According to legend, on December 8, 1531, the Virgin Mary appeared to the newly Christianized Juan Diego on the Mexican hill of Tepeyacac. As proof of her divine visit, she miraculously imprinted her image upon his mantle. That image, known as Our Lady of Guadalupe, has become a symbol of national consciousness in Mexico and a talisman for Mexican Americans. Yet its notable features include obviously European artistic techniques. How is...