Brief "History": Long ago and far away, monks used to recite all 150 Psalms each day. To aid them with this, they would use a rope with 150 knots tied in it. Because the laity wanted to imitate this piety, the "Psalter of Our Lady", developed into The Rosary.
The 150 beads were grouped into sets of 10 Hail Marys, preceded by an Our Father, and concluded with a Doxology, (the Glory-be). The 15 decades were each assigned an image from the story of our salvation as a mystery to be contemplated during the recitation. The Mysteries were grouped into 3 sets of 5 each, the Joyful, Sorrowful and Glorious, giving us the more common 5 decade chaplet we see today. Recently, Pope John Paul II provided us with another set of five mysteries to contemplate, calling them the "Luminous" mysteries. The four sets point to different parts of the story of our redemption:
For years, many folks thought the "Luminous" part was "missing". I was one of them, and I welcomed this development. After all, that's a big gap, from Finding the Child Jesus in the Temple to the Agony in the garden. Whether 5, 15 or 20 decades, the primary focus of the rosary is meditation on the gospel story of our salvation, and it is a devotion rather than a liturgical celebration of the Church.For more information on the Rosary and how to say it, click here.