Mary is called Mother of the Lord
As We have already mentioned, Venerable Brothers, according to ancient tradition and the sacred liturgy the main principle on which the royal dignity of Mary rests is without doubt her Divine Motherhood. In Holy Writ, concerning the Son whom Mary will conceive, We read this sentence: He shall be called the Son of the most High, and the Lord God shall give unto him the throne of David his father, and he shall reign in the house of Jacob forever, and of his kingdom there will be no end; and in addition Mary is called [by the Davidic title] Mother of the Lord. From this it is easily concluded that she is a Queen, since she bore a son who, at the very moment of His conception, because of the hypostatic union of the human nature with the Word, was also as man King and Lord of all things. So with complete justice St. John Damascene could write: When she became Mother of the Creator, she truly became Queen of every creature. Likewise, it can be said that the heavenly voice of the Archangel Gabriel was the first to proclaim Mary's royal office.
But the Blessed Virgin Mary should be called Queen, not only because of her Divine Motherhood, but also because God has willed her to have an exceptional role in the work of our eternal salvation. What more joyful, what sweeter thought can we have—as Our Predecessor of happy memory, Pius XI wrote—than that Christ is our King not only by natural right, but also by an acquired right: that which He won by the redemption? Would that all men, now forgetful of how much we cost Our Savior, might recall to mind the words, 'You were redeemed, not with gold or silver which perishes, . . . but with the precious blood of Christ, as of a Lamb spotless and undefiled. We belong not to ourselves now, since Christ has bought us at a great price'.
Now, in the accomplishing of this work of redemption, the Blessed Virgin Mary was most closely associated with Christ; and so it is fitting to sing in the sacred liturgy: Near the cross of Our Lord Jesus Christ there stood, sorrowful, the Blessed Mary, Queen of Heaven and Queen of the World. Hence, as the devout disciple of St. Anselm wrote in the Middle Ages: Just as . . . God, by making all through His power, is Father and Lord of all, so the blessed Mary, by repairing all through her merits, is Mother and Queen of all; for God is the Lord of all things, because by His command He establishes each of them in its own nature, and Mary is the Queen of all things, because she restores each to its original dignity through the grace which she merited. For, just as Christ, because He redeemed us, is our Lord and king by a special title, so the Blessed Virgin also (is our queen), on account of the unique manner in which she assisted in our redemption, by giving of her own substance, by freely offering Him for us, by her singular desire and petition for, and active interest in, our salvation. …
Certainly, in the full and strict meaning of the term, only Jesus Christ, the God-Man, is King; but Mary, too, as Mother of the divine Christ, as His associate in the redemption, in his struggle with His enemies and His final victory over them, has a share, though in a limited and analogous way, in His royal dignity. For from her union with Christ she attains a radiant eminence transcending that of any other creature; from her union with Christ she receives the royal right to dispose of the treasures of the Divine Redeemer's Kingdom; from her union with Christ finally is derived the inexhaustible efficacy of her maternal intercession before the Son and His Father.
Besides, the Blessed Virgin possessed, after Christ, not only the highest degree of excellence and perfection, but also a share in that influence by which He, her Son and our Redeemer, is rightly said to reign over the minds and wills of men. For if through His Humanity the divine Word performs miracles and gives graces, if He uses His Sacraments and Saints as instruments for the salvation of men, why should He not make use of the role and work of His most holy Mother in imparting to us the fruits of redemption? With a heart that is truly a mother's, to quote again Our Predecessor of immortal memory, Pius IX, does she approach the problem of our salvation, and is solicitous for the whole human race; made Queen of heaven and earth by the Lord, exalted above all choirs of angels and saints, and standing at the right hand of her only Son, Jesus Christ our Lord, she intercedes powerfully for us with a mother's prayers, obtains what she seeks, and cannot be refused.
Let all Christians, therefore, glory in being subjects of the Virgin Mother of God, who, while wielding royal power, is on fire with a mother's love.