VATICAN CITY, OCT. 5, 2007 (Zenit) - Here is a translation of the address Benedict XVI delivered Wednesday at the general audience in St. Peter's Square. The reflection focused on St. Cyril of Alexandria.

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Dear brothers and sisters!

Today, continuing our journey in the footsteps of the Fathers of the Church, we meet a great figure: St. Cyril of Alexandria. Linked to the Christological controversy that led to the Council of Ephesus in 431, and the last noteworthy representative of the Alexandrian tradition, Cyril was later defined in the East as the “custodian of accuracy” -- in other words, a guardian of the true faith -- and even the “seal of all the Fathers."

These ancient expressions manifest something that is, in fact, characteristic of Cyril, that is, the constant references the bishop of Alexandria makes to preceding ecclesiastical authorities -- including, above all, Athanasius -- with the goal of showing the continuity of his own theology with tradition.

Cyril took care to ensure that his theology was firmly situated within the tradition of the Church, by which he sees the guarantee of continuity with the Apostles and with Christ himself.

Venerated as a saint in both the East and the West, in 1882 St. Cyril was proclaimed a doctor of the Church by Pope Leo XIII, who at that time also gave the same title to another important representative of Greek patristics, St. Cyril of Jerusalem. This shows that Pope's attention and love for the Eastern Christian traditions; he would later proclaim St. John Damascene a doctor of the Church, showing how the Eastern and Western traditions express the doctrine of the one Church of Christ.

Information on the life of Cyril before his election to the important See of Alexandria is scarce. A nephew of Theophilus -- who, as bishop from 385, upheld the Diocese of Alexandria with resolve and prestige -- Cyril was most likely born in that same Egyptian city sometime between 370-380. He soon embraced the ecclesiastical life and received a good education, both in culture and theology. In 403, he was in Constantinople following his powerful uncle and, here, he participated in the so-called Synod of the Oak, which deposed the city’s bishop -- John, later called Chrysostom. This indicated the triumph of the Alexandrian See over its traditional rival, the See of Constantinople, where the emperor resided.

Upon the death of his uncle Theophilus, though still young, Cyril was elected bishop of the influential Church of Alexandria in 412, which he governed with great energy for 32 years, working tirelessly to affirm its primacy in the East, strengthened by its traditional bonds with Rome.

Two or three years later, in 417 or 418, the bishop of Alexandria showed himself to be a realist and healed the rift in the communion with Constantinople, which had been going on since 406, in the wake of Chrysostom’s removal from office.

But the old conflict with the See of Constantinople was rekindled some 10 years later, when Nestorius was elected in 428, a prestigious but severe monk, educated in Antioch. The new bishop of Constantinople quickly brought much opposition because he preferred the title “Mother of Christ” (Christotòkos) for Mary, in place of “Mother of God” (Theotòkos), which was already beloved in popular devotion.

The reason for Bishop Nestorius’ choice was his adhesion to the Christology of the Antiochean tradition, which, to safeguard the importance of Christ’s humanity, ended up affirming its separation from his divinity. Thus, there was no longer an authentic union between God and the man Christ, and therefore, one could no longer speak of a “Mother of God."

Cyril -- the leading exponent of Alexandrian Christology at the time, one who emphatically underlined the unity of Christ’s person -- reacted almost immediately, using every means possible beginning in 429, even writing letters to Nestorius himself.

In the second letter (PG 77, 44-49) which Cyril sent to him, in February 430, we read a clear affirmation of the pastor’s task to preserve the faith of God’s people. This was his criterion, which is still valid today: The faith of God’s people is an expression of tradition, a guarantee of sound doctrine. He wrote to Nestorius: “It is necessary to explain the teaching and interpretation of the faith to the people in an irreproachable way, and recall that he who scandalizes even one of these little ones who believes in Christ will suffer an intolerable punishment."

In the same letter to Nestorius -- which later, in 451, would be approved by the Fourth Ecumenical Council of Chalcedon -- Cyril describes his Christological faith with clarity: "The natures that have united in a true unity are different, but from both resulted one Christ and Son, not ...