Disputationes metaphysicae

1. From what has been said hitherto against the preceding opinions, it seems to remain, as it were from a sufficient enumeration of the parts, that every singular substance is singular by itself, or through its own entity,¹ and needs no other principle of individuation besides its entity, or besides the intrinsic principles of which its entity consists. For if such a substance, physically considered, is simple, it is individual of itself and by its simple entity; but if it is composite, for example of matter and form united, then, just as the principles of its entity are matter, form and their union, so the same taken in the individual are the principles of its individuation; and these, since they are simple, will be individual by themselves. This opinion Aureolus held, in Capreolus, In II, dist. 3, q. 2; and Durandus holds it in substance, In II, dist. 3, q. 2. But Fonseca, reporting it, Metaphysics V, c. 6, q. 3, says in sect. 2 that it is the most involved of all, and that, if it is reduced to its true sense, it leaves the question unsolved. To me, however, it seems the clearest of all, and I think that both he and almost all the others finally fall into it, because in truth the foundation of unity cannot be distinguished from the entity itself. Whence, just as individual unity formally cannot add anything positive and real over the individual entity, because as regards this the reason is the same of it and of every unity, so the positive foundation of this unity, as regards the negation which it expresses, can add nothing positive, physically speaking, to that entity which is denominated one and individual; therefore that entity by itself is the foundation of this negation, and in this sense it is said by that opinion to be by itself the principle of individuation. For this opinion does not deny that in that individual entity the common nature can be distinguished by reason from the singular entity, and in this way² that the individual adds over the species something distinct by reason, which, according to metaphysical consideration, has the notion of an individual difference, as was said in the preceding section and as Durandus does not deny, but rather seems to suppose. But this opinion nevertheless adds (what properly pertains to the present question) that that individual difference does not have in the individual substance some special principle or foundation which is distinct in the thing from its entity; and therefore in this sense it says that each entity by itself is the principle of its individuation. This opinion, then, rightly explained, is true; but in order that it may become clearer we shall declare it one by one in all substantial things.

Through what prime matter is individuated

2. First, then, beginning from prime matter, it must be said that it is individual in the thing, and that the foundation of such unity is its entity by itself, as it is in the thing without anything extrinsic superadded. It is proved, because the matter which is under this form of wood is diverse in number from that which is under the form of water or of man; it is therefore individual and singular in itself. But the foundation of such unity in it is not the substantial form, nor order to this or that form, as was proved above against Durandus, because, whatever substantial form is varied, the same matter in number always remains, which, although it is actually united to this or that form, nevertheless of itself expresses a common and indifferent relationship to any form whatever which it can receive. Again, neither can quantity be the foundation of this individual unity of matter, as the same argument proves, if it is true that matter loses and acquires various quantities as the substantial forms are varied. Likewise, because according to the same opinion matter, prior in nature to receiving quantity, underlies the action of the agent inducing the form or quantity; but it does not underlie it except as individual and singular, because actions are about singulars. But if we hold that the same quantity is coeval with matter, the same argument can be accommodated, at least in order to the power of God; for God can take away this quantity from this matter and give another, or preserve it altogether without quantity; the same matter in number, therefore, would be without the same quantity in number; therefore quantity is not the foundation of such unity for matter itself; otherwise it could in no way retain its unity without it. And moreover there are all the common arguments made above: that substance is not individuated through an accident, nor through order to an accident; for matter is substance, although partial. Likewise that the individual substance is being per se. Likewise that the accident supposes its subject as it is in the thing, and consequently singular. Likewise that the individual difference is not distinct in the thing from the entity which it constitutes; whence neither can it be founded in a distinct entity.

3. Corollary.—And these reasons proceed a fortiori of any accidents or dispositions whatever of matter. Wherefore, when it is wont to be said by some that matter is individuated by the agent, in so far as its indifference to this form is individuated and restricted through dispositions, in order that it may be true in some way, it must be understood in a sound manner; because the agent, in order to act on matter, supposes it individual, and by its action cannot take away or change its individuation; otherwise it would destroy it and introduce another in its place; nor can it happen that what in the thing is already individual should receive another individuation in itself through the addition of some entity. Matter, therefore, is said to be limited or determined by the agent through dispositions to this form, not in order to being, but in order to the action of the agent itself and the reception of the form; and this either only per accidens and as it were negatively, because through the dispositions impediments to this action and to the introduction of this form are removed, or also in some way per se and positively, if these dispositions are naturally necessary for the eduction or union of this form with this matter; for this is controverted among philosophers and does not matter to the present difficulty, because this adaptation through dispositions is as it were extrinsic to matter itself, which, even taken in the individual, is of itself capable of any form whatever; and if dispositions are required, it is rather by reason of the form than by reason of matter itself; this, therefore, matters nothing to its intrinsic individuation.

4. Some objections are satisfied.—You will say: this matter is not distinguished from another except through quantity, because, since it is pure potency, it cannot be distinguished except through act. Likewise matter essentially regards form according to its species; therefore this individual matter must be individuated through form, or through a relationship to this form. To the first the answer is that one matter is distinguished from another in order to site through quantity, but entitatively and really it is distinguished through its own entity, as was said above; because, just as matter of itself has something of entity, whether of existence or of essence, so by reason of that it has something of entitative actuality, through which it can be transcendentally distinguished from another. To the second the answer is: in the way in which matter essentially has a transcendental relationship to form, so this matter has this transcendental relationship to form, because it has this capacity and potency in number, and it is individuated through a relationship to form; but this very thing is to be individuated physically by itself, because its entity essentially includes this relationship. But it is not necessary that this individuation come about through the determination of the form (in which sense the argument would have to proceed in order to have any difficulty), because not only matter in the species, but also this matter in number, regards form in common as the adequate object of its capacity, even taken in the individual; and therefore it is not rightly said that matter is individuated through this form, but that it is individuated by an individuated relationship to form. Just as the visual power in the species expresses a relationship to colour in common, and in the individual similarly expresses a relationship not to this or that colour, but to colour in common; and therefore it is not properly individuated through this colour, although it is individuated with, or through, such a transcendental and entitative relationship to colour.

What the principle of individuation of the substantial form is

5. Secondly it must be said that the substantial form is this intrinsically through its own entity, from which, according to its ultimate grade or reality, its individual difference is taken. This conclusion can be proved by the same proportional reasons as the preceding, and can easily be confirmed from what was said above, especially from what was said in the first and second opinions. For first of all no accidents can be intrinsic principles individuating the substantial form, because such a form too, as it is this, is being per se, although incomplete, and pertains to the predicament of substance, and is placed under the specific notion of such a form, although reductively. Likewise this form either is simply and in every respect prior to accidents and their origin, or, if it supposes some in the genus of material cause, it does not express per se a relationship to them, but at most requires them as conditions or dispositions necessary for preparing the subject; therefore it can in no way be individuated by accidents. Next, matter by itself cannot be the intrinsic principle of individuating any form, because it is not the intrinsic principle of its entity; but the principle of unity is the same as the principle of entity, as has often been said, because unity adds no thing to entity, but a negation intrinsically accompanying it. The antecedent is evident, because matter is an intrinsic principle of the composite, because through its entity it composes it; but it does not so compose the entity of the form; it is not, therefore, its intrinsic principle. But with respect to those forms which depend on matter in becoming and in being, matter is a per se cause of the form in its genus, not as intrinsically composing it, but as sustaining it, which is a certain genus of causality as it were extrinsic; and in this way matter can be called the cause and principle of the individuation of such forms in its genus, from the principle posited, that the cause of entity is the cause of unity, and because matter does not cause a form except a singular and individual one; therefore by causing its entity it causes its individuation. Nevertheless, because the individual difference is predicated intrinsically of the individual thing, it is therefore not taken from causes in any way extrinsic to the individual thing itself, but from its intrinsic principle or entity; and therefore in this way matter cannot be the intrinsic principle of the individuation of forms. Which is declared a posteriori in order to the divine power: for this substantial form can be preserved without matter, and then, just as it retains its individual difference, so also its intrinsic principle of individuation; therefore matter is not an intrinsic principle of this kind. This is more manifest in the rational soul, in which, just as being is not caused per se by matter, so neither is unity or individuation, as St. Thomas noted, Contra Gentiles II, c. 75, in the solution of the first reason, and c. 81, at the beginning; therefore matter not only is not the intrinsic principle of the individuation of the soul, but not even its per se cause, although it is as it were a certain occasion that, such a body having been organized, God creates such a soul in it.

6. A small doubt.—But the difficulty is whether the form is individuated at least through matter as through the term to which it expresses a relationship. For in this there seems to be a difference between matter and form, that matter, because the same in number underlies several forms, cannot have an individual termination from the form which it regards; but form does not have that indifference, but is determined to actuating this matter, and therefore it can be individuated from this matter as from the term to which it expresses a relationship, as it is such a form. And so the Thomists commonly think, and so they understand St. Thomas in the places cited above and in others, where he says that form is individuated through matter. And in the same sense can be expounded what he says, sole question De Anima, a. 3, ad 13, that the principles of individuation of forms are not of their essence, but that this is true only in composites. But first of all the reason given has no place in the rational soul, which, remaining the same in number, can actuate diverse matters. For first it at the same time so actuates diverse parts of matter composing the same body that it is whole in each part; therefore it cannot be individuated through adaptation to the whole body and to its individual parts. But it presses more that it can successively inform diverse integral matters, as when through continual nutrition the whole matter into which the form was first introduced is little by little lost, and another new one is acquired and informed by the same form. Likewise it is accidental to nutrition itself that it be made from these or those foods, and yet thence it comes about that the soul afterwards informs this or that matter; therefore this too is contingent and accidental to it; it is not, therefore, individuated thence, nor is it of itself adapted to this matter in number.

7. Someone will perhaps say that this soul of itself postulates that at least in the beginning it be introduced into such matter, although afterwards it can leave it and inform another; and by this reason that it is individuated by that matter into which it is first introduced. But this first of all is said gratuitously; for, if the same soul can at diverse times naturally inform various matters, it is a sign that its informative power or aptitude for informing does not regard this matter in number as its adequate term. On what foundation, then, can it be said that of itself it postulates one matter in the beginning more than another, or regards one more intrinsically than another? Otherwise in the same way it could be said that matter by its nature postulated that it be created under those forms in number under which it was created, and that it was individuated by them, although afterwards it could be preserved under other forms; just as, therefore, this would there be said gratuitously, so also it is said without foundation of the soul. For suppose that that matter in number which the offspring acquires and informs through its own nutrition was previously under the form of the maternal blood from which in the beginning the body of the same offspring was formed; certainly, just as into that matter afterwards disposed through nutrition this form in number could be introduced, so also, if in the first formation it had been disposed by the power of the seed from the maternal blood, the same form could similarly have been naturally introduced into it; for no philosophical reason can be given why it could not; therefore this soul, even as this, is indifferent to informing several matters, whether in the beginning in production or afterwards in conservation.

8. A theological note.—Nor does it matter if someone says that these matters are judged one and the same because the change takes place little by little under dispositions and organization of the same notion; because this unity of matter or of body is rather according to external species and appearance than according to the true and physical entity of the body or matter. Add that, although it happened that the whole matter came about through the integral separation of one body and the conjunction of other matter, nevertheless the soul would naturally inform both; as it is probable will sometimes happen in the resurrection. As, if it happens that in this life two souls have informed altogether the same matters, a body from other matter can be given to one of them, which it will inform no less connaturally than if it consisted of the former matter. It is therefore a sign that this soul, as apt to inform, in no way regards determinately this matter, and consequently is not individuated by this matter, as it is this, even as by the term of its transcendental relationship, because it is not its adequate term. This soul, therefore, is individuated by itself and by virtue of its entity; and consequently because it intrinsically has such an individual aptitude for informing the human body, in the way in which we said a little before of the relationship of matter. And so Toletus teaches in particular of the rational soul, De Anima III, q. 18, concls. 2 and 3, who confirms this by the argument made above by us, that in assigning the principle of individuation one must stop at something which is individuated per se; therefore, if matter or quantity are said to be individuated per se, much more must this be said of the rational soul, which is per se subsisting and gives being to the others rather than receives it from them. The variety of bodies, therefore, is an excellent sign a posteriori of the distinction of souls, because it is as it were the occasion of producing diverse souls; it is not, however, the proper and intrinsic principle of their individuation.

9. But whether the reason is the same of all other substantial forms which depend on matter in being does not seem able to be judged by the argument just made, because these forms so inform this matter in number that they are altogether determined to informing it, nor can they naturally inform another matter distinct in number, since they cannot be separated from this, either all at once or little by little; which also proceeds of the souls of perfect brutes, if they are extended and divisible, as the common and perhaps more probable opinion holds (for if they are supposed to be indivisible, the argument made about rational souls will proceed in them); it can rightly be said, then, that the material substantial form is this intrinsically indeed through adaptation to this matter in number, but through the matter itself as through the term of this relationship. But nevertheless even in these material forms this cannot properly be said; because either in this matter in number are included the dispositions by which this matter is prepared by the agent for this form, or this prime matter alone according to its bare entity is understood; but in neither way can this be sufficiently understood or explained.

10. The first is evident, because matter with accidents cannot be the reason of the individuation of the form, even as the term of its relationship, because, since this relationship is transcendental and substantial, it does not include accidents in its primary and per se term. Likewise, because, if we suppose that the same dispositions are not in what is generated which preceded in what was corrupted, the arguments made above proceed, that the form prior³ in nature absolutely and simply informs matter bare of accidents; but it informs it as it is individual and singular; therefore in the same way it regards it according to its aptitude and individual adaptation. But if we suppose that the dispositions which were in what was corrupted remain in matter, then too the form does not inform matter as affected by accidents, although these are presupposed as necessary conditions, or perhaps only because they are left from the preceding alteration; therefore neither does this form as this regard accidents, but matter only. All the more because, although these accidents in number are varied, either little by little naturally or all at once supernaturally, and other similar ones are given, the same form in number will be preserved in the same matter; therefore this form as this in no way regards such accidents in number, so as to be individuated by them. Rather, even if we granted that this form requires these accidents in number, the form itself would not on that account be such in the individual on account of the accidents, but rather conversely the accidents would be required to be such on account of such a form, speaking a priori and simply, although as regards us, or in order to production or generation, such dispositions are the principle or occasion of distinguishing forms.

11. But the second, namely that neither can this prime matter purely taken be in this way the principle individuating the form, is proved, first, because this matter can be common to many forms, diverse either in species or in number; therefore as such it is not a sufficient principle individuating the form, because what is of itself common cannot as such be the principle of individuation. Secondly, on the side of the form itself, because, although this form once made in and from this matter cannot be in another on account of the dependence which it has on it—which dependence is such that neither can that form be naturally preserved without that genus of material causality, nor is there any natural way or mode by which this form could be transferred into another matter so as to be preserved by it—nevertheless, if the entity of such a form is considered according to itself, its intrinsic aptitude does not seem to be determined to informing this matter in number, so that it would intrinsically be unapt to inform naturally any other matter whatever distinct in number; therefore it does not receive its intrinsic individuation from this matter in number, even as from the term of its informative relationship or aptitude. The consequence is proved, because this matter is not the adequate term of that relationship, since the aptitude of this form according to itself could be exercised equally connaturally in another and another matter, if it were placed in any whatever. For that it is placed by natural causes only in this matter and not in another does not take away its intrinsic aptitude, nor does it make this matter its adequate term. As perhaps there is in the universe some portion of matter which has always been under the same form in number and always will be, and perhaps there is no natural way of varying it, and not on that account is the aptitude of matter of itself determined to such a form.

12. But the antecedent can be persuaded by many conjectures, which are common also to rational souls. The first, because by absolute power this form can be transferred into another matter and inform it; it is therefore a sign that there is in such a form an intrinsic natural aptitude for informing it, as far as depends on itself. The consequence is proved, because, although that action or transmigration of this form from matter to matter would be supernatural as regards its mode, nevertheless the term produced would be natural, for that composite of such form and matter would subsist naturally. The second: any other matter distinct in number is capable, as far as depends on itself, of any individual form whatever, even if it happens to be in another matter distinct in number; for one would think without foundation that the capacity of this matter in number is of itself limited to these forms rather than to those, because perhaps natural agents according to the natural order cannot effect in it those individual forms which they effect in other matters. Because, since matter of itself is pure potency and indifferent, such a determination cannot fittingly be attributed to it; that matter in number, therefore, which in fact is under this form of this horse would, as far as depends on itself, be capable of the soul of another horse distinct in number, which in fact informs another matter; therefore conversely that soul too is apt, as far as depends on itself, to inform this or that matter. The consequence is evident, because natural potency and act mutually correspond to each other; whence potency does not naturally regard any act except that which has a natural aptitude for informing it.

13. Thirdly, because, if this horse’s soul, for example, were apt of itself only to inform this matter in number, all the horses’ souls which could inform that matter in number at diverse times would have among themselves some real agreement which they would not have with the horses’ souls informing other matters, because all of them would have an aptitude for informing this matter in number, which other horses’ souls could not inform. And the same argument can be made in all the forms of water, fire and the like, namely that under the same species of the form of fire, for example, there would be a certain breadth of individuals regarding only this matter in number, and another breadth of others regarding that matter in number, and so of the others; and so under the specific concept there could be given an objective substantial concept common to many individuals of that species and not to others; which seems absurd, for that agreement, since it is real and substantial, will also be essential to such forms, and consequently the lowest species will be divisible through several essential differences, which involves an open repugnance. But this reason is more apparent than efficacious, because it can have some evasions and difficulties, which we shall touch on more conveniently in the following disputations; yet the other reasons are efficacious, which we shall confirm and declare more fully in the following section. The conclusion posited, then, remains sufficiently proved, that the intrinsic principle from which the individual difference of the substantial form is taken is the very entity of the form, in so far as of itself it has such an aptitude for informing matter; for all things extrinsic or distinct from the form itself have been excluded, so that it cannot be individuated by them; whence it comes about that the form is this not because it regards this matter, but only in so far as it has such an aptitude for informing matter.

By what principle substantial modes are individuated

14. I say, thirdly: a substantial mode, which is simple and in its own way indivisible, also has its individuation from itself, and not from some principle distinct from itself from the nature of the thing. It is declared by examples in the union, for example, of form to matter, or of matter to form, which I suppose from what is to be said below is a substantial mode. Likewise in simple subsistence; and the same would hold of existence, if it were a real mode of essence distinct from it from the nature of the thing. And so it is evident that the union which my soul now has to my body is one in number and individual, both because it is something real and existing in reality, and distinct from the nature of the thing from the soul; and also because it differs in number and not in species from the mode of union of another soul to its body; it therefore has its individual difference; therefore also some intrinsic principle or foundation of it; this principle, then, we say can be nothing other than the entity of the mode itself, whatever that entity may be. This can be proved, first, by the general reasons made, that each thing is one as it is, and that the negation which unity adds is immediately founded in the entity of the thing according as it is in itself; and finally because each simple entity is intrinsically such by itself, or is constituted in its being in our mode of understanding, and consequently is also distinguished from others by itself. Secondly it is proved by excluding other principles of this individuation; for, if there were any, it would most of all be this soul or this matter with respect to this union (to pursue the example begun; I omit accidents, because they have already been sufficiently excluded by the reasons made about matter and form); but this mode is not properly individuated from this matter and from this form; because, although this mode of union in the individual cannot be in another form on account of the special real identity which it has with this form, nor can it be made or preserved in another matter distinct in number, because it regards this not according to aptitude, but according to a certain actual notion which is adequately terminated at this matter, nevertheless this soul and this matter could be united by another union distinct in number. For it is not necessary that, if the union of this soul and matter is now dissolved and perishes, and again this matter and this form are united by God, they receive the same union in number which they had before. For although we grant that this can be done, of which some also doubt, there is no reason why it should be necessary, because in other modes of figure, of sitting, or similar ones, it is not necessary that the same in number be reproduced; indeed this is not natural. Those unions, therefore, can be distinguished in number in the same form with respect to the same matter; therefore the principle of its individuation is not sufficiently taken from this form or this matter; therefore it is necessary that such a mode have of itself the intrinsic foundation of its individuation, although according to it it regards this form and this matter by a transcendental relationship; because this is the nature of such a mode.

What is the principle of individuation of the substantial composite

15. Fourthly it must be said that in composite substance, as such a composite, the adequate principle of individuation is this matter and this form united among themselves, among which the chief principle is the form, which alone suffices for this composite, in so far as it is an individual of such a species, to be judged the same in number. This conclusion follows from the preceding and from what was said in sect. 4, and is consonant with the opinion of Durandus and Toletus treated above; and in substance Scotus and Henry do not dissent, nor all the nominalists; Fonseca too does not dissent, Metaphysics V, q. 5, although he says that it is an improper expression when we say that this matter and this form are physical principles of individuation, because neither this form, nor this matter, nor both together could be added to the specific nature of man so as to constitute this man with it, and because also this matter and this form are individual, constituted from their specific natures and proper principles of individuation. But in these reasons he turns aside from the physical notion to metaphysical composition; for when this matter and this form are said to be physical principles of the individuation of this composite, they are not compared to the common specific nature, but to the physical composite which they compose; and therefore it is not necessary that they be added to the common specific nature, but that they compose it by composing the individual in which it is included. Whence according to the same physical constitution such principles are simple, nor do they have others by which they are physically individuated, but they are individuated by themselves, as has been declared. It is not, therefore, an improper expression, but true and proper, because the intrinsic principles of individuation are the same as the intrinsic principles of entity, as has often been said, because individuation follows entity as it is a certain negation; but as it includes the positive it is the entity itself and adds nothing to it; but this matter and this form united among themselves are the intrinsic principles of the whole entity of the composite substance of which we are treating; therefore they are also the intrinsic physical principles of individuation. And it is confirmed, for matter and form taken absolutely are the physical principles of the species of composite substance and of its specification; therefore this matter and this form will be the physical principles of the individual and of its individuation. And in the same way it can be concluded that neither by itself, but both together, are this adequate principle. Because this composite, in order to be altogether and completely the same in number, requires not only this form or this matter, but both together, and, whichever is varied, the composite does not remain simply and in every respect the same in number as it was before, because in some respect its entity has been varied; therefore matter and form are the adequate principle of the numerical unity of the whole composite as such. And it is confirmed by the reason given, because the principles of unity are the same as those of entity; but this matter and this form are the adequate intrinsic principle of this composite entity; therefore also of unity and individuation.

16. Inference.—An objection is solved.—And hence it is also evident that this same union in number is required for the perfect unity of such a composite, because in its own way it concurs intrinsically to its constitution; for the entity of the composite intrinsically includes not only the entity of matter and form, but also their union among themselves; therefore, when the union is varied, the entity is in some respect varied, and consequently the unity of the composite itself; it is therefore required for perfect unity and individuation; by this reason, then, this union too could be numbered among those things which complete the perfect principle of individuation of the composite itself. It is not, however, as necessary as matter and form, because these are simply the essential principles of such a composite; but the union is as it were a required condition, or the causality of matter and form, as I said in tom. 2 of the Third Part, disp. XXXIV, sect. 2. Comparing also matter and form among themselves, the chief principle is the form, not only with respect to the specific nature, form being taken in the species, but also with respect to this individual, form being taken as individual; because this form is most proper to this individual, and because it is that which completes this integral substance in number; for this matter only begins it, and as far as depends on itself does not begin this more than another. Likewise because this form is the chief principle of being, and consequently is also the chief principle of distinguishing this substance from others; but the principle of unity is the same as the principle of being and of its distinction from others; therefore. You will say that form is the principle of specific distinction, because it makes things differ formally; therefore it cannot be the principle of numerical distinction; otherwise numerical distinction would be formal and essential. The answer is that form according to its specific and essential notion makes specific and essential difference, but individual form according to its entity makes entitative and numerical distinction. For Peter and Paul differ among themselves in number more because they have souls distinct in number than because they have distinct bodies. And from these things the last part of the conclusion is evident, which is also sufficiently proved from the common manner of speaking which we noted above; for he is simply judged the same man, not only according to appearance but also according to truth, who has the same soul in number, even if the body is changed. But the reason is that form is simply judged to constitute the species, and similarly this form this individual under such a species.

17. A question.—Answer.—But you will ask whether the individual difference is rigorously taken from the complete principle, namely matter and form, or from one only; for authors seem more frequently to think that it is taken from one only; for, since this difference is simple, it does not seem to be taken from the whole composite, nor from a double partial principle, but from one only which is simple. They differ, however; for some say that that principle is matter, as Cajetan and others; others say that it is form, as Scotus; and Durandus inclines to the same. And this latter is truer, the former foundation being supposed, namely that the individual difference is to be taken from one only of these principles. We speak, however, of the thing itself according to itself; for as regards us, who take our knowledge from material things, the distinction of individuals is often taken from matter, or from the accidents which follow upon matter, such as are quantity and other properties; but according to itself, just as the difference is to be taken from a substantial principle and not from an accidental one, so among the substantial principles themselves it is to be taken from that which is chief and more proper and the ultimate constitutive of the thing itself; but such is the form, as has been shown. Likewise this is true speaking of the individual of such a nature or species, as it is formally constituted in it. For which reason we said above that the supposit is one in number if it has one subsistence in number, even if the nature is not one, because the formal constitutive of the supposit is incommunicable subsistence, from which alone the individual notion of the supposit as such is to be taken; but conversely we said that the unity and individual difference of the singular thing, as constituted under such a species or substantial essence, is to be taken from the substantial nature, which formally constitutes such an individual. In this manner, then, we say in the present case that the individual difference of this man formally taken, as he is an individual of the human species, is taken from this soul. But if we speak of this composite as it is perfectly and in every respect one, it will more truly be said that its individual difference is taken from its whole entity, and so from the adequate physical principle, which includes matter and form, so that in this way it is verified also of that whole composite that it is individuated by itself, or through its own entity; for through it it has identity simply in itself and diversity from every other. Nor is it unfitting that a difference which according to the metaphysical concept is simple, that is, not composed of genus and difference, should be taken from a physically composite entity or nature, in so far as it is one and is conceived after the manner of one individual nature.

18. By what complete spiritual substances are individuated.—Finally, from what has been said it is sufficiently evident what is to be said of immaterial substances, in which too individual differences are found, as we have shown; whence, since in them there is only a simple complete substantial entity, it is evident that in them there can be no other principle of individuation besides the very entity of each thing, which is such of itself and is distinguished per se from others. And in this all agree who confess that these substances are individual, by whatever reason they declare their individuation. But those who say that it belongs of itself to such a specific spiritual nature teach much more and a fortiori that they are individuated through their entities, as is evident from Capreolus, In II, dist. 3; Cajetan and others, I, q. 3, a. 3, and q. 50, a. 4; Soncinas, Metaphysics XII, q. 49; Javellus, q. 25; Ferrariensis, Contra Gentiles I, c. 21. But those who think that also in immaterial things individuation comes about through the addition of a difference necessarily also teach that it is to be taken from the substantial entity of the angel itself according to itself; because it is neither to be taken from accidents, nor is there anything else from which it could be taken; all of which have been sufficiently proved from what has been said. But the common argument, that if these substances differ through their entities they necessarily differ formally and essentially, has already been solved in a similar case of other forms. For those entities, however formal, can be altogether similar in essential notion; and then, although they are distinguished by themselves, the distinction is nevertheless numerical, because it is in entity, not in formal notion. But they are said to be distinguished by themselves not because they are not similar, but because one has of itself that it is not the other; for likeness does not exclude distinction, as will be said below.