QUESTION 31: OF WHAT BELONGS TO THE UNITY OR PLURALITY IN GOD
We now consider what belongs to the unity or plurality in God; which
gives rise to four points of inquiry:
(1) Concerning the word "Trinity";
(2) Whether we can say that the Son is other than the Father?
(3) Whether an exclusive term, which seems to exclude otherness, can be
joined to an essential name in God?
(4) Whether it can be joined to a personal term?
Article 1: Whether there is trinity in God?
Objection 1: It would seem there is not trinity in God. For every name in God
signifies substance or relation. But this name "Trinity" does not signify
the substance; otherwise it would be predicated of each one of the
persons: nor does it signify relation; for it does not express a name
that refers to another. Therefore the word "Trinity" is not to be applied
Objection 2: Further, this word "trinity" is a collective term, since it
signifies multitude. But such a word does not apply to God; as the unity
of a collective name is the least of unities, whereas in God there exists
the greatest possible unity. Therefore this word "trinity" does not apply
Objection 3: Further, every trine is threefold. But in God there is not
triplicity; since triplicity is a kind of inequality. Therefore neither
is there trinity in God.
Objection 4: Further, all that exists in God exists in the unity of the divine
essence; because God is His own essence. Therefore, if Trinity exists in
God, it exists in the unity of the divine essence; and thus in God there
would be three essential unities; which is heresy.
Objection 5: Further, in all that is said of God, the concrete is predicated
of the abstract; for Deity is God and paternity is the Father. But the
Trinity cannot be called trine; otherwise there would be nine realities
in God; which, of course, is erroneous. Therefore the word trinity is not
to be applied to God.
On the contrary, Athanasius says: "Unity in Trinity; and Trinity in
Unity is to be revered."
I answer that, The name "Trinity" in God signifies the determinate
number of persons. And so the plurality of persons in God requires that
we should use the word trinity; because what is indeterminately signified
by plurality, is signified by trinity in a determinate manner.
Reply to Objection 1: In its etymological sense, this word "Trinity" seems to
signify the one essence of the three persons, according as trinity may
mean trine-unity. But in the strict meaning of the term it rather
signifies the number of persons of one essence; and on this account we
cannot say that the Father is the Trinity, as He is not three persons.
Yet it does not mean the relations themselves of the Persons, but rather
the number of persons related to each other; and hence it is that the
word in itself does not express regard to another.
Reply to Objection 2: Two things are implied in a collective term, plurality of
the "supposita," and a unity of some kind of order. For "people" is a
multitude of men comprehended under a certain order. In the first sense,
this word "trinity" is like other collective words; but in the second
sense it differs from them, because in the divine Trinity not only is
there unity of order, but also with this there is unity of essence.
Reply to Objection 3: "Trinity" is taken in an absolute sense; for it signifies
the threefold number of persons. "Triplicity" signifies a proportion of
inequality; for it is a species of unequal proportion, according to
Boethius (Arithm. i, 23). Therefore in God there is not triplicity, but
Reply to Objection 4: In the divine Trinity is to be understood both number and
the persons numbered. So when we say, "Trinity in Unity," we do not place
number in the unity of the essence, as if we meant three times one; but
we place the Persons numbered in the unity of nature; as the "supposita"
of a nature are said to exist in that nature. On the other hand, we say
"Unity in Trinity"; meaning that the nature is in its "supposita."
Reply to Objection 5: When we say, "Trinity is trine," by reason of the number
implied, we signify the multiplication of that number by itself; since
the word trine imports a distinction in the "supposita" of which it is
spoken. Therefore it cannot be said that the Trinity is trine; otherwise
it follows that, if the Trinity be trine, there would be three
"supposita" of the Trinity; as when we say, "God is trine," it follows
that there are three "supposita" of the Godhead.
Article 2: Whether the Son is other than the Father?
Objection 1: It would seem that the Son is not other than the Father. For
"other" is a relative term implying diversity of substance. If, then, the
Son is other than the Father, He must be different from the Father; which
is contrary to what Augustine says (De Trin. vii), that when we speak of
three persons, "we do not mean to imply diversity."
Objection 2: Further, whosoever are other from one another, differ in some way
from one another. Therefore, if the Son is other than the Father, it
follows that He differs from the Father; which is against what Ambrose
says (De Fide i), that "the Father and the Son are one in Godhead; nor is
there any difference in substance between them, nor any diversity."
Objection 3: Further, the term alien is taken from "alius" [other]. But the
Son is not alien from the Father, for Hilary says (De Trin. vii) that "in
the divine persons there is nothing diverse, nothing alien, nothing
separable." Therefore the Son is not other that the Father.
Objection 4: Further, the terms "other person" and "other thing" [alius et
aliud] have the same meaning, differing only in gender. So if the Son is
another person from the Father, it follows that the Son is a thing apart
from the Father.
On the contrary, Augustine [*Fulgentius, De Fide ad Petrum i.] says:
"There is one essence of the Father and Son and Holy Ghost, in which the
Father is not one thing, the Son another, and the Holy Ghost another;
although the Father is one person, the Son another, and the Holy Ghost
I answer that, Since as Jerome remarks [*In substance, Ep. lvii.], a
heresy arises from words wrongly used, when we speak of the Trinity we
must proceed with care and with befitting modesty; because, as Augustine
says (De Trin. i, 3), "nowhere is error more harmful, the quest more
toilsome, the finding more fruitful." Now, in treating of the Trinity, we
must beware of two opposite errors, and proceed cautiously between
them---namely, the error of Arius, who placed a Trinity of substance with
the Trinity of persons; and the error of Sabellius, who placed unity of
person with the unity of essence.
Thus, to avoid the error of Arius we must shun the use of the terms
diversity and difference in God, lest we take away the unity of essence:
we may, however, use the term "distinction" on account of the relative
opposition. Hence whenever we find terms of "diversity" or "difference"
of Persons used in an authentic work, these terms of "diversity" or
"difference" are taken to mean "distinction." But lest the simplicity and
singleness of the divine essence be taken away, the terms "separation"
and "division," which belong to the parts of a whole, are to be avoided:
and lest quality be taken away, we avoid the use of the term "disparity":
and lest we remove similitude, we avoid the terms "alien" and
"discrepant." For Ambrose says (De Fide i) that "in the Father and the
Son there is no discrepancy, but one Godhead": and according to Hilary,
as quoted above, "in God there is nothing alien, nothing separable."
To avoid the heresy of Sabellius, we must shun the term "singularity,"
lest we take away the communicability of the divine essence. Hence Hilary
says (De Trin. vii): "It is sacrilege to assert that the Father and the
Son are separate in Godhead." We must avoid the adjective "only" [unici]
lest we take away the number of persons. Hence Hilary says in the same
book: "We exclude from God the idea of singularity or uniqueness."
Nevertheless, we say "the only Son," for in God there is no plurality of
Sons. Yet, we do not say "the only God," for the Deity is common to
several. We avoid the word "confused," lest we take away from the Persons
the order of their nature. Hence Ambrose says (De Fide i): "What is one
is not confused; and there is no multiplicity where there is no
difference." The word "solitary" is also to be avoided, lest we take away
the society of the three persons; for, as Hilary says (De Trin. iv), "We
confess neither a solitary nor a diverse God."
This word "other" [alius], however, in the masculine sense, means only a
distinction of "suppositum"; and hence we can properly say that "the Son
is other than the Father," because He is another "suppositum" of the
divine nature, as He is another person and another hypostasis.
Reply to Objection 1: "Other," being like the name of a particular thing, refers
to the "suppositum"; and so, there is sufficient reason for using it,
where there is a distinct substance in the sense of hypostasis or person.
But diversity requires a distinct substance in the sense of essence. Thus
we cannot say that the Son is diverse from the Father, although He is
Reply to Objection 2: "Difference" implies distinction of form. There is one form
in God, as appears from the text, "Who, when He was in the form of God"
(Phil. 2:6). Therefore the term "difference" does not properly apply to
God, as appears from the authority quoted. Yet, Damascene (De Fide Orth.
i, 5) employs the term "difference" in the divine persons, as meaning
that the relative property is signified by way of form. Hence he says
that the hypostases do not differ from each other in substance, but
according to determinate properties. But "difference" is taken for
"distinction," as above stated.
Reply to Objection 3: The term "alien" means what is extraneous and dissimilar;
which is not expressed by the term "other" [alius]; and therefore we say
that the Son is "other" than the Father, but not that He is anything
Reply to Objection 4: The neuter gender is formless; whereas the masculine is
formed and distinct; and so is the feminine. So the common essence is
properly and aptly expressed by the neuter gender, but by the masculine
and feminine is expressed the determined subject in the common nature.
Hence also in human affairs, if we ask, Who is this man? we answer,
Socrates, which is the name of the "suppositum"; whereas, if we ask, What
is he? we reply, A rational and mortal animal. So, because in God
distinction is by the persons, and not by the essence, we say that the
Father is other than the Son, but not something else; while conversely we
say that they are one thing, but not one person.
Article 3: Whether the exclusive word "alone" should be added to the essential term in God?
Objection 1: It would seem that the exclusive word "alone" [solus] is not to
be added to an essential term in God. For, according to the Philosopher
(Elench. ii, 3), "He is alone who is not with another." But God is with
the angels and the souls of the saints. Therefore we cannot say that God
Objection 2: Further, whatever is joined to the essential term in God can be predicated of every person "per se," and of all the persons together; for, as we can properly say that God is wise, we can say the Father is a wise God; and the Trinity is a wise God. But Augustine says (De Trin. vi, 9): "We must consider the opinion that the Father is not true God alone." Therefore God cannot be said to be alone.
Objection 3: Further if this expression "alone" is joined to an essential
term, it would be so joined as regards either the personal predicate or
the essential predicate. But it cannot be the former, as it is false to
say, "God alone is Father," since man also is a father; nor, again, can
it be applied as regards the latter, for, if this saying were true, "God
alone creates," it would follow that the "Father alone creates," as
whatever is said of God can be said of the Father; and it would be false,
as the Son also creates. Therefore this expression "alone" cannot be
joined to an essential term in God.
On the contrary, It is said, "To the King of ages, immortal, invisible,
the only God" (1 Tim. 1:17).
I answer that, This term "alone" can be taken as a categorematical term,
or as a syncategorematical term. A categorematical term is one which
ascribes absolutely its meaning to a given "suppositum"; as, for
instance, "white" to man, as when we say a "white man." If the term
"alone" is taken in this sense, it cannot in any way be joined to any
term in God; for it would mean solitude in the term to which it is
joined; and it would follow that God was solitary, against what is above
stated (Article ). A syncategorematical term imports the order of the
predicate to the subject; as this expression "every one" or "no one"; and
likewise the term "alone," as excluding every other "suppositum" from the
predicate. Thus, when we say, "Socrates alone writes," we do not mean
that Socrates is solitary, but that he has no companion in writing,
though many others may be with him. In this way nothing prevents the term
"alone" being joined to any essential term in God, as excluding the
predicate from all things but God; as if we said "God alone is eternal,"
because nothing but God is eternal.
Reply to Objection 1: Although the angels and the souls of the saints are always
with God, nevertheless, if plurality of persons did not exist in God, He
would be alone or solitary. For solitude is not removed by association
with anything that is extraneous in nature; thus anyone is said to be
alone in a garden, though many plants and animals are with him in the
garden. Likewise, God would be alone or solitary, though angels and men
were with Him, supposing that several persons were not within Him.
Therefore the society of angels and of souls does not take away absolute
solitude from God; much less does it remove respective solitude, in
reference to a predicate.
Reply to Objection 2: This expression "alone," properly speaking, does not affect
the predicate, which is taken formally, for it refers to the
"suppositum," as excluding any other suppositum from the one which it
qualifies. But the adverb "only," being exclusive, can be applied either
to subject or predicate. For we can say, "Only Socrates"---that is, no
one else---"runs: and Socrates runs only"---that is, he does nothing
else. Hence it is not properly said that the Father is God alone, or the
Trinity is God alone, unless some implied meaning be assumed in the
predicate, as, for instance, "The Trinity is God Who alone is God." In
that sense it can be true to say that the Father is that God Who alone is
God, if the relative be referred to the predicate, and not to the
"suppositum." So, when Augustine says that the Father is not God alone,
but that the Trinity is God alone, he speaks expositively, as he might
explain the words, "To the King of ages, invisible, the only God," as
applying not to the Father, but to the Trinity alone.
Reply to Objection 3: In both ways can the term "alone" be joined to an essential
term. For this proposition, "God alone is Father," can mean two things,
because the word "Father" can signify the person of the Father; and then
it is true; for no man is that person: or it can signify that relation
only; and thus it is false, because the relation of paternity is found
also in others, though not in a univocal sense. Likewise it is true to
say God alone creates; nor, does it follow, "therefore the Father alone
creates," because, as logicians say, an exclusive diction so fixes the
term to which it is joined that what is said exclusively of that term
cannot be said exclusively of an individual contained in that term: for
instance, from the premiss, "Man alone is a mortal rational animal," we
cannot conclude, "therefore Socrates alone is such."
Article 4: Whether an exclusive diction can be joined to the personal term?
Objection 1: It would seem that an exclusive diction can be joined to the personal term, even though the predicate is common. For our Lord speaking to the Father, said: "That they may know Thee, the only true God" (Jn. 17:3). Therefore the Father alone is true God.
Objection 2: Further, He said: "No one knows the Son but the Father" (Mt. 11:27); which means that the Father alone knows the Son. But to know the
Son is common (to the persons). Therefore the same conclusion follows.
Objection 3: Further, an exclusive diction does not exclude what enters into
the concept of the term to which it is joined. Hence it does not exclude
the part, nor the universal; for it does not follow that if we say
"Socrates alone is white," that therefore "his hand is not white," or
that "man is not white." But one person is in the concept of another; as
the Father is in the concept of the Son; and conversely. Therefore, when
we say, The Father alone is God, we do not exclude the Son, nor the Holy
Ghost; so that such a mode of speaking is true.
Objection 4: Further, the Church sings: "Thou alone art Most High, O Jesus
On the contrary, This proposition "The Father alone is God" includes two assertions---namely, that the Father is God, and that no other besides the Father is God. But this second proposition is false, for the Son is another from the Father, and He is God. Therefore this is false, The Father alone is God; and the same of the like sayings.
I answer that, When we say, "The Father alone is God," such a
proposition can be taken in several senses. If "alone" means solitude in
the Father, it is false in a categorematical sense; but if taken in a
syncategorematical sense it can again be understood in several ways. For
if it exclude (all others) from the form of the subject, it is true, the
sense being "the Father alone is God"---that is, "He who with no other is
the Father, is God." In this way Augustine expounds when he says (De
Trin. vi, 6): "We say the Father alone, not because He is separate from
the Son, or from the Holy Ghost, but because they are not the Father
together with Him." This, however, is not the usual way of speaking,
unless we understand another implication, as though we said "He who alone
is called the Father is God." But in the strict sense the exclusion
affects the predicate. And thus the proposition is false if it excludes
another in the masculine sense; but true if it excludes it in the neuter
sense; because the Son is another person than the Father, but not another
thing; and the same applies to the Holy Ghost. But because this diction
"alone," properly speaking, refers to the subject, it tends to exclude
another Person rather than other things. Hence such a way of speaking is
not to be taken too literally, but it should be piously expounded,
whenever we find it in an authentic work.
Reply to Objection 1: When we say, "Thee the only true God," we do not understand
it as referring to the person of the Father, but to the whole Trinity, as
Augustine expounds (De Trin. vi, 9). Or, if understood of the person of
the Father, the other persons are not excluded by reason of the unity of
essence; in so far as the word "only" excludes another thing, as above
The same Reply can be given to OBJ 2. For an essential term applied to
the Father does not exclude the Son or the Holy Ghost, by reason of the
unity of essence. Hence we must understand that in the text quoted the
term "no one" [*Nemo = non-homo, i.e. no man] is not the same as "no
man," which the word itself would seem to signify (for the person of the
Father could not be excepted), but is taken according to the usual way of
speaking in a distributive sense, to mean any rational nature.
Reply to Objection 3: The exclusive diction does not exclude what enters into the
concept of the term to which it is adjoined, if they do not differ in
"suppositum," as part and universal. But the Son differs in "suppositum"
from the Father; and so there is no parity.
Reply to Objection 4: We do not say absolutely that the Son alone is Most High;
but that He alone is Most High "with the Holy Ghost, in the glory of God