St. Leo the Great: Christ's foundation on Peter abides

"It is from this ultimate inexhaustible source of security that we have received strength in our apostolic task; for his activity is never relaxed. The powerful foundation upon which the whole structure of the Church rests is never shaken by the weight of the temple that presses upon it. That faith which Christ commended in the prince of the apostles remains forever unshaken. And, just as Peter's faith in Christ endures, so does Christ's foundation upon Peter. The structure of truth persists; blessed Peter retains his rock-like strength and has not abandoned the helm of the Church which he took over. Peter is called the rock; he is declared to be the foundation; he is made doorkeeper of the heavenly kingdom; he is made judge of what is to be bound or loosed, and his judgments remain valid even in heaven; in these various ways, he is assigned a rank above the others. By reflecting on the hidden meaning of these titles of his, we can come to appreciate how close he is to Christ. In our day he carries out his trust over a wider field and with greater power; he attends to every department of his duties and responsibilities in and along with him who gave him that dignity. And so, if I do anything well, if my judgment is sound, if I obtain anything from God's mercy by my daily prayer, all this is due to the achievement and the deserts of Peter; it is his power that lives on in his See, it is his prestige that reigns. This, beloved, is the outcome of that profession of faith which God the Father inspired in the apostle's heart. That declaration rose above the doubts of all merely human opinion, and took on the solidity of a rock unshaken by any outside pressure. For, in the world-wide Church, every day Peter declares: You are the Christ, the Son of the living God, and every man who acknowledges the Lord is enabled to proclaim what those words mean." – St. Leo the Great (395-461 AD)