One of the great apparitions of Our Lady was in the Irish village of Knock. On August 21, 1879, surrounded by light, wearing a brilliant golden crown, and a long white gown covered by a dazzling white cloak, she appeared. On her right appeared St. Joseph inclining reverently towards her; on her left St. John the Evangelist, attired as a bishop and holding a book, his hand raised as if preaching. To St. John's left was an altar on which stood a lamb, surrounded by angels' wings, a symbol of the Holy Sacrifice of the Mass. This wondrous spectacle lasted two hours in the rain. No word was spoken to the fifteen persons of different ages, occupations and intelligence who knelt while witnessing the apparition. Since nothing was spoken, it was to become known as "The Silent Apparition," to bring to our attention the importance of the Holy Sacrifice of the Mass, and that Christ is truly present in the Blessed Sacrament which we should venerate in silence, awe and reverence.

Wherever approved apparitions of our Blessed Lady have taken place, churches or chapels have been erected in order that the Holy Sacrifice of the Mass may be offered for the greater honor and glory of God, and as places to keep the Blessed Sacrament.

Hidden Treasure, The Riches of the Eucharist
Louis Kaczmarek