non habet genus, neque differentias; neque est definitio ipsius"; STh I, q. 3, a. 5.

(38) STh I, q. 50, a. 2, ad 1; I, q. 50, a. 4, c. and ad 1. Thomas is clear about the fact that angels have true differentiae, even though we cannot reach a proper understanding of them: see Thomas Aquinas, De ente et essentia (hereafter, "DEE"), ch. 5 (Leonine ed., vol. 43, p. 379, ll. 72-6).

(39) STh I, q. 54, a. 2, ad 2; see I, q. 7, a. 2.

(40) "Esse autem cuiuslibet creaturae est determinatum ad unum secundum genus et speciem"; STh I, q. 54, a. 2.

(41) The related passages are DEE, ch. 5 (Leonine ed., vol. 43, 378, ll. 7-14, quoted below, n. 42); In Sent., bk. 1, d. 8, q. 4, a. 2, s.c. 2; In Sent., bk. 1, d. 35, q. 1, a. 4; DV, q. 2, a. 11 (quoted below, n. 50); DV q. 27, a. 1, ad 8; DP, q. 7, a. 3; Summa contra gentiles (hereafter, "SCG"), bk. 1, ch. 25 ("Item. Quiequid est ..."); CT, p. 1, ch. 14. A helpful survey of the various texts, under the heading of "The 'Genus' Argument," is found in John F. Wippel, The Metaphysical Thought of Thomas Aquinas. From Finite Being to Uncreated Being (hereafter, "MTTA"), Monographs of the Society for Medieval and Renaissance Philosophy 1 (Washington, D.C.: The Catholic University of America Press, 2000), 157-61.

(42) For example: "essentia sua [scil. Dei] non est aliud quam esse eius. Et ex hoc sequitur quod ipse non sit in genere; quia omne quod est in genere oportet quod habeat quiditatem preter esse suum, cum quiditas uel natura generis aut speciei non distinguatur secundum rationem nature in illis, quorum est genus uel species, sed esse est diuersum in diuersis"; DEE, ch. 5 (Leonine ed., vol. 43, p. 378, ll. 7-14).

(43) Kenny does not seem to have grasped this. Speaking of DP, q. 7, a. 3, he says: "everything shares the thin and universal predicate [esse]--it is the very same predicate that is true of each and every item--but ... each thing has its very own individual instance of that predicate. In the same way, if two peas are as alike as two peas can be, they will share the very same shade of green, but nonetheless the greenness of the pea on the right of my plate is a different entity from the greenness of the pea on the left of my plate"; Kenny, AB, 122. For Thomas, what Kenny says about greenness would be correct; but Thomas is maintaining precisely that esse is not like greenness in this respect. Esse is not the very same predicate--it is not the same in signification or ratio--in any two cases. The ratio of esse is diverse in diverse things.

(44) Thus in SCG, bk. 1, ch. 25 ("Item. Quicquid est ..."), he gives this simple reason why things in a genus must differ secundum esse: "alias genus de pluribus non praedicaretur."

(45) This is in fact how Thomas glosses the De potentia version of the argument: "nihil ponitur in genere secundum esse suum, sed ratione quidditatis suae; quod ex hoc patet, quia esse uniuscuiusque est ei proprium, et distinctum ab esse cuiuslibet alterius rei; sed ratio substantiae potest esse communis: propter hoc etiam Philosophus dicit, quod ens non est genus. Deus autem est ipsum suum esse: unde non potest esse in genere"; DP, q. 7, a. 3 (see also In Sent., bk. 1, d. 35, q. 1, a. 4, c.).

(46) "Esse enim hominis terminatum est ad hominis speciem, quia est receptum in natura speciei humanae; et simile est de esse equi, vel cuiuslibet creaturae"; DP, q. 1, a. 2.

(47) Thomas says that this is how we distinguish between one esse and another: by identifying the distinct natures that they are the esse of. ("Life," for example, means the esse of something that is of such a nature as to move itself.) See DP, q. 7, a. 2, ad 9. This does not mean that there is not an intrinsic diversity between one esse and another; rather, we get at the intrinsic diversity through the diversity in their proper subjects. As he explains in the same place, it is in a similar way that we distinguish the forms of different kinds of things: by identifying the matter proper to each (as soul is defined as the act of a physical organic body). Clearly the forms of different kinds of things are intrinsically diverse.

(48) Metaphysics 7.12.1037b8-38a35; 8.6.1045a8-b24.

(49) "Impossibile est enim aliquid esse in actu nisi omnibus existentibus quibus esse substantiale designatur: non enim potest esse animal in actu quin sit animal rationale vel irrationale"; SCG, bk. 1, ch. 24. More succinctly: "Ex genere enim habetur quid est res, non autem rem esse; nam per differentias specificas constituitur res in proprio esse"; CT, pt. 1, ch. 13.

(50) "Illa enim quae secundum eamdem rationem sunt in diversis, sunt eis communia secundum rationem substantiae sive quidditatis, sed sunt discreta secundum esse. Quidquid autem est in Deo, hoc est suum proprium esse; sicut enim essentia in eo est idem quod esse, ira scientia est idem quod esse scientem in eo; unde, cum esse quod est proprium unius rei non possit alteri communicari, impossibile est ut creatura pertingat ad eamdem rationem habendi aliquid quod habet Deus, sicut impossibile est quod ad idem esse perveniat. Similiter etiam esset in nobis: si enim in Socrate non differret homo et hominem esse, impossibile esset quod homo univoce diceretur de eo et Platone, quibus est esse diversum"; DV, q. 2, a. 11. 51 See above, n. 40.

(52) For similar reasons, the esse of an individual belonging to a common species cannot be identified with its "principle of individuation." Although the esse of one individual is intrinsically diverse from that of others, this diversity presupposes and results from diversity in the constitution of the esse's subject, that is, diversity either in form or at least in matter. For simplicity's sake I concentrate here on the diversity of esse in things of a common genus that differ in species, but the discussion would apply, mutatis mutandis, to distinct individuals of a common species. On Thomas's not regarding esse as the principle of individuation in creatures, see Lawrence Dewan, "The Individual as a Mode of Being According to Thomas Aquinas," The Thomist 63 (1999): 403-24.

(53) See STh I, q. 50, a. 2, ad 3.

(54) See DEE, ch. 2 (Leonine ed., vol. 43, p. 373, ll. 223-36); STh I, q. 76, a. 3, c. & ad 4; a. 4; a. 6, ad 1; DSC, q. un., a. 1, ad 24; Thomas Aquinas, De substantiis separatis (hereafter "DSS"), ch. 5 (Leonine ed., vol. 40, p. D-50, ll. 88-124). It is true that in things composed of matter and form, there is a certain correspondence between genus and matter, and between differentia and form; but the correspondence is not a strict identity. On this see DEE, ch. 2 (Leonine ed., vol. 43, p. 372, ll. 135-207); In Sent., bk. 2, d. 3, q. 1, a. 5; CM, bk. 10, lect. 10, [section] 2115-16.

(55) See DEE, ch. 2 (Leonine ed., vol. 43, p. 371, ll. 96-104); CM, bk. 8, lect. 2, [section] 1697; CM, bk. 10, lect. 10, [section] 2114.

(56) See DEE, ch. 2 (Leonine ed., vol. 43, p. 372, ll. 207-17).

(57) See STh I, q. 87, a. 1 (near the end of the corpus).

(58) See STh I, 13, a. 1; a. 2, ad 1 and ad 3; a. 4.

(59) On genus and differentia as indeterminate and determining, see DEE, ch. 2 (Leonine ed., vol. 43, p. 373, ll. 233-42); STh I, q. 50, a. 2, ad 1.

(60) A sign that being an animal and being rational are not related as genus and differentia is that they have an element in common: "being." Yet they do not express two distinct acts of being, as being a man and being white do. Both signify a man's one substantial act of being.

(61) As discussed above (p. 285), it is not that things differ according to esse in the same way that they differ according to their ... differentiae. Man's act of being rational, and a horse's act of being whatever the differentia of a horse is, are both acts of being an animal. Only, what being an animal signifies in the two cases is not entirely the same. Yet there is an analogy between them, such as to allow for the same expression. By contrast, the horse's differentia cannot be termed "rational" even by analogy. The horse is not rational. However, even between man's act of being rational and a horse's act of being whatever the differentia of a horse is, there is still some analogy, according to which both are called acts of being.

(62) In the judgment of John Wippel, if Thomas's argument does not involve a petitio principii--that is, if it does not presuppose a real distinction between esse and essence in things that are in a genus or a species--then "as it first appears in the argument, esse may signify nothing more than a particular actually existing member of a generic or specific class, that is, a particular concrete existent"; Wippel, MTTA, 161. Yet "Thomas himself would not allow for real distinction between a universal intelligible content and a particular instantiation of the same" (ibid.). But on the interpretation that I am proposing, what esse initially signifies in the argument is simply the actuality of a thing's essence. A certain property of it is then isolated, namely, that its ratio contains nothing univocally common. From this it is concluded that in a thing belonging to a genus, esse and essence cannot be identical, since the ratio of the essence does contain something univocally common. That the concrete existent cannot be identical with its esse would follow by the same reasoning. As for the "real distinction," the argument does seem to assume that both essence and esse are real. Neither is a negation or a relation of reason; each is a perfection of the thing. Does the argument show that they are distinct perfections? Might they be one simple perfection, considered merely according to distinct rationes, like genus and differentia in an angel? Certainly the argument shows that the ratio of the essence is neither identical with nor part of the ratio of the esse. What I am suggesting is that it also assumes, as basis for the premise of the diversity of esse in diverse things, that the ratio of a thing's esse is determinate, and that it is a function of the determinate ratio of the thing's essence. This means that the ratio of the esse is not part of the ratio of the essence, and that they are not related as indeterminate and determining. The overall result, I believe, is that they cannot be rationes of the same perfection.

(63) Esse is "maxime formale": STh I, q. 7, a. 1.

(64) Kenny, AB, 59.

(65) "Cum ens dicat aliquid proprie esse in actu, actus autem proprie ordinem habeat ad potentiam; secundum hoc simpliciter aliquid dicitur ens, secundum quod primo discernitur ab eo quod est in potentia tantum. Hoc autern est esse substantiale rei uniuscuiusque; unde per suum esse substantiale dicitur unumquodque ens simpliciter"; STh I, q. 5, a. 1, ad 1. As Thomas indicates a few pages later, the substantial esse of a thing is nothing other than the esse that it has in virtue of its substantial form: "Prima perfectio ignis consistit in esse quod habet per suam formam substantialem"; STh I, q. 6, a. 3.

(66) Thus Thomas both distinguishes and connects the "existential" and copulative senses of the verb "est"; see EP, bk. 1, lect. 5 (Leonine ed., vol. I*1, p. 31, ll. 382-407).

(67) "Per actus autem superadditos, dicitur aliquid esse secundum quid, sicut esse album significat esse secundum quid; non enim esse album aufert esse in potentia simpliciter, cum adveniat rei iam praeexistenti in actu"; STh I, q. 5, a. 1, ad 1.

(68) See Kenny, AB, 151-2.

(69) "There is one type of being where no predicate can be attached, where something just is, full stop. This type of being is unique to God"; Kenny, AB, 191.

(70) See Kenny, AB, 110-12.

(71) Clearly his esse is not a "substantial" esse, in the sense of the esse of something in the genus of substance; and even less is it an "additional" esse. "Quidquid autem creatura perfectionis habet ex essentialibus principiis et accidentalibus simul coniunctis, hoc totum deus habet per unum suum esse simplex"; DV, q. 21, a. 5. (See also STh I-II, q. 18, a. 1.) "Substantial" signifies a particular mode of esse. But rather than to say that God has no mode of esse (cf. Kenny, AB, 112), Thomas says that he has a universal mode: "Ea quae a primo ente esse participant, non participant esse secundum universalem modum essendi, secundum quod est in primo principio, sed particulariter secundum quendam determinatum essendi modum qui convenit vel huic generi vel huic speciei"; DSS, ch. 8 (Leonine ed., vol. 40, p. D-50, ll. 199-204). On what this means, compare with the text quoted below, n. 89.

(72) Kenny, AB, 145-7. He quotes Peter Geach: "When Aquinas tells us that God is wisdom itself, Deus est ipsa sapientia, he is not meaning that God is that of which the noun 'wisdom' is a proper name; for the Platonists are wrong in thinking that there is such an object, and Aquinas says they are wrong. But we can take it to mean that 'God' and 'the wisdom of God' are two names of the same thing"; Peter Geach, "Form and Existence," in Aquinas: A Collection of Critical Essays, ed. Anthony Kenny (London: Macmillan, 1969), 39.

(73) Kenny, AB, 146.

(74) It may help to note that Thomas employs a very similar expression, "ipsa forma subsistens," to describe an angel: "Subtracta ergo materia, et posito quod ipsa forma subsistat non in materia, adhuc remanet comparatio formae ad ipsum esse ut potentiae ad actum. Et talis compositio intelligenda est in angelis. Et hoc est quod a quibusdam dicitur, quod angelus est compositus ex quo est et quod est, vel ex esse et quod est, ut Boetius dicit, nam quod est est ipsa forma subsistens; ipsum autem esse est quo substantia est, sicut cursus est quo currens currit"; STh I, q. 50, a. 2, ad 3. And a little later: "cum angelus sit ipsa forma subsistens, ut ex dictis patet, impossibile est quod eius substantia sit corruptibilis ... Sed si ipsa forma subsistat in suo esse, sicut est in angelis, ut dictum est, non potest amittere esse"; STh I, q. 50, a. 5. Obviously Thomas does not mean that an angel is "form itself" subsisting, as though the nature of the angel were nothing other than the absolute nature of "form." An angel is a form itself, subsisting; indeed, one among many. The created subsistent forms constitute a genus. Thus Thomas also says that an angel is "a certain" subsistent form: "[A]ngelus autem, cum sit immaterialis, est quaedam forma subsistens, et per hoc intelligibilis actu"; STh I, q. 56, a. 1. Naturally God is not "a certain" subsistent esse, one among many. There can only be one. So we can say that he is "the" subsistent esse itself. But there is no warrant for saying that he is simply esse itself, subsisting.

(75) STh I, q. 3, a. 2; STh I, q. 13, a. 12, obj. 2. The divine form is called deitas: STh I, q. 3, a. 3.

(76) This is because we can know God to the extent that his creatures represent him, and "quaelibet creatura intantum eum repraesentat, et est ei similis, inquantum perfectionem aliquam habet, non tamen ita quod repraesentet eum sicut aliquid eiusdem speciei vel generis, sed sicut excellens principium, a cuius forma effectus deficiunt, cuius tamen aliqualem similitudinem effectus consequuntur"; STh I, q. 13, a. 2 (emphasis added).

(77) SCG, bk. 1, ch. 12.

(78) "Per illam formam intelligibilem specificatur intellectualis operatio, quae facit intellectum in actu. Et haec est species principalis intellecti, quae in Deo nihil est aliud quam essentia sua, in qua omnes species rerum comprehenduntur. Unde non oportet quod ipsum intelligere divinum, vel potius ipse Deus, specificetur per aliud quam per essentiam suam"; STh I, q. 14, a. 5, ad 3. See also STh I, q. 14, a. 4.

(79) There is no need to interpret esse sine additione as esse sine forma. It signifies an esse to which nothing is added. What is "added" is always distinct from what it is added to. The esse of God would be an esse that is identical with its form. Nor is this a purely equivocal use of the term "form"; the term still retains something of the meaning of "formal cause." Agent and material causes, Thomas says, are always distinct from what they are causes of, but a thing can be its own form, "as is clear in the case of all immaterial things"; STh I, q. 39, a. 2, ad 5. He is speaking of the expression "three persons of one essence," as referred to the Blessed Trinity. In this expression, he says, "essence" is signified in the role of a form, in habitudine formae.

(80) On there not being more than one, see STh I, q. 11, a. 3, c. (the second argument), together with I, q. 4, a. 2.

(81) Space prevents considering how Thomas conceives the "grades" of esse, but we may at least note that he is alert to the question whether "more or less" does not imply univocity (see above, n. 25). For example: "[M]agis et minus nunquam univocationem auferunt; sed ea ex quibus magis et minus causatur, possunt differentiam speciei facere, et univocationem auferre: et hoc contingit quando magis et minus causantur non ex diversa participatione unius naturae, sed ex gradu diversarum naturarum; sicut angelus est homine intellectualior"; In Sent., bk. 1, d. 35, q. 1, a. 4, ad 3. Again: "[M]agis et minus, secundum quod causantur ex intensione et remissione unius formae, non diversificant speciem. Sed secundum quod causantur ex formis diversorum graduum, sic diversificant speciem, sicut si dicamus quod ignis est perfectior aere"; STh I, q. 50, a. 4, ad 2.

(82) "Relinquitur ergo quod omnia alia a Deo non sint suum esse, sed participant esse. Necesse est igitur onmia, quae diversificantur secundum diversam participationem essendi, ut sint perfectius vel minus perfecte, causari ab uno primo ente, quod perfectissime est"; STh I, q. 44, a. 1. In this article Thomas does not specify that God is "his" esse. However, he does specify that other things are not "their" esse. And in other places where he employs the same sort of argument, his premise is explicitly that God is "his" esse. See STh I, q. 61, a. 1; DV, q. 21, a. 5; SCG, bk. 2, ch. 15 ("Item. Quod per essentiam ..."); CT, pt. 1, ch. 15; Quaestiones de quodlibet 3, q. 8, a. un.; DSS, ch. 9 (Leonine ed., vol. 40, p. D-50, ll. 102-18).

(83) STh I, q. 4, a. 3.

(84) See Metaphysics 5.6.1016b31-1017a3; cf. 5.9.1018a13.

(85) See STh I, q. 4, a. 3, ad 1.

(86) "Non dicitur esse similitudo creaturae ad Deum propter communicantiara in forma secundum eandem rationem generis et speciei, sed secundum analogiam tantum; prout scilicet Deus est ens per essentiam, et alia per participationem"; STh I, q. 4, a. 3, ad 3. I would suggest that the analogy here, the proportionality, resides in the fact that both in God and in other things, there is something "through which" they are beings. (It is important that "a being" is said properly both of God and of creatures: see STh I, q. 44, a. 1, ad 1.) This is an "agreement in form," because all of them are beings, precisely, through their forms. (See STh I, q. 5, a. 4: "... ipsa forma, per quam est ens.") God is a being because his form is his esse; the others are beings because, in virtue of their forms, they participate in their esse. (Here it is crucial not to confuse "per participationem" with "per accidens." We have already seen that for Thomas, things are beings, not per accidens, but through the principles of their essences.) This would also be a case in which the common proportionality is verified, not equally, but per prius et posterius (see above, n. 21). The priority is that of a model in relation to its imitations. In creatures, there exists a strong affinity between their forms and their esse--they have their esse through their forms; this affinity resembles, without equaling, the perfect identity that obtains between form and esse in God.

(87) In this text Thomas says simply, "Deus est ipsum esse per se subsistens." I speak of "an" esse itself, in line with the foregoing considerations. That this is acceptable is indicated by the version of the same argument given in SCG, bk. 1, ch. 28: "... Sed rei quae est suum esse ..."

(88) With the quotation from ps.-Dionysius, it is clear that Thomas recognizes the platonic background for the notion of a perfection that is found both in a received or participated mode, in which its perfection is limited, and in a subsistent mode, in which it is maximally perfect; see also DP, q. 6, a. 6. However, this by itself does not make him guilty of platonism, in the sense criticized by Berti and Kenny. That involves treating the perfection, taken absolutely, as constitutive of the thing in which it is found subsisting, in such a way that the thing's essence would be determined according to the ratio of that perfection. See below, VII.

(89) Thus see DP, q. 6, a. 6: "cum esse et reliquae perfectiones etformae inveniantur in corporibus quasi particulariter, per hoc quod sunt in materia receptae, oportet praeexistere aliquam substantiam incorpoream, quae non particulariter, sed cum quadam universali plenitudine perfectionem essendi in se habeat" (emphasis added).

(90) SCG, bk. 1, ch. 28 ("Omnis enim nobilitas ...").

(91) STh I, q. 4, a. 2, obj. 1 and 2.

(92) Thomas in fact holds that created species, although existing in God in a "higher" way than they exist in the creatures themselves, belong "more truly" to the creatures: STh I, q. 18, a. 4, ad 3. For example, God is the idea, the productive exemplar, of horses, and this idea is is a more perfect being than a physical and material horse; but a "true" horse, that which "is a horse" in the proper sense, is a physical one.

(93) In De ente et essentia he explains it thus: "[Deus], quamuis sit esse tantum, non oportet quod deficiant ei relique perfectiones et nobilitates. Immo habet omnes perfectiones que sunt in omnibus generibus ...; sed habet eas modo excellentiori omnibus rebus, quia in eo unum sunt, sed in aliis diuersitatem habent. Et hoc est, quia omnes ille perfectiones conueniunt sibi secundum esse suum simplex; sicut si aliquis per unam qualitatem posset efficere operationes omnium qualitatum, in illa una qualitate omnes qualitates haberet, ita Deus in ipso esse suo omnes perfectiones habet"; DEE, ch. 5 (Leonine ed., vol. 43, p. 378, ll. 30-43).

(94) "Ens alio modo se habet ad ea quae sub ente continentur, et alio modo animal vel quodlibet aliud genus ad species suas. Species enim addit supra genus, ut homo supra animal, differentiam aliquam quae est extra essentiam generis. Animal enim nominat tantum naturam sensibilem, in qua rationale non continetur; sed ea quae continentur sub ente, non addunt aliquid supra ens quod sit extra essentiam eius; unde non oportet quod illud quod est causa animalis in quantum est animal, sit cansa rationalis in quantum huiusmodi. Oportet autem illud quod est causa entis in quantum est ens, esse causam omnium differentiarum entis"; DP, q. 3, a. 16, ad 4.

(95) "Ratio enim entis, cum sit diversificata in diversis, non est sufficiens ad specialem rerum cognitionem"; In Sent., bk. 1, Prologus, q. 1, a. 2.

(96) See STh I-II, q. 2, a. 5, ad 2.

(97) "Divina essentia est aliquod incircumscriptum, continens in se supereminenter quidquid potest significari vel intelligi ab intellectu creato. Et hoc nullo modo per aliquam speciem creatam repraesentari potest, quia omnis forma creata est determinata secundum aliquam rationem, vel sapientiae, vel virtutis, vel ipsius esse, vel aliquid huiusmodi"; STh I, q. 12, a. 2 (emphasis added). "Does Ipsum esse subsistens name God Via a concept that is so representationally rich that it expresses the totality of all perfections? Obviously not. If it did (a) we would be enjoying the beatific Vision, and (b) one divine name would suffice"; Ralph McInerny, "Esse ut Actus Intensivus," in Being and Predication, Studies in Philosophy and the History of Philosophy, vol. 16 (Washington, D.C.: The Catholic University of America Press, 1986), 234.

(98) Recently, in a very interesting article, Franco Ferrari has sought to show that in the Republic, "the relation that binds the idea of the good to being is not pushed to the point of a true and proper identification, since the [TEXT NOT REPRODUCIBLE IN ASCII.] is not being in itself (Esse ipsum subsistens), but possesses [TEXT NOT REPRODUCIBLE IN ASCII.] this characteristic insofar as it is cause thereof"; Franco Ferrari, "La causalita del bene nella Repubblica di Platone," Elenchos 22.1 (2001): 37 (my translation). What I am suggesting here is that notwithstanding his use of the expression "ipsum esse subsistens," neither does Thomas make a true and proper identification of God with "esse itself."

(99) This is the explanation that Thomas gives of the non-univocity of the names said in common of God and creatures: "[O]mnes rerum perfectiones, quae sunt in rebus creatis divisim et multipliciter, in Deo praeexistunt unite. Sic igitur, cure aliquod nomen ad perfectionem pertinens de creatura dicitur, significat illam perfectionem ut distinctam secundum rationem defmitionis ab aliis, puta cum hoc nomen sapiens de homine dicitur, significamus aliquam perfectionem distinctam ab essentia hominis, eta potentia et ab esse ipsius, et ab omnibus huiusmodi. Sed cum hoc nomen de Deo dicimus, non intendimus significare aliquid distinctum ab essentia vel potentia vel esse ipsius. Et sic, cum hoc nomen sapiens de homine dicitur, quodammodo circumscribit et comprehendit rem significatam, non autem cum dicitur de Deo, sed relinquit rem significatam ut incomprehensam, et excedentem nominis significationem"; STh I, q. 13, a. 5. As regards esse, perhaps even clearer is this passage from his commentary on De divinis nominibus: "[I]psum esse creatum non est finitum si comparetur ad creaturas, quia ad omnia se extendit; si tamen comparetur ad esse increatum, invenitur deficiens et ex praecogitatione divinae mentis, propriae rationis determinationem habens"; Thomas Aquinas, In librum Beati Dionysii De divinis nominibus expositio, ch. 13, lect. 3, [section] 989, ed. C. Pera (Turin: Marietti, 1950), 368. The finitude of created esse does not derive solely from what receives it; it also has an intrinsic finitude, that of the proper ratio of esse (see above, n. 97), according to which it is distinct from other perfections. By contrast, the esse of God includes, but also exceeds, the ratio of esse.

(100) If esse can be properly predicated of God, whereas horse cannot, this is only because the ratio of esse does not positively exclude real identity with all other perfections, as the ratio of horse does. But the divine essence is not determined according to either ratio. Thomas is explicit about the fact that esse is not predicated of God in such a way as to signify what he is; see In Sent., bk. 1, d. 8, q. 1, a. 1, ad 4.
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Title Annotation:Aquinas on Being by Anthony Kenny
Author:Brock, Stephen L.
Publication:The Review of Metaphysics
Article Type:Critical essay
Geographic Code:1USA
Date:Dec 1, 2006
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