To this teaching, the Church adds the principle of circumincession: the mutual presence of the three Divine persons in one another — each is present in each other without ceasing to be distinct.
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The divine Unity is Triune. … Because of that unity the Father is wholly in the Son and wholly in the Holy Spirit; the Son is wholly in the Father and wholly in the Holy Spirit; the Holy Spirit is wholly in the Father and wholly in the Son.* CCC #254, 255