St. Francis de Sales on Our Lady as Theotokos
Mosaic of Our Lady from the Hagia Sophia, taken from The Religion Network
[The following is excerpted from St. Francis de Sales' sermon on Our Lady's Nativity, given on 10 September 1620, and translated by the Nuns of the Visitation in Frederick, Maryland, USA in "The Sermons of St. Francis de Sales on Our Lady," published by TAN Books. 11 October is the feast of Our Lady's Maternity on the traditional sanctoral calendar.]
"The great Apostle St. Paul, who is certainly admirable in all that he said, offered an argument by which we can understand how great is the dignity of the Mother of God: Is there an angel, even a seraphim, to whom the Eternal Father has said: 'This one is My Son'? (Heb. 1:5). Oh no, that applied only to our dear Savior and Master, who was His true and natural Son. And we can add: Is there any creature to whom the Son of God has said, 'My Mother'? No, certainly, that was due to this Virgin [Mary] alone, who had carried him for nine months in her sacred womb. Let us conclude, then following this great saint, that the greatest title that can be given to the Holy Virgin is to name her Mother of God."