From what I have heard with my own ears and from the many accounts in the Lives of the Brethren, it seems that she is our special Mother, bringing forth, advancing and defending the Order whose purpose is to praise, to bless and to preach her Son. (Commentary on the Constitutions of the Order of Preachers, Bl. Humbert of Romans)
Devotion to the Blessed Virgin Mary has been part of Dominican life and preaching from the beginning of the Order of Preachers. All the early histories of the Order mention apparitions of the Virgin to St. Dominic.
The Blessed Mother has always been tenderly solicitous for the well-being of the Dominican Order. St. Dominic had a vision one night in which Mary was blessing the sleeping friars in the dormitory. Even individuals enjoyed her motherly care. For example, the Blessed Mother appeared to Blessed Jordan of Saxony, to tell him how, at the words “eia ergo” in the Salve Regina, she implored her Son’s help for the Order. She appeared to St. Albert the Great at a difficult time in his novice year, when the future saint was wavering in his vocation, giving him the courage to persevere.
Perhaps the most dramatic apparition of Our Lady to a Dominican friar was to Blessed Reginald of Orleans, who was dying of a fever. She “anointed his eyes, nose, ears, mouth, chest, hands, and feet with a soothing ointment and said these words, ‘I anoint your feet with a holy oil in preparation for the gospel of peace’” (Libellus). Not only did her prayers bring about his complete cure, but she showed him the white scapular and told him that from that time on, the scapular was to be part of the Dominican habit.
Once, at a difficult point in the preaching ministry, St. Dominic had a dream in which he saw heaven. Christ was there, arrayed like a king, with His Mother beside Him cloaked in a magnificent mantle. Around the Blessed Mother were countless souls from all walks of life: clergy, laypersons, and members of every religious order ever founded. Among the religious there were Benedictines, Augustinians, Carmelites, Franciscans, everyone, except the Order of Preachers. Struck to the heart, Dominic said, “Is there not a single one of mine?” The Lord gestured to his Mother, who opened her mantle. There, under it, were hundreds and hundreds of Dominican souls in their black and white habits. The Lord said, “Behold, I have left your Order in the care of My Mother.”