"[Mary is called] the gate of heaven, because no one can enter that blessed kingdom without passing through her."
 

 "God has placed in Mary the plenitude of every good, in order to have us understand that if there is any trace of hope in us, any trace of grace, any trace of salvation, it flows from her."

"I greet you, Lady, Holy Queen, Holy Mary, Mother of God, Virgin who became the Church, chosen by the most holy Father of Heaven; consecrated to holiness through His most holy and beloved Son and the Holy Spirit, the Comforter. In you was and is the whole fullness of grace and everything that is good."

"All gifts, virtues, and graces of the Holy Ghost are administered by the hands of Mary to whomsoever she desires, when she desires, and in the manner she desires, and to whatever degree she desires."

"O Lady, since thou art the dispenser of all graces, and since the grace of salvation can only come through thy hands, our salvation depends on thee."

 "God, who gave us Jesus Christ, wills that all graces that have been, that are, and will be dispensed to men to the end of the world through the merits of Jesus Christ, should be dispensed by the hands and through the intercession of Mary." (The Glories of Mary, Ch. 5). 

Against the contention that this doctrine is "a pious exaggeration, St. Alphonsus replied, "I consider it as indubitably true that all graces are dispensed by Mary.”

St. Alphonsus Liguori, The Glories of Mary, p. 32.

  "Every grace which is communicated to this world has a threefold origin: it flows from God to Christ, from Christ to the Virgin, and from the Virgin to us . . . Nothing comes to us except through the mediation of Mary, for such is the will of God. Thus, just as no man goes to the Father but by the Son, so likewise no one goes to Christ except through His Mother. Whosoever will not have recourse to her is trying to fly without wings . . . O Virgin Most Holy, no one abounds in the knowledge of God except through thee; no one, O Mother of God, attains salvation except through thee!"

"The maternal office of Mediatrix really began at the very moment of Her consent to the Incarnation; it was manifested for the first time by the first sign of Christ's grace, at Cana in Galilee; from that moment it rapidly spread down through the ages with the growth of the Church."

Apostolic Letter, Per Christi Matrem, May 15, 1947

"So if the Apostle tells us to pray for one another, we have much more reason to ask Mary to pray for us, because her prayer will be much more pleasing to the Lord in view of her dignity as Mother of God and her closer union with Christ, true God and true Man, by reason of her mission of Co-redemptrix with Christ as well as of her great sanctity."

Pope John Paul II recognized Mary as co-redemptrix during a speech in Guayaquil, Ecuador. He said, "Mary’s role as
Co-redemptrix did not cease with the glorification of her Son." 

 In his encyclical Redemptoris Mater, Pope John Paul II "referred to Mary as 'Mediatrix' three times, and as 'Advocate' twice.