The history of the rosary traces to the 13th century. It is believed that Mary gave St. Dominic the rosary to rescue the church from the Albigensian heresy.
Initially, 150 Hail Marys were prayed as a part of the rosary.
"The prayer of the rosary, originally composed of 150 Hail Marys, is based on the 150 psalms of the Psalter prayed in monasteries since antiquity," said Gretchen Crowe, editor-in-chief of OSV Newsweekly in Huntington, Indiana, and author of the new book "Why the Rosary, Why Now?"