92 As for Paul, he is able to end the description of his ministry with the amazing words which he had heard from the Lord himself: "My grace is sufficient for you, for my power is made perfect in weakness"; consequently, he can exclaim: "When I am weak, then I am strong" ( 2 Cor 12:9-10). This is a basic characteristic of the Christian experience. As the heir to the mission of Peter in the Church, which has been made fruitful by the blood of the Princes of the Apostles, the Bishop of Rome exercises a ministry originating in the manifold mercy of God. This mercy converts hearts and pours forth the power of grace where the disciple experiences the bitter taste of his personal weakness and helplessness. The authority proper to this ministry is completely at the service of God's merciful plan and it must always be seen in this perspective. Its power is explained from this perspective.
Source: Ut Unum Sint (Vatican.va)