Chapter 6 of the Gospel of John is the best explanation of the Holy Eucharist.  I strongly encourage you read the entire chapter in one sitting.  There we learn the Holy Eucharist is Jesus's Body, Blood, Soul, and Divinity. 

Over the centuries, many Eucharistic miracles have occurred and I encourage you to read more about them.  Click on each of the three images below to learn more about three of my favorite Eucharistic miracles...

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 More Eucharistic miracles can be found by clicking on the image below...

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 The Sioux Falls diocese has this additional information...

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Also, a national website has this information...