QUESTION 2: OF THE MODE OF UNION OF THE WORD INCARNATE
Now we must consider the mode of union of the Incarnate Word; and,
first, the union itself; secondly, the Person assuming; thirdly, the
Under the first head there are twelve points of inquiry:
(1) Whether the union of the Word Incarnate took place in the nature?
(2) Whether it took place in the Person?
(3) Whether it took place in the suppositum or hypostasis?
(4) Whether the Person or hypostasis of Christ is composite after the
(5) Whether any union of body and soul took place in Christ?
(6) Whether the human nature was united to the Word accidentally?
(7) Whether the union itself is something created?
(8) Whether it is the same as assumption?
(9) Whether the union of the two natures is the greatest union?
(10) Whether the union of the two natures in Christ was brought about by
(11) Whether any merits preceded it?
(12) Whether the grace of union was natural to the man Christ?
Article 1: Whether the Union of the Incarnate Word took place in the nature?
Objection 1: It would seem that the Union of the Word Incarnate took place in
the nature. For Cyril says (he is quoted in the acts of the Council of
Chalcedon, part ii, act. 1): "We must understand not two natures, but one
incarnate nature of the Word of God"; and this could not be unless the
union took place in the nature. Therefore the union of the Word Incarnate
took place in the nature.
Objection 2: Further, Athanasius says that, as the rational soul and the flesh
together form the human nature, so God and man together form a certain
one nature; therefore the union took place in the nature.
Objection 3: Further, of two natures one is not denominated by the other
unless they are to some extent mutually transmuted. But the Divine and
human natures in Christ are denominated one by the other; for Cyril says
(quoted in the acts of the Council of Chalcedon, part ii, act. 1) that
the Divine nature "is incarnate"; and Gregory Nazianzen says (Ep. i ad
Cledon.) that the human nature is "deified," as appears from Damascene
(De Fide Orth. iii, 6,11). Therefore from two natures one seems to have
On the contrary, It is said in the declaration of the Council of
Chalcedon: "We confess that in these latter times the only-begotten Son
of God appeared in two natures, without confusion, without change,
without division, without separation---the distinction of natures not
having been taken away by the union." Therefore the union did not take
place in the nature.
I answer that, To make this question clear we must consider what is
"nature." Now it is to be observed that the word "nature" comes from
nativity. Hence this word was used first of all to signify the begetting
of living beings, which is called "birth" or "sprouting forth," the word
"natura" meaning, as it were, "nascitura." Afterwards this word "nature"
was taken to signify the principle of this begetting; and because in
living things the principle of generation is an intrinsic principle, this
word "nature" was further employed to signify any intrinsic principle of
motion: thus the Philosopher says (Phys. ii) that "nature is the
principle of motion in that in which it is essentially and not
accidentally." Now this principle is either form or matter. Hence
sometimes form is called nature, and sometimes matter. And because the
end of natural generation, in that which is generated, is the essence of
the species, which the definition signifies, this essence of the species
is called the "nature." And thus Boethius defines nature (De Duab. Nat.):
"Nature is what informs a thing with its specific difference,"---i.e.
which perfects the specific definition. But we are now speaking of nature
as it signifies the essence, or the "what-it-is," or the quiddity of the
Now, if we take nature in this way, it is impossible that the union of the Incarnate Word took place in the nature. For one thing is made of two or more in three ways. First, from two complete things which remain in their perfection. This can only happen to those whose form is composition, order, or figure, as a heap is made up of many stones brought together without any order, but solely with juxtaposition; and a house is made of stones and beams arranged in order, and fashioned to a figure. And in this way some said the union was by manner of confusion (which is without order) or by manner of commensuration (which is with order). But this cannot be. First, because neither composition nor order nor figure is a substantial form, but accidental; and hence it would follow that the union of the Incarnation was not essential, but accidental, which will be disproved later on (Article ). Secondly, because thereby we should not have an absolute unity, but relative only, for there remain several things actually. Thirdly, because the form of such is not a nature, but an art, as the form of a house; and thus one nature would not be constituted in Christ, as they wish.
Secondly, one thing is made up of several things, perfect but changed,
as a mixture is made up of its elements; and in this way some have said
that the union of the Incarnation was brought about by manner of
combination. But this cannot be. First, because the Divine Nature is
altogether immutable, as has been said (FP, Question , Articles ,2), hence neither
can it be changed into something else, since it is incorruptible; nor can
anything else be changed into it, for it cannot be generated. Secondly,
because what is mixed is of the same species with none of the elements;
for flesh differs in species from any of its elements. And thus Christ
would be of the same nature neither with His Father nor with His Mother.
Thirdly, because there can be no mingling of things widely apart; for the
species of one of them is absorbed, e.g. if we were to put a drop of
water in a flagon of wine. And hence, since the Divine Nature infinitely
exceeds the human nature, there could be no mixture, but the Divine
Nature alone would remain.
Thirdly, a thing is made up of things not mixed nor changed, but
imperfect; as man is made up of soul and body, and likewise of divers
members. But this cannot be said of the mystery of the Incarnation.
First, because each nature, i.e. the Divine and the human, has its
specific perfection. Secondly, because the Divine and human natures
cannot constitute anything after the manner of quantitative parts, as the
members make up the body; for the Divine Nature is incorporeal; nor after
the manner of form and matter, for the Divine Nature cannot be the form
of anything, especially of anything corporeal, since it would follow that
the species resulting therefrom would be communicable to several, and
thus there would be several Christs. Thirdly, because Christ would exist
neither in human nature nor in the Divine Nature: since any difference
varies the species, as unity varies number, as is said (Metaph. viii,
Reply to Objection 1: This authority of Cyril is expounded in the Fifth Synod
(i.e. Constantinople II, coll. viii, can. 8) thus: "If anyone proclaiming
one nature of the Word of God to be incarnate does not receive it as the
Fathers taught, viz. that from the Divine and human natures (a union in
subsistence having taken place) one Christ results, but endeavors from
these words to introduce one nature or substance of the Divinity and
flesh of Christ, let such a one be anathema." Hence the sense is not that
from two natures one results; but that the Nature of the Word of God
united flesh to Itself in Person.
Reply to Objection 2: From the soul and body a double unity, viz. of nature and
person---results in each individual---of nature inasmuch as the soul is
united to the body, and formally perfects it, so that one nature springs
from the two as from act and potentiality or from matter and form. But
the comparison is not in this sense, for the Divine Nature cannot be the
form of a body, as was proved (FP, Question , Article ). Unity of person results
from them, however, inasmuch as there is an individual subsisting in
flesh and soul; and herein lies the likeness, for the one Christ subsists
in the Divine and human natures.
Reply to Objection 3: As Damascene says (De Fide Orth. iii, 6,11), the Divine
Nature is said to be incarnate because It is united to flesh personally,
and not that It is changed into flesh. So likewise the flesh is said to
be deified, as he also says (De Fide Orth. 15,17), not by change, but by
union with the Word, its natural properties still remaining, and hence it
may be considered as deified, inasmuch as it becomes the flesh of the
Word of God, but not that it becomes God.
Article 2: Whether the union of the Incarnate Word took place in the Person?
Objection 1: It would seem that the union of the Incarnate Word did not take
place in the person. For the Person of God is not distinct from His
Nature, as we said (FP, Question , Article ). If, therefore, the union did not
take place in the nature, it follows that it did not take place in the
Objection 2: Further, Christ's human nature has no less dignity than ours. But
personality belongs to dignity, as was stated above (FP, Question , Article , ad 2). Hence, since our human nature has its proper personality, much more
reason was there that Christ's should have its proper personality.
Objection 3: Further, as Boethius says (De Duab. Nat.), a person is an
individual substance of rational nature. But the Word of God assumed an
individual human nature, for "universal human nature does not exist of
itself, but is the object of pure thought," as Damascene says (De Fide
Orth. iii, 11). Therefore the human nature of Christ has its personality.
Hence it does not seem that the union took place in the person.
On the contrary, We read in the Synod of Chalcedon (Part ii, act. 5):
"We confess that our Lord Jesus Christ is not parted or divided into two
persons, but is one and the same only-Begotten Son and Word of God."
Therefore the union took place in the person.
I answer that, Person has a different meaning from "nature." For nature,
as has been said (Article ), designates the specific essence which is
signified by the definition. And if nothing was found to be added to what
belongs to the notion of the species, there would be no need to
distinguish the nature from the suppositum of the nature (which is the
individual subsisting in this nature), because every individual
subsisting in a nature would be altogether one with its nature. Now in
certain subsisting things we happen to find what does not belong to the
notion of the species, viz. accidents and individuating principles, which
appears chiefly in such as are composed of matter and form. Hence in such
as these the nature and the suppositum really differ; not indeed as if
they were wholly separate, but because the suppositum includes the
nature, and in addition certain other things outside the notion of the
species. Hence the suppositum is taken to be a whole which has the nature
as its formal part to perfect it; and consequently in such as are
composed of matter and form the nature is not predicated of the
suppositum, for we do not say that this man is his manhood. But if there
is a thing in which there is nothing outside the species or its nature
(as in God), the suppositum and the nature are not really distinct in it,
but only in our way of thinking, inasmuch it is called "nature" as it is
an essence, and a "suppositum" as it is subsisting. And what is said of a
suppositum is to be applied to a person in rational or intellectual
creatures; for a person is nothing else than "an individual substance of
rational nature," according to Boethius. Therefore, whatever adheres to a
person is united to it in person, whether it belongs to its nature or
not. Hence, if the human nature is not united to God the Word in person,
it is nowise united to Him; and thus belief in the Incarnation is
altogether done away with, and Christian faith wholly overturned.
Therefore, inasmuch as the Word has a human nature united to Him, which
does not belong to His Divine Nature, it follows that the union took
place in the Person of the Word, and not in the nature.
Reply to Objection 1: Although in God Nature and Person are not really distinct,
yet they have distinct meanings, as was said above, inasmuch as person
signifies after the manner of something subsisting. And because human
nature is united to the Word, so that the Word subsists in it, and not so
that His Nature receives therefrom any addition or change, it follows
that the union of human nature to the Word of God took place in the
person, and not in the nature.
Reply to Objection 2: Personality pertains of necessity to the dignity of a
thing, and to its perfection so far as it pertains to the dignity and
perfection of that thing to exist by itself (which is understood by the
word "person"). Now it is a greater dignity to exist in something nobler
than oneself than to exist by oneself. Hence the human nature of Christ
has a greater dignity than ours, from this very fact that in us, being
existent by itself, it has its own personality, but in Christ it exists
in the Person of the Word. Thus to perfect the species belongs to the
dignity of a form, yet the sensitive part in man, on account of its union
with the nobler form which perfects the species, is more noble than in
brutes, where it is itself the form which perfects.
Reply to Objection 3: The Word of God "did not assume human nature in general,
but 'in atomo'"---that is, in an individual---as Damascene says (De Fide
Orth. iii, 11) otherwise every man would be the Word of God, even as
Christ was. Yet we must bear in mind that not every individual in the
genus of substance, even in rational nature, is a person, but that alone
which exists by itself, and not that which exists in some more perfect
thing. Hence the hand of Socrates, although it is a kind of individual,
is not a person, because it does not exist by itself, but in something
more perfect, viz. in the whole. And hence, too, this is signified by a
"person" being defined as "an individual substance," for the hand is not
a complete substance, but part of a substance. Therefore, although this
human nature is a kind of individual in the genus of substance, it has
not its own personality, because it does not exist separately, but in
something more perfect, viz. in the Person of the Word. Therefore the
union took place in the person.
Article 3: Whether the union of the Word Incarnate took place in the suppositum or hypostasis?
Objection 1: It would seem that the union of the Word Incarnate did not take
place in the suppositum or hypostasis. For Augustine says (Enchiridion
xxxv, xxxviii): "Both the Divine and human substance are one Son of God,
but they are one thing [aliud] by reason of the Word and another thing
[aliud] by reason of the man." And Pope Leo says in his letter to Flavian
(Ep. xxviii): "One of these is glorious with miracles, the other succumbs
under injuries." But "one" [aliud] and "the other" [aliud] differ in
suppositum. Therefore the union of the Word Incarnate did not take place
in the suppositum.
Objection 2: Further, hypostasis is nothing more than a "particular
substance," as Boethius says (De Duab. Nat.). But it is plain that in
Christ there is another particular substance beyond the hypostasis of the
Word, viz. the body and the soul and the resultant of these. Therefore
there is another hypostasis in Him besides the hypostasis of the Word.
Objection 3: Further, the hypostasis of the Word is not included in any genus
or species, as is plain from FP, Question , Article . But Christ, inasmuch as He
is made man, is contained under the species of man; for Dionysius says
(Div. Nom. 1): "Within the limits of our nature He came, Who far
surpasses the whole order of nature supersubstantially." Now nothing is
contained under the human species unless it be a hypostasis of the human
species. Therefore in Christ there is another hypostasis besides the
hypostasis of the Word of God; and hence the same conclusion follows as
On the contrary, Damascene says (De Fide Orth. iii, 3,4,5): "In our Lord
Jesus Christ we acknowledge two natures and one hypostasis."
I answer that, Some who did not know the relation of hypostasis to
person, although granting that there is but one person in Christ, held,
nevertheless, that there is one hypostasis of God and another of man, and
hence that the union took place in the person and not in the hypostasis.
Now this, for three reasons, is clearly erroneous. First, because person
only adds to hypostasis a determinate nature, viz. rational, according to
what Boethius says (De Duab. Nat.), "a person is an individual substance
of rational nature"; and hence it is the same to attribute to the human
nature in Christ a proper hypostasis and a proper person. And the holy
Fathers, seeing this, condemned both in the Fifth Council held at
Constantinople, saying: "If anyone seeks to introduce into the mystery of
the Incarnation two subsistences or two persons, let him be anathema. For
by the incarnation of one of the Holy Trinity, God the Word, the Holy
Trinity received no augment of person or subsistence." Now "subsistence"
is the same as the subsisting thing, which is proper to hypostasis, as is
plain from Boethius (De Duab. Nat.). Secondly, because if it is granted
that person adds to hypostasis something in which the union can take
place, this something is nothing else than a property pertaining to
dignity; according as it is said by some that a person is a "hypostasis
distinguished by a property pertaining to dignity." If, therefore, the
union took place in the person and not in the hypostasis, it follows that
the union only took place in regard to some dignity. And this is what
Cyril, with the approval of the Council of Ephesus (part iii, can. 3),
condemned in these terms: "If anyone after the uniting divides the
subsistences in the one Christ, only joining them in a union of dignity
or authority or power, and not rather in a concourse of natural union,
let him be anathema." Thirdly, because to the hypostasis alone are
attributed the operations and the natural properties, and whatever
belongs to the nature in the concrete; for we say that this man reasons,
and is risible, and is a rational animal. So likewise this man is said to
be a suppositum, because he underlies [supponitur] whatever belongs to
man and receives its predication. Therefore, if there is any hypostasis
in Christ besides the hypostasis of the Word, it follows that whatever
pertains to man is verified of some other than the Word, e.g. that He was
born of a Virgin, suffered, was crucified, was buried. And this, too, was
condemned with the approval of the Council of Ephesus (part iii, can. 4)
in these words: "If anyone ascribes to two persons or subsistences such
words as are in the evangelical and apostolic Scriptures, or have been
said of Christ by the saints, or by Himself of Himself, and, moreover,
applies some of them to the man, taken as distinct from the Word of God,
and some of them (as if they could be used of God alone) only to the Word
of God the Father, let him be anathema." Therefore it is plainly a heresy
condemned long since by the Church to say that in Christ there are two
hypostases, or two supposita, or that the union did not take place in the
hypostasis or suppositum. Hence in the same Synod (can. 2) it is said:
"If anyone does not confess that the Word was united to flesh in
subsistence, and that Christ with His flesh is both---to wit, God and
man---let him be anathema."
Reply to Objection 1: As accidental difference makes a thing "other" [alterum],
so essential difference makes "another thing" [aliud]. Now it is plain
that the "otherness" which springs from accidental difference may pertain
to the same hypostasis or suppositum in created things, since the same
thing numerically can underlie different accidents. But it does not
happen in created things that the same numerically can subsist in divers
essences or natures. Hence just as when we speak of "otherness" in regard
to creatures we do not signify diversity of suppositum, but only
diversity of accidental forms, so likewise when Christ is said to be one
thing or another thing, we do not imply diversity of suppositum or
hypostasis, but diversity of nature. Hence Gregory Nazianzen says in a
letter to Chelidonius (Ep. ci): "In the Saviour we may find one thing and
another, yet He is not one person and another. And I say 'one thing and
another'; whereas, on the contrary, in the Trinity we say one Person and
another (so as not to confuse the subsistences), but not one thing and
Reply to Objection 2: Hypostasis signifies a particular substance, not in every
way, but as it is in its complement. Yet as it is in union with something
more complete, it is not said to be a hypostasis, as a hand or a foot. So
likewise the human nature in Christ, although it is a particular
substance, nevertheless cannot be called a hypostasis or suppositum,
seeing that it is in union with a completed thing, viz. the whole Christ,
as He is God and man. But the complete being with which it concurs is
said to be a hypostasis or suppositum.
Reply to Objection 3: In created things a singular thing is placed in a genus or
species, not on account of what belongs to its individuation, but on
account of its nature, which springs from its form, and in composite
things individuation is taken more from matter. Hence we say that Christ
is in the human species by reason of the nature assumed, and not by
reason of the hypostasis.
Article 4: Whether after the Incarnation the Person or Hypostasis of Christ is composite?
Objection 1: It would seem that the Person of Christ is not composite. For the Person of Christ is naught else than the Person or hypostasis of the Word, as appears from what has been said (Article ). But in the Word, Person and Nature do not differ, as appears from FP, Question , Article . Therefore since the Nature of the Word is simple, as was shown above (FP, Question , Article ), it is impossible that the Person of Christ be composite.
Objection 2: Further, all composition requires parts. But the Divine Nature is
incompatible with the notion of a part, for every part implicates the
notion of imperfection. Therefore it is impossible that the Person of
Christ be composed of two natures.
Objection 3: Further, what is composed of others would seem to be homogeneous
with them, as from bodies only a body can be composed. Therefore if there
is anything in Christ composed of the two natures, it follows that this
will not be a person but a nature; and hence the union in Christ will
take place in the nature, which is contrary to Article .
On the contrary, Damascene says (De Fide Orth. iii, 3,4,5), "In the Lord
Jesus Christ we acknowledge two natures, but one hypostasis composed from
I answer that, The Person or hypostasis of Christ may be viewed in two
ways. First as it is in itself, and thus it is altogether simple, even as
the Nature of the Word. Secondly, in the aspect of person or hypostasis
to which it belongs to subsist in a nature; and thus the Person of Christ
subsists in two natures. Hence though there is one subsisting being in
Him, yet there are different aspects of subsistence, and hence He is
said to be a composite person, insomuch as one being subsists in two.
And thereby the solution to the first is clear.
Reply to Objection 2: This composition of a person from natures is not so called
on account of parts, but by reason of number, even as that in which two
things concur may be said to be composed of them.
Reply to Objection 3: It is not verified in every composition, that the thing
composed is homogeneous with its component parts, but only in the parts
of a continuous thing; for the continuous is composed solely of
continuous [parts]. But an animal is composed of soul and body, and
neither of these is an animal.
Article 5: Whether in Christ there is any union of soul and body?
Objection 1: It would seem that in Christ there was no union of soul and body.
For from the union of soul and body in us a person or a human hypostasis
is caused. Hence if the soul and body were united in Christ, it follows
that a hypostasis resulted from their union. But this was not the
hypostasis of God the Word, for It is eternal. Therefore in Christ there
would be a person or hypostasis besides the hypostasis of the Word, which
is contrary to Articles ,3.
Objection 2: Further, from the union of soul and body results the nature of
the human species. But Damascene says (De Fide Orth. iii, 3), that "we
must not conceive a common species in the Lord Jesus Christ." Therefore
there was no union of soul and body in Him.
Objection 3: Further, the soul is united to the body for the sole purpose of
quickening it. But the body of Christ could be quickened by the Word of
God Himself, seeing He is the fount and principle of life. Therefore in
Christ there was no union of soul and body.
On the contrary, The body is not said to be animated save from its union
with the soul. Now the body of Christ is said to be animated, as the
Church chants: "Taking an animate body, He deigned to be born of a
Virgin" [*Feast of the Circumcision, Ant. ii, Lauds]. Therefore in Christ
there was a union of soul and body.
I answer that, Christ is called a man univocally with other men, as
being of the same species, according to the Apostle (Phil. 2:7), "being
made in the likeness of a man." Now it belongs essentially to the human
species that the soul be united to the body, for the form does not
constitute the species, except inasmuch as it becomes the act of matter,
and this is the terminus of generation through which nature intends the
species. Hence it must be said that in Christ the soul was united to the
body; and the contrary is heretical, since it destroys the truth of
Reply to Objection 1: This would seem to be the reason which was of weight with
such as denied the union of the soul and body in Christ, viz. lest they
should thereby be forced to admit a second person or hypostasis in
Christ, since they saw that the union of soul and body in mere men
resulted in a person. But this happens in mere men because the soul and
body are so united in them as to exist by themselves. But in Christ they
are united together, so as to be united to something higher, which
subsists in the nature composed of them. And hence from the union of the
soul and body in Christ a new hypostasis or person does not result, but
what is composed of them is united to the already existing hypostasis or
Person. Nor does it therefore follow that the union of the soul and body
in Christ is of less effect than in us, for its union with something
nobler does not lessen but increases its virtue and worth; just as the
sensitive soul in animals constitutes the species, as being considered
the ultimate form, yet it does not do so in man, although it is of
greater effect and dignity, and this because of its union with a further
and nobler perfection, viz. the rational soul, as has been said above
(Article , ad 2).
Reply to Objection 2: This saying of Damascene may be taken in two ways: First,
as referring to human nature, which, as it is in one individual alone,
has not the nature of a common species, but only inasmuch as either it is
abstracted from every individual, and considered in itself by the mind,
or according as it is in all individuals. Now the Son of God did not
assume human nature as it exists in the pure thought of the intellect,
since in this way He would not have assumed human nature in reality,
unless it be said that human nature is a separate idea, just as the
Platonists conceived of man without matter. But in this way the Son of
God would not have assumed flesh, contrary to what is written (Lk. 24:39), "A spirit hath not flesh and bones as you see Me to have."
Neither can it be said that the Son of God assumed human nature as it is
in all the individuals of the same species, otherwise He would have
assumed all men. Therefore it remains, as Damascene says further on (De
Fide Orth. iii, 11) that He assumed human nature "in atomo," i.e. in an
individual; not, indeed, in another individual which is a suppositum or a
person of that nature, but in the Person of the Son of God.
Secondly, this saying of Damascene may be taken not as referring to
human nature, as if from the union of soul and body one common nature
(viz. human) did not result, but as referring to the union of the two
natures Divine and human: which do not combine so as to form a third
something that becomes a common nature, for in this way it would become
predicable of many, and this is what he is aiming at, since he adds: "For
there was not generated, neither will there ever be generated, another
Christ, Who from the Godhead and manhood, and in the Godhead and manhood,
is perfect God and perfect man."
Reply to Objection 3: There are two principles of corporeal life: one the
effective principle, and in this way the Word of God is the principle of
all life; the other, the formal principle of life, for since "in living
things to be is to live," as the Philosopher says (De Anima ii, 37),
just as everything is formally by its form, so likewise the body lives by
the soul: in this way a body could not live by the Word, Which cannot be
the form of a body.
Article 6: Whether the human nature was united to the Word of God accidentally?
Objection 1: It would seem that the human nature was united to the Word of God
accidentally. For the Apostle says (Phil. 2:7) of the Son of God, that He
was "in habit found as a man." But habit is accidentally associated with
that to which it pertains, whether habit be taken for one of the ten
predicaments or as a species of quality. Therefore human nature is
accidentally united to the Son of God.
Objection 2: Further, whatever comes to a thing that is complete in being
comes to it accidentally, for an accident is said to be what can come or
go without the subject being corrupted. But human nature came to Christ
in time, Who had perfect being from eternity. Therefore it came to Him
Objection 3: Further, whatever does not pertain to the nature or the essence
of a thing is its accident, for whatever is, is either a substance or an
accident. But human nature does not pertain to the Divine Essence or
Nature of the Son of God, for the union did not take place in the nature,
as was said above (Article ). Hence the human nature must have accrued
accidentally to the Son of God.
Objection 4: Further, an instrument accrues accidentally. But the human nature
was the instrument of the Godhead in Christ, for Damascene says (De Fide
Orth. iii, 15), that "the flesh of Christ is the instrument of the
Godhead." Therefore it seems that the human nature was united to the Son
of God accidentally.
On the contrary, Whatever is predicated accidentally, predicates, not
substance, but quantity, or quality, or some other mode of being. If
therefore the human nature accrues accidentally, when we say Christ is
man, we do not predicate substance, but quality or quantity, or some
other mode of being, which is contrary to the Decretal of Pope Alexander
III, who says (Conc. Later. iii): "Since Christ is perfect God and
perfect man, what foolhardiness have some to dare to affirm that Christ
as man is not a substance?"
I answer that, In evidence of this question we must know that two
heresies have arisen with regard to the mystery of the union of the two
natures in Christ. The first confused the natures, as Eutyches and
Dioscorus, who held that from the two natures one nature resulted, so
that they confessed Christ to be "from" two natures (which were distinct
before the union), but not "in" two natures (the distinction of nature
coming to an end after the union). The second was the heresy of Nestorius
and Theodore of Mopsuestia, who separated the persons. For they held the
Person of the Son of God to be distinct from the Person of the Son of
man, and said these were mutually united: first, "by indwelling,"
inasmuch as the Word of God dwelt in the man, as in a temple; secondly,
"by unity of intention," inasmuch as the will of the man was always in
agreement with the will of the Word of God; thirdly, "by operation,"
inasmuch as they said the man was the instrument of the Word of God;
fourthly, "by greatness of honor," inasmuch as all honor shown to the Son
of God was equally shown to the Son of man, on account of His union with
the Son of God; fifthly, "by equivocation," i.e. communication of names,
inasmuch as we say that this man is God and the Son of God. Now it is
plain that these modes imply an accidental union.
But some more recent masters, thinking to avoid these heresies, through
ignorance fell into them. For some conceded one person in Christ, but
maintained two hypostases, or two supposita, saying that a man, composed
of body and soul, was from the beginning of his conception assumed by the
Word of God. And this is the first opinion set down by the Master (Sent.
iii, D, 6). But others desirous of keeping the unity of person, held that
the soul of Christ was not united to the body, but that these two were
mutually separate, and were united to the Word accidentally, so that the
number of persons might not be increased. And this is the third opinion
which the Master sets down (Sent. iii, D, 6).
But both of these opinions fall into the heresy of Nestorius; the first,
indeed, because to maintain two hypostases or supposita in Christ is the
same as to maintain two persons, as was shown above (Article ). And if stress
is laid on the word "person," we must have in mind that even Nestorius
spoke of unity of person on account of the unity of dignity and honor.
Hence the fifth Council (Constantinople II, coll. viii, can. 5) directs
an anathema against such a one as holds "one person in dignity, honor and
adoration, as Theodore and Nestorius foolishly wrote." But the other
opinion falls into the error of Nestorius by maintaining an accidental
union. For there is no difference in saying that the Word of God is
united to the Man Christ by indwelling, as in His temple (as Nestorius
said), or by putting on man, as a garment, which is the third opinion;
rather it says something worse than Nestorius---to wit, that the soul and
body are not united.
Now the Catholic faith, holding the mean between the aforesaid
positions, does not affirm that the union of God and man took place in
the essence or nature, nor yet in something accidental, but midway, in a
subsistence or hypostasis. Hence in the fifth Council (Constantinople II,
coll. viii, can. 5) we read: "Since the unity may be understood in many
ways, those who follow the impiety of Apollinaris and Eutyches,
professing the destruction of what came together" (i.e. destroying both
natures), "confess a union by mingling; but the followers of Theodore and
Nestorius, maintaining division, introduce a union of purpose. But the
Holy Church of God, rejecting the impiety of both these treasons,
confesses a union of the Word of God with flesh, by composition, which is
in subsistence." Therefore it is plain that the second of the three
opinions, mentioned by the Master (Sent. iii, D, 6), which holds one
hypostasis of God and man, is not to be called an opinion, but an article
of Catholic faith. So likewise the first opinion which holds two
hypostases, and the third which holds an accidental union, are not to be
styled opinions, but heresies condemned by the Church in Councils.
Reply to Objection 1: As Damascene says (De Fide Orth. iii, 26): "Examples need
not be wholly and at all points similar, for what is wholly similar is
the same, and not an example, and especially in Divine things, for it is
impossible to find a wholly similar example in the Theology," i.e. in the
Godhead of Persons, "and in the Dispensation," i.e. the mystery of the
Incarnation. Hence the human nature in Christ is likened to a habit, i.e.
a garment, not indeed in regard to accidental union, but inasmuch as the
Word is seen by the human nature, as a man by his garment, and also
inasmuch as the garment is changed, for it is shaped according to the
figure of him who puts it on, and yet he is not changed from his form on
account of the garment. So likewise the human nature assumed by the Word
of God is ennobled, but the Word of God is not changed, as Augustine says
(Qq. 83, qu. 73).
Reply to Objection 2: Whatever accrues after the completion of the being comes
accidentally, unless it be taken into communion with the complete being,
just as in the resurrection the body comes to the soul which pre-exists,
yet not accidentally, because it is assumed unto the same being, so that
the body has vital being through the soul; but it is not so with
whiteness, for the being of whiteness is other than the being of man to
which whiteness comes. But the Word of God from all eternity had complete
being in hypostasis or person; while in time the human nature accrued to
it, not as if it were assumed unto one being inasmuch as this is of the
nature (even as the body is assumed to the being of the soul), but to one
being inasmuch as this is of the hypostasis or person. Hence the human
nature is not accidentally united to the Son of God.
Reply to Objection 3: Accident is divided against substance. Now substance, as is
plain from Metaph. v, 25, is taken in two ways: first, for essence or
nature; secondly, for suppositum or hypostasis---hence the union having
taken place in the hypostasis, is enough to show that it is not an
accidental union, although the union did not take place in the nature.
Reply to Objection 4: Not everything that is assumed as an instrument pertains to
the hypostasis of the one who assumes, as is plain in the case of a saw
or a sword; yet nothing prevents what is assumed into the unity of the
hypostasis from being as an instrument, even as the body of man or his
members. Hence Nestorius held that the human nature was assumed by the
Word merely as an instrument, and not into the unity of the hypostasis.
And therefore he did not concede that the man was really the Son of God,
but His instrument. Hence Cyril says (Epist. ad Monach. Aegyptii): "The
Scripture does not affirm that this Emmanuel," i.e. Christ, "was assumed
for the office of an instrument, but as God truly humanized," i.e. made
man. But Damascene held that the human nature in Christ is an instrument
belonging to the unity of the hypostasis.
Article 7: Whether the union of the Divine nature and the human is anything created?
Objection 1: It would seem that the union of the Divine and human natures is
not anything created. For there can be nothing created in God, because
whatever is in God is God. But the union is in God, for God Himself is
united to human nature. Therefore it seems that the union is not anything
Objection 2: Further, the end holds first place in everything. But the end of
the union is the Divine hypostasis or Person in which the union is
terminated. Therefore it seems that this union ought chiefly to be judged
with reference to the dignity of the Divine hypostasis, which is not
anything created. Therefore the union is nothing created.
Objection 3: Further, "That which is the cause of a thing being such is still
more so" (Poster. i). But man is said to be the Creator on account of the
union. Therefore much more is the union itself nothing created, but the
On the contrary, Whatever has a beginning in time is created. Now this
union was not from eternity, but began in time. Therefore the union is
I answer that, The union of which we are speaking is a relation which we
consider between the Divine and the human nature, inasmuch as they come
together in one Person of the Son of God. Now, as was said above (FP,
Question , Article ), every relation which we consider between God and the
creature is really in the creature, by whose change the relation is
brought into being; whereas it is not really in God, but only in our way
of thinking, since it does not arise from any change in God. And hence we
must say that the union of which we are speaking is not really in God,
except only in our way of thinking; but in the human nature, which is a
creature, it is really. Therefore we must say it is something created.
Reply to Objection 1: This union is not really in God, but only in our way of
thinking, for God is said to be united to a creature inasmuch as the
creature is really united to God without any change in Him.
Reply to Objection 2: The specific nature of a relation, as of motion, depends on
the subject. And since this union has its being nowhere save in a created
nature, as was said above, it follows that it has a created being.
Reply to Objection 3: A man is called Creator and is God because of the union,
inasmuch as it is terminated in the Divine hypostasis; yet it does not
follow that the union itself is the Creator or God, because that a thing
is said to be created regards its being rather than its relation.
Article 8: Whether union is the same as assumption?
Objection 1: It would seem that union is the same as assumption. For
relations, as motions, are specified by their termini. Now the term of
assumption and union is one and the same, viz. the Divine hypostasis.
Therefore it seems that union and assumption are not different.
Objection 2: Further, in the mystery of the Incarnation the same thing seems
to be what unites and what assumes, and what is united and what is
assumed. But union and assumption seem to follow the action and passion
of the thing uniting and the united, of the thing assuming and the
assumed. Therefore union seems to be the same as assumption.
Objection 3: Further, Damascene says (De Fide Orth. iii, 11): "Union is one
thing, incarnation is another; for union demands mere copulation, and
leaves unsaid the end of the copulation; but incarnation and humanation
determine the end of copulation." But likewise assumption does not
determine the end of copulation. Therefore it seems that union is the
same as assumption.
On the contrary, The Divine Nature is said to be united, not assumed.
I answer that, As was stated above (Article ), union implies a certain
relation of the Divine Nature and the human, according as they come
together in one Person. Now all relations which begin in time are brought
about by some change; and change consists in action and passion. Hence
the "first" and principal difference between assumption and union must be
said to be that union implies the relation: whereas assumption implies
the action, whereby someone is said to assume, or the passion, whereby
something is said to be assumed. Now from this difference another
"second" difference arises, for assumption implies "becoming," whereas
union implies "having become," and therefore the thing uniting is said to
be united, but the thing assuming is not said to be assumed. For the
human nature is taken to be in the terminus of assumption unto the Divine
hypostasis when man is spoken of; and hence we can truly say that the Son
of God, Who assumes human nature unto Himself, is man. But human nature,
considered in itself, i.e. in the abstract, is viewed as assumed; and we
do not say the Son of God is human nature. From this same follows a
"third" difference, which is that a relation, especially one of
equiparance, is no more to one extreme than to the other, whereas action
and passion bear themselves differently to the agent and the patient, and
to different termini. And hence assumption determines the term whence and
the term whither; for assumption means a taking to oneself from another.
But union determines none of these things. hence it may be said
indifferently that the human nature is united with the Divine, or
conversely. But the Divine Nature is not said to be assumed by the
human, but conversely, because the human nature is joined to the Divine
personality, so that the Divine Person subsists in human nature.
Reply to Objection 1: Union and assumption have not the same relation to the
term, but a different relation, as was said above.
Reply to Objection 2: What unites and what assumes are not the same. For
whatsoever Person assumes unites, and not conversely. For the Person of
the Father united the human nature to the Son, but not to Himself; and
hence He is said to unite and not to assume. So likewise the united and
the assumed are not identical, for the Divine Nature is said to be
united, but not assumed.
Reply to Objection 3: Assumption determines with whom the union is made on the
part of the one assuming, inasmuch as assumption means taking unto
oneself [ad se sumere], whereas incarnation and humanation (determine
with whom the union is made) on the part of the thing assumed, which is
flesh or human nature. And thus assumption differs logically both from
union and from incarnation or humanation.
Article 9: Whether the union of the two natures in Christ is the greatest of all unions?
Objection 1: It would seem that the union of the two natures in Christ is not
the greatest of all unions. For what is united falls short of the unity
of what is one, since what is united is by participation, but one is by
essence. Now in created things there are some that are simply one, as is
shown especially in unity itself, which is the principle of number.
Therefore the union of which we are speaking does not imply the greatest
of all unions.
Objection 2: Further, the greater the distance between things united, the less
the union. Now, the things united by this union are most
distant---namely, the Divine and human natures; for they are infinitely
apart. Therefore their union is the least of all.
Objection 3: Further, from union there results one. But from the union of soul
and body in us there arises what is one in person and nature; whereas
from the union of the Divine and human nature there results what is one
in person only. Therefore the union of soul and body is greater than that
of the Divine and human natures; and hence the union of which we speak
does not imply the greatest unity.
On the contrary, Augustine says (De Trin. i, 10) that "man is in the Son of God, more than the Son in the Father." But the Son is in the Father by unity of essence, and man is in the Son by the union of the Incarnation. Therefore the union of the Incarnation is greater than the unity of the Divine Essence, which nevertheless is the greatest union; and thus the union of the Incarnation implies the greatest unity.
I answer that, Union implies the joining of several in some one thing.
Therefore the union of the Incarnation may be taken in two ways: first,
in regard to the things united; secondly, in regard to that in which they
are united. And in this regard this union has a pre-eminence over other
unions; for the unity of the Divine Person, in which the two natures are
united, is the greatest. But it has no pre-eminence in regard to the
Reply to Objection 1: The unity of the Divine Person is greater than numerical
unity, which is the principle of number. For the unity of a Divine Person
is an uncreated and self-subsisting unity, not received into another by
participation. Also, it is complete in itself, having in itself whatever
pertains to the nature of unity; and therefore it is not compatible with
the nature of a part, as in numerical unity, which is a part of number,
and which is shared in by the things numbered. And hence in this respect
the union of the Incarnation is higher than numerical unity by reason of
the unity of the Divine Person, and not by reason of the human nature,
which is not the unity of the Divine Person, but is united to it.
Reply to Objection 2: This reason regards the things united, and not the Person
in Whom the union takes place.
Reply to Objection 3: The unity of the Divine Person is greater than the unity of
person and nature in us; and hence the union of the Incarnation is
greater than the union of soul and body in us.
And because what is urged in the argument "on the contrary" rests upon
what is untrue---namely, that the union of the Incarnation is greater
than the unity of the Divine Persons in Essence---we must say to the
authority of Augustine that the human nature is not more in the Son of
God than the Son of God in the Father, but much less. But the man in some
respects is more in the Son than the Son in the Father---namely, inasmuch
as the same suppositum is signified when I say "man," meaning Christ, and
when I say "Son of God"; whereas it is not the same suppositum of Father
Article 10: Whether the union of the Incarnation took place by grace?
Objection 1: It would seem that the union of the Incarnation did not take
place by grace. For grace is an accident, as was shown above (FS, Question , Article ). But the union of the human nature to the Divine did not take place
accidentally, as was shown above (Article ). Therefore it seems that the
union of the Incarnation did not take place by grace.
Objection 2: Further, the subject of grace is the soul. But it is written (Col. 2:9): "In Christ [Vulg.: 'Him'] dwelleth all the fulness of the Godhead corporeally." Therefore it seems that this union did not take place by grace.
Objection 3: Further, every saint is united to God by grace. If, therefore,
the union of the Incarnation was by grace, it would seem that Christ is
said to be God no more than other holy men.
On the contrary, Augustine says (De Praed. Sanct. xv): "By the same
grace every man is made a Christian, from the beginning of his faith, as
this man from His beginning was made Christ." But this man became Christ
by union with the Divine Nature. Therefore this union was by grace.
I answer that, As was said above (FS, Question , Article ), grace is taken in
two ways:--first, as the will of God gratuitously bestowing something;
secondly, as the free gift of God. Now human nature stands in need of the
gratuitous will of God in order to be lifted up to God, since this is
above its natural capability. Moreover, human nature is lifted up to God
in two ways: first, by operation, as the saints know and love God;
secondly, by personal being, and this mode belongs exclusively to Christ,
in Whom human nature is assumed so as to be in the Person of the Son of
God. But it is plain that for the perfection of operation the power needs
to be perfected by a habit, whereas that a nature has being in its own
suppositum does not take place by means of a habit.
And hence we must say that if grace be understood as the will of God
gratuitously doing something or reputing anything as well-pleasing or
acceptable to Him, the union of the Incarnation took place by grace, even
as the union of the saints with God by knowledge and love. But if grace
be taken as the free gift of God, then the fact that the human nature is
united to the Divine Person may be called a grace, inasmuch as it took
place without being preceded by any merits---but not as though there were
an habitual grace, by means of which the union took place.
Reply to Objection 1: The grace which is an accident is a certain likeness of the
Divinity participated by man. But by the Incarnation human nature is not
said to have participated a likeness of the Divine nature, but is said to
be united to the Divine Nature itself in the Person of the Son. Now the
thing itself is greater than a participated likeness of it.
Reply to Objection 2: Habitual grace is only in the soul; but the grace, i.e. the
free gift of God, of being united to the Divine Person belongs to the
whole human nature, which is composed of soul and body. And hence it is
said that the fulness of the Godhead dwelt corporeally in Christ because
the Divine Nature is united not merely to the soul, but to the body also.
Although it may also be said that it dwelt in Christ corporeally, i.e.
not as in a shadow, as it dwelt in the sacraments of the old law, of
which it is said in the same place (Col. 2:17) that they are the "shadow
of things to come but the body is Christ" [Vulg.: 'Christ's'], inasmuch
as the body is opposed to the shadow. And some say that the Godhead is
said to have dwelt in Christ corporeally, i.e. in three ways, just as a
body has three dimensions: first, by essence, presence, and power, as in
other creatures; secondly, by sanctifying grace, as in the saints;
thirdly, by personal union, which is proper to Christ.
Hence the reply to the third is manifest, viz. because the union of the
Incarnation did not take place by habitual grace alone, but in
subsistence or person.
Article 11: Whether any merits preceded the union of the Incarnation?
Objection 1: It would seem that the union of the Incarnation followed upon
certain merits, because upon Ps. 32:22, "Let Thy mercy, o Lord, be upon
us, as," etc. a gloss says: "Here the prophet's desire for the
Incarnation and its merited fulfilment are hinted at." Therefore the
Incarnation falls under merit.
Objection 2: Further, whoever merits anything merits that without which it
cannot be. But the ancient Fathers merited eternal life, to which they
were able to attain only by the Incarnation; for Gregory says (Moral.
xiii): "Those who came into this world before Christ's coming, whatsoever
eminency of righteousness they may have had, could not, on being divested
of the body, at once be admitted into the bosom of the heavenly country,
seeing that He had not as yet come Who, by His own descending, should
place the souls of the righteous in their everlasting seat." Therefore it
would seem that they merited the Incarnation.
Objection 3: Further, of the Blessed Virgin it is sung that "she merited to
bear the Lord of all" [*Little Office of B. V. M., Dominican Rite, Ant.
at Benedictus], and this took place through the Incarnation. Therefore
the Incarnation falls under merit.
On the contrary, Augustine says (De Praed. Sanct. xv): "Whoever can find
merits preceding the singular generation of our Head, may also find
merits preceding the repeated regeneration of us His members." But no
merits preceded our regeneration, according to Titus 3:5: "Not by the
works of justice which we have done, but according to His mercy He saved
us, by the laver of regeneration." Therefore no merits preceded the
generation of Christ.
I answer that, With regard to Christ Himself, it is clear from the above
(Article ) that no merits of His could have preceded the union. For we do
not hold that He was first of all a mere man, and that afterwards by the
merits of a good life it was granted Him to become the Son of God, as
Photinus held; but we hold that from the beginning of His conception this
man was truly the Son of God, seeing that He had no other hypostasis but
that of the Son of God, according to Luke 1:35: "The Holy which shall be
born of thee shall be called the Son of God." And hence every operation
of this man followed the union. Therefore no operation of His could have
been meritorious of the union.
Neither could the needs of any other man whatsoever have merited this
union condignly: first, because the meritorious works of man are
properly ordained to beatitude, which is the reward of virtue, and
consists in the full enjoyment of God. Whereas the union of the
Incarnation, inasmuch as it is in the personal being, transcends the
union of the beatified mind with God, which is by the act of the soul in
fruition; and therefore it cannot fall under merit. Secondly, because
grace cannot fall under merit, for the principle of merit does not fall
under merit; and therefore neither does grace, for it is the principle of
merit. Hence, still less does the Incarnation fall under merit, since it
is the principle of grace, according to Jn. 1:17: "Grace and truth came
by Jesus Christ." Thirdly, because the Incarnation is for the reformation
of the entire human nature, and therefore it does not fall under the
merit of any individual man, since the goodness of a mere man cannot be
the cause of the good of the entire nature. Yet the holy Fathers merited
the Incarnation congruously by desiring and beseeching; for it was
becoming that God should harken to those who obeyed Him.
And thereby the reply to the First Objection is manifest.
Reply to Objection 2: It is false that under merit falls everything without which there can be no reward. For there is something pre-required not merely for reward, but also for merit, as the Divine goodness and grace and the very nature of man. And again, the mystery of the Incarnation is the principle of merit, because "of His fulness we all have received" (Jn. 1:16).
Reply to Objection 3: The Blessed Virgin is said to have merited to bear the Lord
of all; not that she merited His Incarnation, but because by the grace
bestowed upon her she merited that grade of purity and holiness, which
fitted her to be the Mother of God.
Article 12: Whether the grace of union was natural to the man Christ?
Objection 1: It would seem that the grace of union was not natural to the man
Christ. For the union of the Incarnation did not take place in the
nature, but in the Person, as was said above (Article ). Now a thing is
denominated from its terminus. Therefore this grace ought rather to be
called personal than natural.
Objection 2: Further, grace is divided against nature, even as gratuitous
things, which are from God, are distinguished from natural things, which
are from an intrinsic principle. But if things are divided in opposition
to one another, one is not denominated by the other. Therefore the grace
of Christ was not natural to Him.
Objection 3: Further, natural is that which is according to nature. But the
grace of union is not natural to Christ in regard to the Divine Nature,
otherwise it would belong to the other Persons; nor is it natural to Him
according to the human nature, otherwise it would belong to all men,
since they are of the same nature as He. Therefore it would seem that the
grace of union is nowise natural to Christ.
On the contrary, Augustine says (Enchiridion xl): "In the assumption of
human nature, grace itself became somewhat natural to that man, so as to
leave no room for sin in Him."
I answer that, According to the Philosopher (Metaph. v, 5), nature
designates, in one way, nativity; in another, the essence of a thing.
Hence natural may be taken in two ways: first, for what is only from the
essential principles of a thing, as it is natural to fire to mount;
secondly, we call natural to man what he has had from his birth,
according to Eph. 2:3: "We were by nature children of wrath"; and Wis.
12:10: "They were a wicked generation, and their malice natural."
Therefore the grace of Christ, whether of union or habitual, cannot be
called natural as if caused by the principles of the human nature of
Christ, although it may be called natural, as if coming to the human
nature of Christ by the causality of His Divine Nature. But these two
kinds of grace are said to be natural to Christ, inasmuch as He had them
from His nativity, since from the beginning of His conception the human
nature was united to the Divine Person, and His soul was filled with the
gift of grace.
Reply to Objection 1: Although the union did not take place in the nature, yet it
was caused by the power of the Divine Nature, which is truly the nature
of Christ, and it, moreover, belonged to Christ from the beginning of His
Reply to Objection 2: The union is not said to be grace and natural in the same
respect; for it is called grace inasmuch as it is not from merit; and it
is said to be natural inasmuch as by the power of the Divine Nature it
was in the humanity of Christ from His nativity.
Reply to Objection 3: The grace of union is not natural to Christ according to
His human nature, as if it were caused by the principles of the human
nature, and hence it need not belong to all men. Nevertheless, it is
natural to Him in regard to the human nature on account of the "property"
of His birth, seeing that He was conceived by the Holy Ghost, so that He
might be the natural Son of God and of man. But it is natural to Him in
regard to the Divine Nature, inasmuch as the Divine Nature is the active
principle of this grace; and this belongs to the whole Trinity---to wit,
to be the active principle of this grace.