I love reading this in the Office of Readings and look forward to it each year – especially since it unites two apostles that are especially important to me, as I am named after both of them: St. Peter and St. John.
It is usually read today, the Saturday after Ascension, but when the Ascension is transferred to Sunday (as it is in all but six dioceses in the US) we read it on Friday.
From a treatise on John by Saint Augustine, bishop
Two kinds of life
The Church recognizes two kinds of life as having been commended to her by God. One is a life of faith, the other a life of vision; one is a life passed on pilgrimage in time, the other in a dwelling place in eternity; one is a life of toil, the other of repose; one is spent on the road, the other in our homeland; one is active, involving labor, the other contemplative, the reward of labor.
The first kind of life is symbolized by the apostle Peter, the second by John. All of the first life is lived in this world, and it will come to an end with this world. The second life will be imperfect till the end of this world, but it will have no end in the next world. And so Christ says to Peter:Follow me; but of John he says: If I wish him to remain until I come, what is that to you? Your duty is to follow me.
You are to follow me by imitating my endurance of transient evils; John is to remain until my coming, when I will bring eternal blessings. A way of saying this more clearly might be: Your active life will be perfect if you follow the example of my passion, but to attain its full perfection John’s life of contemplation must wait until I come.
Perfect patience is to follow Christ faithfully, even to death, but for perfect knowledge we must await his coming. Here, in the land of the dying, the sufferings of the world must be endured; there, in the land of the living, shall be seen the good things of the Lord.
Christ’s words, I wish him to remain until I come, should not be taken to imply that John was to remain on earth until Christ’s coming, but rather that he was to wait because it is not now but only when Christ comes that the life he symbolizes will find fulfillment. On the other hand, Christ says to Peter: Your duty is to follow me, because the life Peter symbolizes can attain its goal only by action here and now.
Yet we should make no mental separation between these great apostles. Both lived the life symbolized by Peter; both were to attain the life symbolized by John. Symbolically, one followed, the other remained, but living by faith they both endured the sufferings of this present life of sorrow and they both longed for the joys of the future life of happiness.
Nor were they alone in this. They were one with the whole Church, the bride of Christ, which will in time be delivered from the trials of this life and live for ever in the joy of the next. These two kinds of life were represented respectively by Peter and John, yet both apostles lived by faith in this present, passing life and in eternal life both have the joy of vision.
And so for the sake of all the saints inseparably united to the body of Christ, to bide them through the storms of this life, Peter, the chief of the apostles, received the keys of the kingdom of heaven with the power to bind and loose sins; and for the sake of those same saints, to plumb the depths of that other, hidden life, John the evangelist reclined on the breast of Christ.
For it is not only Peter but the whole Church that binds and looses from sin; and as for the sublime teaching of John about the Word, who in the beginning was God with God, and everything else he told us about Christ’s divinity, and about the trinity and unity of the Godhead, which now, until the Lord comes, is all like a faint reflection in a mirror, but which will be seen face to face in the kingdom of heaven—it was not only John who drank in this teaching that came forth from the Lord’s breast as from a fountain. All who belong to the Lord are to drink it in, each according to his capacity, and this is why the Lord himself has spread John’s gospel throughout the world.