5 If in all this series of Mysteries, Venerable Brethren, are developed the counsels of God in regard to us - "counsels of wisdom and of tenderness" (St. Bernard) - not less apparent is the greatness of the benefits for which we are debtors to the Virgin Mother. No man can meditate upon these without feeling a new awakening in his heart of confidence that he will certainly obtain through Mary the fulness of the mercies of God. And to this end vocal prayer chimes well with the Mysteries. First, as is meet and right, comes the Lord's Prayer, addressed to Our Father in Heaven: and having, with the elect petitions dictated by Our Divine Master, called upon the Father, from the throne of His Majesty we turn our prayerful voices to Mary. Thus is confirmed that law of merciful meditation of which We have spoken, and which St. Bernardine of Siena thus expresses: "Every grace granted to man has three degrees in order; for by God it is communicated to Christ, from Christ it passes to the Virgin, and from the Virgin it descends to us." And we, by the very form of the Rosary, do linger longest, and, as it were, by preference upon the last and lowest of these steps, repeating by decades the Angelic Salutation, so that with greater confidence we may thence attain to the higher degrees-that is, may rise, by means of Christ, to the Divine Father. For if thus we again and again greet Mary, it is precisely that our failing and defective prayers may be strengthened with the necessary confidence; as though we pledged her to pray for us, and as it were in our name, to God.
Source: Iucunda Semper Expectatione (Vatican.va)