Jesus is the mediator of justice and Mary obtains for us grace

Jesus is the mediator of justice; Mary obtains for us grace; for, as St Bernard, St Bonaventure, St Bernardine of Sienna, St Germanus, St Antoninus, and others say, it is the will of God to dispense through the hands of the Blessed Virgin whatever graces He is pleased to bestow upon us.

With God, the prayers of the saints are the prayers of His friends, but the prayers of the Blessed Virgin are the prayers of his Mother. Happy they who confidently and at all times have recourse to this Divine Mother! This, above all others, is the most pleasing devotion to the Blessed Virgin, ever to have recourse to her and to say: "O Mary, intercede for me with thy Son Jesus."

The Blessed Virgin is very powerful by grace; she obtains whatever she asks for. It is impossible, says St Antoninus, that this mother should ask any favor of her Son for those who are devout to her, and the Son not grant her request. Jesus delights to honor His mother by granting whatever she asks of Him.

Hence St Bernard exhorts us to seek for grace, and to seek for it through Mary because she is a mother to whom nothing can be denied.

If, then, we should be saved, let us recommend ourselves to Mary, that she may intercede for us, because her prayers are always heard. "O Mother of Mercy, have pity on me. Thou art styled the advocate of sinners; assist me, therefore, a sinner placing my confidence in thee."

Let us not doubt whether Mary will hear us when we address our prayers to her. It is her delight to exercise her powerful influence with God in obtaining for us whatever graces we stand in need of. It is sufficient to ask favors of Mary to obtain them. If we are unworthy of them, she renders us worthy, by her powerful intercession; and she is very desirous that we should have recourse to her, that she may save us.

What sinner ever perished, who, with confidence and perseverance, had recourse to Mary, the refuge of sinners? He is lost who has not recourse to Mary.

Saint Alphonsus Liguori, The Way of Salvation, part I, chap.15