From Dom Guéranger's The Liturgical Year.
The Gothic Church of Spain deputes, today, one of her most glorious Prelates, to represent her at the Crib of the Divine Babe, and to celebrate his ineffable Birth. The praise, which falls from Ildephonsus’ lips, seems, at our first hearing it, to have the Mother’s dear honour for its only theme: but, how can we honour the Mother, without at the same time proclaiming the praise of the Son, to whose Birth she owes all her greatness?
Among the glorious Pontiffs, who honoured the noble episcopate of Spain, during the 7th and 8th centuries—for example: Leander, Isidore, Fulgentius, Braulio, Eugenius, Julian, Helladius—among them, and in the foremost rank, stands Ildephonsus, with his glory of having been the Doctor of the Virginity of the Mother of God, just as Athanasius is the Doctor of the Divinity of the Word, Basil the Doctor of the Divinity of the Holy Ghost, and Augustine the Doctor of Grace. The holy Bishop of Toledo has treated the dogma of Mary’s Virginity in all its completeness. With profound learning and with fervid eloquence, he proves, against the Jews, that Mary conceived without losing her Virginity; against the followers of Jovinian, that she was a Virgin in her Delivery; against the disciples of Helvidius, that she remained a Virgin, after she had given birth to her Divine Son. Other holy Doctors had treated separately on each of these sublime questions, before our Saint: but he brought together all their teachings, and merited that a Virgin-Martyr should rise from her tomb to thank him for having defended the honour of the Queen of Heaven. Nay, Mary herself, with her own pure hand, clothed him with that miraculous Chasuble, which was an image of the robe of light wherewith Ildephonsus shines now in heaven, at the foot of Mary’s Throne.
The Monastic Breviary gives us the following Lessons, in the Office of our holy Bishop.
We salute thee with devout hearts, O holy Pontiff! who standest pre-eminent in thy love of the Mother of God, even in that glorious Spain, where her honour has had such brave defenders. Come, and take thy place near the Crib of Jesus, where this incomparable Mother is watching over this Babe, who, being both her God and her Son, consecrated her virginity, but did not impair it. Pray for us to her, and remind her that she is our Mother also. Ask her to receive the hymns we sing in her honour, and to bless the offering we make of our hearts to her divine Son. That our prayer may find a readier welcome from this august Queen, we will make use of thy own words, O holy Doctor of Mary’s Virginity; and thus will we speak to her:
I come to thee, the sole Virgin-Mother of God; I prostrate myself before thee, the sole co-operatrix of the Incarnation of my God; I humble myself before thee, that wast alone found worthy to be the Mother of my Lord; I pray to thee, the Handmaid, unlike all others, of thy Son, that thou obtain for me the forgiveness of my sins, that thou procure for me the being cleansed from my evil deeds, that thou get me a love of thy grand glory, that thou reveal unto me the exceeding sweetness of thy Jesus, that thou grant me to proclaim and defend the purity of our holy Faith. Grant, that I may cling to my God and to thee, and be faithful to thy Son and to thee—to him as my Creator, to thee as Mother of my Creator; to him as the Lord of hosts, to thee as the Handmaid of the Lord of all; to him as God, to thee as Mother of God; to him as my Redeemer, to thee as the instrument of my redemption.
He became the price of my ransom, but he became so by his becoming incarnate from thy flesh. He assumed a mortal Body, but he took it from thine, and with this his sacred Body he blotted out my sins. My own human nature, which he took to his kingdom, and set it, above the Angels, on the right hand of his Father, he took from thy pure flesh and blood, when he humbled himself and was made Man.
I, then, am thy servant, O Mary! because thy Son is my Lord. Thou art our Lady, because thou art the Handmaid of our Lord. I am the servant of the Handmaid of my Lord, because thou, that art our Lady, wast made Mother of my Lord. I pray thee, I fervently pray thee, O Holy Virgin! that I may receive Jesus by that Holy Spirit, by whom thou didst become Mother of Jesus. May I be made to know Jesus by that Holy Spirit, by whom thou didst know, and possess, and bring forth Jesus. May I speak of Jesus in that same Holy Spirit, in whom thou didst confess thyself the Handmaid of the Lord. May I love Jesus in that same Holy Ghost, in whom thou adorest him as thy God, and gazest upon him as thy Son. And may I obey this thy Jesus as faithfully, as he himself, though God, was subject to thee, and to Joseph.
 Non minuit, sed sacravit. Prayer of the Church, on the Feast of the Nativity of Mary, September 8th.
 St. Ildephonsus, On the perpetual Virginity of Mary, ch. xii.x