"Hear me and understand well, my son the least, that nothing should frighten or grieve you. Let not your heart be disturbed. Do not fear that sickness, nor any other sickness or anguish. Am I not here, who is your Mother? Are you not under my protection? Am I not your health? Are you not happily within my fold? What else do you wish? Do not grieve nor be disturbed by anything."
— Our Lady to Juan Diego
In the winter of 1531, a poor, 57-year-old Aztec Indian living five miles outside of Mexico City encountered a miraculous happening on his way to morning Mass. First he heard strange music coming from Tepeyac Hill, and then he heard a woman's voice calling his name. Juan Diego climbed the hill and encountered a young woman, appearing to be of his own people in physical appearance and dress. The woman identified herself as the Virgin Mary, and told Juan Diego to ask the bishop of Mexico City to build a church on the hill to assist in the conversion of the nation and be a source of consolation to the people.
Juan Diego obeyed the request, but the bishop was skeptical regarding the message, even though he perceived that Juan was a humble, and well meaning Catholic. Juan reported the bishop's doubt to Our Lady at Tepeyac Hill, and she asked him to return to the bishop once again, bearing the same message. The bishop once again heard the story, and told Juan Diego to ask Our Lady for a sign that it was indeed herself that wished for the church to be built.
When he returned to the hill, Mary gave Juan Diego such a sign. Miraculously, roses appeared on the hill in the middle of winter, and Juan gathered them in his tilma, or cloak. Our Lady arranged the roses in his tilma with her own hands, and Juan returned to the bishop's presence. When Juan released the tilma, allowing the flowers to fall to the floor, it was revealed that a miraculous image of Our Lady had imprinted itself on his tilma (see above).
The bishop immediately fell to his knees, and came to believe in Juan Diego's message. A church was built on the spot of the apparition, as Mary had requested, and 8 million people converted to Catholicism in a short period of time upon hearing of or viewing the miraculous image of Our Lady.
The tilma of Juan Diego has been the subject of much modern research. The tilma, woven out of coarse cactus fiber, should have disintegrated after 20 years, but although over 500 years have passed the tilma is still in perfect condition. The pupils of Mary in the picture reflect the Indians and clergy present at the time of the first revelation of the image. No paint was used, and chemical analysis has not been able to identify the color imprint. Additionally, studies have revealed that the stars on Mary's mantle match exactly what a Mexican would have seen in the sky in December of 1531.
~from Catholic Culture