9 From the fact that this warfare of prayer is "enrolled under the name of the Mother of God," fresh efficacy and fresh honour are thereby added to it. Hence the frequent repetition in the Rosary of the "Hail Mary" after each "Our Father." So far from this derogating in any way from the honour due to God, as though it indicated that we placed greater confidence in Mary's patronage than in God's power, it is rather this which especially moves God, and wins His mercy for us. We are taught by the Catholic faith that we may pray not only to God himself, but also to the Blessed in heaven (Conc. Trill. Sess. xxv.), though in different manner; because we ask from God as from the Source of all good, but from the Saints as from intercessors. "Prayer," says St. Thomas, "is offered to a person in two ways-one as though to be granted by himself; another, as to be obtained through him. In the first way we pray to God alone, because all our prayers ought to be directed to obtaining grace and glory, which God alone gives, according to those words of Psalm lxxxiii., 12, "The Lord will give grace and glory." But in the second way we pray to holy angels and men, not that God may learn our petition through them, but that by their prayers and merits our prayers may be efficacious. Wherefore, it is said in the Apocalypse (viii., 4): "The smoke of the incense of the prayers of the Saints ascended up before God from the hand of the angel" (Summa Theol. 2a tae, q. lxxxiii. a. iv.). Now, of all the blessed in heaven, who can compare with the august Mother of God in obtaining grace? Who seeth more clearly in the Eternal Word what troubles oppress us, what are our needs? Who is allowed more power in moving God? Who can compare with her in maternal affection? We do not pray to the Blessed in the same way as to God; for we ask the Holy Trinity to have mercy on us, but we ask all the Saints to pray for us (Ibid.). Yet our manner of praying to the Blessed Virgin has something in common with our worship of God, so that the Church even addresses to her the words with which we pray to God: "Have mercy on sinners." The members of the Rosary Sodality, therefore, do exceedingly well in weaving together, as in a crown, so many salutations and prayers to Mary. For, so great is her dignity, so great her favour before God, that whosoever in his need will not have recourse to her is trying to fly without wings.
Source: Augustissimae Virginis Mariae (Vatican.va)