Miracle tales, in which people are rewarded for piety or punished for sin through the intervention of the Virgin Mary, were a popular literary form throughout the Middle Ages. Milagros Nuestra Senora, a collection of such stories by the Spanish secular priest Gonzalo de Berceo, is not only a premier example of this genre but is also widely regarded as one of the four most important texts of medieval Spain. These miracle tales use the verse form cuaderna via (fourfold way) of fully rhymed quatrains - which Berceo may even have invented - and are told in the language of the common man. They were written to be read aloud, most likely to an audience of pilgrims, and are an outstanding example of oral religious narrative. The total work comprises twenty-five miracles, preceded by a renowned introduction that celebrates the Virgin in rich symbolic allegory.