VATICAN CITY - Pope Benedict XVI asked Catholics for their prayers as he began his weeklong Lenten retreat March 13.

Before reciting the Angelus prayer at midday with visitors in St. Peter's Square, he also prayed that Mary would intercede to help everyone have a Lent that is "rich in the fruits of conversion."

Carmelite Father Francois-Marie Lethel, a theology professor and the secretary of the Pontifical Academy of Theology, was chosen to preach the retreat March 13-19 for Pope Benedict and top Vatican officials. The French priest's topic was to be "The Light of Christ in the Heart of the Church: John Paul II and the Theology of Saints."