Well, Eucharist is a the Body, Blood, Soul, and Divinity of Jesus truly present in Holy Communion. What was once an ordinary piece of bread and an ordinary cup of wine, has now been change into Jesus. In other words, just like Jesus changed the substance of water into wine at Cana, the priest, through the power of Jesus given to him at his ordination, changes the substances of bread and wine into the Body and Blood of Jesus at the consecration.