The Church's devotion to the Blessed Virgin is an intrinsic element of Christian worship.
The honor which the Church has always and everywhere shown to the Mother of the Lord, from the blessing with which Elizabeth greeted Mary (cf. Lk. 1:42-45) right up to the expressions of praise and petition used today, is a very strong witness to the Church's norm of prayer and an invitation to become more deeply conscious of her norm of faith.
And the converse is likewise true. The Church's norm of faith requires that her norm of prayer should everywhere blossom forth with regard to the Mother of Christ. Such devotion to the Blessed Virgin is firmly rooted in the revealed word and has solid dogmatic foundations. It is based on the singular dignity of Mary, "Mother of the Son of God, and therefore beloved daughter of the Father and Temple of the Holy Spirit -- Mary, who, because of this extraordinary grace, is far greater than any other creature on earth or in heaven."
This devotion takes into account the part she played at decisive moments in the history of the salvation which her Son accomplished, and her holiness, already full at her Immaculate Conception yet increasing all the time as she obeyed the will of the Father and accepted the path of suffering (cf. Lk. 2:34-35, 41-52; Jn. 19:25-27), growing constantly in faith, hope and charity.
Devotion to Mary recalls too her mission and the special position she holds within the People of God, of which she is the preeminent member, a shining example and the loving Mother; it recalls her unceasing and efficacious intercession which, although she is assumed into heaven, draws her close to those who ask her help, including those who do not realize that they are her children. It recalls Mary's glory which ennobles the whole of mankind, as the outstanding phrase of Dante recalls: "You have so ennobled human nature that its very Creator did not disdain to share in it."
Mary, in fact, is one of our race, a true daughter of Eve -- though free of that mother's sin -- and truly our sister, who as a poor and humble woman fully shared our lot.
We would add further that devotion to the Blessed Virgin finds its ultimate justification in the unfathomable and free will of God who, being eternal and divine charity (cf. 1 Jn. 4:7-8, 16), accomplishes all things according to a loving design. He loved her and did great things for her (cf. Lk. 1:49). He loved her for His own sake, and He loved her for our sake, too; He gave her to Himself and He gave her also to us.
Apostolic Letter Marialis cultus §56, by Pope Paul VI
March 29, 1974