And I will give unto you the keys of the kingdom of heaven: and whatsoever you shall bind on earth shall be what has been bound in heaven: and whatsoever you shall loose on earth shall be what has been loosed in heaven.
All Commentaries on Matthew 16:19 Go To Matthew 16
Glossa Ordinaria
AD 1480
As soon as the Lord had taken His disciples out of the teaching of the Pharisees, He then suitably proceeds to lay deep the foundations of the Gospel doctrine; and to give this the greater solemnity, it is introduced bythe name of the place, “When Jesus came into the coasts of Caesarea Philippi.”
When about to confirm the disciples in the faith, He would first takeaway from their minds the errors and opinions of others, whence it follows, "And he asked his disciples, saying, Whom do men say that the Son of Man is?”.
So by this instance of the Apostles, the followers of the Bishops are instructed, that whatever opinions they may hear out of doors concerning their Bishops, they should tell them to them.
That is, shall not separate it from the love and faith of Me.
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. Some say that the words “upon earth” denote that power was not given to men to bind and loose the dead, but the living; forhe who should loose the dead would do this not upon earth, but after the earth. Second Council of Constantinople, Concil.Con. ii. Collat. 8: 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. Moreover there are divers letters read of Augustine of religious memory, who was of great renown among the African bishops, which affirmed We read in Leviticus of the lepers, how they are commanded to show 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. Inthe 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.