Augustine of Hippo
Catena Aurea · Johannesevangelium 17
I pray for them: I pray not for the world, but for them which thou hast given me; for they are thine. And all mine are thine, and thine are mine; and I am glorified in them. And now I am no more in the world, but these are in the world, and I come to thee. Holy Father, keep through thine own name those whom thou hast given me, that they may be one, as we are. While I was with them in the world, I kept them in thy name: those that thou gavest me I have kept, and none of them is lost, but the son of perdition; that the scripture might be fulfilled. And now come I to thee; and these things I speak in the world, that they might have my joy fulfilled in themselves.
(Tr. cvii. 6) The Son as man kept His disciples in the Father’s name, being placed among them in human form: the Father again kept them in the Son’s name, in that He heard those who asked in the Son’s name. But we must not take this carnally, as if the Father and Son kept us in turns, for the Father, Son, and Holy Ghost guard us at the same time: but Scripture does not raise us, except it stoop to us. Let us understand then that when our Lord says this, He is distinguishing the persons, not dividing the nature, so that when the Son was keeping His disciples by His bodily presence, the Father was waiting to succeed Him on His departure; but both kept them by spiritual power, and when the Son withdrew His bodily presence, He still held with the Father the spiritual keeping. For when the Son as man received them into His keeping, He did not take them from the Father’s keeping, and when the Father gave them into the Son’s keeping, it was to the Son as man, who at the same time was God. Those that Thou gavest Me I have kept, and none of them is lost but the son of perdition; i. e. the betrayer of Christ, predestined to perdition; that the Scripture might be fulfilled, especially the prophecy in Psalm 108.