The following was written by the editor of St. Anthony Messenger, appearing in the preface of Joanne Turpin's book, The Healing Mysteries of the Rosary:
"Pious tradition has it that the mother of Jesus, Mary herself, gave the rosary to St. Dominic Guzman and told him to preach this prayer. More likely, the rosary developed out of the 12th-century chaplets of Pater's or Ave's recited by the Catholics of that time.
"These chaplets were a kind of poor person's Breviary made up of 150 Our Fathers (Pater Noster's) or Hail Marys (Ave's) corresponding to the 150 psalms of the Psalter...
"In time the 'psalters' of Our Fathers and Hail Marys came to be joined and merged. The Our Fathers and Hail Marys were prayed alternately, each Our Father followed by a Hail Mary. The 50 mysteries came to be reduced to five--one for each decade. Finally the rosary took its present form."