In De ente et essentia D. Thomae Aquinatis commentaria

But note that the minor contains two things, namely that designated matter is opposed to being communicated to many, and that this opposition belongs to it first. The first of these is evident from itself: it is impossible for matter capable only of this quantity to be multiplied. The second is proved as follows: that belongs first to designated matter which belongs to it when anything else is abstracted, and which, when it is abstracted, belongs to no other thing (from the First Book of the Posterior Analytics); but not being communicated to many as a universal to a particular, with anything else existing in sensible substance abstracted, belongs to designated matter, and, when it is abstracted, belongs to no other thing; therefore not being communicated to many belongs first to designated matter among all things found in sensible substance. The minor is proved with respect to both its parts. As to the first: what designated matter, taken precisely, claims for itself, so that under its opposite it is not intelligible, belongs to it with anything else abstracted; this is clear from the terms. But incommunicability belongs to designated matter precisely as so taken, so that under its opposite designated matter is not intelligible; for the proper matter of a communicable individual cannot be understood; therefore incommunicability belongs to designated matter with anything else abstracted. The second part of the minor is clear by example: for when Socrates’ designated matter, or proper matter—which is the same thing—is abstracted, it is certain that neither his form remains here nor will remain here, nor does matter itself; for if he does not have proper matter, through what does he leave the order of common things? Second, the same conclusion is proved thus: what can be done through fewer things, and equally well, is done in vain through more; but individuation of a composite substance is sufficiently preserved through designated matter without any other things; therefore everything else is added in vain. The minor will become clear from what follows, where, once the arguments of the adversaries have been solved, our stable and firm position will remain. It is also confirmed because, since in a composite substance there are only matter, form, and the composite formed from them, and whatever accidents happen to the individual have no other intrinsic cause than one of these, it is not necessary to wander outside this in investigating the cause of individuation. Third, the same conclusion is proved by the authorities of Aristotle and the Commentator cited above, which need not be repeated. It is plainly evident in them that every distinction arises either from forms or from quantity. Designated matter is therefore the intrinsic principle of individuation, through which Socrates is intrinsically—though particularly—this individual. I say “particularly,” because I do not think designated matter is the individual property itself, or the individual difference, but rather the essential principle of the individual difference. For I think that the proportion of designated matter to the individual property or difference is like the proportion of the human soul to the constitutive difference of man. For just as the intellective soul is not the difference itself, namely rational, but that from which it is taken, so designated matter is not the individual difference itself, but that from which it is taken and which causes it intrinsically. And just as man is man both through rational as a total formal principle and through the intellective soul as an intrinsic partial formal principle, from which rational borrows and is caused, so Socrates is this individual through the individual difference as a certain total denomination—which is nothing other than an individual grade, just as specific difference is a specific grade—and through designated matter as the prior intrinsic cause from which the individual difference borrows. Thus the difference between us and the Scotists is that they multiply individual differences without essential dependence on designated matter, whereas we would no more know how to contract animal to man and ox without the forms of the parts from which the contracting differences of animal are caused than we know how to contract a species—for example, man—to an individual without designated matter, which is the cause of individual differences, and consequently the first intrinsic principle of individuation. I am moved to say this because I hold that Socrates, taken substantially, in the direct line—that is, in the predicamental line—under the species is one numerically, not with a unity belonging to the category of quantity, but with substantial unity. This unity must precede it, since it is a passion of being arising from the individual grade which the individual difference itself signifies. Let no one judge whether this is the mind of the holy Doctor before reading him himself, both in the Compendium of Theology, chapter CLV, where he wishes Socrates to be the same in number after his resurrection with his numbered quantity, and in the treatise mentioned above. As to the fifth point, Scotus argues against the conclusion and the things said in it above. First, thus: it is impossible for something naturally dependent on what is posterior to be naturally identical with what is prior, because then it would be prior and not prior; but substance is naturally prior to quantity; therefore nothing caused by quantity, or in any way presupposing the nature of quantity, can be identical with substance; therefore this designation caused by quantity is not the same as substance. The proof of the major is this: wherever there is true and real identity, even if it is not formal, it is impossible for this to be and that not to be, because the same thing would really be and not be; but what is naturally prior can be without what is naturally posterior; therefore, much more, it can be without what is left behind or caused by what is naturally posterior. Moreover, what is a necessary condition of a cause in causing cannot have its being from the caused, because then the cause, insofar as it is sufficient for causing, would be caused by its caused effect, and that effect would be the cause of itself. But the singularity or designation of substance is a necessary condition in substance for causing quantity, because a singular effect requires a singular cause; therefore it is impossible for this designation or singularity to be from quantity. Moreover, I ask what it is for quantity to cause or leave such a mode or designation in substance. If this means nothing except that it preceded quantity, then designation is in no way through quantity, because designation of substance would then naturally precede quantity itself. But if it means something else, I ask how it is caused by quantity, and in what kind of cause. Moreover, why does quantity rather than quality leave such a mode in substance? No reason appears, because just as quality informs a surface in itself, leaving nothing in it, so quantity informs substance in itself and not through another form left behind. Moreover, the quantity that concurs in individuation is either terminated or indeterminate. It is not terminated, because terminated quantity follows form in matter and consequently the singularity of substance: just as substance is its cause insofar as it is terminated, so this substance is its cause insofar as it is terminated here. This is confirmed because, since terminated quantity is varied by rarefaction alone, the same individual would be the same with many singularities, which is impossible. If it is indeterminate, the contrary follows: it remains the same in what is generated and what is corrupted. Moreover, if quantity concurs in individuation as what first distinguishes, it must itself first be numerically distinct from another. But then your proposition is not true, namely that every formal difference is specific: for this quantity and that quantity, since they are forms, would differ specifically. If you exempt quantity from that foundational proportion of the ruinous structure, how will it be proved that formal difference is specific? Whatever reason is brought forward concerning form will apply to quantity, since quantity is a form. Moreover, the whole breadth of the category of substance is prior to the other categories; therefore, since the substance-individual is enclosed within this breadth, it must be intrinsically complete without dependence on quantity, which is posterior. This is confirmed because nothing is placed in a genus through something outside that genus. Scotus and others make many other arguments; but because they conclude that matter alone, or quantity alone, or the aggregate of matter and quantity is not the principle of individuation, I have omitted them, for they are not against us. I have also omitted arguments indirectly against our position, out of a concern for brevity. So much for the fifth point. As to the sixth, one must answer the arguments just made, and then others brought forward for the contrary opinion. To the first of these it is said that the major is false. For clarity, it should be noted that the proportion of designated matter to this quantity is the proportion of potency to its proper act. Thus, just as the potency of matter is really identical with matter itself and nevertheless depends on form, so the potency or capacity of matter with respect to this quantity, which is called its designation, depends on quantity and is nevertheless identical with matter. And because potency is prior and posterior, naturally prior to act in the genus of material cause and posterior in the order of formal cause, the designation of matter is prior to quantity in the order of material cause but posterior in the order of formal cause. Thus the major is false in either way, whether it is understood of priority and posteriority according to the genus of material cause or according to the order of formal cause. For something dependent on form is really identical with matter, and something dependent on matter is really identical with form, as is clear. To the first proof, where it is said that then it would be prior and not prior, I say that there is no contradiction in different genera of causes. To the other proof, where it is said, “wherever there is true and real identity,” and so on, the second proposition assumed is denied: not everything prior can be without what is posterior, as will be shown elsewhere. To the second, the major is denied when the caused is the cause of its cause in another genus of cause, as happens here. Designated matter is the cause of quantity in the genus of material cause; quantity is the cause of designated matter in the genus of formal cause, as act is the cause of potency. The falsity of the major is clear in the example given above: the potency of matter is a necessary condition of matter for causing form, and nevertheless depends on form in the genus of formal cause. To the proof it is said that material cause, according to its causality, depends on its effect, namely form, but not insofar as it is its effect; rather, it depends on it insofar as it is the cause of matter. For causes are causes of one another, as is said in Physics II, text XXX. It is therefore not impossible for a cause, in causing, to depend on what is caused—not as caused, but as it is a cause according to another genus. To the third it is said that for quantity to cause such a designation in matter is nothing other than for matter, under this agent, to have been made capable of this quantity to such a degree that it is not capable of that one. Thus quantity concurs in the designation of matter as the act on account of which such capacity comes to be. But the agent causes it as efficient cause, and such designation or capacity precedes quantity itself in the genus of material cause; it cannot therefore be inferred from this that it is not made through quantity, because it is made through quantity in the genus of formal cause, which, like the end, is numbered among causes posterior in being. To the fourth it is said that not only quantity designates matter in this way, but also proper qualities. For Socrates’ matter is capable of these qualities in such a way that it is not capable of others. But because quantity alone is immediately received in substance, and material distinction arises radically from quantity alone, for the present purpose we speak of designated matter, matter under determinate dimensions, and not under determinate qualities.

To the fifth it is said that the quantity which concurs in individuation as the original, not intrinsic, principle of individuation is terminated quantity. Nor is it an objection that it follows form, because form too follows the potency of matter, by which it is nevertheless caused. We concede that this substance is the material cause of this quantity; conversely, in the genus of formal cause, this quantity is the cause of this designation of matter in the manner explained above. To Anthony Trombeta’s confirmation it is said that terminated quantity which concurs in individuation does not stand at an indivisible point, but has breadth. For just as every natural species determines for itself a maximum and minimum quantity within a certain breadth, so every individual determines for itself this quantity within such limits, and not at an indivisible point. Hence rarefaction can occur without variation of it insofar as it is individuative. Terminated quantity is not taken here pointwise, but with a certain breadth. To the sixth it is said that the first consequence is conceded, but that what follows from it is the falsity of that foundational proposition of the very firm structure is denied. For the objector committed the greatest error by failing to distinguish between formal difference and difference of forms. Every formal difference is specific, but not every difference of forms, as St. Thomas says in Against the Gentiles II, chapter LXXXI; otherwise the form of this fire and the form of that fire would differ specifically, since they are forms and differ. Thus a mathematical line divided into parts has two individuals: each part of the line is a line, and those individuals are forms and differ, but not by formal difference. Formal difference is called that which is through quiddative principles; for this always arises from form insofar as it is form, and there is no such difference between this line and that line, since the quiddity of both is the same. Indeed, the objector’s error is very childish: they are forms and they differ; therefore they differ formally; he is a monk and he is white; therefore he is a white monk. To the last, the consequence is denied. Although what is in the category of substance is simply prior to anything in any other category, nevertheless some condition—without which an individual as such is not in a category—can be posterior in the genus of formal cause and belong to another category, because formal cause is posterior in being. To the confirmation it is said that every category is completed by things of its own genus, if we speak of what is placed in categories and of the reason for placing them in them, but not if we speak of the condition of the thing placed in a category. Socrates is nothing but substance, and the reason placing him in the category is substance; but the condition of individuation, without which there is no reason for placing him in the category, may nevertheless require some accident, such as quantity. To the first of the arguments brought forward for the contrary conclusion it is said that the minor is false: numerical unity first follows designated matter. To the second it is said that the difference of individuals is reduced to quantities. Quantities, however, differ by their proper positions, which are differences of quantity. Position is not constituted only by those two things, namely the permanence and continuity of the parts, but by these two together with a third, namely the order of the parts in the whole, as Alberic teaches in the Categories, in the chapter on quantity. For by this it differs from position, the special category which signifies the order of parts in place. Hence positions in the present case are distinguished by their orders of parts in the whole, which belong to their account; and orders by themselves. For distinction enters into the definition of order. Thus it is clear that there is not equal doubt concerning the things to which we reduce the matter and concerning quantities, and that quantities need not for this reason be formally distinct. Such order of parts in the whole, as something material, is in quantity itself, and is found in no other form. To Anthony Trombeta’s third argument it is said that the minor is false: designated matter, as has been proved, is that to which it first belongs to be divided as a universal into particulars; for it is contrary in reason to haecceity. It is explained in what way the essences of genus, species, and individuals are distinguished both absolutely and as conceived under the names of first imposition; in what way genus, species, difference, and definition differ among themselves; and finally how the essences of species are compared with individuals. It is therefore clear that the essence of man and of Socrates differ only according to the designated and the non-designated. Hence the Commentator says on Metaphysics VIII that Socrates is nothing other than animality and rationality, which are his quiddity. The essence of genus and the essence of species likewise differ according to the designated and the non-designated, although the mode of designation is different in each case: for the designation of an individual with respect to a species is through matter determined by dimensions, whereas the designation of a species with respect to a genus is through the constitutive difference, which follows from the thing’s form,

After it has been determined in general what the essence of composite substances is, in this third chapter, intending to treat the difference among composite essences, since composite essences are three—generic, specific, and individual—he does five things. First he speaks of their difference absolutely; second, intending to determine their difference as they underlie first intentions and their names, he shows how generic essence differs from specific essence; third, he explains how genus, species, difference, and definition differ among themselves; fourth, he excludes a certain doubt; fifth, he assigns the difference between specific and individual essence. For clarity concerning what will be said, it should first be noted that we can speak of essences in three ways: first, of them absolutely, without relation to first or second intentions; second, of them as they underlie names of first intention; third, as they underlie names of second intention. For example, it is possible to speak of human nature according to itself, that is, according to what belongs to it by reason of itself; it is possible to speak of it as standing under this name, “humanity,” and this name, “man,” and similar names; and third, it is possible to speak of it as standing under this name, “species.” St. Thomas therefore, in the first part of this chapter, speaks of the essences of things in the first way; throughout the remainder he speaks of them taken in the second way; in the following chapter he will speak of them taken in the third way.

And this, if you do not wish to be deceived in this chapter, must be noted most diligently: therefore, in assigning the difference between generic, specific, and individual essence considered in themselves, he establishes this conclusion: The aforesaid essences differ only according to the designated and the non-designated. This is explained as follows. The essences of animal, man, and Socrates properly differ only in this: in the account of animal there falls an animated sensitive substance without its determination by rational; in the account of man there is posited an animated, sensitive, rational substance, and thus designation by the difference is added to it; while the account of Socrates posits an animated, sensitive, rational substance in these particular flesh and bones, and thus the designation of matter is added to it, which was not posited in the account of man. Hence, speaking absolutely and according to their proper accounts, these essences appear to differ only according to the designated and the non-designated, that is, according to the explicit inclusion of some designation or determination, and not its implicit inclusion; although such designation is not uniform in specific nature and individual nature. For the designation that specific nature adds above generic nature is formal, essentially diversifying the genus, as taken from form precisely insofar as it is form; but the determination that individual nature adds above specific nature is material, producing diversity in the species not formally but only materially, as taken from the material conditions of the thing.

From this you have that man and humanity, and animal and animality in themselves—that is, the natures signified—do not differ in any way; the account of the nature signified by man and by humanity is altogether the same, so that they differ by no designation. But, as will be said later, they differ insofar as they are subject to names of first intention. Since the distinction according to the designated and non-designated is not a real distinction, therefore the Commentator says in VII Metaphysics, commentary 10, that Socrates taken substantially is nothing other than animality and rationality, which are his quiddity; for “Socrateity,” which names the nature of Socrates, is really the same as animality and rationality.

This determination or designation, which is in the species with respect to the genus, is not through something existing in the essence of the species that is in no way in the essence of the genus; rather, whatever is in the species is also in the genus, although not determined. For if animal were not the whole that man is, but a part of him, it would not be predicated of him, since no integral part is predicated of its whole.

In this second part of the chapter it is determined how generic essence differs from specific essence, insofar as both stand beneath names of first intention: namely, how the essence of man and the essence of animal differ beneath the names man and animal. He intends that the essence signified by the generic name, such as animal, and the essence signified by the specific name, such as man, do not differ because the essence signified by the specific name includes some determination wholly outside the thing signified by the generic name, but because the essence imported by the name of the species actually includes the specific designation produced by its constitutive difference, just as man actually includes rational, since it is placed in his definition. But the essence signified by the generic name confusedly and indeterminately imports that designation; thus animal potentially includes rational, as Porphyry says. Hence animal, and universally every essence imported by a generic name as such, includes the whole that the species includes, although not in the same way.

Therefore, to explain the proposed difference, he establishes this conclusion: The genus states the whole being of the species. He proves it thus: every predicate states the whole being of that of which it is predicated; the genus is predicated of the species itself; therefore generic nature, such as animal, states the whole being of the species. He proves the major premise by saying that no part is predicated of its whole. It must be observed that this statement is true of direct predication in the nominative, whether essential or denominative, and of a part insofar as it is a part, not of a part insofar as it is signified after the manner of a whole. For a part can be signified in either way: matter is signified as a part of a thing by the word “matter,” but as a whole by the word “material.” With these conditions so modified, the proposition “no part is predicated of its whole” suffers no exception. When I say, “Man is white,” “white” gathers into itself implicitly the whole that is in man; likewise, when I say, “Man is material,” “material” implicitly comprehends the whole that man is. Thus, when it is said, “Man is animal,” “animal” implicitly contains the whole that man is, in the way to be explained below. Thus it is proved that the essence imported by the generic name includes the specific designation, for outside the whole there is nothing.

How this occurs can be seen if one considers body insofar as it is posited as a part of animal and insofar as it is posited as a genus. It cannot be said to be a genus in the same way in which it is an integral part. Therefore this name body can be taken in many ways. Body insofar as it is in the category of substance is said from having such a nature that three dimensions can be designated in it; but the three designated dimensions themselves are body, which is in the category of quantity. In things it happens that what has one perfection reaches a further perfection, as is clear in man, who has a sensitive nature and, beyond it, an intellectual nature. Likewise, above this perfection—which is having such a form that three dimensions can be designated in it—another perfection, such as life, can be added. Thus body can designate a thing having such a form that the designability of three dimensions follows from it, with the precision that no further perfection follows from that form, so that if anything else is added it is outside the signification of body so taken. In this way body will be the material and integral part of animal, because soul will then be outside what is signified by body and will come to it, so that animal is constituted from these two, soul and body, as from parts. Body can also be taken to signify a thing having such a form that three dimensions can be designated in it, whatever that form may be, whether a further perfection can proceed from it or not. In this way body is the genus of animal, because in animal there is nothing to be taken that is not implicitly contained in body. For soul is not other than that form through which three dimensions could be designated in that thing. Thus, when I said that body is what has such a form that three dimensions can be designated in it, I understood whatever that form might be, whether it were soul, stoniness, or any other form; and so the form of animal is implicitly contained in body, or in the form of body, insofar as body is its genus.

Since it has been declared that genus is related to species not as its part but as its whole, he plainly intends here to show how the thing signified by a generic name can be taken in both ways, as part and as whole: first in body, as the more evident case, and then in animal. Since the same thing, taken in the same way, cannot be both a part of a thing and its genus, you must know that the name body is taken in two ways. It is equivocal for body, which is a thing in the category of substance, and body, which is a thing in the category of quantity. Body insofar as it signifies a thing in the category of substance imports the nature from which three dimensions are apt to flow; but body insofar as it signifies a thing in the category of quantity imports the three dimensions themselves.

Again, body signifying a thing in the category of substance, which is now under discussion, is taken in two ways. In one way it signifies that nature from which three dimensions are apt to flow, with precision from every further substantial perfection. In another way it signifies that very nature without precision from a further substantial perfection. He assigns the cause of this and similar distinctions in the text: a thing having some substantial perfection does not exclude from itself another further substantial perfection, just as man, from having sensitive perfection, does not exclude intellectual perfection. Likewise, body, from having bodily perfection, does not exclude vital perfection, and so on. Since the prior substantial perfection excludes neither the second nor the third, while it is also clear that it does not actually include them, the prior perfection can be conceived and signified both with precision or exclusion of the others and with their confused inclusion. Because it does not formally include the others, it can be conceived and signified precisely; because it does not exclude union with the others, it can be conceived and signified with their confused and potential inclusion. Hence the nature signified by body, since it does not formally include vital, sensitive, or intellectual perfection, can be conceived and signified with precision from all these; and since it does not exclude its essential union with them, it can be conceived and signified without their precision, as confusedly and indeterminately including them all. The text gathers a threefold difference between these. First, body in the first way states bodily nature alone, from which three dimensions are apt to flow, with no further perfection; body in the second way states any form whatever from which corporeity arises, from which three dimensions are apt to flow together with any other perfection. Second, body in the first way is a part of the species, since its formal signified is beyond and outside its signified, just as rational soul is outside corporeity; in man there are two things, bodily perfection, which when taken precisely plainly does not include intellectuality in any way, and intellectual perfection, which is the other part. But body in the second way is the whole with respect to the species, because the perfection or form formally imported by the species is included in the signified of body so taken: it signifies any form from which bodily perfection arises, and thus intellectual soul is included in “any.” Third, body in the first way is not in the direct line of the categories, just as no part is; but body in the second way is directly in the category of substance, like every other genus.

Animal also has this relation to man. If animal named only a thing having a certain perfection, so that it could sense and move through a principle existing in it, with precision from another perfection, then any further perfection that came to it would relate to animal as a part, and not as implicitly contained in the account of animal; animal would not be a genus. It is a genus insofar as it signifies a thing from whose form sensation and motion can proceed, whatever that form may be, whether it is a merely sensitive soul or a sensitive and rational soul together.

He also explains this through the genus animal. Animal can be taken to signify the form from which sensation and motion arise precisely, by which animal is distinguished from what is not animal, as is said in I On the Soul, text 19. It can also be taken to state any form whatever from which sensation and motion arise, not precisely; and in this way it is a genus. In the first way it is a part of the species, so that man is composed of animal and an intellectual principle as essential parts, taking animal in the first way, for then intellectual nature is outside its signified. But animal in the second way is the whole with respect to man, implicitly including the specific perfections. When I say “animal” in this way, I say “having a sensitive nature” indeterminately, leaving open through which form it has sensitive nature; thus all specific forms are implicitly included. Sensitive nature is had only through the form of man, lion, ox, and so on. From this the difference between generic and specific essence is clear, insofar as they are subject to generic and specific names of first intention: they differ as that which includes implicitly and that which includes explicitly.

Thus genus signifies indeterminately the whole that is in the species; it does not signify matter alone. Difference likewise signifies the whole that is in the species, not form alone; definition and species also signify the whole, but in different ways. Genus signifies the whole as a kind of denomination determining what is material in the thing without determination of its proper form; hence genus is taken from matter, although it is not matter. Thus body is said from having such a perfection that three dimensions can be designated in it, and this perfection is material in relation to a further perfection. Difference, conversely, is a determination taken from a determinate form, beyond the fact that determinate matter is first understood in it; thus “animated” means that which has a soul, without determining what it is, whether body or something else. Hence Avicenna says that genus is not in difference as a part of its essence, but only as a being outside its quiddity or essence, just as the subject is included in the understanding of properties. Therefore genus, speaking per se, is not predicated of difference, as Aristotle says in II On the Soul and IV Topics, except perhaps as a subject is predicated of a property. But definition or species comprehends both: determinate matter, designated by the name of the genus, and determinate form, designated by the name of the difference.

In this third part of the chapter he compares genus, species, difference, and definition with one another in agreement and difference. He says that all agree in this, that each signifies the whole that is in the species. This follows immediately from what was said: if genus signifies the whole because it is truly and properly predicated of the species and gathers into itself everything to which it extends, then, by the same reasoning, difference, since it is truly and properly predicated of the species and gathers into itself everything to which it extends as a predicable, will signify the whole. But he posits a twofold difference among them. First they differ with respect to their formal signifieds: the formal signified of genus is a material perfection; that of difference is a formal perfection; that of species is an aggregate from both perfections without distinguishing them; and that of definition is likewise an aggregate from both, but dividing them into their individual parts. For example, the formal signified of animal is sensitive nature, which is related as material to intellectual perfection, formally imported by rational, and consequently intellectual perfection is related as formal. The formal signified of man and of rational animal is an aggregate of sensitive and intellectual nature; but rational animal explains each separately, whereas man does not.

For understanding this, note that the formal signified of a name here is a perfection or form determinate and first explained by that name. The material signified is what falls under the signification of the name not first. Thus, considering everything imported both formally and materially by genus, species, difference, and definition, he says that they signify the same and agree; but considering their formal signifieds, we say that they differ and do not signify the same. Do not wander by seeking a difference between the formal signified of species and of definition, for there is none; they differ only in the manner of expressing the same formal signified. Species explains the whole actually but indistinctly; definition divides it into individual parts, as Aristotle says in I Physics, text 5. The generic name, animal, therefore formally and determinately explains the material perfection of man, namely the sensitive perfection; hence genus is taken from matter, VIII Metaphysics, text 9. The name of the difference, rational, formally and determinately explains the formal perfection of the thing; hence it is said there to be taken from form. Just as the perfection imported by difference does not fall into the formal signified of genus, because it is included in it indeterminately, so genus does not fall into the formal concept of difference for the same reason: generic perfection falls into the name of difference indeterminately.

Just as animal, from signifying “having a sensitive nature,” signifies two things—sensitive nature formally and first, and that which has it indeterminately, since it does not explain whether that thing is man or ox—so rational, from signifying “having rationality,” signifies rationality formally and first, and that which has it secondarily and indeterminately, since it does not determine what that bearer is, whether man or animal. Therefore Avicenna says that genus is not in difference as a part of its essence, that is, as a part of its formal signified, but is outside its formal signified, as a subject is outside the formal signified of its property. White signifies a pure quality, as is said in the Categories. Although genus is not included in the understanding of difference in this way, namely as what is formally signified by it, it is nevertheless included in its understanding in another way, as a subject is included in the understanding of a property. For something falls into the account of another in two ways. In one way as a part of its quiddity; in another as its subject, in the way a subject enters the definition of a property, as you have in VII Metaphysics, text 19. Therefore Aristotle says in III Metaphysics, text 10, and IV Topics, chapter 3, that genus is not per se predicated of difference, except perhaps as a subject is predicated of a property.

The reason for the first statement is that genus is predicated of difference in none of the modes of per se predication: not in the fourth, because difference does not explain the cause of genus; nor in the second, because difference is not placed in the definition of genus; nor properly in the first, because first-mode predicates in the direct line, which are properly predicated, are those that fall intrinsically into the account, not those that are present in it by addition. Man, for example, is not properly predicated of risible in the first mode; this is clear because “Risible is man” is accidental, as is said in I Posterior Analytics, chapter 18. The reason for the second statement is that if genus is in the understanding of difference as a subject is in the understanding of a property, it follows that genus is predicated of difference as a subject is predicated of a property. His “perhaps” is not the expression of doubt, but of non-determination: he customarily places matters not decided in a doubtful verbal form.

Observe that although genus falls determinately into the understanding of difference, the name of the difference does not explain that genus determinately. Rational does not explain animal together with rationality, but “having rationality,” just as man falls into the definition of risible; yet the name risible does not explain man determinately, for it signifies “having risibility.”

From this the reason is clear why genus, species, and difference are proportioned to matter, form, and composite in nature, although they are not the same as those realities. Genus is not matter, but is taken from matter while signifying the whole; difference is not form, but is taken from form while signifying the whole. Hence we say that man is a rational animal, not that he is from animal and rational, just as we say that he is from body and soul. For man is said to be from body and soul as a third thing constituted from two things, which is neither of them: man is neither soul nor body. But if man is in some way said to be from animal and rational, this is not as a third thing from two things, but as a third understanding from two understandings. The understanding of animal expresses the nature of the thing without determination of a special form, because it is material in relation to the ultimate perfection. The understanding of the difference rational consists in determination of a special form. From these two understandings is constituted the understanding of species or definition. Therefore, just as a thing constituted from certain things does not receive the predication of the things from which it is constituted, so neither does an understanding receive the predication of the understandings from which it is constituted: we do not say that the definition is genus or difference.

As a corollary he concludes the second difference between genus, species, and difference: genus is proportioned to matter, which is a part of the composite, but does not signify matter itself; difference is proportioned to form, but does not signify form itself; species is proportioned to the composite from matter and form, but as such does not signify the composite from matter and form, but something comprehending genus and difference. In assigning this difference, two clauses are posited for each member: in the first, the first clause is that genus is proportioned to matter, and the second that genus does not signify matter; likewise in the second and third members. The first clause follows from what was said above. If generic perfection, formally imported by genus, is material in relation to differential perfection, formally imported by difference, then genus must be related to difference in the rational composite, namely the species, as matter is related to form in a natural composite, such as Socrates. As matter is potential and is perfected and specified by form, so generic perfection is potential, capable of perfection, and capable of specification through difference. The second clause also follows from what was said: because genus, difference, and species signify the whole, it follows immediately that genus does not signify matter, since matter is not the whole; that difference does not signify form, since form is not the whole; and that species as such does not state the composite from matter and form, since its parts as such are not matter and form but genus and difference.

Nevertheless, St. Thomas proves it in this way: matter and form are parts of their whole as two things of a third thing; genus and difference are not parts of their whole, namely the species, as two things of a third thing; therefore genus and difference are not the matter and form of the species. The major is evident in itself: man is another thing from his matter and another from his form. It does not matter now whether he is really or rationally distinct from those two conjoined; it is enough that he is a third thing really distinct from either part. The minor is explained thus: if genus and difference composed the species as two things compose a third, man would be composed of animal and rational; this is false. Therefore, by destruction of the consequent, genus and difference do not compose the species as two things compose a third; which was to be proved. The inference is evident in itself; the falsity of the consequent is proved because no part is predicated of its whole, as was said above and is found in IV Topics, chapter 11. But animal is predicated of man, and likewise rational: we say that man is animal and that he is rational.

It must be observed that St. Thomas, explaining the major by an example in the text, says that man is from soul and body as a third thing from two things. Concerning these words there is doubt how this can be true while maintaining his doctrine, which posits one substantial form in the composite: for things that are really the same do not constitute something as two things constituting a third; but bodily perfection and soul are really the same if one form is posited. How, then, will they constitute man as two things constituting a third?

Because of its great difficulty, this doubt is solved in different ways. Some say that body and soul are not really parts of a human being, but only according to reason: for although the soul is truly a part, body in reality is the whole; for it signifies the composite of matter and form, which is the soul. Therefore the composite is not composed of soul and body as of two parts in reality, but according to reason; yet it is well composed of them as of two things, in the way in which whole and part are two things, so that the third thing is distinct according to reason from one, namely body, and in reality from the other, namely soul.

Others say—and this amounts to the same—that a human being is composed of soul and body as of a formal cause and that of which it is the formal cause. For according to Avicenna, the formal cause and that of which it is the formal cause are different things; just as the luminous is composed of light and the luminous. Hence these too say that a human being is composed of two things, namely whole and part, but not of two parts in reality.

Others say that this expression is to be understood by synecdoche: “A human being is composed of soul and body” by reason of its part, namely matter. For the present, however, it seems to me that one should say that a human being is composed of soul and body, not merely as of two things forming a third thing, but as of two parts which are really the whole, taking body not as it is a genus but as it signifies a part, and taking soul precisely as it is defined in II On the Soul. Body taken in this way signifies a composite precisely of matter and corporeal perfection; soul, precisely of vital perfection. The intended conclusion is proved as follows: body really differs from soul, and not as whole from part; therefore as part from part. The middle proposition is proved because a whole at least confusedly includes its part, whereas body taken in this way excludes soul. Hence in the definition of soul body is posited as the subject bearing soul, as St Thomas says there. The first proposition is self-evident and conceded by all. The consequence draws its force from a sufficient division: if body and soul really differ, body must differ from soul either as whole from part or as part from part. Therefore a human being is composed of body and soul as of parts really distinct: which was intended.

And notice that body, as a part, when it imports corporeity precisely outside itself, is the identity of corporeal perfection with soul, or with vital perfection. For it happens, through an extrinsic accident of body taken precisely, that its perfection is identical with soul; in itself it cuts off soul, and therefore, speaking strictly, it has been correctly said that a human being is really composed of soul and body. Accordingly, in response to the objection brought forward, say that although corporeal perfection, or the form of corporeity, is really the same as soul, body nevertheless is really other than soul, and corporeal perfection, strictly speaking, is not really the same as soul itself; indeed, when taken precisely, it excludes soul. Therefore body and soul, taken precisely, may strictly be conceded to be really parts of the human being. The words of the text favor this response, where the exclusion of soul from the signification of body is assigned as the reason for the statement. What we have said about body and soul with respect to animal, you may say about animal and intellectual soul with respect to human being, and about body and the form of a stone with respect to a stone, and so in other cases, always taking the terms precisely for parts. Although it is not customary to say that inanimate things are composed of body and specific form, as animate things are of soul and body, this is because of the hidden difference between corporeity and the form of animate things; and also because the form of animate things raises the composite to the point that it moves itself, so that in it one had to distinguish a moving part and a moved part, namely soul and body. This is not found in the forms of inanimate things.

Notice secondly that, to clarify the minor proposition, St Thomas says that a human being is not from animal and rational as from two things forming a third thing, but as a third concept from two concepts. Here it should be known that genus, species, and difference can be taken in three ways. First, for the thing signified by a generic, specific, or differential name of first intention. Secondly, for the formal concept of such names. Thirdly, for the thing signified by their names of second intention. For example, animal, human being, and rational may first be taken for the things signified by these names; secondly, for their formal concepts; thirdly, for the relations of genus, species, and difference. In the first way neither species nor definition is composed of genus and difference, since the thing signified by species and definition is really the same as the thing signified by genus and difference: the same thing is not composed of itself. In the third way likewise neither species nor definition is composed of genus and difference, since the relation of species is added to the relation of genus, as Porphyry says. But no correlate is composed of its correlate, and generally it is not apparent how a relation could be composed of other relations. Hence, just as the relation signified by the name proposition is not composed of the relation of predicate to subject, but is a relation attributed by the intellect to the complex formed from predicate and subject, so the relation of definition is a relation attributed to such a concept formed in the first operation of the intellect, distinctly explaining genus and difference.

In the second way, however, both species and definition are composed of genus and difference: for the formal concept of species is integrated from the formal concept of genus and the formal concept of difference as from two parts. For example, the formal concept of human being is something aggregated from the formal concept of animal and the formal concept of rational. This follows from what was said above: since we showed that genus, difference, and species differ in formal signification, it is clear that the formal concept of animal is the concept of sensitive perfection, the formal concept of rational is the concept of intellectual perfection, and the formal concept of human being is the concept embracing both perfections, formed from them as a third concept by their union. Thus human being is from animal and rational as a third concept from two concepts: that is, as a third concept from two concepts, and not as a thing from two things. And because no part as a part is predicated directly of its whole, the intellect or formal concept of animal is not predicated directly of the intellect, that is, the formal concept of human being. The following is false: “The formal concept of human being is the formal concept of animal,” because the formal concept of human being aggregates the whole composed of intellectual and sensitive perfection, whereas the formal concept of animal states only a part, namely sensitive perfection. Although, as was said above, according to the material and formal concept or signification taken together it states the whole, human being, taken according to its formal intellect or concept, is therefore not animal or rational, but from animal and rational. And as was said of human being, which is a species, so say of animal rational, which is a definition: animal rational according to its formal concept is neither animal nor rational, but from animal and rational. For the formal concept of animal rational differs from the formal concept of animal and from that of rational as whole from parts.

What was said—that the formal concept of species and definition is composed of the formal concepts of genus and difference—can be understood in two ways: in one way of a mental concept, in another of an objective concept formally taken. If in the first way, it can still be understood in two ways: either of a mental concept according to subjective being, or according to what it is; or of it according to representative being. The mental concept of species according to what it is is not composed of the mental concepts of genus and difference according to what they are, since all are simple qualities and cannot be distinguished into several composing parts. For one must not imagine that, when the intellect forms the concept of the definition of human being, namely animal rational, it forms several concepts, but only one, which is a certain simple quality distinctly representing each thing. So too in external reality the defined thing has the reality of genus and difference without real composition. Hence in this first way our statement is not true. But the mental concept of species, formally taken according to representative being, is composed of the mental concepts of genus and difference formally taken according to representative being, like an image representing a whole from images of its parts. For human being in the mind represents an aggregate of sensitive and intellectual perfection; whereas animal in the mind formally represents only sensitive perfection, and rational only intellectual perfection. Thus our statement is verified in this way. The objective concept of species, formally taken, since it is nothing other than formal signification, is composed according to reason of the objective concepts of genus and difference formally taken; just as the formal signification of species is composed according to reason of the formal significations of genus and difference, as was shown above.

Thus human being, taken as the object of its own mental concept, namely the specific concept, is neither animal nor rational, but from animal and rational, taking animal and rational also insofar as they are objects of their mental concepts. This is shown by the falsity of the proposition: “The specific formal object is the generic or differential formal object.” For human being, taken in this way, says an aggregate of sensitive and intellectual perfection; animal, taken in this way, says only one part of the aggregate, namely sensitive nature; and rational, taken in this way, only the other part, namely intellectual perfection. But it is manifest that an aggregate is not one of the things aggregated. In this way, therefore, our statement is true and is most pertinent.

Thus animal, as to the thing imported, is neither part nor whole with respect to human being and animal rational; but as to the material and formal signification taken together, it is the whole, while as to formal signification it is a part, both objectively and representatively taken. Hence when I say, “Human being is animal,” if the thing itself alone is considered, neither the notion of part nor of whole is preserved. But if the thing signified in this way, namely implicitly including its inferiors, is considered, it has the notion of whole. If the thing signified in this way is considered according to what it explicitly includes as such, it receives the notion of part. For this reason animal is placed in the definition of human being as a thing: a thing is predicated of a thing as a whole because it is predicated directly, and as a part because a difference is added which explains something else, and so on.

What we said above about species, say about definition, always preserving what is said in I Physics, text V, namely that definition divides into individual things, whereas species does not. Do not be misled when reading our statements in this matter and above: above, by formal concept we understood a mental concept distinguished from an objective one; in this matter, however, by intellect or formal concept we intend both the mental concept and the objective concept formally taken.

Although genus signifies the whole essence of species, it does not follow that there is one essence of the diverse species of which it is the same genus, because the unity of genus proceeds from indetermination or indifference itself. It is not that what is signified by genus is one nature numerically in diverse species, with another thing supervening upon it as a difference determining it, as form determines matter, which is one numerically. Rather, genus signifies a certain form, but not determinately this or that form; difference expresses it determinately, and the form expressed by difference is none other than that which was signified indeterminately by genus. Therefore the Commentator says in II Metaphysics that prime matter is called one through the removal of all forms, but genus is called one through the commonness of the signified form. Hence it is clear that, when the difference is added and the indetermination which was the cause of the unity of genus is removed, species diverse in essence remain.

In the fourth part of this chapter he intends to exclude the following objection: whatever has one genus has one essence; diverse species have one genus; therefore diverse species have one essence. This is false, because species differ essentially. The major is proved from the fact that, according to what was said above, genus states the whole essence of species. And although this objection could easily be solved by saying that species have the same essence generically but not specifically, nevertheless, because the argument seeks a deeper difficulty, it was necessary to respond from a higher principle. For this objection was introduced to conclude that diverse species have the same essence absolutely, and not merely generically, as is clear from the assumed middle term: those whose whole essence is one have the same essence absolutely; the whole essence of diverse species of the same genus is one; therefore diverse species of the same genus have the same essence absolutely. The minor is clear from the fact that genus states the whole essence of species and is one in them.

To exclude this objection, he explains how genus is one and intimates the following distinction. Something signifies one in two ways: in one way through the position of one determinate thing signified; in another through the indifference or indetermination of several things imported. Genus does not signify one in the first way, but in the second. That signifies one in the first way whose signification, taken in itself, is one certain and determinate nature, as human being signifies humanity, which is a certain and determinate nature, namely human nature. But what signifies one in the second way has as its signification not one determinate nature, but several natures indeterminately. Thus animal, signifying sensitive perfection or nature, does not signify any certain and determinate nature or form: for no form in the universe is the sensitive soul, but each is bovine, leonine, human, and so on. Hence it is said in VII Physics, text XXXI, that many things lie hidden beside genus; in X Metaphysics, text XXIV, that the nature of genus is diverse in species; and in I On the Soul, that the account of animal is different in each animal. Genus is therefore one in the second way. Thus, according to the distinction given, the form of the argument says that those whose whole essence is one in the first way have the same essence absolutely, but not those whose whole essence is one in the second way, as in the present case. For genus unites the whole essence of species only with the unity of indetermination.

It should also be noted that the text introduced a difference between the unity of genus and the unity of prime matter for greater clarity regarding the foregoing; the Commentator also gives this difference in XII Metaphysics, commentary XIV. Here note that one can speak of matter in two ways. In one way, as a certain universal whole referring to this or that matter as subjective parts; in this way it is not now under discussion, for the judgment concerning its unity is the same as the judgment concerning the unity of any universal. In another way, one can speak of it taken alone in itself, neither as universal nor particular, nor as it exists in this species or that; the Commentator and St Thomas speak of it there and here in this way. The unity of matter taken in this way and the unity of genus therefore differ in that the unity of matter is numerical unity founded upon a determinate thing, while generic unity is not numerical unity but unity of indetermination, founded upon diverse natures indeterminately. When you hear that the unity of prime matter is numerical unity, understand this negatively, not positively.

For something is called one numerically in two ways, namely positively and negatively. That is numerically one positively which is one through the position of a numerical property or difference, as Socrates; in this way prime matter in itself is not numerically one, because it includes no individual property. That is numerically one negatively which, since it is not a universal, is not numerically many. This is what includes no distinguishing feature in itself whereby it could have plurality and number. In this way prime matter in itself is numerically one, and this numerical unity is founded upon a determinate entity, namely matter, which includes no distinguishing feature, since it has been stripped of every actuality whose function is to distinguish. Therefore the Commentator says that matter is one through the removal of all forms, because it has its unity negatively, from the fact that it does not have distinctive forms. Genus, however, is not numerically one, either positively or negatively, properly speaking. For numerical unity, both positive and negative, is founded upon a certain and determinate thing, which is not found in genus: genus states several natures and things from which it can be numbered.

That genus is one with the unity of indetermination is also clear from the fact that the several natures imported by genus are united in its signification only because it signifies them indeterminately. Animal unites horse, ox, lion, and so on in itself because it does not explain determinately which of them possesses sensitive perfection. Hence the Commentator says there that genus is one through the commonness of the signified form, that is, because it signifies forms commonly and not determinately. Thus it is clear how the authority introduced serves St Thomas’s purpose. If matter and genus differ in this, that the unity of matter is founded on the negation of forms upon a determinate entity, while genus is one only because it signifies several things commonly, it follows that genus is one only through indetermination. This was the intended conclusion.

And because, as was said, the nature of species is indeterminate with respect to the individual, just as the nature of genus is indeterminate with respect to species, it follows that, just as what is genus, insofar as it is predicated of species, implicitly, though indistinctly, includes everything that is determinate in the species, so what is species, insofar as it is predicated of an individual, must signify everything essential in the individual, though indistinctly. In this way the essence of species is signified by the name human being; hence human being is predicated of Socrates. But if the nature of species is signified with the precision of designated matter, which is the principle of individuation, it will have the mode of a part; and in this way the name humanity signifies it. For humanity signifies that whereby a human being is human. Designated matter, however, is not that whereby a human being is human, and so it is in no way contained among those things from which a human being has that it is human. Since humanity in its understanding includes only those things from which a human being has that it is human, it is clear that determinate or designated matter is excluded or cut off from its signification. And because a part is not predicated of the whole, humanity is predicated neither of human being nor of Socrates. Hence Avicenna says that the quiddity of a composite is not the composite itself whose quiddity it is, although the quiddity itself is also composite. Thus humanity, although composite, is not a human being; rather, it must be received in something which is designated matter. But because, as was said, the designation of species is through forms, while the designation of the individual with respect to species is through matter, a name signifying that from which the nature of genus is taken, with the precision of the determinate form perfecting the species, signifies the material part of the whole, as body is the material part of a human being. A name signifying that from which the nature of species is taken, with the precision of designated matter, signifies the formal part; therefore humanity is signified as a certain form. It is called the form of the whole, not as though it were added to the essential parts of matter and form, as the form of a house is added to its integral parts, but rather as a form which is the whole, embracing form and matter, though with the precision of those features through which matter is naturally designated. Thus it is clear that the essence of a human being is signified by the name human being and by the name humanity, but in different ways, as was said. The name human being signifies it as a whole, insofar as it does not cut off the designation of matter but implicitly and indistinctly contains it, just as genus contains difference and therefore the name human being is predicated of individuals. But the name humanity signifies it as a part, and contains in its signification only what belongs to a human being insofar as it is human, cutting off every designation of matter; hence it would not be predicated of human individuals. For this reason the name essence is sometimes found predicated of a thing: Socrates is said to be a certain essence; and sometimes it is denied, as when we say that the essence of Socrates is not Socrates.

In this fifth and final part of the chapter he compares specific essence with the individual according to totality, partiality, predicability, and formality.

For clarity regarding these points, it should be noted that, just as it was said above of generic essence that it can be signified in the mode of a whole and in the mode of a part, so now it is said that specific essence can be taken as signified by a name of first intention in the mode of a whole and in the mode of a part. In the mode of a whole, for example, human essence is signified by the term human being; in the mode of a part, that same essence is signified by the term humanity. The same essence, signified in the other way, differs from itself in this respect: what is signified in the mode of a whole implicitly includes individuals, whereas what is signified in the mode of a part excludes them from its signification. This is explained by an example. Since human being signifies one possessing human nature, it implicitly includes under “one possessing” all human individuals: for possessing human nature is any human individual. But since humanity signifies that whereby a human being is human, it excludes everything other than humanity from “that whereby”; nothing other than humanity is that whereby a human being is human. Therefore, since individuating principles are other than humanity, as was said above, it follows that humanity excludes individuating principles from its signification and consequently excludes individuals, which cannot be understood without individuation, just as species cannot be understood without difference. And since a part as a part is not predicated of its whole, while every predicate taken directly has the character of a whole, essence signified in the first way, that is, in the mode of a whole, is predicated directly of individuals, whereas essence signified in the mode of a part is not at all. Hence “Socrates is a human being” is true, while, properly speaking, “Socrates is humanity” is false. Thus the proportion of specific essence to the individual is already clear in three respects: totality, partiality, and predicability.

As to formality, the text explains the difference introduced between generic essence signified in the mode of a part with respect to species and specific essence signified in the mode of a part with respect to the individual. They differ in that the former is the material part of the species, while the latter is the formal part of the individual. The reason is that the former, namely generic essence, is compared with the other part of the species as matter to form and as the perfectible to its perfection, since the designation or determination of genus to species is made through difference, which is taken from the specific form that perfects and completes generic perfection. The latter, namely specific essence, is compared with the other part of the individual as form to matter and perfection to the perfectible, since the designation or determination of species to individuals is made through designated matter, which is evidently more imperfect than the specific form from which specific essence is taken. Therefore animality is the material part of a human being, while humanity is the formal part of Socrates; and it is said to be the form of the whole, not as though it were added, and so on.

To make these words clear, it should be noted that the form of the whole and the form of a part, as was seen in the second chapter, differ really—not as one form differs from another, for example whiteness from sweetness, but as whole and part. Hence it is said here that the form of the whole is not as though superadded to the parts, that is, it is not a form added to matter and form, as the form of a house is a form added to wood, stones, cement, and the other parts; rather, it is a form that is the whole, that is, the very composite resulting from the parts. When it is signified in the mode of a formal part, it is called the form of the whole, because it completely certifies, distinguishes, and determines the whole: for these are the conditions of a form. The summary of the remaining discussion is self-evident.