O Maria sine labe concepta, ora pro nobis!
"'I will put enmities between thee and the woman.' In these words the Immaculate Conception of the Blessed Virgin Mary was announced to our first parents. It was to be the reversal of the friendship with the serpent contracted by Eve, when she listened to his voice and fell under his power. The second Eve was never to be under the power of the devil; the enmity between them was to admit of no possible exception. This involved the grace of being conceived immaculate. Mary's Immaculate Conception was the foundation of all her graces. The absence of any stain or spot of sin distinguished her from all the rest of mankind. It distinguished her from the holiest of the Saints, since they, one and all, were sinners. Her perfect sinlessness was the source of all her glory and all her majesty; it was this which opened the door to the unlimited graces that she received from God; it was this that qualified her for her divine maternity, and raised her to her throne as Queen of heaven." - Roman Missal 1962 on the Immaculate Conception
"O God, who by the Immaculate Conception of the Virgin Mary, didst prepare for Thy Son a worthy habitation, we beseech Thee, that as Thou didst preserve her from every stain by the foreseen death of this Thy Son, so Thou wouldst grant that we also being cleansed from guilt by her intercession, may come to Thee."
"Let all the children of the Catholic Church, who are so very dear to us, hear these words of ours. With a still more ardent zeal for piety, religion and love, let them continue to venerate, invoke and pray to the most Blessed Virgin Mary, Mother of God, conceived without original sin. Let them fly with utter confidence to this most sweet Mother of mercy and grace in all dangers, difficulties, needs, doubts and fears. Under her guidance, under her patronage, under her kindness and protection, nothing is to be feared; nothing is hopeless. Because, while bearing toward us a truly motherly affection and having in her care the work of our salvation, she is solicitous about the whole human race. And since she has been appointed by God to be the Queen of heaven and earth, and is exalted above all the choirs of angels and saints, and even stands at the right hand of her only-begotten Son, Jesus Christ our Lord, she presents our petitions in a most efficacious manner. What she asks, she obtains. Her pleas can never be unheard." - Ineffabilis Deus (Papal Encyclical on the Immaculate Conception - Pope Bl. Pius IX, 1854)