St. Vincent of Lérins: "She is truly the Mother of God"

“THEREFORE, MAY God forbid that anyone should attempt to defraud holy Mary of her privileges of divine grace and of her special glory. For by a unique favor of our Lord and God she is to be confessed to be the most true and blessed Mother of God (Theotokos). She is truly the Mother of God, not merely in name . . . but rather because, as has already been said, in her sacred womb was accomplished the mystery that, by reason of a certain singular and unique Unity of person, even as the Word is flesh in flesh, so the man is God in God.”

~St. Vincent of Lérins (died c. 445): Commonitoria, 15.