Catena Fidei

Ephesians 1:23 (WEB)
which is his body, the fullness of him who fills all in all.

Catechism · 2

§2632Article 3 · In the Age of the ChurchRead at vatican.va
“It is the prayer of Paul, the apostle par excellence, which reveals to us how the divine solicitude for all the churches ought to inspire Christian prayer.” — Catechism footnote: Cf. Rom 10:1; Eph 1:16-23; Phil 1911; Col 1:3-6; 4:3-4, 12.

§830Paragraph 3 · The Church is One, Holy, Catholic, and ApostolicRead at vatican.va
“In her subsists the fullness of Christ's body united with its head; this implies that she receives from him "the fullness of the means of salvation"” — Catechism footnote: UR 3; AG 6; Eph 1:22-23.

Leo the Great, Letters Letter 59
“…and hath put all things under His feet, and given Him to be the head over all the Church which is His body, and the fulness of Him Who filleth all in all.”” — editor's note: Ephes. i. 15–23.
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Jerome, Letters Letter 90
“In every age he bestows the same grace upon his church, that His Body may be preserved intact and that the poison of heretical opinions may nowhere prevail over it.” — editor's note: Eph. i. 23.
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Tertullian, On Monogamy Chapter 13
“Therefore, if he bids us “be made dead to the law through the body of Christ,” (which is the Church, which consists in the spirit of newness,) not “through the letter of oldness,” (that is, of the law,)—taking you away from the law, which does not keep a wife,…” — editor's note: Comp. Eph. i. 23, and the references there.
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Tertullian, The Five Books Against Marcion V.18Book V
“As, however, he says elsewhere, that the Church is the body of Christ, so here also (the apostle) declares that he “fills up that which is behind of the afflictions of Christ in his flesh for His body’s sake, which is the Church.”” — editor's note: Eph. i. 23.
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Augustine of Hippo, On the Holy Trinity IV.9Book IV
“He did not say, I and they are one thing; although, in that He is the head of the church which is His body, He might have said, and they are, not one thing, but one person, because the head and the body is one Christ; but in order to show His own Godhead…” — editor's note: Eph. i. 22, 23
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Augustine of Hippo, Sermons on New Testament Lessons Sermon 83
“So then we are He, in that we are His members, in that we are His Body, in that He is our Head, in that Whole Christ is both Head and Body.” — editor's note: Eph. i. 22, 23; 1 Cor. xii. 12.
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Augustine of Hippo, The City of God XXII.18Book XXII
“This fullness he spoke of also in the place where he says of Christ, “And gave Him to be the Head over all things to the Church, which is His body, the fullness of Him that filleth all in all.”” — editor's note: Eph. i. 22, 23.
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Gregory of Nazianzus, Orations Oration 2
“For if all men were to shirk this office, whether it must be called a ministry or a leadership, the fair fulness of the Church would be halting in the highest degree, and in fact cease to be fair.” — editor's note: Eph. i. 23.
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