by Fr. Jonathan Atchley
Two of the most powerful words conjoined in any language were literally spoken by an Angel, recorded in the New Testament, attested to by the most holy and venerated of saints, and prayed perhaps more than any other prayer worldwide: "Hail, Mary!"
So important is this prayer that St. Thomas Aquinas preached 40 continuous days in Rome on just the Hail Mary. St. Alphonsus Liguori wrote in his book, "The Glories of Mary," that were he in heaven, he would be most pleased to return to earth just to pray one more Hail Mary. St. Don Bosco said: “all my work began with a simple Hail Mary for Our Lady’s help.” St. Louis de Montfort wrote that when joined to the Word of God, the Hail Mary “gives the preacher the strength to pierce, move, and convert the most hardened hearts.” Thomas a Kempis said that “Satan and hell tremble when I repeat Hail Mary.”
Whence all the outpouring of love and respect for such a simple prayer? Know that at any time it is a great event when an angel appears. More so when the angel acknowledges respect for a human person, because an angel’s dignity is greater than that of our own fallen human nature. St. Thomas Aquinas asserted in his salutary preaching on Mary: “it was not fitting that an Angel should show reverence to man, until someone could be found in human nature who excelled the Angels.”  Thus a heavenly messenger reverenced Mary with his words, “Hail, full of grace!”
God gives his grace that we might do good and avoid evil. Mary, full of grace, was always sinless, free from every mortal and venial sin, sanctified in the womb and preserved from the stain of Original Sin.  So, too, she is the model of all virtues, whom the Lord himself regarded her highly in her humility (Luke 1: 48); His grace affected not only her soul but her body as well, so that from her the Son of God might be born in her. Unlike any other saint, Mary is “full of grace,” effective not only for her own salvation but with such an overabundance that it suffices for the salvation of all mankind as well. Hence she bears the title, "Co-Mediatrix," for she helps dispense all grace won by Our Lord through his Passion, Death and Resurrection. 
The Angel’s greeting goes on: “The Lord is with Thee.” These are the most praiseworthy words the Angel could have uttered, says St. Thomas Aquinas in a Marian homily, for she is “the Noble abode of the Most Blessed Trinity.” Mother of Our Lord and Our Mother, Mary is blessed among women and most especially because of the blessed fruit of her womb, Jesus. Now some women are honored for the beauty or their accomplishments, but Mary is honored above all other women (and men) for her grace. What blessings Eve took away Mary restored; for while Eve’s fruit was mundanely tempting, Mary’s fruit was Jesus Christ, to whom “every tongue should confess is Lord to the glory of God the Father” (Phil. 2:11). Of her St. Bernard of Clairvaux said: "It is no great thing to be humble when you are brought low; but to be humble when you are praised is a great and rare attainment."
For this reason, the Church recommends the faithful pray the Hail Mary with reverence, full of confidence that Our Heavenly Mother will come to our aid. She is beyond generous and delights in showing it. Scripture says of Our Lady: “I am the mother of fair love, and of fear, and of knowledge, and of holy hope. In me is all grace of the way and of the truth, in me is all hope of life and of virtue” (Sirach, 24:24-25). Anyone who loves Our Lady knows that in favoring her, they in turn will be favored. It is no wonder that the saints extol the Humble Maiden’s prayer and encourage us to pray it frequently for the benefit of blessings on earth and eternal salvation to come. After all, what good children do not delight in greeting their mother with respect and love?
 "That the doctrine, which holds that the Most Blessed Virgin Mary at the first moment of her conception was, by singular grace and privilege of the Omnipotent God, in virtue of the merits of Jesus Christ, Saviour of the Human race, preserved from all stains of original sin, is revealed by God, and therefore to be firmly and resolutely believed by all the faithful." (Denz, 1641. Dogmatic Bull Ineffabilis Deus of Dec. 8, 1854.)
 "Mary, since she surpasses all creatures in holiness and union with Christ, and since she has been associated by Him with the work of salvation, has merited for us de congruo (of becomingness), as it is termed, all that Christ merited for us de condigno (in justice),and is the principal minister in the distribution of graces." (Denz. 3034. Encyclical Ad Diem lllum of Feb. 2, 1904)