Summa Theologica Part I (Prima Pars) Part 51

_I answer that,_ The very mode of expression itself shows that this term "person" is common to the three when we say "three persons"; for when we say "three men" we show that "man" is common to the three.

Now it is clear that this is not community of a real thing, as if one essence were common to the three; otherwise there would be only one person of the three, as also one essence.

What is meant by such a community has been variously determined by those who have examined the subject. Some have called it a community of exclusion, forasmuch as the definition of "person" contains the word "incommunicable." Others thought it to be a community of intention, as the definition of person contains the word "individual"; as we say that to be a species is common to horse and ox. Both of these explanations, however, are excluded by the fact that "person" is not a name of exclusion nor of intention, but the name of a reality.

We must therefore resolve that even in human affairs this name "person" is common by a community of idea, not as genus or species, but as a vague individual thing. The names of genera and species, as man or animal, are given to signify the common natures themselves, but not the intentions of those common natures, signified by the terms genus or species. The vague individual thing, as "some man,"

signifies the common nature with the determinate mode of existence of singular things--that is, something self-subsisting, as distinct from others. But the name of a designated singular thing signifies that which distinguishes the determinate thing; as the name Socrates signifies this flesh and this bone. But there is this difference--that the term "some man" signifies the nature, or the individual on the part of its nature, with the mode of existence of singular things; while this name "person" is not given to signify the individual on the part of the nature, but the subsistent reality in that nature. Now this is common in idea to the divine persons, that each of them subsists distinctly from the others in the divine nature.

Thus this name "person" is common in idea to the three divine persons.

Reply Obj. 1: This argument is founded on a real community.

Reply Obj. 2: Although person is incommunicable, yet the mode itself of incommunicable existence can be common to many.

Reply Obj. 3: Although this community is logical and not real, yet it does not follow that in G.o.d there is universal or particular, or genus, or species; both because neither in human affairs is the community of person the same as community of genus or species; and because the divine persons have one being; whereas genus and species and every other universal are predicated of many which differ in being.

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QUESTION 31

OF WHAT BELONGS TO THE UNITY OR PLURALITY IN G.o.d (In Four Articles)

We now consider what belongs to the unity or plurality in G.o.d; 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 G.o.d?

(4) Whether it can be joined to a personal term?

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FIRST ARTICLE [I, Q. 31, Art. 1]

Whether There Is Trinity in G.o.d?

Objection 1: It would seem there is not trinity in G.o.d. For every name in G.o.d 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 to G.o.d.

Obj. 2: Further, this word "trinity" is a collective term, since it signifies mult.i.tude. But such a word does not apply to G.o.d; as the unity of a collective name is the least of unities, whereas in G.o.d there exists the greatest possible unity. Therefore this word "trinity" does not apply to G.o.d.

Obj. 3: Further, every trine is threefold. But in G.o.d there is not triplicity; since triplicity is a kind of inequality. Therefore neither is there trinity in G.o.d.

Obj. 4: Further, all that exists in G.o.d exists in the unity of the divine essence; because G.o.d is His own essence. Therefore, if Trinity exists in G.o.d, it exists in the unity of the divine essence; and thus in G.o.d there would be three essential unities; which is heresy.

Obj. 5: Further, in all that is said of G.o.d, the concrete is predicated of the abstract; for Deity is G.o.d and paternity is the Father. But the Trinity cannot be called trine; otherwise there would be nine realities in G.o.d; which, of course, is erroneous. Therefore the word trinity is not to be applied to G.o.d.

_On the contrary,_ Athanasius says: "Unity in Trinity; and Trinity in Unity is to be revered."

_I answer that,_ The name "Trinity" in G.o.d signifies the determinate number of persons. And so the plurality of persons in G.o.d requires that we should use the word trinity; because what is indeterminately signified by plurality, is signified by trinity in a determinate manner.

Reply Obj. 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 Obj. 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 mult.i.tude 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 Obj. 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 G.o.d there is not triplicity, but Trinity.

Reply Obj. 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 Obj. 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, "G.o.d is trine," it follows that there are three _supposita_ of the G.o.dhead.

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SECOND ARTICLE [I, Q. 31, Art. 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."

Obj. 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 G.o.dhead; nor is there any difference in substance between them, nor any diversity."

Obj. 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 than the Father.

Obj. 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 another."

_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 G.o.d, 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 G.o.dhead": and according to Hilary, as quoted above, "in G.o.d 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 a.s.sert that the Father and the Son are separate in G.o.dhead." 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 G.o.d the idea of singularity or uniqueness." Nevertheless, we say "the only Son," for in G.o.d there is no plurality of Sons. Yet, we do not say "the only G.o.d," 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 G.o.d."

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 Obj. 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 another.

Reply Obj. 2: "Difference" implies distinction of form. There is one form in G.o.d, as appears from the text, "Who, when He was in the form of G.o.d" (Phil. 2:6). Therefore the term "difference" does not properly apply to G.o.d, 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 Obj. 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 "alien."

Reply Obj. 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 G.o.d 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.

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THIRD ARTICLE [I, Q. 31, Art. 3]

Whether the Exclusive Word "Alone" Should Be Added to the Essential Term in G.o.d?