5 But in view of the importance and the difficulty of such an undertaking, and the necessity of perseverance in the practice of any virtue, it is well to recall the Apostle's apt counsel: "Be instant in prayer"(1) - counsel all the more to the point because an auspicious beginning of the enterprise will supply the best inducement to perseverance in prayer. Next October, therefore, if you and your people devoutly spend the whole month with Us in praying assiduously to the Virgin Mother of God through her Rosary and the other customary devotions, nothing could do more to further this project or be more pleasing to Us. We have the best reasons for entrusting Our plans and Our aspirations to her protection and the highest hopes of seeing them realized.
Source: Adiutricem (Vatican.va)