the nature of a form requires it to be "in" that of which it
is the form, we must say that the properties are in the persons, and
yet that they are the persons; as we say that the essence is in God,
and yet is God.

Reply Obj. 1: Person and property are really the same, but differ in
concept. Consequently, it does not follow that if one is multiplied,
the other must also be multiplied. We must, however, consider that in
God, by reason of the divine simplicity, a twofold real identity
exists as regards what in creatures are distinct. For, since the
divine simplicity excludes the composition of matter and form, it
follows that in God the abstract is the same as the concrete, as
"Godhead" and "God." And as the divine simplicity excludes the
composition of subject and accident, it follows that whatever is
attributed to God, is His essence Itself; and so, wisdom and power
are the same in God, because they are both in the divine essence.
According to this twofold identity, property in God is the same as
person. For personal properties are the same as the persons because
the abstract and the concrete are the same in God; since they are the
subsisting persons themselves, as paternity is the Father Himself,
and filiation is the Son, and procession is the Holy Ghost. But the
non-personal properties are the same as the persons according to the
other reason of identity, whereby whatever is attributed to God is
His own essence. Thus, common spiration is the same as the person of
the Father, and the person of the Son; not that it is one
self-subsisting person; but that as there is one essence in the two
persons, so also there is one property in the two persons, as above
explained (Q. 30, A. 2).

Reply Obj. 2: The properties are said to be in the essence, only by
mode of identity; but in the persons they exist by mode of identity,
not merely in reality, but also in the mode of signification; as the
form exists in its subject. Thus the properties determine and
distinguish the persons, but not the essence.

Reply Obj. 3: Notional participles and verbs signify the notional
acts: and acts belong to a _suppositum._ Now, properties are not
designated as _supposita,_ but as forms of _supposita._ And so their
mode of signification is against notional participles and verbs being
predicated of the properties.
_______________________

SECOND ARTICLE [I, Q. 40, Art. 2]

Whether the Persons Are Distinguished by the Relations?

Objection 1