Out of the whole world one man, Peter, is chosen to preside at the head of all nations and to be set over all the apostles and all the fathers of the church. Though there are in God's people many bishops and many shepherds, Peter is thus appointed to rule in his own person those whom Christ also rules as the original ruler. Beloved, how great and wonderful is this sharing in his power that God in his goodness has given to this man. Whatever Christ has willed to be shared in common by Peter and the other leaders of the Church, it is only through Peter that he has given to others what he has not refused to bestow on them.
Jesus said: "Upon this rock I will build my Church, and the gates of hell shall not prevail against it." On this strong foundation, he says, I will build an everlasting temple. The great height of my Church, which is to penetrate the heavens, shall rise on the firm foundation of this faith.
Blessed Peter is therefore told: "To you I will give the keys of the kingdom of heaven. Whatever you bind on earth shall be bound also in heaven. Whatever you loose on earth shall be loosed also in heaven."
--from a sermon by Pope Saint Leo the Great
Catholic