42 Besides, the Blessed Virgin possessed, after Christ, not only the highest degree of excellence and perfection, but also a share in that influence by which He, her Son and our Redeemer, is rightly said to reign over the minds and wills of men. For if through His Humanity the divine Word performs miracles and gives graces, if He uses His Sacraments and Saints as instruments for the salvation of men, why should He not make use of the role and work of His most holy Mother in imparting to us the fruits of redemption? "With a heart that is truly a mother's," to quote again Our Predecessor of immortal memory, Pius IX, "does she approach the problem of our salvation, and is solicitous for the whole human race; made Queen of heaven and earth by the Lord, exalted above all choirs of angels and saints, and standing at the right hand of her only [55a] Son, Jesus Christ our Lord, she intercedes powerfully for us with a mother's prayers, obtains what she seeks, and cannot be refused." On this point another of Our Predecessors of happy memory, Leo XIII, has said that an "almost immeasurable" power has been given Mary in the distribution of graces; St. Pius X adds that she fills this office "as by the right of a mother."
Source: Ad Caeli Reginam (Vatican.va)