The Mysteries of the Rosary
The object of an Apostolate is the spread of truth. The motto of the order which St. Dominic founded is "Veritas," i.e. Truth; and the first principle of the rule which he gave to its members is "the salvation of souls by the teaching and preaching of truth." The teaching and preaching may vary, according to circumstances of time and place, but the end of the teaching is always the same. "But what then? So that every way, whether by occasion or by truth, Christ be preached; in this also I rejoice, yea, and will rejoice" (Phil. 1:18). One of these "ways" in which the Dominican commission of preaching Christ is fulfilled is by means of the Rosary, which, having been entrusted by the Divine Mother to St. Dominic, was by him handed down as an heirloom, we might almost say as an entailed inheritance, to his children.
For we must ever bear in mind that an integral, and even essential, part of this heaven-sent Devotion is the meditation which we make upon the mysteries which we commemorate, as we repeat our Aves, to the counting of our beads. You may say the "Our Father," the "Hail Mary," ten times, and then a "Glory be to the Father," but if your mind has not adverted to the subject-matter of the mystery proposed you have said a decade of Aves, but not a decade of the Rosary. The Sacred Congregation of Indulgences (August 13th, 1720), has decided that "the meditation of the mysteries, at least in intention, is of the essence of the Rosary, and is necessary for the gaining of the Indulgences," that even " if in the place of the mysteries we were, when saying the Rosary, to meditate upon death or judgment or other pious and religious subjects, we should not gain (the Rosary) Indulgences" (27th of August 1726). A later decree makes an exception in favour of ignorant and uncultured people, although even they are exhorted to "accustom themselves to think about the most holy mysteries of our Redemption, for which purpose the Rosary was instituted" (28th of January 1842).
No set form and no definite method of meditation are enjoined: according to the Apostolic maxim, "every one may abound in his own sense"; but meditation there must be, and that too on the mystery proposed, if the Indulgences granted for saying the Rosary are to be obtained.
The Rosary consists of fifteen decades or mysteries. Five of these are called "Joyful" because they tell of the joys of Our Lord's life. The five "Sorrowful" mysteries are the records in brief of the principal events in the Passion of Our Lord, and they sum up the sad yet glad history of our redemption. The five "Glorious" mysteries tell of triumph of Jesus Christ. These are the mysteries which are comprised in the Devotion of the Rosary. We have called them "Gospel Mysteries," and we have said that they preach Jesus Christ, His Incarnation, His Life, His Redemption, and His triumphs to the world. Our Holy Father, Pope Leo XIII., in his Apostolic Constitution on the Rosary, approves of the general custom which assigns the Joyful, Sorrowful, and Glorious mysteries to the different days of each week. "We desire (the Holy Father says) that the custom, already approved by the Holy See should be retained of reciting each series of mysteries in rotation throughout the week, namely, the Joyful mysteries on Monday and Thursday, the Sorrowful on Tuesday and Friday, and the Glorious on Sunday, Wednesday, and Saturday".