9th Century
St. Paschasius Radbertus
Medieval Period
St. Paschasius Radbertus (c. 785 – c. 865), Carolingian abbot who wrote the first major treatise on the Eucharist. Wikipedia
"Understand that these spiritual realities that are indeed neither locally nor carnally before the sight are borne up to the heights of the divine majesty. Think then whether any corporeal thing could be more sublime since the substance of bread and wine is effectively and interiorly changed into the flesh and blood of Christ, so that after the consecration it is rightly believed to be truly the very flesh and blood of Christ and nothing other than Christ "
On the Body and Blood of the Lord
View Source