In the Mass, the bread and wine are changed into the Body and Blood of Christ, not visibly, but sacramentally and substantially. It retains the accidental properties of bread and wine, such as the shape, color, and physical properties, but it becomes the Body and Blood of the Lord substantially. This is called transubstantiation, which means through the substance. Your substantial properties define you, not your accidental properties. If they change, you are still you. What you are is a human being, but you happen to be a human being of a certain age, weight, and height. As you get older, taller, shorter, heavier, or lighter you still remain a human being. You can think of the Eucharist as being the opposite. At consecration, the appearance remains the same while the substance, what it is, changes. However, throughout the centuries there have been miracles recorded where the host visibly and physically turns into human flesh, or the blood in the chalice turns into human blood. One such miracle happened on August 18, 1996, in Buenos Aires, Argentina. After the 7 pm Mass, Fr. Alejandro Pezet was approached by a woman who had found a discarded Host on a candleholder in the back of Church. Fr. Alejandro retrieved the Host and placed it in a container of water in the tabernacle, to let it dissolve (so it could be disposed of in a reverent way). Over a week later, on August 26, he went back to check on it and found that it had transformed into a bloody substance. He informed Cardinal Bergoglio (now Pope Francis), who instructed him to have pictures taken professionally and then placed back in the tabernacle in the container of water. Over three years later, on October 5, 1999, a sample was taken by Dr. Castanon and sent to Dr. Frederic Zugiba for analysis. Dr. Zugiba was not informed where the sample came from or what it was. His tests determined that the fragment was real, human flesh and blood. Specifically, it was a piece of heart muscle from the left ventricle, which is responsible for pumping blood throughout the body. He further determined, from the presence of white blood cells, that the heart was alive when the sample was taken, and that the heart was under severe stress, “as if the owner had been beaten severely about the chest.” This has only happened a few times in the history of the Church. There are stories of this happening during the Middle Ages in Italy and France, and a few more modern Eucharistic Miracles as well. They are a sign pointing to the great gift of the Eucharist, in which the Lord Jesus Christ has given us His very self. In the Mass, the bread and wine symbolize the Body and Blood of the Lord, and through that symbolism, the prayer of the Church, and the power of the Holy Spirit, the bread and wine truly become the Body and Blood of Christ. If God can transform the Eucharist into a piece of the living heart of Jesus Christ, then He can certainly turn ordinary bread and wine into His Body and Blood in the Eucharist, and He can use them to transform us to be more and more like Him.