Le Pelerinage de Lourdes §28

²⁸ Soon the illustrious Pontiff who, like his predecessors, had honored the anniversary celebrations of the apparitions by sending a legate, decided to conclude the Jubilee of the Redemption at the Grotto of Massabielle where, in his own words, "the Immaculate Virgin Mary appeared several times to Blessed Bernadette Soubirous, and, in her kindness, exhorted all men to do penance at the scene of these wondrous apparitions, a place she has showered with graces and miracles." Truly, Pius XI concluded, is this sanctuary "now justly considered one of the principal Marian shrines in the world."