St. Alphonsus Liguori, the Prince of Moral Theologians, was one of the greatest preachers in Church history. A religious founder, consummate theologian, and holy man of God, Saint Alphonsus never fails to utter a stirring word that draws out a lively penitence and redoubled dedication to the work of God from his audience. He was also a great mariologist and a devout son of Our Lady (his congregation eventually gained custody of the icon of Our Lady of Perpetual Help).

The first part of his larger work The Glories of Mary (also available from TAN), Hail Holy Queen! focuses on the Salve Regina prayer, elucidating its text and showing how it bears witness to Mary's unique glory and privileges of grace. To this end, St. Alphonsus quotes many Fathers and Doctors of the Church, including St. Bonaventure, who wrote, "No one can enter Heaven unless by Mary, as though through a door." St. Alphonsus explains that Mary is the Gate of Heaven, the portal through which mankind meets the Divine in Jesus Christ.

"Out of the fullness of the heart, the mouth speaketh," and St. Alphonsus's heart was only filled to the brim with genuine desire for innocence and purity of heart in all his spiritual children, most especially through devotion to the Blessed Mother. Written to defend her against impious attacks and diminishments of Marian devotion, St. Alphonsus shows that devotion to Our Lady is a most certain mark of eternal salvation. His words gives profound encouragement and firm hope for eternal victory through Mary; the Mother of God—who can obtain from her Divine Son anything she asks.