St. Ignatius was the first person in Christian literature to attribute to the Church the adjective "catholic" or "universal": "Wherever Jesus Christ is", he said, "there is the Catholic Church" (Smyrnaeans, 8: 2).
And precisely in the service of unity to the Catholic Church, the Christian community of Rome exercised a sort of primacy of love: "The Church which presides in the place of the region of the Romans, and which is worthy of God, worthy of honour, worthy of the highest happiness... and which presides over love, is named from Christ, and from the Father..." (Prologue, from a letter to the Romans by Saint Ignatius of Antioch).
From Benedict XVI's catechesis on on St. Ignatius of Antioch: