"...8. From early times Christians have believed, and not without reason, that she of whom was born the Son of the Most High received privileges of grace above all other beings created by God. He "will reign in the house of Jacob forever," "the Prince of Peace," the "King of Kings and Lord of Lords." And when Christians reflected upon the intimate connection that obtains between a mother and a son, they readily acknowledged the supreme royal dignity of the Mother of God.
9. Hence it is not surprising that the early writers of the Church called Mary "the Mother of the King" and "the Mother of the Lord," basing their stand on the words of St. Gabriel the archangel, who foretold that the Son of Mary would reign forever, and on the words of Elizabeth who greeted her with reverence and called her "the Mother of my Lord." Thereby they clearly signified that she derived a certain eminence and exalted station from the royal dignity of her Son..."Pope Pius XII's Encyclical: Ad Caeli Reginam
"Mary, then, is a Queen; but for our common consolation, be it known that she is a Queen so sweet, clement, and so ready to help us that Holy Church wills that we salute her as Queen of Mercy. Mary is Queen of Mercy as Jesus is King of Justice."Picture source
"The purpose of the universal feast of the Queenship of Mary which we again happily observe and welcome this week is to stir up in our souls renewed love and devotion to our Mother and Queen and to invite all to rededicate themselves to her Immaculate Heart. These are indeed days of tension and worry throughout the world with talk of total destruction to mankind by nuclear weapons. Mary, however, our Queen and our Mother, has come to the rescue of civilization in the centuries that have passed. She will do it again if we but turn to her and beseech her for true peace throughout the world. Would that the prayer of Pope Pius XII to Mary our Queen be realized in the minds and wills of all.
'Reign over the minds of men, that they may seek only what is true; over their wills, that they may follow solely what is good; over their hearts, that they may love nothing but what you yourself love.'"
Homily of John J. Cardinal Carberry given on the occasion of the Queenship of Mary, May, 1959. Source: Mary Queen and Mother: Marian Pastoral Reflections by John J. Cardinal Carberry