Jesus Truly Present in the Eucharist. At St. Legontian Church in Lanciano, Italy, in the 8th century, a priest who doubted Jesus' true presence was privileged to watch the host and wine turn to blood as he said the consecration. The host & wine were studied many times and found to be human heart tissue and AB blood. The miracle has continued for 12 centuries and can be viewed to this day in the monstrance in Lanciano
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http://www.therealpresence.org/eucharst/mir/lanciano.html