Whether It Must Be Said That the Three Persons Are of One Essence?
Objection 1: It would seem not right to say that the three persons are
of one essence. For Hilary says (De Synod.) that the Father, Son and
Holy Ghost "are indeed three by substance, but one in harmony." But
the substance of God is His essence. Therefore the three persons are
not of one essence.
Obj. 2: Further, nothing is to be affirmed of God except what can be
confirmed by the authority of Holy Writ, as appears from Dionysius
(Div. Nom. i). Now Holy Writ never says that the Father, Son and Holy
Ghost are of one essence. Therefore this should not be asserted.
Obj. 3: Further, the divine nature is the same as the divine essence.
It suffices therefore to say that the three persons are of one nature.
Obj. 4: Further, it is not usual to say that the person is of the
essence; but rather that the essence is of the person. Therefore it
does not seem fitting to say that the three persons are of one
essence.
Obj. 5: Further, Augustine says (De Trin. vii, 6) that we do not say
that the three persons are "from one essence [ex una essentia]," lest
we should seem to indicate a distinction between the essence and the
persons in God. But prepositions which imply transition, denote the
oblique case. Therefore it is equally wrong to say that the three
persons are "of one essence [unius essentiae]."
Obj. 6: Further, nothing should be said of God which can be occasion
of error. Now, to say that the three persons are of one essence or
substance, furnishes occasion of error. For, as Hilary says (De
Synod.): "One substance predicated of the Father and the Son
signifies either one subsistent, with two denominations; or one
substance divided into two imperfect substances; or a third prior
substance taken and assumed by the other two." Therefore it must not
be said that the three persons are of one substance.
_On the contrary,_ Augustine says (Contra Maxim. iii) that the word
_homoousion,_ which the Council of Nicaea adopted against the Arians,
means that the three persons are of one essence.
_I answer that,_ As above explained (Q. 13, AA. 1, 2), divine things
are named by our intellect, not as they really are in themselves, for
in that way it knows them not; but in a way that belongs to things
created. And as in the objects of the senses, whence the intellect
derives its knowledge, the nature of the species is made individual by
the matter, and thus the nature is as the form, and the individual is
the _suppositum_ of the form; so also in God the essence is taken as
the form of the three persons, according to our mode of signification.
Now in creatures we say that every form belongs to that whereof it is
the form; as the health and beauty of a man belongs to the man. But we
do not say of that which has a form, that it belongs to the form,
unless some adjective qualifies the form; as when we say: "That woman
is of a handsome figure," or: "This man is of perfect virtue." In like
manner, as in God the persons are multiplied, and the essence is not
multiplied, we speak of one essence of the three persons, and three
persons of the one essence, provided that these genitives be
understood as designating the form.
Reply Obj. 1: Substance is here taken for the "hypostasis," and not
for the essence.
Reply Obj. 2: Although we may not find it declared in Holy Writ in so
many words that the three persons are of one essence, nevertheless we
find it so stated as regards the meaning; for instance, "I and the
Father are one (John 10:30)," and "I am in the Father, and the Father
in Me (John 10:38)"; and there are many other texts of the same
import.
Reply Obj. 3: Because "nature" designates the principle of action
while "essence" comes from being [essendo], things may be said to be
of one nature which agree in some action, as all things which give
heat; but only those things can be said to be of "one essence" which
have one being. So the divine unity is better described by saying
that the three persons are "of one essence," than by saying they are
"of one nature."
Reply Obj. 4: Form, in the absolute sense, is wont to be designated
as belonging to that of which it is the form, as we say "the virtue
of Peter." On the other hand, the thing having form is not wont to be
designated as belonging to the form except when we wish to qualify or
designate the form. In which case two genitives are required, one
signifying the form, and the other signifying the determination of
the form, as, for instance, when we say, "Peter is of great virtue
[magnae virtutis]," or else one genitive must have the force of two,
as, for instance, "he is a man of blood"--that is, he is a man who
sheds much blood [multi sanguinis]. So, because the divine essence
signifies a form as regards the person, it may properly be said that
the essence is of the person; but we cannot say the converse, unless
we add some term to designate the essence; as, for instance, the
Father is a person of the "divine essence"; or, the three persons are
"of one essence."
Reply Obj. 5: The preposition "from" or "out of" does not designate
the habitude of a formal cause, but rather the habitude of an
efficient or material cause; which causes are in all cases
distinguished from those things of which they are the causes. For
nothing can be its own matter, nor its own active principle. Yet a
thing may be its own form, as appears in all immaterial things. So,
when we say, "three persons of one essence," taking essence as having
the habitude of form, we do not mean that essence is different from
person, which we should mean if we said, "three persons from the same
essence."
Reply Obj. 6: As Hilary says (De Synod.): "It would be prejudicial to
holy things, if we had to do away with them, just because some do not
think them holy. So if some misunderstand _homoousion,_ what is that
to me, if I understand it rightly? . . . The oneness of nature does
not result from division, or from union or from community of
possession, but from one nature being proper to both Father and Son."
_______________________