8 Moreover, we may well believe that the Queen of Heaven herself has granted an especial efficacy to this mode of supplication, for it was by her command and counsel that the devotion was begun and spread abroad by the holy Patriarch Dominic as a most potent weapon against the enemies of the faith at an epoch not, indeed, unlike our own, of great danger to our holy religion. The heresy of the Albigenses had in effect, one while covertly, another while openly, overrun many countries, and this most vile off spring of the Manicheans, whose deadly errors it reproduced, were the cause in stirring up against the Church the most bitter animosity and a virulent persecution. There seemed to be no human hope of opposing this fanatical and most pernicious sect when timely succour came from on high through the instrument of Mary's Rosary. Thus under the favour of the powerful Virgin, the glorious vanquisher of all heresies, the forces of the wicked were destroyed and dispersed, and faith issued forth unharmed and more shining than before. All manner of similar instances are widely recorded, and both ancient and modern history furnish remarkable proofs of nations saved from perils and winning benedictions therefrom. There is another signal argument in favour of this devotion, inasmuch as from the very moment of its institution it was immediately encouraged and put into most frequent practice by all classes of society. In truth, the piety of the Christian people honours, by many titles and in multiform ways, the Divine Mother, who, alone most admirable among all creatures, shines resplendent in unspeakable glory. But this title of the Rosary, this mode of prayer which seems to contain, as it were, a final pledge of affection, and to sum up in itself the honour due to Our Lady, has always been highly cherished and widely used in private and in public, in homes and in families, in the meetings of confraternities, at the dedication of shrines, and in solemn processions; for there has seemed to be no better means of conducting sacred solemnities, or of obtaining protection and favours.
Source: Octobri Mense (Vatican.va)