Yes. According to each of three points of consideration the Son and the Father are in each other: the essence, the relation, and the origin.
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.
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 applies to the Holy Ghost.