"Who does not know that the holy Church is founded on the solidity of the Chief Apostle, whose name expressed his firmness, being called Peter from Petra (Rock)?...Though there were many Apostles, only the See of the Prince of the Apostles...received supreme authority in virtue of its very principate." (Letter to the Patriarch Eulogius of Alexandria, Ep. 7)
And also in Epistle 13.50, he speaks of:
"the Apostolic See, which is the head of all Churches"
“”Who does not know that the holy Church is founded on the solidity of the Chief Apostle, whose name expressed his firmness, being called Peter from Petra (Rock)?...Though there were many Apostles, only the See of the Prince of the Apostles...received supreme authority in virtue of its very principate.” (Letter to the Patriarch Eulogius of Alexandria, Ep. 7)”
Key words, the See of Peter in THREE places, governed with divine authority by three Bishops, who are yet “one” see, which is Antioch, Rome and Alexandria. We’re not talking about the Primacy of Peter, which they had believed at that time, but the Primacy of Rome.