A miracle is not a question of God's intervention from the outside into the physical laws of nature because these laws are His creative action sustaining the universe. God is present by his power and wisdom in all his creatures and free to modify them as He wills. If we have any difficulty with miracles it is because we may consider these physical laws as unchanging from our limited perspective. We may consider the universe as a closed system which it is not. The following Eucharistic miracles are God's way of confirming the truths about the Eucharist which the Church has been teaching for two thousand years and by so doing moving hearts to believe in the Real Presence.
This first miracle took place in Toulouse, France. There was a man there who disputed St. Anthony's claim that Christ was really present in the Blessed Eucharist. Tired of talking, he proposed a challenge to St. Anthony. He would starve his mule for three days, after which he would bring the mule to the plaza, place a bale of hay before it while St. Anthony would bring the Blessed Sacrament. If the mule disregarded the bale of hay and turned toward the Blessed Sacrament he would believe. And so at the end of three days, the heretic and St. Anthony met in the plaza before the people. The heretic freed the mule and as the mule was walking toward the bale of hay St. Anthony called out and said in these or similar words, "Mule, in the name of the Lord our God, I command you to come here and adore your Creator!" The mule stopped suddenly, turned toward St. Anthony, bent his forelegs and bowed its head before the Blessed Sacrament. The heretic was amazed and became a Catholic.
What you see is the town of Cascia, Umbria, Italy and the blood stained paper of a Eucharistic miracle that happened in the c.1330 AD.
One day a priest was asked to bring the Eucharist to a sick peasant. The priest lacking a sense of reverence placed the host between the pages of his breviary. Arriving at the peasant home, he opened the breviary and found that the host had turned red with blood and that the blood had spread in the pages. Not knowing what to do, he asked the advice to a pius and respected priest named Simone Fidati, now Blessed. The priest took the two pages, placed one in the tabernacle at Perugia and the other in Cascia. Today it rests in the Minor Basilica of St. Rita in Cascia.