force of its own proper signification.

Reply Obj. 1: This word "person" is said in respect to itself, not to
another; forasmuch as it signifies relation not as such, but by way
of a substance--which is a hypostasis. In that sense Augustine says
that it signifies the essence, inasmuch as in God essence is the same
as the hypostasis, because in God what He is, and whereby He is are
the same.

Reply Obj. 2: The term "what" refers sometimes to the nature
expressed by the definition, as when we ask; What is man? and we
answer: A mortal rational animal. Sometimes it refers to the
_suppositum,_ as when we ask, What swims in the sea? and answer, A
fish. So to those who ask, Three what? we answer, Three persons.

Reply Obj. 3: In God the individual--i.e. distinct and incommunicable
substance--includes the idea of relation, as above explained.

Reply Obj. 4: The different sense of the less common term does not
produce equivocation in the more common. Although a horse and an ass
have their own proper definitions, nevertheless they agree univocally
in animal, because the common definition of animal applies to both.
So it does not follow that, although relation is contained in the
signification of divine person, but not in that of an angelic or of a
human person, the word "person" is used in an equivocal sense. Though
neither is it applied univocally, since nothing can be said
univocally of God and creatures (Q. 13, A. 5).
_______________________

QUESTION 30

THE PLURALITY OF PERSONS IN GOD
(In Four Articles)

We are now led to consider the plurality of the persons: about which
there are four points of inquiry:

(1) Whether there are several persons in God?

(2) How many are they?

(3) What the numeral terms signify in God?

(4) The community of the term "person."
_______________________

FIRST ARTICLE [I, Q. 30, Art. 1]

Whether There Are Several Persons in God?

Objection 1: It would seem that there are not several persons in God.
For person is "the individual substance of a rational nature." If then
there are several persons in God, there must be several substances;
which appears to be heretical.

Obj. 2: Further, Plurality of absolute properties does not make a
distinction of persons, either in God, or in ourselves. Much less
therefore is this effected by a plurality of relations. But in God
there is no plurality but of relations (Q. 28, A. 3). Therefore
there cannot be several persons in God.

Obj. 3: