19 And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose upon earth, it shall be loosed also in heaven.
Rabanus: With a zeal beyond the others he had confessed the King of heaven, he is deservedly entrusted more than the others with the keys of the heavenly kingdom, that it might be clear to all, that without that confession and faith none ought to enter the kingdom of heaven. By the keys of the kingdom He means discernment and power; power, by which he binds and looses; discernment, by which he separates the worthy from the unworthy.
It follows, “And whatsoever thou shalt bind;” that is, whomsoever thou shalt judge unworthy of forgiveness while he lives, shall be judged unworthy with God; and “whatsoever thou shalt loose,” that is, whomsoever thou shalt judge worthy to be forgiven while he lives, shall obtain forgiveness of his sins from God.
This power of binding and loosing, though it seems given by the Lord to Peter alone, is indeed given also to the other Apostles [Matt 18:18], and is even now in the Bishops and Presbyters in every Church. But Peter received in a special manner the keys of the kingdom of heaven, and a supremacy of judicial power, that all the faithful throughout the world might understand that all who in any manner separate themselves from the unity of the faith, or from communion with him, such should neither be able to be loosed from the bonds of sin, nor to enter the gate of the heavenly kingdom.
Gloss: This power was committed specially to Peter, that we might thereby be invited to unity. For He therefore appointed him the head of the Apostles, that the Church might have one principal Vicar of Christ, to whom the different members of the Church should have recourse, if ever they should have dissensions among them. But if there were many heads in the Church, the bond of unity would be broken.
Second Council of Constantinople: How is it that some do presume to say that these things are said only of the living? Know they not that the sentence of anathema is nothing else but separation? They are to be avoided who are held of grievous faults, whether they are among the living, or not. For it is always behoveful to fly from the wicked.
Jerome: Bishops and Presbyters, not understanding this passage, assume to themselves something of the lofty pretensions of the Pharisees, and suppose that they may either condemn the innocent, or absolve the guilty; whereas what will be enquired into before the Lord will be not the sentence of the Priests, but the life of him that is being judged. We read in Leviticus [13:1-46] of the lepers, how they are commanded to shew themselves to the Priests; and if they have the leprosy, then they are made unclean by the Priest; not that the Priest makes them leprous and unclean, but that the Priest has knowledge of what is leprosy and what is not leprosy, and can discern who is clean, and who is unclean. In the same way then as there the Priest makes the leper unclean, here the Bishop or Presbyter binds or looses not those who are without sin, or guilt, but in discharge of his function when he has heard the varieties of their sins, he knows who is to be bound, and who loosed.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. I (London: Rivington, 1842).