ch is irreconcilable with the idea of
universal, the parts of which are distinguished in being. Person
likewise is not a universal term in God as we have seen above (Q. 30,
A. 4). Wherefore all the relations together are not greater than only
one; nor are all the persons something greater than only one; because
the whole perfection of the divine nature exists in each person.
_______________________

FIFTH ARTICLE [I, Q. 42, Art. 5]

Whether the Son Is in the Father, and Conversely?

Objection 1: It would seem that the Son and the Father are not in each
other. For the Philosopher (Phys. iv, text. 23) gives eight modes of
one thing existing in another, according to none of which is the Son
in the Father, or conversely; as is patent to anyone who examines each
mode. Therefore the Son and the Father are not in each other.

Obj. 2: Further, nothing that has come out from another is within.
But the Son from eternity came out from the Father, according to Mic.
5:2: "His going forth is from the beginning, from the days of
eternity." Therefore the Son is not in the Father.

Obj. 3: Further, one of two opposites cannot be in the other. But the
Son and the Father are relatively opposed. Therefore one cannot be in
the other.

_On the contrary,_ It is said (John 14:10): "I am in the Father, and
the Father is in Me."

_I answer that,_ There are three points of consideration as regards
the Father and the Son; the essence, the relation and the origin; and
according to each the Son and the Father are in each other. The
Father is in the Son by His essence, forasmuch as the Father is His
own essence and communicates His essence to the Son not by any change
on His part. Hence it follows that as the Father's essence is in the
Son, the Father Himself is in the Son; likewise, since the Son is His
own essence, it follows that He Himself is in the Father in Whom is
His essence. This is expressed by Hilary (De Trin. v), "The
unchangeable God, so to speak, follows His own nature in begetting an
unchangeable subsisting God. So we understand the nature of God to
subsist in Him, for He is God in God." It is also manifest that as
regards the relations, each of two relative opposites is in the
concept of the other. Regarding origin also, it is clear that the
procession of the intelligible word is not outside the intellect,
inasmuch as it remains in the utterer of the word. What also is
uttered by the word is therein contained. And the same ap