Mother of Mercy
We shall consider this title first in itself and then in its principal manifestations which are, as it were, that radiance of the revealed doctrine concerning Mary which makes it accessible to all minds.
The title of Mother of Mercy is one of Mary's greatest. Mercy is not the same thing as mere emotional pity. Mercy is in the will, pity is but a good inclination of the sensibility. Pity , which does not exist in God Who is a pure spirit, leads us to suffer in unison with our neighbor as if we felt his suffering in ourselves. It is a good inclination but usually a timid one, being accompanied by fear of harm to ourselves and often helpless to render effective aid.
Mercy, on the contrary, is a virtue of the will, and, as St. Thomas so well notes,  whereas pity is found most of all in feeble and timid beings who feel themselves threatened by the evil that has befallen their neighbor, mercy is the virtue of the powerful and the good, who are capable of giving real assistance. That is why it is found in God especially: as one of the prayers of the Missal says,  it is one of the greatest manifestations of His power and goodness. St. Augustine remarked that it was more glorious for God to obtain good out of evil than to create out of nothing: it is greater to convert a sinner by giving him grace than to make a whole universe, heaven and earth, out of nothing. 
As Mother of Mercy, Mary reminds us that if God is Being,
Wisdom, He is also Goodness and Love, and that His infInite Mercy,
is the radiation of His Goodness, flows from His love and anticipates
vindicatory Justice which proclaims the inalienable right that the
Good has to be loved above every other object: 'Mercy exalteth itself
justice' (James ii, 13). she teaches us, though, that if mercy is not
it is not opposed to it as injustice is, but unites itself to it and
beyond it: most of all in pardoning, for to pardon is to go beyond what
is demanded by justice in forgiving an offense. 
Every work of divine justice presupposes a work of mercy or of gratuitous goodness.  If God can be said to owe anything to a creature it is because of some preceding gratuitous gift: if He owes a recompense to our merits, it is because He has first of all given the grace to merit, and if He punishes, it is after having given us the assistance which made the accomplishment of His precepts really possible, for He never commands the impossible.
Mary reminds us too that God often gives us His mercy more than we need, more than He is obliged in justice to Himself to give; that He gives us more than we merit, the grace of Holy Communion, for example, which is not merited. She tells us that mercy is wedded to justice in the trials of this life. Trials are a medicine to heal us, to make us right again, to bring us to the good. She tells us finally that mercy often makes the good inequality of natural conditions among men by a correspondingly more generous distribution of graces. This is the lesson of the different beatitudes of the poor, the meek, those that weep, those that hunger and thirst after justice, those that are merciful, those that are pure of heart, those that are peacemakers, those that suffer persecution for justice.
Mary manifests herself as Mother of Mercy by being 'Health of the sick, Refuge of sinners, Comforter of the afflicted, Help of Christians.' The gradation of titles here is very beautiful. It shows that Mary is merciful to those who are sick of body in order to benefit their souls, and that afterwards she consoles them in their afflictions and strengthens them in the midst of all the difficulties they have to overcome. Among creatures no one is higher than Mary , and yet no one is more approachable, more helpful, and more gentle. 
Health of the Sick
Mary is Health of the Sick by the many providential or miraculous cures which have been obtained through her intercession in Christian sanctuaries up to our own days. So many have these cures been that it may be said that Mary is a fathomless ocean of miraculous healing. But it is to help the infirmity of the soul that she cures the body. Her most important cures are those of the four spiritual wounds which we have suffered as a result of original sin and our personal sins ---- the wounds of concupiscence, of weakness, of ignorance, and of malice.
She heals concupiscence
wound of our sensibility ---- by
diminishing the ardor of our passions and by breaking our sinful
She helps the sinner to begin to will what is right with sufficient
to enable him to reject evil desires as well as the appeal of honors
riches. In this way she cures the concupiscence of the flesh and that
She heals the wound of weakness too, our feeble pursuit of the good, our spiritual sloth. She makes the will constant and firm in its practice of virtue and helps it to despise the attractions of this world by throwing itself into the arms of God. she strengthens those who falter and lifts up those who have fallen.
She heals the wound of ignorance by lighting up the darkness of our minds and providing us with the means to escape from error. She calls to our minds the simple and profound truths of the Our Father, thereby lifting our minds up to God. St. Albert the Great, to whom she gave the light to persevere in his vocation and to see through the wiles of Satan, said frequently that she preserves us from losing rightness and firmness of judgment, that she helps us not to grow weary in the pursuit of truth, and that she leads us eventually to a relish of the things of God. He himself speaks of her in his Mariale with a spontaneity , an admiration, a freshness, and a fluency which are rarely found in the works of great students.
She heals us finally of the wounds of malice, by urging our wills Godwards, sometimes by gentle advice, sometimes by stern reproaches. Her sweetness checks anger, her humility lowers pride and restrains the temptations of the evil one. In a word, she heals us of the wounds which we bear as a result of original sin and which our personal sin has made all the more dangerous.
Sometimes this healing power of hers works in a miraculous manner by producing its effects instantaneously. An example is the conversion of the young Alphonse Ratisbonne, at the time a Jew and far removed from the faith, who visited the Church of Sant' Andrea delle Frate in Rome through curiosity. Mary appeared to him there, as she is represented on the miraculous medal, with rays of light issuing from her hands. She indicated gently to him to kneel. He obeyed, and while on his knees lost the use of his senses. when he returned to himself he expressed an intense desire for Baptism. He was baptized and later, with his brother who had been converted before him, founded the congregation of the Fathers of Sion and that of the Religious of Sion, to pray, suffer, and work for the conversion of the Jews, saying daily at Holy Mass: 'Father, forgive them, for they know not what they do.'
Refuge of Sinners
Mary is Refuge of sinners precisely because she is so holy. Detesting sin, which does so much harm to souls, she welcomes sinners and wishes to bring them to repentance. She frees them from the bonds of sinful habits by the power of her intercession; she obtains their reconciliation with God by the merits of her Son, and reminds the sinner too of the same merits. Once converted to penance, she protects them from Satan, against everything which could lead to fresh falls. She helps them to learn of the sweetness of penance.
To her, after Jesus, all sinners now in Heaven owe their salvation. she has converted them in countless numbers, especially in places of pilgrimage ---- at Lourdes where she issued the invitation 'Pray and do penance,' and more recently at Fatima where the number of conversions since 1917 is known to God alone. There are many condemned criminals who owe to her their conversion at the last moment. She has inspired the foundation of religious orders consecrated to prayer, to penance, and to the apostolate of the conversion of sinners ---- those of St. Dominic and of St. Francis, the Redemptorists, the Passionists, and so many others.
What sinners are there whom she does not protect? Those only who despise God's mercy and call down His malediction on themselves. She is not the refuge of those who are obstinate in evil ---- in blasphemy, perjury, impurity, avarice, pride of the spirit. But even to them she sends from time to time, as Mother of Mercy, graces for the mind and the will, and if they accept them they will be led from grace to grace and finally to the grace of conversion. To such she has suggested by the lips of a dying mother that they should say at least one Hail Mary each day, and often it has happened that though they made no other effort than that to change their lives, the feeble spark of good-will it contained was enough to light them the way to a worthy and penitent reception of the Last Sacraments. They have been laborers of the last hour, called and saved by Mary.  For almost two thousand years Mary has been the Refuge of sinners.
Consoler of the Afflicted
Mary was Consoler of the afflicted even during her lifetime on earth: she consoled Jesus by her presence on Calvary; she consoled the Apostles in the difficulties they encountered in the conversion of the pagan world and obtained for them a spirit of strength and holy joy in their sufferings. she must have helped St. Stephen by her prayers when he was being stoned to death. She obtained for many the grace to bear persecution patiently and without giving way to cowardly fears. Though she saw the dangers which threatened the infant Church, she did not waver; her face was ever calm, for her soul was tranquil and confident. Sadness never took possession of her heart. What we know of the intensity of her love of God assures us that she remained joyous in affliction, that she did not complain of poverty or privations, that insults had no power to alter her meekness. Her example alone was enough to hearten many a despairing soul.
She has given to many Saints the grace to be themselves consolers of the afflicted. Such were St. Genevieve, St. Elizabeth, St. Catherine of Siena, St. Germaine de Pibrac.
The Holy Ghost is called the Consoler most of all because He makes us shed tears of contrition, thereby to wash away our sins and to restore to us the joy of God's friendship. For the same reason the Blessed Virgin is the Consoler of the afflicted when she prompts them to bewail their sins from a contrite heart.
Mary is particularly attentive to our inner or secret poverty: she knows how little are the resources of our hearts, and she comes to their assistance. She knows all the needs of soul and body: she has consoled christians in persecution, she has delivered the possessed, she has assisted and strengthened the dying by calling to their minds the infInite merits of her Son. She lessens the rigors of Purgatory, and obtains for those who suffer there that the faithful pray and have Masses offered on their behalf.
In a sense, Mary's power as Consoler of the afflicted is
the terrible regions of Hell. For St. Thomas tells us that the damned
less than they deserve 
since the Divine Mercy is found
even in the strictest exercise of divine justice. Whatever less there
of the pain of Hell than there might be is due to the merits of Jesus
Mary. St. Odilon of Cluny says in his sermon on the Assumption that the
Feast of the Assumption brings some slight alleviation of pain to
Help of Christians
Mary is Help of Christians. Help is an effect of love, and Mary has now consummated fulness of love. She loves the souls redeemed by Jesus' blood. She helps them in their difficulties and assists them in the practice of the virtues.
The thought of Mary, Help of Christians, inspired St. Bernard in the well-known passage from his second homily on the Missus est: 'If the tempest of temptation rages, if the torrent of tribulation carries you away, look at the star, look at Mary. If the waves of pride and ambition, of slander and jealousy, buffet you and almost engulf you, look at the star, look at Mary. If anger or avarice or passion tosses the frail bark of your soul and threatens to wreck it, look once more at Mary. Let her memory be ever in your heart and her name always on your lips . . . But remember that to obtain the benefit of her prayer you must walk in her footsteps.'
She has been the refuge of whole peoples as well as of individuals. Baronius tells us that Narses, general of the armies of the Emperor Justinian, delivered Italy by her help in 553 from bondage to Totila the Goth. He tells us also that in 718 the city of Constantinople was rescued from the Saracens, who had been put to flight on many similar occasions already with Mary's aid. In the 13th century, Simon, Count of Montfort, defeated a powerful Albigensian army near Toulouse while St. Dominic invoked the Mother of God. In 1513 the city of Dijon was delivered miraculously through her. On the 7th of October, 1571, a Turkish fleet, much more numerous and powerful than that of the Christians, was defeated at Lepanto, at the entrance of the Gulf of Corinth, through the help of Mary invoked in the Rosary . Finally, Mary's title of Our Lady of Victories reminds us how often her intervention on the battlefield has been decisive in favor of oppressed Christian peoples.
The four invocations of the Litany of Loreto, Health of the Sick, Refuge of Sinners, Consoler of the Afflicted, Help of Christians, recall unceasingly to the faithful how truly Mary is Mother of Divine grace and Mother of mercy. The Church sings that she is our hope: Hail, Holy Queen, Mother of mercy! Hail, our life, our sweetness, and our hope! She is our hope in that she has merited, with her Son, all that we need of help from God, and in that she transmits it to us now by her intercession. She is therefore the living expression and the instrument of God's helping Mercy, which is the formal motive of our hope. Confidence, or firm hope, is certain in its tendency to salvation,  and its certainty increases with our growth in grace. This certainty derives from our faith in the goodness of God Omnipotent and in His fidelity to His promises. Thence comes that almost constant sense of His watchful Paternity which we find in the saints. Mary's influence leads us gradually to this perfect confidence and makes its motive ever more clear.
Mary is even called Mother of holy joy and Cause of our joy, for she obtains for generous souls the hidden treasure or spiritual joy in the midst of suffering. She obtains for them from time to time the grace to carry their cross with joy after the Lord Jesus. She initiates them into love of the cross. And even though they do not experience that joy uninterruptedly themselves, she helps them to communicate it to others.I. Ia, q. 21, a. 3; IIa IIae, q. 30, a. 4.
2. Deus qui maxime parcendo et miserando, potentiam tuam manifestas.
3. Cf. Ia IIae, q. 113, a. 9.
4. Ia, q. 21, a. 3, ad 2.
5. ib. a. 4: 'Opus divinae justitiae semper praesupponit opus misericordiae et in eo fundatur.'
6. These points are developed by the Polish Dominican, Justin of Miechow, in his Collationes in Litanias B. Mariae Virginis, translated into French by A. Ricard under the title Conferences sur les litanies de la Tres Sainte Vierge, 3rd edit., Paris, 1870. We shall draw much of our inspiration for the following pages from this work.
7. This was the case in France of the immoral writer Armand Silvestre.
8. Ia, q. 21, a. 4, ad 1. In La Vie Spirituelle, April, 1941, p. 281, Fr. M. J. Nicolas, O.P., has written of a holy religious, Fr. Vayssiere, who died as Provincial of the Dominicans at Toulouse: 'The grace of intimacy with Mary that he received, he owed first of all to the state oflitdeness to which he had been reduced and to which he had consented. But he owed it as well to his Rosary. During the long days of solitude at Sainte-Baume, he had acquired the habit of saying several Rosaries in the day, sometimes as many as six. He often said the whole of it kneeling. And it was not a mechanical and superficial recitation: his whole soul went into it, he delighted in it, he devoured it, he was persuaded that he found in it all that one could seek for in prayer. "Recite each decade," he used to say, "less reflecting on the mystery than communicating through the heart in its grace, and in the spirit of Jesus and Mary as the mystery presents it to us. The Rosary is the evening Communion (elsewhere he calls it the Communion of the whole day) and it translates into light and fruitful resolution the morning Communion. It is not merely a series of Ave Marias piously recited; it is Jesus living again in the soul through Mary's maternal action." Thus he lived in the perpetually moving cycle of his Rosary, as if "surrounded" by Christ and by Mary, communicating, as he said, in each of their states, in each aspect of their grace, entering thus into and remaining in the depth of God's Heart: "The Rosary is a chain oflove from Mary to the Trinity." One can understand what a contemplation it had become for him, what a way to pure union with God, what a need, like to that of Communion.'
9. IIa IIae, q. 18, a. 4: 'Spes certitudinaliter tendit ad suam finem, quasi participans certitudinem a fide.'