A Question Concerning the Union of the Incarnate Word

1. Whether this union took place in the person or the nature.
2. Whether in Christ there is only one hypostasis or supposit or two
3. Whether Christ is one in the abstract or two.
4. Whether in Christ there is only one act of existence.
5. Whether in Christ there is only one operation.

The First Article

The question concerns the union of the Incarnate Word. First it is asked whether this union took place in the person or the nature. It seems that it took place in the nature.

1. For Athanasius says that "as a rational soul and flesh are one man, so God and man are one Christ." But a rational soul and flesh are united in one human nature. Therefore God and man are united in one nature of Christ.

2. Furthermore, Damascene says in book III, "this produces an error of the heretics because they say that nature and hypostasis are the same thing." But this does not seem to be false because in whatever is simple, especially in God, supposit and nature are the same. Therefore what the heretics say is not false, namely that if the union took place in the person it is in the nature.

3. Furthermore, Damascene says in book III that the two natures of Christ are unchangeably and unalterably united to each other. But a union of natures seems to signify a natural union. Therefore the union took place in the nature.

4. Furthermore, in all those things in which the supposit has something beyond the nature of the species, whether an accident or individual matter, it is necessary that the supposit differ from the nature, as is clear from the Philosopher in book VII of the Metaphysics. But if the union of human nature to the Word did not take place in the divine nature, it would not pertain to the nature of the species of the Word Himself; therefore it would follow that the supposit of the Word should be something other than the divine nature of the Word, which is impossible. Therefore it seems that the union should be in the nature.

5. Furthermore, every union terminates in a unity which is posterior to that union. But the unity of the person of the Word, since it is eternal, is not posterior to the union which took place "in the fullness of time." Therefore the union did not take place in the person.

6. Furthermore, union signifies a certain addition; hence a union cannot take place in something which is perfectly simple. But the person of the Word, since He is truly God, is perfectly simple. Therefore a union cannot come to be in the person of the Word.

7. Furthermore, two things which do not belong to the same genus cannot be united in something, for a single thing is not made out of a line and whiteness. But human nature differs from divine nature much more than those things which differ by genus. Therefore the union of human and divine nature cannot take place in one person.

8. Furthermore, the person and the nature of the Word differ only according to the mode of understanding, insofar as relation of origin is signified in the person of the Word but not in the nature. But through the relation of origin the Word is not referred to the human nature but to the Father. Therefore the person of the Word and His nature are related in the same way to the nature assumed. Therefore if the union took place in the person it would have taken place in the nature.

9. Furthermore, the Incarnation inspires us to love God Incarnate. But we ought not to love one divine person more than another because love should be the same for those whose goodness is the same. Therefore the union of the Incarnation took place in the nature common to the three persons.

10. Furthermore, according to the Philosopher in book II of On the Soul, "for living things, to live is to be." But in Christ life is twofold, namely human and divine. Therefore there is in Christ a twofold act of existence and consequently a twofold person, for an act of existence belongs to a supposit or a person. Therefore the union did not take place in the person.

11. Furthermore, as the form of a part is compared to matter, so the form of the whole is compared to a supposit. But the form of a part cannot exist except in its own matter. Therefore the form of the whole, which is a nature, cannot exist except in its own supposit, which is a human person. In the same way the divine nature is in the divine person. Therefore if there were two natures it would be necessary that there be two persons.

12. Furthermore, everything that is truly predicated of something can stand in place of it. But divine nature is truly predicated of the person of the Word; therefore it can stand in its place. Therefore if the union took place in the person, it can truly be said that the union took place in the nature.

13. Furthermore, everything which is united to something is united to it either essentially or accidentally. But human nature is not united to the Word accidentally because it would thus retain its own personhood and there would be two persons. For every substance being joined to another retains its own singularity as clothes to the wearer or a horse to its rider. Therefore the human nature is joined to the Word essentially, as pertaining to the essence or nature of the Word. Therefore the union took place in the nature.

14. Furthermore, nothing which is comprehended by another thing extends itself to anything outside that thing, as what is confined to a place is not outside that place. But a supposit of any nature is comprehended by that nature; hence it is called a thing of nature. Thus an individual thing is comprehended by the species just as the species is comprehended by the genus. Therefore since the Word is a supposit of the divine nature, it cannot extend itself to any other nature so that it would be a supposit of that nature, unless a single nature is produced.

15. Furthermore, a nature is related to a supposit through a more formal, simpler and constitutive mode. But human nature cannot be related to the person of the Word in this way. Therefore the person of the Word cannot be the person of the human nature.

16. Furthermore, according to the Philosopher an action is attributed to a supposit or person, because actions belong to individuals. But in Christ there are two actions, as Damascene shows in book III. Therefore there are two persons. And therefore the union did not take place in the person.

17. Furthermore, person is determined to be distinct by uniqueness of nature. Therefore if the union were in the person, it would follow that the union should be in the nature.

But on the contrary Augustine says in the book, On the Faith to Peter, "the truth of the two natures in Christ remains belonging to the one person."

2. Furthermore, To Orosius says, "We know there are two natures in the one person [1] of the Son."

Response. It must be said that to clarify this question it is necessary to consider first what a nature is, second what a person is and third in what way the union of the Incarnate Word took place in the person, not in the nature. Now it should be observed that the word "nature" is taken from "nascendo"-"to be born." [2] Hence nature was said first of all to mean the very "being born" itself-the birth of living things, namely animals and plants. Afterwards the word "nature" was applied to the principle of the aforementioned birth. Because the principle of this kind of birth is intrinsic, the word "nature" was further employed to signify the more interior principle of motion, according to what is said in book II of the Physics, that nature is a "principle of motion in that in which it is essentially, not accidentally." And since natural motion especially in generation terminates in the essence of the species, the essence of the species which the definition signifies is further called "nature." Hence also Boethius says in the book On the Two Natures that nature is "the specific difference informing each thing." Concerning our question, nature is taken in this way.

To understand what a person is, it must be considered that if there is any thing in which there is nothing other than the essence of the species, the very essence of the species will be an individually self-subsisting thing. Thus in this kind of thing, the supposit and the nature will be really the same, differing only logically, namely insofar as it is appropriately said that nature is the essence of the species but a supposit insofar as it subsists through itself. But if there is a thing in which there is some other thing, beyond the essence of the species which the definition signifies, whether an accident or individual matter, then the supposit will not be altogether the same as the nature but will have something in addition to nature, as appears particularly in those things which are composed of matter and form. And what was said concerning a supposit must also be understood concerning a person in a rational nature, since a person is nothing other than a supposit of a rational nature as Boethius says in the book On the Two Natures, that "a person is an individual substance of a rational nature." Therefore it is clear that nothing precludes things from being united in a person which are not united in nature. For an individual substance of a rational nature can have something which does not pertain to the nature of the species, and this is united to it personally, not naturally.

Therefore that a human nature was united to the Word of God in the person, not in the nature, must be taken in this way: namely that it does not pertain to the divine nature but pertains to His person insofar as the person of the Word joined a human nature to Himself by assuming it. But doubt and discord arise concerning the mode of this conjoining.

For we see that in creatures one thing is joined to another in two ways, namely accidentally and essentially. So Nestorius and before him Theodore of Mopsuestia maintained that a human nature was conjoined to the Word accidentally, namely according to the indwelling of grace. They held that the Word of God had been united to the man-Christ as someone dwelling in him as in His own temple. But we see that every substance conjoined to another accidentally, retains its own proper singularity separately, as clothes being put on a man or a house containing an inhabitant; hence it follows that such a man would have his own singularity which is his personhood. Therefore it follows according to Nestorius that in Christ the person of the man was distinct from the person of the Word and that one should be one son of man and the other the Son of God; hence he did not confess the Blessed Virgin to be the mother of God but the mother of a man.

But this is altogether absurd. Firstly, sacred Scripture speaks in one way about men in whom the word of God dwelt by grace and in another way about Christ. For it says about others that the word of the Lord came to such and such a prophet, but about Christ it says, "the Word became flesh," that is, man, as if the Word Himself personally were a man. Secondly, the Apostle's letter to the Philippians (2:7) calls this union an emptying of the Son of God. But it is manifest that the indwelling of grace does not suffice to explain an emptying, otherwise an emptying would not only be fitting to the Son but also to the Father and the Holy Spirit, about Whom the Lord says (John 14), "He will remain with you and will be in you;" and of Himself and the Father, "We will come to him and make our dwelling with him." For this reason and many others, the aforementioned error was condemned at the Council of Ephesus.

Certain men, maintaining with Nestorius that the human nature had been accidentally united to the Word, wanted to avoid the duality of persons which Nestorius held. They asserted that the Word assumed to Himself a soul and body not united to each other, so that a human person, of body and soul, would thus not be constituted. But from this follows the greater incoherence that Christ was not truly man, since the essence of man consists in the union of soul and body. And therefore this error too was condemned under Alexander III at the Council of Tours. [3]

Others accepted the opposite, maintaining that the human nature was united to the Word essentially so that one nature or essence was, as it were, conflated from the divine nature and the human nature. For this reason, Apollinarius of Laodicea asserted three teachings, as Pope Leo says in a certain letter to the Constantinopolitans. The first of these teachings was that a soul was not united in Christ, but the Word had been united to flesh in place of the soul so that thus one nature was made from the Word and flesh, as in us one nature comes to be from the soul and the body. In this teaching, Apollinarius followed Arius. Now since the Gospel writings explicitly speak about the soul of Christ, as in John 11, [4] "I have the power of laying down my soul," the second teaching arises in which Apollinarius maintains that there is a sensitive soul in Christ, but not a rational one-the Word was in place of the intellect for the man-Christ. But this is unfitting because according to this account, the Word would not have assumed a human nature but a bestial one, as Augustine argues against him in the Book of Eighty-Three Questions. His third teaching was that the flesh of Christ "was not taken from a woman but was made from the Word having been changed and converted into flesh." But this is absolutely impossible because the Word of God, since He is truly God, is altogether unchanging. Hence on account of this teaching, Apollinarius was condemned at the Council of Constantinople and Eutyches, who followed Apollinarius' third teaching, was condemned at the Council of Chalcedon.

Thus if the union did not take place in the person but only through indwelling, as Nestorius maintained, then nothing new happened in the Incarnation of Christ. But it is altogether impossible that the union took place in the nature, as Apollinarius and Eutyches held. Since the species of things are like numbers, in which things added or subtracted vary the species, as is said in book VIII of the Metaphysics, it is impossible that any nature perfect in itself should receive the addition of another nature; if it were to receive it, it would not be the same nature but another. Now the divine nature is most perfect, and similarly human nature has the perfection of its own species. Hence it is impossible that one should be joined to the other by a natural union. And if it were possible, what would be constituted from the two would be neither divine nature nor human. Thus Christ would be neither man nor God, which is unfitting. Therefore it follows that the human nature was united to the Word neither accidentally nor essentially, but substantially insofar as substance signifies hypostasis, hypostatically or personally.

Among created things, no example of this union is closer than the union of the rational soul to the body, as Athanasius sets forth. It is not an example insofar as the soul is the form of the body, since the Word cannot be a form in matter, but insofar as the body is the instrument of the soul, not an extrinsic or adventitious one, but a proper and conjoined one. Hence Damascene says that human nature is an instrument of the Word. But it would be more similar still as Augustine says in Against Felicianus: "If we should imagine, as most people would, a universal soul to be in the world, which forming changeable matter to its own uses, would make a person one with itself."

Nevertheless all examples of this kind are deficient because the union of an instrument is accidental, but in Christ there is a certain singular union above all modes of union known to us. For just as God is His very own goodness and His own existence, so also He is unity itself through His Essence. Therefore just as His power is not limited to these kinds of goodness and existence which are in created things, but He can create new kinds of goodness and existence unknown to us, so also by the infinity of His power He can create a new mode of union, so that a human nature is united to the Word personally, not accidentally, although for this reason no sufficient example may be found in created things. Hence Augustine says in a letter To Volusianus concerning this mystery, "If an explanation is sought it is not surprising, if an example is demanded, it is not singular; let us give to God the power to do whatever we acknowledge we cannot investigate. For in such cases the whole intelligibility of the created thing is the power of the creator." Also Dionysius says in chapter two of On the Divine Names, "According to us Jesus is a divine composition," that is, union, "which is ineffable to every word and unknown to the mind, even to him foremost among the most august angels."

1. To the first objection therefore it should be said that the similitude is not in the fact that from a soul and flesh there is one nature of man but in the fact that one person is constituted. [5]

2. To the second objection it should be said that although in divine things nature and supposit or person do not differ really, they do nevertheless differ logically, as was said. Since there is one same thing subsisting in the human nature and the divine nature but not one same essence composed from the two, so it is that the union took place in the person to whose meaning it pertains to subsist, and not to the nature which signifies the essence of the thing.

3. To the third objection it should be said that the natures are indeed united in Christ, not in a nature but in a person. This is apparent from the very fact that the natures are said to be united unchangeably and unalterably.

4. To the fourth objection it should be said that the heretics, arguing that if the union took place in the person then consequently it took place in the nature, did not consider the person to be one thing and the nature another thing, either in reality or in the mind. Therefore they were deceived.

5. To the fifth objection it should be said that something is properly said to be united with respect to a union, just as it is said that something is one with respect to a unity. Therefore a union is not understood to terminate in the divine person insofar as it is one in itself from eternity, but insofar as it was united to a human nature in time. So the union according to the mode of understanding precedes the person, not inasmuch as it is one but inasmuch as it is united.

6. To the sixth objection it should be said that union is not said to take place in the divine person as if the divine person Himself were constituted from two things themselves united to each other. For this would contravene His most perfect simplicity. But the union is said to have taken place in the person insofar as the divine person, simple, subsists in two natures, divine and human.

7. To the seventh objection it should be said that two things which are different according to genus are not united in one essence or nature. Nevertheless nothing prohibits them from being united in one supposit, just as an essence is not made out of a line and whiteness but still they are found in one supposit.

8. To the eighth objection it should be said that the person of the Son of God can be considered in two ways: in one way, according to a common meaning of person, as it signifies a certain subsisting thing. And according to this way, the union took place in the person according to the meaning of person just mentioned. In another way, the person of the Son can be considered with respect to that which is proper to the person of the Son, namely the relation by which He is referred to the Father. But the union of two natures is not considered according to the meaning of this relation.

9. To the ninth objection it should be said that just as the Incarnation adds no goodness to the divine person, so also it adds no lovability to Him. Hence the person of the Incarnate Word is not to be loved more than the person of the Word simply, although he is to be loved for another reason. In any case, this reason is included under the universal goodness of the Word. For this reason it does not follow that if the union of the Incarnation took place in one person and not in another that therefore one person ought to be loved more than another.

10. To the tenth objection it should be said that an act of existence belongs both to the subsisting person and to the nature in which the person subsists, as it were having existence according to that nature. Therefore the act of existence of the person of the Incarnate Word is one on the part of the person subsisting, and not on the part of the nature.

11. To the eleventh objection it should be said that nature is not related to supposit in the same way as form is related to matter. For matter is not constituted into existence except through a form, and therefore a form requires determinate matter which it makes to be in act. But a supposit is not only constituted through the nature of a species but can also have certain other things. Therefore nothing prohibits a nature from being attributed to a supposit of another nature.

12. To the twelfth objection it should be said that divine nature is predicated of a divine person on account of the identity of the thing and not according to the propriety of the mode of signifying. Therefore it is not necessary that when one is supposed so also is the other, because although it is true that in divine things "person generates," it is not true that "essence generates."

13. To the thirteenth objection it should be said that a human nature was united to the Word neither accidentally nor even essentially as pertaining to the divine nature of the Word, but substantially, that is, hypostatically, as pertaining to the hypostasis or person of the Word.

14. To the fourteenth objection it should be said that the person of the Word is included under the nature of the Word and cannot extend itself to something beyond it. But the nature of the Word by reason of its infinity comprehends every finite nature. Therefore when the person of the Word assumes a human nature it does not extend itself beyond the divine nature but rather takes what is within. Hence it is said in the letter to the Philippians 2:6-7 that "Although He was in the form of God, the Son of God emptied Himself," not laying aside the greatness of the form of God but assuming the smallness of human nature.

15. To the fifteenth objection it should be said that just as the nature of the Word is infinite, so also the person of the Word is infinite. Therefore the divine nature of the Word corresponds as an equal to the very person of the Word in Himself, but human nature corresponds to the Word insofar as He became man. Hence it is not necessary that the nature be simpler and more formal than [6] the Word in Himself. But it is simpler and more formal than that man who is the Word made flesh, and it constitutes him insofar as he is man.

16. To the sixteenth objection it should be said that an action belongs to a supposit according to some nature or form. Therefore not only are actions diversified according to the diversity of supposits but also according to the diversity of nature or form, just as also in one and the same man it is one action to see and another to hear, on account of diverse powers. Hence in Christ there are two actions on account of two natures, although there is only one person or hypostasis.

17. To the seventeenth objection it should be said that a person is indeed substance distinct by uniqueness pertaining to dignity, not insofar as a substance signifies an essence or nature but insofar as it signifies a hypostasis.

The Second Article

Secondly it is asked whether in Christ there is only one hypostasis or supposit, or two. It seems that there is not only one.

1. Augustine says in the book Against Felicianus, "In the mediator between God and men, the Son of God is one thing and the son of man is another." But nothing which is one according to supposit or hypostasis is one thing and another. Therefore Christ is not one according to supposit or hypostasis.

2. Furthermore, Augustine says in the book On the Trinity that in Christ "God is both on account of God assuming and man is both on account of the man assumed." But nothing which is one according to supposit or hypostasis is two such that it could be called both. Therefore in Christ there is not only one hypostasis or supposit.

3. Furthermore, the human nature in Christ is a certain substance. But it was not a universal substance because a universal substance is not outside the soul. [7] Therefore it was a particular substance. But a particular substance is a hypostasis. Therefore the human nature in Christ was a hypostasis. But the human nature in Christ is something beyond the hypostasis of the Word of God. Therefore in Christ there is another hypostasis beyond the hypostasis of the Word of God and so in Christ there is more than one hypostasis.

4. Furthermore, the word "man" is said univocally of Christ and Peter. But when it is said of Peter, it signifies nothing other than something composed of a rational soul and body. So also when it is said of Christ. But beyond the soul and body there is in Christ a hypostasis or supposit of the Word of God. Therefore in Christ there is one hypostasis or supposit of the human nature and another hypostasis or supposit of the divine nature. Thus in Christ there is not only one hypostasis or supposit.

5. Furthermore, nothing infinite can be contained in a finite nature. But the supposit or hypostasis of the Word of God has infinity. Therefore it cannot be contained in a human nature which is finite. But every supposit is contained in the nature of which it is a supposit. Therefore the supposit which is the Word of God cannot be the supposit of the human nature, but is necessarily His own supposit. Therefore in Christ there is some other supposit beyond the supposit which is the Word of God. Therefore in Christ there are two supposits or hypostases.

6. Furthermore, just as genus is related to species, so species is related to individuals. But the same species cannot be in different genera. Therefore one individual cannot be in different species. But a hypostasis is an individual substance and likewise a supposit. Therefore there cannot be one hypostasis or supposit of human nature and divine nature, which are not of one species.

7. Furthermore, just as in the Trinity there is one nature in three persons, so in Christ there are two natures in one person. But the three persons are one on account of the unity of nature, according to John 10:30, "I and the Father are one." Therefore Christ is two on account of a duality of natures. But it cannot be said about anything which is one according to supposit or hypostasis, that it is two. Therefore Christ is not one according to supposit or hypostasis.

8. Furthermore, Christ, insofar as he is the Son of God, has something in common with the Father, but insofar as he is called the son of man has nothing in common with the Father. Therefore in Christ the Son of God is one thing and the son of man is another. Therefore Christ is not one according to supposit or hypostasis.

9. Furthermore, that which is of itself incommunicable does not seem of itself to be able to become communicable, just as neither can what is of itself impossible become possible, as the Commentator says in book X of the Metaphysics. But human nature insofar as it is in Christ is of itself incommunicable since it is something particular. Therefore it cannot be communicated to a supposit of divine nature. Therefore there cannot be one same supposit of human and divine nature.

10. Furthermore, every single thing is reduced to those things of which it consists. If, granting an impossibility, it were given that the Word of God laid aside His human nature, the human nature would at that moment have its own hypostasis and supposit. Therefore, still united, it has its own hypostasis and supposit. Therefore in Christ there is not only one hypostasis or one supposit.

11. Furthermore, nature does not depend more on supposit than supposit on nature. But a supposit of human nature could not be assumed by the Word of God unless human nature itself were assumed. Therefore neither could human nature be assumed unless a supposit of human nature were assumed. Now the one assuming is not the one assumed. Therefore the supposit of human nature is not the very supposit of the Word of God. Therefore in Christ there are two supposits.

12. Furthermore, the soul and body in Christ were not of lesser virtue or dignity than in us. But in us the hypostasis or supposit is constituted from a composition of soul and body. So also in Christ, but not the supposit or hypostasis of the Word of God, which is eternal, whereas the aforementioned union is temporal. Therefore in Christ there are two supposits or two hypostases.

13. Furthermore, in Christ there are three substances: a body, a soul and God. But the soul is not a supposit of the body. Therefore God is not a supposit of human nature.

14. Furthermore, according to Porphyry, an aggregation of particular properties, which are impossible to find in another thing, makes an individuation. But in Christ there was an aggregation of particular properties pertaining to his human nature which cannot be found in another thing. Therefore they made an individuation, but not an individuation of the Word of God, which is not receptive of accidents. Therefore in Christ there is an individual or supposit other than the supposit of the Word of God. Therefore in Christ there are two supposits.

15. Furthermore, one thing cannot be made from things among which there is no proportion. But there is no proportion between the divine nature, which is infinite, and the human, which is finite. Therefore one hypostasis or one supposit cannot be made from two natures.

16. Furthermore, generation terminates in a supposit; for a particular is what is generated. But in Christ there is a twofold birth, namely temporal and eternal. Therefore in Christ there is a twofold supposit and not only one.

17. Furthermore, the Word of God assumed a body and soul, not as separated but as united. But a supposit of human nature is nothing other than a soul and body inasmuch as they are united. Therefore in Christ there is another supposit beyond the supposit of the Word of God.

18. Furthermore, the same thing cannot be simple and composed. But a supposit of human nature is composed because human nature is composed. For a supposit cannot be more simple than the nature of which it is a supposit. Therefore since the supposit of divine nature is simple, there is in Christ another supposit beyond the supposit of divine nature.

But on the contrary Damascene says in book III, "In the Lord Jesus Christ we recognize one hypostasis."

2. Furthermore, among things that differ by supposit, one thing is not predicated about the other. Therefore if in Christ there were one supposit of man and another of God, it could not be said that man is God or God is man: this is erroneous. Therefore in Christ there is not one supposit of God and another of man.

Response. It should be said that certain men, wanting to avoid the heresy of Nestorius, who maintained that there are two persons in Christ, asserted that in Christ there is one person but two hypostases or two supposits. They said that this man, referring to Christ, is a supposit and a hypostasis of human nature but of not divine nature, because what is called "this man" signifies nothing other than a certain particular substance composed of soul and flesh. Nevertheless they said that the human hypostasis or supposit pertained to the person of the Word because it was assumed by the Word. And this is the opinion which is given first in the sixth distinction of the third book of the Sentences.

But firstly those who maintained this were ignorant of proper linguistic expression. For a hypostasis is nothing other than an individual substance which is also signified by the word "supposit." Boethius says in the book On the Two Natures that "person is an individual substance of a rational nature." Therefore it is clear that there cannot be a hypostasis of a rational nature unless it is a person. But it is manifest that human nature is a rational nature. Hence if in Christ there were a proper hypostasis of a human nature or a proper supposit beyond the hypostasis or supposit of the Word of God, it follows that there would be a proper person of a human nature in Christ beyond the hypostasis of the Word. And this position does not differ from the position of Nestorius.

Secondly if it is given that person adds, above hypostasis even in a rational nature, some uniqueness pertaining to dignity, just as some are said to have a persona as if having a dignity, it would follow that the union of human nature to the Word took place only in something accidental, that is, in some uniqueness pertaining to dignity-which Nestorius also held. Hence it must be observed that this is a heresy condemned at the fifth council celebrated at Constantinople, where it was written thus: "If anyone attempts to introduce two subsistences or two persons into the mystery of Christ and says one person is according to dignity and honor and adoration, as Theodore and Nestorius being foolish wrote, let him be anathema. For the Holy Trinity did not receive an addition of person or subsistence when the Word of God, one of the Holy Trinity, was incarnated."

Therefore so that it can be known what ought to be affirmed in such questions and what ought to be denied, it should be considered that words pertaining to individuation are either words of primary meaning, such as "person" or "hypostasis," which signify things themselves, or they are words of secondary meaning, such as "individual," "supposit" or words of this kind, which signify the intention of individuation. Certain of these pertain to the genus of substance alone, such as "supposit" and "hypostasis," which are not predicated of accidents. Examples of these would include both a person of a rational nature and even a thing of nature according to the understanding of Hilary. But certain words pertain to individuation in each genus, such as "individual," "particular" and "singular" which are even said to be in accidents.

It is proper to a substance that it subsist in and through itself, whereas it is proper to an accident to exist in another. And therefore those words which pertain to the individuation of substance only have reference to those things which subsist in and through themselves. For this reason they are not predicated of parts of substances because these exist not in themselves but in a whole, although they might not be in a subject. Nevertheless some words pertaining to individuation can be predicated of parts universally, in substances as well as in accidents. For it cannot be said that this hand is a person or hypostasis or supposit, but it can be said that it is a particular, singular or individual thing. For although a hand pertains to the genus of substance, because it is not a complete substance subsisting in itself, it is not called a hypostasis or supposit or person. Thus because the human nature in Christ does not subsist through itself separately but exists in another, that is, in the hypostasis of the Word of God-not however as an accident in a subject, nor properly as a part in a whole, but through an ineffable assumption-therefore the human nature in Christ can be called an individual or particular or singular thing. But it cannot be called either a hypostasis or a supposit, just as it cannot be called a person. Hence it is affirmed that in Christ there is only one hypostasis or supposit, namely of the divine Word.

1. To the first objection it should be said that both human things and divine things are predicated of Christ. Concerning that about which they are predicated, he is one and the same. But considering that according to which they are predicated, he is one and another, as Augustine says in the first book of On the Trinity, because divine things are predicated of Christ according to the divine nature but human things according to the human nature. Therefore when it is said that in Christ the Son of God is one thing and the son of man another, the difference must not refer to that about which both are predicated, which is the one supposit of both filiations, but to that according to which it is predicated. Therefore Augustine adds in the same work, "I say another thing by reason of the difference of substance," that is, of nature, "and not another thing by reason of the unity of person."

2. To the second objection it should be said that divine nature is predicated of Christ but human nature cannot be predicated of him, as neither can it be predicated of Peter with whom Christ is univocally man. [8] Hence it cannot be said that Christ is two or both, as if he were two natures. But a supposit of human nature is indeed predicated of Christ though it does not add to the number of the supposit of the divine nature, as has been shown. Hence it follows that when Christ is said to be both, it is understood materially, just as when it is said that "a wall and a roof are a house" because both come together in one house. So also Augustine says in the book Against Felicianus that "one and the same man is taught to be both body and soul."

Or it can be said that what is said to be "both" must refer to the number of words signifying two natures. For the man-Christ is called both God and man just as also God the Word is called God and man. And this is what is meant by "God is both on account of God assuming," because this word "God" is predicated of both God and of man. And this is what is meant by "man is both on account of the man assumed," because this word "man" is predicated of both.

3. To the third objection it should be said that it does not suffice for the meaning of hypostasis or supposit that something be a particular in the genus of substance, but it is required further that it be complete and subsisting in itself, as has been said.

4. To the fourth objection it should be said that univocation and equivocation are understood insofar as the meaning of a word is the same or not the same. But the meaning of a word is that which the definition signifies. And therefore equivocation and univocation are understood according to signification and not according to supposition. Therefore this word "man" is said univocally of Christ and Peter because in both cases it signifies one nature, namely human, composed of soul and body. But in Christ an eternal supposit is supposed that is not supposed in Peter.

5. To the fifth objection it should be said that it belongs to the supposit or hypostasis of the Word of God to be infinite according to the divine nature. But according to the human nature it is fitting for it to be within human nature. Hence Dionysius says in chapter I of On the Divine Names that "He Who supersubstantially exceeds every order according to every nature was made within our nature."

6. To the sixth objection it should be said that the name of a species signifies a nature as does also the name of a genus. Hence if one species were in different genera, it would follow that one nature would be two natures. But an individual signifies something which does not pertain to nature, and therefore it is not contrary to the meaning of an individual that the same individual be a supposit of two natures.

7. To the seventh objection it should be said that the divine nature is altogether really the same as any of the three persons, and therefore the three persons can be said to be one. But human nature is not altogether really the same as its own supposit, and therefore human nature cannot be predicated of the supposit. Thus Christ cannot be said to be two on account of two natures.

8. To the eighth objection it should be said that the Son of God has divine nature in common with the Father but not hypostasis or person. Now the son of man has neither hypostasis nor nature in common with God the Father. So from this it does not follow that between the Son of God and the son of man there is a distinction in person or hypostasis, but only in nature.

9. To the ninth objection it should be said that the human nature assumed by the Word of God, insofar as it is individual, cannot be in many things. And in this way it is said to be incommunicable. But from the very fact that it is a nature, it may be in any supposit 10. To the tenth objection it should be said that as long as the human nature is united to the Word, it does not have its own supposit or hypostasis beyond the person of the Word since the human nature does not exist of itself. If it were separated from the Word, it would have not only its own hypostasis or supposit but also its own person because it would already exist through itself, just as also a part of a continuous body, while it is not divided from the whole, exists in potency, not in act unless a division is made.

11. To the eleventh objection it should be said that nature is included in a supposit but not vice versa. Therefore a supposit could not be assumed unless a nature were assumed. But the converse could occur.

12. To the twelfth objection it should be said that the union of soul and body in Christ is more noble than in us from the very fact that the union in Christ does not terminate in a created supposit but in the eternal supposit of the Word of God.

13. To the thirteenth objection it should be said that the soul is united to the body as its form to constitute human nature. But in Christ divinity is not united to humanity because the union did not take place in the nature, as was said above. Therefore the same argument does not apply.

14. To the fourteenth objection it should be said that an aggregation of proper accidents sufficiently proves the individuation of the human nature in Christ, but not that it has the notion of a supposit or hypostasis, because it does not exist through itself.

15. To the fifteenth objection it should be said that the union of human nature to the person or hypostasis of the Word in Christ did not take place in such a way that the human nature is made equal to the person of the Word as if comprehending it, or in such a way that the human nature is exceeded by the person of the Word according to some certain proportion, because it still remains that the person of the Word exceeds human nature into infinity. Nevertheless He Who is an infinite remove from us did not separate Himself from us, but rather in a certain ineffable way, a divine person joined a human nature to Himself in the unity of a hypostasis. Indeed the infinite power of the One assuming works more efficaciously to a greater union.

16. To the sixteenth objection it should be said that generation terminates in a supposit as to what is generated and in a nature as to that which is received through generation. Hence form is called the terminus of generation. And because generations and movements are distinguished according to termini, there are thus two births of Christ according to two natures but one who is born on account of the unity of the supposit.

17. To the seventeenth objection it should be said that the soul and body united constitute a supposit and hypostasis, if what is composed from both exists through itself, which does not happen in the case proposed.

18. To the eighteenth objection it should be said that Christ is simple according to the divine nature but composed according to human nature, as is clear from chapter I of Dionysius' On the Divine Names.

The Third Article

Third it is asked whether Christ is one in the abstract or two. And it seems that he is two in the abstract.

1. For Augustine says in book I of On the Trinity, "Because the form of God assumes the form of man, God is both and man is both." But both cannot be said to be in that which is only one thing. Therefore Christ is not only one.

2. Furthermore, just as in three divine persons there is one nature, so in one person of Christ there are two natures. But three divine persons are called one on account of the unity of nature. Therefore Christ ought to be called two on account of two natures.

3. Furthermore, Augustine says in Against Felicianus, "The Son of God is one thing and the son of man is another." But wherever there is one and another, there are two. Therefore Christ insofar as he is Son of God and son of man is two.

4. Furthermore, that which is one in supposit becomes qualitatively different of its very self, successively on account of different accidents, just as the aged Socrates came from a very boy himself. But just as an accidental difference makes qualitatively different, so a substantial difference makes another thing. Therefore if the same supposit could be changed into another thing by one substantial difference, it would be one thing and another. So for the same reason if the same supposit has two substantial differences simultaneously, it will be one thing and another simultaneously. But to have two natures is to have two substantial differences since nature is the specific difference informing each thing, as Boethius says in the book On the Two Natures. Therefore Christ is simultaneously one thing and another. So he is two simultaneously.

5. Furthermore, each thing is that which is truly predicated of it. But the word "man" predicates one thing of Christ and the word "God" predicates something else. For both words predicate what they signify. Just as the word "white" signifies nothing other than a quality, according to the Philosopher, so the word "man" signifies nothing other than humanity, which is other than deity which the word "God" signifies. Therefore Christ is one thing and another and so is two.

6. But he [9] said that the word "man" includes in its signification a supposit of humanity, which is not other than a supposit of divinity. And therefore Christ insofar as he is God and man is not one thing and another. But on the contrary, it is not required for the diversity of things that they be diverse according to everything that is in them. Rather it suffices that they be diverse according to anything. For a man and an ass belong to the genus of animal but differ as rational and irrational. Therefore in order for the word "man" to predicate one thing about Christ and the word "God" another, it suffices that the nature signified be one thing and another, even should it be the same supposit.

7. Furthermore, insofar as he is God, Christ is one thing by an uncreated unity, but insofar as he is man he is another one thing by a created unity. But a created unity and an uncreated unity are two unities. Therefore Christ is two.

8. Furthermore, it follows: if Christ is only one, then he is this thing and not another thing. Now from the refutation of the conclusion, it follows that if it cannot be said that Christ is man and not another thing then it cannot be said that Christ is only one. But it is false to say that Christ is only man. Therefore Christ is man and something else, and so Christ is two.

9. Furthermore, the proposition, "Christ is God and man," is a complex proposition since it involves a compound predicate. But every such proposition predicates a plurality. Therefore Christ is not only one but more than one.

10. Furthermore, according to the Philosopher in book VIII of the Metaphysics, out of a plurality of things of which one thing is not in potency to another, there comes not some one thing but many. Hence when I say, "man is a two-footed animal," one thing is predicated about man, but not when it is said, "Socrates is a white and musical." But humanity and divinity are not related as potency and act. Therefore when it is said, "Christ is God and man," not one thing but many are predicated. And so Christ is not one but two.

11. Furthermore, a supposit is said to be that which is subsisting. But a different way of subsisting belongs to the son of man and to the Son of God. Therefore there is one and another supposit, and so Christ is not one but two.

12. Furthermore, difference leads to plurality. But there is the greatest difference between human nature and divine nature. Therefore Christ is most certainly two.

13. Furthermore, no one thing can participate in incompatible properties. But incompatible properties belong to Christ, such as to be eternal and born in time, infinite and circumscribed by place and other things of this kind. Therefore Christ is not one but two.

14. Furthermore, Christ is a man. But a man is humanity because the essence of a thing is the same as that thing whose essence it is, as is said in book VII of the Metaphysics. Therefore Christ is his own humanity. He is also his own divinity. Therefore since humanity is not divinity, it follows that Christ is not one but two.

But on the contrary, Christ is not two persons, nor two hypostases, nor two supposits, as is clear from what has been said above. Nor is he two natures, because human nature is not predicated of Christ. Therefore Christ is not two.

2. Furthermore, according to Boethius every single thing is, because it is one in number. If therefore Christ is not one, it follows that he is not a being.

3. Furthermore, those things which are predicated of each other are not numerically different. But man and God are predicated of each other in Christ. Therefore Christ is not two insofar as he is God and man.

4. Furthermore, the union of divine and human nature in Christ is greater than the union of accident and subject, as was mentioned above. But an accident and a subject are one in number according to the Philosopher. Therefore much more is Christ one insofar as he is God and man.

5. Furthermore, Athanasius says about Christ that "although he is God and man, nevertheless Christ is not two but one."

6. Furthermore, what was made one is one just as what was made white is white. But according to Hugh in the book On the Sacraments, the Word of God was made one with man. Therefore Christ existing as God and man is one.

7. Furthermore, a unity is that by which each thing is said to be one. But after the unity of the Trinity, the greatest unity is the Incarnate Word. Therefore Christ is most certainly one.

Response. It should be said that the masculine gender, because it is formed, usually refers to a person. [10] Therefore it is manifest that Christ is not two in the masculine but one, because in Christ there are not two persons but one. Now certain men, maintaining that there is one person in Christ, asserted that in Christ there are two supposits or hypostases, one of the Son of God and another of the son of man. Hence although they did not say that Christ was two in the masculine on account of the unity of person, they nevertheless said that he was two in the abstract on account of the duality of supposits. But because this opinion contravenes the truth of the faith, as was mentioned above, once this opinion has been set aside, it should be considered, given that in Christ there is one hypostasis and one supposit, whether Christ ought to be said to be two in the abstract or one.

To clarify this question it should be considered that "one" is said denominatively of that which has unity, just as "white" of that which has whiteness or of that which is the subject of whiteness. And for the same reason "many" is denominatively said of a multitude and "two" of a duality. Because "one" is converted with "being," just as being is accidental and substantial, so something is said to be one or many, either according to accidental form or according to substance. According to accidental forms something is said to be many which is the subject of different accidental forms, whether successively or simultaneously: successively, just as Socrates sitting is different from himself standing; hence Socrates, insofar as he is first standing and afterwards sitting, is successively many: simultaneously, as Socrates, insofar as he is white and musical, is many. For that "a two-footed animal," which is predicated of Socrates, is one and not many, derives from the fact that one of the terms is compared to the other as potency to act, as is said in book VIII of the Metaphysics. But white and musical are not thus related to each other. Therefore Socrates insofar as he is white and musical is many, not simply but relatively, just as according to accidents something is said to be, relatively and not simply. Now according to substance something is said to be one or many simply, just as being is. But according to the Philosopher in book V of the Metaphysics, "substance" is predicated in two ways: namely of a supposit, which is not predicated of another thing, and of a form or nature of a species, which is predicated of a supposit. And this, simultaneously one and many, in mere creatures [11] is not indeed a single essence of different supposits. Nor again is there found in mere creatures any one supposit having two natural substances; this is singular in Christ. And a single essence of different supposits is singular in the three divine persons. Therefore it is manifest that Christ can be in some way one because he is one supposit and in some way many or two because he has two natures-much more than Socrates of whom one is predicated insofar as he is one subject and many insofar as he is white and musical.

But it should be considered which of these is said simply and which is said relatively. It should be observed that something is said simply and properly to be such which is such in its very self. But something is said to be in its very self according to the whole more than according to a part, because a part is not simply the same as the whole. And since the whole is a reciprocal term, it has reference to identity. Therefore what belongs to something according to the whole belongs to it more simply than what belongs to it according to a part. Hence if a thing were born to belong to something according to the whole and a part, if it belongs to it only according to the part, it is said to belong relatively and not simply, just as if an Ethiopian who has white teeth were called white. But it is different concerning that which was not born to be in something except according to a part, just as someone is called curly simply if he has curly hair. [12] It is manifest then that a supposit is signified by way of the whole and nature by way of a formal part, as is clear from what has been said. Therefore since one and many can refer both to a supposit and a nature, it is manifest that if any one supposit has many substantial natures, it will be one simply and many relatively-a sign of which is that those things which differ by supposit, and are one in that which in itself pertains to nature, are many simply but one with respect to genus or species. So conversely if one supposit should have many natures, it would be one simply and many relatively. Therefore because Christ is one supposit having two natures, it follows that he is one simply and two relatively.

1. To the first objection it should be said that what Augustine says, "God is both and man is both," must not refer to a duality of supposit according to which Christ would be said to be two simply, but to the duality of natures signified by two words "God" and "man"-namely because human and divine things are predicated of God, and these divine and human things are predicated of man.

2. To the second objection it should be said that each of the divine persons is altogether really the same as the divine essence, and nothing is added by a person beyond the divine nature which would introduce some substantial diversity. Therefore because three persons belong in the divine nature, they are one simply. But the human nature is not similarly related to the divine person. Hence the same argument does not apply.

3. To the third objection it should be said that in Christ the son of man is said to be one thing and the Son of God another because each name predicates a different nature-not because there are different supposits, in which case it would follow that Christ was two simply. For since a human supposit and a divine supposit are different, it would be necessary that they differ substantially.

4. To the fourth objection it should be said that different forms inhering either at the same or different times do not make another thing simply, if the same supposit remains. They only make another thing simply on account of the supposit, when the supposit is different.

5. To the fifth objection it should be said that in the word "white" is understood whiteness and the subject of whiteness. But whiteness is understood determinately and the subject of whiteness indeterminately. For when we say "white," we understand something informed with whiteness, but it is not determined what that thing is as determined by form. Similarly when I say that "man" or some other thing is said substantially, one having humanity is understood. But because something is determined to a species by its own essence or nature and not by its own accidents, something having humanity is more determinately understood in the word "man," than something having whiteness is understood in the word "white." And because that which is determinately understood by a word is properly the thing signified by the word, the word "man" signifies a supposit of humanity more than the word "white" signifies a subject of whiteness. Nevertheless the word "man" does not signify a supposit of humanity insofar as it is determined in its singularity, but only insofar as it is determined in the nature of a species. Therefore because the supposit of the human nature and the divine nature in Christ-though separated insofar as it is taken in its own singularity-is one and the same in two determined natures, it is one simply in its very self but two relatively, insofar as it has two natures.

6. To the sixth objection it should be said that regarding the fact that something be other than another thing, it is not necessary that it be distinguished according to the whole. But regarding the fact that something be other than another thing simply, it is necessary that it be distinguished according to itself.

7. To the seventh objection it should be said that from the fact that a created unity is not an uncreated unity, it cannot be concluded that Christ is two, but that he subsists in a twofold unity, just as he subsists in a twofold nature.

8. To the eighth objection it should be said that if Christ were one thing which is man and not something other than man, it would follow that he would be one altogether, that is, both according to nature and according to supposit. But from the fact that Christ is one thing which is man and another thing which is God, it follows that he is two according to nature, but not that he is altogether and simply two, on account of the unity of the supposit.

9. To the ninth objection it should be said that that about which many things are predicated, in a proposition which involves a compound predicate, is not necessarily many simply. Otherwise Socrates would be many simply if he should be white and musical. Therefore it is not necessary that if Christ is God and man that he be two simply.

10. To the tenth objection it should be said that according to nature, a single thing does not come to be from the divine nature and human nature. Nevertheless they come together in one supposit, on account of which Christ is one.

11. To the eleventh objection it should be said that just as it is not necessary that Christ be two sons because he was born in one way from his Father and in another way from his mother, [13] so also it is not necessary that he be two according to supposit because of a diverse way of subsisting, by which he subsists insofar as he is God and insofar as he is man.

12. To the twelfth objection it should be said that the great difference between human nature and divine nature shows that there cannot be one nature of God and man. But from this it does not follow that there cannot be one supposit of both natures.

13. To the thirteenth objection it should be said that nothing prohibits contrary and incompatible differences from being in the same thing in different ways, just as man with respect to his soul is incorruptible and with respect to his body is corruptible. And so also in Christ certain opposites come together, such as a human nature and a divine nature.

14. To the fourteenth objection it should be said that it is false to say, "a man is humanity." For the same thing is not altogether signified by both, because as the Philosopher says in book VII of the Metaphysics, what a thing is, namely the essence of each thing, is the same as that thing in the case of those things which exist through themselves but not in the case of those things which exist through accidents. Therefore whatever thing there is, to which something can be added beyond the nature of its own species, is not altogether the same as its own essence. But many things add to a man beyond the essence of the species. Hence it is clear that a "man" and "humanity" are not altogether the same. For "humanity" is said to be that by which someone is a man, and thus it includes in its signification those things alone which pertain to the essence of the species. But a "man" is said to be he who has humanity, in whom there are also many other things beyond the essence of the species.

The Fourth Article

Fourthly it is asked whether in Christ there is only one act of existence. It would seem not to be the case.

1. For in Christ there is a divine act of existence and a human act of existence, which cannot be one because an act of existence is not predicated univocally of God and creatures. Therefore in Christ there is not only one act of existence but two.

2. Furthermore, a thing's act of existence corresponds to whatever form is present. For it is one thing to be white and another to be curly. But in Christ there are two forms because although he was in the form of God, he took the form of a slave, as is said in Philippians 2:6-7. Nevertheless he did not lay aside the form of God. Therefore in Christ there is a twofold act of existence.

3. Furthermore, according to the Philosopher in book II of On the Soul, for living things, to live is to be. But in Christ life is twofold, namely human which was taken away through death, and divine which cannot be taken away through death. Therefore in Christ there is not only one act of existence but two.

But on the contrary whatever is one simply is one according to the act of existence. But Christ is one simply, as was shown above. Therefore in him there is one act of existence.

Response. It should be said that in a certain way the argumentation of this question and the previous one are the same because something is said to be one and a being, in the same way. For an act of existence is properly and truly predicated of a subsisting supposit. For accidents and non-subsisting forms are said to exist insofar as something exists through them, just as whiteness is called a being insofar as through it something is white. Now it should be considered that some forms are those through which something is a being not simply but relatively, as are all accidental forms. But some forms are those through which a subsisting thing has an act of existence simply, because they constitute the substantial act of existence of the subsisting thing. Now in Christ the subsisting supposit is the person of the Son of God, which is a substance simply through the divine nature. But it is not a substance simply through the human nature because the person of the Son of God existed before the assumed humanity; nor was the person in any way augmented or more perfect by the human nature assumed. But the eternal supposit is a substance through the human nature insofar as he is "this man". Therefore just as Christ is one simply because of the unity of the supposit, and two relatively because of the two natures, so he has one act of existence simply because of one eternal act of existence of an eternal supposit. But there is also another act of existence belonging to this supposit, not insofar as He is eternal but insofar as He became man temporally. Although it is not an accidental act of existence, because "man" is not predicated accidentally of the Son of God, as was shown above, nevertheless it is not the principal act of existence of his own supposit but a secondary one. If in Christ there were two supposits, then each supposit would have a principal act of existence proper to itself, and thus in Christ there would be a twofold act of existence simply.

1. To the first objection it should be said that the act of existence of the human nature is not the act of existence of the divine. Nevertheless it should not be said that Christ is two simply, according to the act of existence, because the eternal supposit does not regard both acts of existence equally.

And the other objections should be answered similarly.

The Fifth Article

Fifthly it is asked whether in Christ there is only one operation. And it would seem so.

5. For Dionysius says in a Letter to Gaius, the Monk, "God, having become man, associated with us by a certain new operation of God and man." But there would be no new operation of God and man unless there were one and the same operation of both. Therefore in Christ there is only one operation of God and man.

2. Furthermore, those things which come together in the same operation do not diversify the operation. But divinity and humanity in Christ come together in the same operation, just as divine power and a bodily touch come together in the healing of leprosy.

3. Furthermore, an action proceeds from an agent through some principle of action, just as heating proceeds from fire through heat. Therefore it is necessary that the multiplicity and the unity of an action be considered either on the part of the agent or on the part of the principle by which the agent acts. But the number of actions in Christ is not taken according to the principle by which an agent acts since thus there would be many more actions of Christ than two, according to the diversity of powers of the soul. Therefore it should be said that there is one action in Christ on account of one supposit acting.

4. Furthermore, one and the same action belongs to a principal agent and its instrument, just as to saw is an action of the carpenter and a saw. But the humanity in Christ was the instrument of the divinity in Christ, as Damascene says in book III. Therefore there is one and the same action of humanity and divinity in Christ.

5. Furthermore, it belongs to supposits to act. But in Christ there is no other supposit except the eternal supposit, about which it cannot be said that it acts by the power of human nature, since thus it would accept something from the human nature and would have existence and actuality through the human nature, since each thing acts insofar as it is a being in act. Therefore there is no action in Christ except that which is by the power of the divine nature. Therefore there are not two actions in Christ according to two natures, namely human and divine.

6. Furthermore, a supposit is more conjoined to a nature than an operation is. But the human nature in Christ does not have its own supposit because of union to the divine. Therefore much less does it have its own operation. Therefore in Christ there are not two operations.

7. Furthermore, operations belong to something conjoined. Hence the Philosopher says in book I of On the Soul that "if someone said that the soul knows, it would be like saying that it constructs and builds." But Christ is one person in whom humanity is conjoined to divinity. Therefore in Christ there is only one operation.

8. Furthermore, the first and primary operation of an intellectual nature is understanding itself. But understanding is not an operation which goes outside of the nature, but remains in the agent itself. Now to act belongs to a supposit. But in Christ there is only one uncreated supposit which is simple. Since therefore there cannot be a twofold intellection in one simple thing, it seems that in Christ there could not be two intellectual operations.

9. Furthermore, the operation of any thing follows its own property. But according to Damascene, the two natures in Christ communicate their own idioms to each other, that is, their own properties, on account of the unity of the supposit. For the same reason then there is a communication of operations, and so there are not distinct operations according to a distinction of natures.

10. Furthermore, all operations in one man are reduced to one first principle, namely the will, which moves all other powers to act. Similarly in Christ there is one first principle, namely his divinity by which his humanity is moved. And so the operations of the humanity are referred in him to the divinity just as to a first principle. Therefore in Christ there is only one operation.

11. Furthermore, just as a rational soul and flesh are one man, so God and man are one Christ, as Athanasius says. But an operation of the human body or rational soul is said to be a human operation. Therefore an operation of the divinity as well as of the humanity of Christ ought to be called a Christian operation. Thus there would only be one operation in Christ, just as there is one Christ.

12. Furthermore, every operation proceeds from some form or power. But a principal agent does not give any form or power to an instrument. Therefore an instrument does not have an operation insofar as it is an instrument. But the human nature in Christ was an instrument of the divinity, as Damascene says. Therefore the human nature in Christ does not have any operation. Thus in Christ there is only one operation, of divinity.

13. Furthermore, an action informs an agent. But in Christ there is only one supposit, namely the eternal supposit, which cannot be informed by a created operation. Since therefore it belongs to a supposit to act, it seems that in Christ there is not any created operation, and so there is only one uncreated operation.

14. Furthermore, the operation of one man is one. But Christ is one simply speaking, as was said above. Therefore in Christ there is only one operation.

But on the contrary, in the declaration of the Sixth Synod, it is said that "We glorify two natural operations, that is, a divine operation and a human operation, indivisibly, unchangeably, without mixture, inseparably in the same Lord Jesus Christ, our true God."

2. Furthermore, Damascene says in book III, "We say that there are two actions in our Lord Jesus Christ. For he has a divine action as One consubstantial with the Father and an action of human nature as one having become man."

3. Furthermore, just as in the Trinity there is one nature in three persons, so in Christ there are two natures in one person. But one operation belongs to the whole Trinity on account of the unity of nature. Therefore in Christ there are two operations on account of a duality of natures.

4. Furthermore, Boethius says in the book On the Two Natures that nature is that which can act and suffer. So an action follows nature. But in Christ there are two natures, therefore also two actions.

5. Furthermore, operation follows power, but power follows essence which is the nature of a thing. Therefore where there are two natures, there are two powers and consequently two operations. Thus in Christ there is not only one operation but two.

Response. It should be said that the unity and plurality of an action can be considered in two ways. In one way they can be considered on the part of the acting subject, and in this way the unity or plurality of an action is considered according to number, just as any other occurrence has unity or plurality counted on the part of the subject. For the vision or hearing of Socrates is different in number from the vision or hearing of Plato.

In another way the unity and plurality of an action can be considered on the part of the principle by which an agent operates. And in this way an action is said to be one or several according to species, just as vision and hearing are operations differing by species. For an action proceeds from an agent according to the nature of the power by which it acts. It does not matter that actions receive their species according to objects, because powers regard determined objects determinately.

Nevertheless it should be considered that if a power which is the principle of an action is moved by another superior power, the operation proceeding from it is not only an action but also a passion, namely insofar as it proceeds from a power which is moved by a superior power. But in man all powers of the sensitive part are moved in a certain way by the will as by a certain first principle. Therefore to hear, to see, to imagine, to desire and to get angry are all not only operations but also certain passions, proceeding from the motion of the will insofar as man progresses from his own will to the aforesaid. Therefore although in one man there might seem to be many actions differing specifically according to diverse powers and habits, nevertheless because all proceed from one first action of the will, it is said to be one action of a man. For instance, if one craftsman operates by many instruments, it would be said to be one operation of his.

So in this way some men maintained that in Christ there is only one operation so that the human nature in him is subjected to the divine and is moved by it. [14] And thus the action of the human nature in comparison to the divine has more the nature of a passion. Hence on account of the unity of the divine action they said that in Christ there is only one action. But this was said irrationally for two reasons: firstly because not every single power has dominion over its own acts, as what is moved by a superior does not act itself but rather is acted upon. Hence also the Philosopher says in book VI of the Ethics that sense is not the principle of any action. But the power which does have dominion over its own acts, namely the will, is moved by a superior, namely by God, and is not only acted upon but also acts. Because in Christ, according to his human nature, there is the created power of the will as well as a created intellect, since there is nothing lacking to him of those things which pertain to the perfection of human nature, it follows that the movement of the human will in Christ is an action and not only a passion. Otherwise he could not have merited according to his human nature.

Secondly, since the operation of any thing has species and unity from a first principle pertaining to the same nature, such as the will, from which all human actions have a unity, there is a certain intrinsic principle of human nature. And there are no actions that have a unity because of the fact that they are reduced to some first principle of another nature. Otherwise it would follow that there would be one action of everything because there is one first principle moving all things, namely God. Therefore although the human nature in Christ is moved by the divine, since there are two distinct natures, it is also necessary that there be two actions. Therefore if someone asserts that there is one action in Christ, it follows that there would be only one nature and only one will. Therefore this position was condemned as heretical at the Sixth Synod.

1. To the first objection it should be said that the operation of Christ according to humanity is said to be theandric, that is, of the God-man, insofar as the humanity of Christ acted by divine power. And because of this, the action of the humanity was a saving action, just as an instrument acts by the power of the agent. Thus it is said that a new action took place because it was a new thing that the humanity of Christ should be an instrument conjoined to divinity in the unity of a person-and not because from two actions there should be one composed action.

2. To the second objection it should be said that the divinity and humanity of Christ came together in the same operation without mixture because each nature did what is proper to itself in communion with the other nature, as is said in Pope Leo's letter. For example divine power healed leprosy, coexisting with the touch of a human body, which received its efficacy from the divine power.

3. To the third objection it should be said that in Christ all actions pertaining to human nature are reduced to one action on account of the unity of a connatural principle, namely the will. But the same argument does not apply to humanity and divinity, as has been said.

4. To the fourth objection it should be said that the human nature in Christ is not such an instrument that it is only acted upon, but is also a principle of action insofar as it has dominion over its own acts.

5. To the fifth objection it should be said that something acts by the power of another in two ways: in one way insofar as it is moved by that power, as natural heat acts in the power of the soul; in another way insofar as some agent uses the power of some instrument, as the soul sees by the power of the eye. And it is in the latter way that the eternal supposit acted by the power of the human nature.

6. To the sixth objection it should be said that a supposit is what is distinct from other things. Therefore if a human nature had a supposit of itself, it would resist personal union. But an operation does not signify any distinction, and therefore that conclusion does not follow.

7. To the seventh objection it should be said that operations belong to something conjoined through many things coming together into one nature. But the conjoining of divinity and humanity in Christ is not so. Hence the conclusion does not follow.

8. To the eighth objection it should be said that to understand is itself intrinsic to the intellect. But in Christ there are two intellects, namely the created and the uncreated. Therefore there is also a twofold understanding.

9. To the ninth objection it should be said that in Christ there is a communication of idioms-not that there is a mixture of natural properties but because the properties of both natures are predicated of the same supposit. And the communication of operations is the same because it is the same supposit to which the same divine and human operation is attributed.

10. To the tenth objection it should be said that the will is the connatural principle to the other powers of the soul, but divinity is not connatural to humanity. Hence the same argument does not apply.

11. To the eleventh objection it should be said that that similitude of which Athanasius speaks is considered with regard to the unity of person not with regard to the unity of nature. For soul and body come together in one person and in one nature, and therefore it is called one human operation. Now divine nature and human nature come together in one person, but not in one nature, and consequently not in one action.

12. To the twelfth objection it should be said that an agent does not always give to an instrument a new form or power resting in itself. Still the instrument, insofar as it is moved by the agent, attains a certain intentional power through the influence of the agent, which moves through the instrument into the effect.

13. To the thirteenth objection it should be said that just as vision informs a man through the eye's mediation, so also a created action informs an eternal supposit through the created nature's mediation.

14. To the fourteenth objection it should be said that Christ is one simply on account of the supposit. Nevertheless there are two natures in him. Therefore Christ is one agent, but there are two actions in him.


[1] Marietti has persona which seems necessary vs. Dondaine's natura.

[2] Cf. ST III, q. 2, a. 1, responsio.

[3] 1163.

[4] Really John 10:18.

[5] Cf. ST III, q. 2, a. 1, ad 2. 6>

[6] Marietti does not have Verbo secundum se, sed est simplicior et formalior.

[7] That is, second substance, or substance in the abstract, does not exist extra-mentally.

[8] Cf. ST III, q. 17, a. 1, responsio.

[9] The Philosopher, just mentioned in arg 5.

[10] "...[F]or the neuter gender signifies something unformed and imperfect, whereas the masculine signifies something formed and perfect" (ST III, q. 17, a. 1, responsio).

[11] Marietti's haec quidem in creaturis puris, non sunt simul unum et multa (Indeed in mere creatures these are not one and many at the same time) seems to be the lectio facilior vs. Dondaine's: hoc quidem in creaturis puris, simul autem unum et multa.

[12] Cf. ST III, q. 16, a. 8, responsio: Things "observed to exist in a part, are not predicated of the whole simply, i.e. without qualification, for we do not say that the Ethiopian is white but that he is white as regards his teeth; but we say without qualification that he is curly, since this can only belong to him as regards his hair." This argument points out a difference in word usage between English and Latin: one does not say that an Ethiopian who has white teeth is white [albus], but he does say that an Ethiopian is "curly" [crispus] who has curly hair because "curly" can only refer to hair.

[13] Cf. ST III, q. 35, a. 5, ad 3.

[14] Marietti has ea, giving "moved by it," which seems necessary vs. Dondaine's eo, which would give, "moved by him."