St. John of Damascus Eucharistic Quotes:

If the Word of God is living and powerful, and if the Lord does all things whatsoever he wills; if he said, "Let there be light", and it happened; if he said, "let there be a firmament", and it happened; ...if finally the Word of God himself willingly became man and made flesh for himself out of the most pure and undefiled blood of the holy and ever Virgin, why should he not be capable of making bread his Body and wine and water his Blood?... God said, "This is my Body", and "This is my Blood."

- St. John of Damascus
 

Of the Eucharist St. John of Damascus has written: "If union is in
truth with Christ and with one another, we are assuredly voluntarily united with
all those who partake with us."