From Dom Guéranger's The Liturgical Year.

‘Praise and glory be to thee, O holy Trinity, who hast brought us all to this day’s solemnity. Praise be to thee also, O holy Mother of God, sceptre of the orthodox faith: through thee the cross triumphs, and man is called back to heaven; through thee the idols are overthrown, and the nations are brought to repentance.’[1] Such words as these, which the Church borrows from her doctors to close the bright octave, were doubtless sung in prophecy by the angels around the new-born babe Mary. And such, in the light of the ages since elapsed, must needs be our answer to the question so often repeated at the cradle side: What shall this child be?

The doctrine lately laid down so magisterially by the infallible successor of St. Peter, is this: Since the days of her mortal life, when Mary was, even in this world, truly the Mother of the Church, the Queen of the apostles and their mistress with regard to the divine oracles; but especially since she has received in heaven an almost infinite power for dispensing the fruits of redemption: the mighty helper of the Christian people, the restorer of the world, has not ceased to prove herself the impregnable rampart of the Church, the solid foundation of the faith, the fountain springing from God, whence the rivers of divine Wisdom pour out their pure waters, sweeping away heresy from all places.[2]

May so glorious a past give us confidence for the future. ‘It is by Mary,’ says the blessed Grignon de Montfort, ‘that the salvation of the world has begun, and it is by Mary that it must be consummated. Being the way by which Jesus Christ came to us the first time, she will also be the way by which He will come the second time, though not in the same manner. Mary must shine forth more than ever in mercy, in might and in grace, in these latter times: in mercy, to bring back and lovingly receive the poor strayed sinners who shall be converted and shall return to the Catholic Church; in might, against the enemies of God, idolaters, schismatics, Mahometans, Jews, and souls hardened in impiety, who shall rise in terrible revolt against God, to seduce all those who shall be contrary to them, and make them fall by promises and threats; and finally, she must shine forth in grace, in order to animate and sustain the valiant soldiers and faithful servants of Jesus Christ, who shall do battle for His interests. Mary must be terrible as an army ranged in battle, principally in these latter times. It is principally of these last and cruel persecutions of the devil, which shall go on increasing daily till the reign of Antichrist, that we ought to understand that first and celebrated prediction and curse of God, pronounced in the terrestrial paradise against the serpent: I will put enmities between thee and the woman, and thy seed and her seed.

God has never made or formed but one enmity; but it is an irreconcilable one: it is between Mary, His worthy Mother, and the devil; between the children and servants of the blessed Virgin and the children and instruments of Lucifer. Satan fears Mary not only more than all angels and men, but in some sense more than God Himself. It is not that the anger, the hatred, and the power of God are not infinitely greater than those of the blessed Virgin, for the perfections of Mary are limited; but it is because satan, being proud, suffers infinitely more from being beaten and punished by a little and humble handmaid of God, and her humility humbles him more than the divine power. The devils fear one of her sighs for a soul more than the prayers of all the saints, and one of her menaces against them more than all other torments.’[3]

Let us sing to Mary on her birthday feast this graceful sequence of the fourteenth century.

Sequence

Nativitas Mariæ Virginis
Quæ nos lavit a labe criminis
Celebratur hodie, dies est lætitiæ:

De radice Jesse propaginis
Hanc eduxit Solveri luminis manu Sapientiæ,
Templum suæ gratiæ.

Stella nova noviter oritur
Cujus ortu mors nostra moritur,
Evæ lapsus jam restituitur in Maria:

Ut aurora surgens progredite,
Sicut luna pulchra describitur,
Super cunctas ut sol eligitur Virgo pia.

Virgo Mater et virgo unica,
Virga fumi sed aromatica,
In te cœli mundique fabrica Gloriatur:

Te signarunt ora prophetica,
Tibi canit Salomon cantica
Canticorum, te vox angelica Protestatur.

Verbum Patris processu temporis,
Intra tui secretum corporis,
In te totum et totum deforis Simul fuit:

Fructus virens arentis arboris,
Christus, gigas immensi roboris,
Nox a nexu funesti pignoris Eripuit.

Condoluit humano generi
Virginalis filius uteri,
Accingantur senes et pueri ad laudem Virginis:

Qui poterat de nobis conqueri
Pro peccato parentum veteri,
Mediator voluit fieri Dei et hominis.

O Maria, dulce commercium
Intra tuum celasti gremium,
Quo salutis reis remedium indulgetur:

O vera spes et verum gaudium,
Fac post vitæ præsentis stadium,
Ut optatu m in cœlis bravium nobis detur.

Amen.
The Nativity of the Virgin Mary,
who cleansed us from the stain of our crimes,
is celebrated to-day: it a day of joy!

This is the branch produced
from the root of Jesse by the Sun of true light;
she is the handiwork of Wisdom, the temple of divine grace.

A new star newly rises,
at whose rising our death dies;
the fall of Eve is now repaired in Mary.

The gentle Virgin comes forth as the rising aurora;
appearing beautiful as the moon,
chosen above all maidens as the sun outshines the stars.

Virgin-Mother and Virgin without peer,
pillar of smoke of aromatical spices,
both heaven and earth are justly proud of thee.

Thee did the ancient seers prophesy;
to thee sang Solomon his Song of songs;
the angel’s voice thy greatness did proclaim.

In course of time, the heavenly Father’s Word,
in thy chaste body took up his abode,
at once wholly within, wholly without.

Christ, the fair fruit of an unwatered tree,
the giant of immeasurable strength,
has freed us from the bond of the fatal pledge.

The Son of a Virgin Mother
has taken pity on the human race:
then let old men and children be prompt to praise the Virgin.

He who might well have spoken against us
for that ancient sin of our first parents,
chose to become the mediator between God and man.

How sweet, O Mary, was the secret commerce
carried on within thy bosom,
whereby the remedy of salvation was mercifully given to the guilty!

O our true joy and most assured hope,
grant that, after the course of this present life,
we may obtain in heaven the reward we so desire.

Amen.

[1] Lessons of the 2nd nocturn, ex Cyrill. Alex. Hom. iv. Ephesi.
[2] Leo xiii. Encycl. Adjutricem populi Christiani, Sept. 5, 1895.
[3] Treatise on the true devotion to the blessed Virgin. Translated by Father Faber.