Cyprian of Carthage, On the Unity of the Church 4
A brief look at these matters makes long arguments unnecessary; the truth sums itself up in a way faith grasps at once.
The Lord says to Peter, "You are Peter, and on this rock I will build my Church, and the gates of the underworld will not conquer it. I will give you the keys of the kingdom of heaven: whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven" (Matt 16:18–19).
After the resurrection he tells him again, "Feed my sheep" (John 21:17), and he builds his Church on this one man, entrusting his flock to his care.
True, the risen Lord gives all the apostles equal authority — "As the Father sent me, so I send you. Receive the Holy Spirit; if you forgive anyone's sins, they are forgiven; if you retain them, they are retained" — yet to make unity visible he establishes a single chair, decreeing by his own authority that this unity must spring from one source.
The other apostles shared Peter's rank, honor, and power, but the beginning proceeds from unity, and the primacy is given to Peter so that Christ's Church and its chair may be seen as one.
All are shepherds, yet there is only one flock, fed by the apostles with one consent, so that the oneness of Christ's Church may be shown.
The Holy Spirit points to this same unity in the Song of Songs, speaking in the Lord's person: "My dove is one, my perfect one, one to her mother, chosen by her parent."
Anyone who fails to hold this unity of the Church cannot claim to hold the faith. Anyone who resists the Church and abandons the chair of Peter, on which the Church is founded, cannot be confident he belongs to the Church.
Even the blessed apostle Paul teaches the same truth and displays the sacrament of unity: "One body and one Spirit, one hope of your calling, one Lord, one faith, one baptism, one God" (Eph 4:4–6).
Latin
Quae si quis consideret et examinet, tractatu longo atque argumentis opus non est. Probatio est ad fidem facilis compendio veritatis. Loquitur Dominus ad Petrum: Ego tibi dico, inquit, quia tu es Petrus, et super hanc petram aedificabo Ecclesiam meam, et portae inferorum non vincent eam. Et tibi dabo claves regni coelorum: et quae ligaveris super terram, erunt ligata et in coelis; et quaecumque solveris super terram, erunt soluta et in coelis. Et iterum eidem post resurrectionem suam dicit: Pasce oves meas. Super illum unum aedificat Ecclesiam suam, et illi pascendas mandat oves suas. Et quamvis Apostolis omnibus post resurrectionem suam parem potestatem tribuat et dicat, Sicut misit me Pater, et ego mitto vos: accipite Spiritum sanctum; si cujus remiseritis peccata, remittentur illi, si cujus tenueritis, tenebuntur, tamen, ut unitatem manifestaret, unam cathedram constituit, unitatis ejusdem originem ab uno incipientem sua auctoritate disposuit. Hoc erant utique et caeteri Apostoli quod fuit Petrus, pari consortio praediti et honoris et potestatis, sed exordium ab unitate proficiscitur, et primatus Petro datur, ut una Christi Ecclesia et cathedra una monstretur. Et pastores sunt omnes, et grex unus ostenditur, qui ab Apostolis omnibus unanimi consensione pascatur, ut Ecclesia Christi una monstretur. Quam unam Ecclesiam etiam in Cantico canticorum Spiritus sanctus ex persona Domini designat et dicit: Una est columba mea, perfecta mea, una est matri suae, electa genitrici suae. Hanc Ecclesiae unitiatem qui non tenet, tenere se fidem credit? Qui Ecclesiae renititur et resistit, qui cathedram Petri, super quem fundata est Ecclesia, deserit, in Ecclesia se esse confidit? quando et beatus apostolus Paulus hoc idem doceat et sacramentum unitatis ostendat dicens: Unum corpus et unus spiritus, una spes vocationis vestrae, unus Dominus, una fides, unum Baptisma, unus Deus.