MATTHEW 26 26 And as they were eating, Jesus took bread, blessed and broke it, and gave it to the disciples and said, “Take, eat; this is My body.”27 Then He took the cup, and gave thanks, and gave it to them, saying, “Drink from it, all of you. 28 For this is My blood of the new covenant, which is shed for many for the remission of sins. 29 But I say to you, I will not drink of this fruit of the vine from now on until that day when I drink it new with you in My Father’s kingdom.”30 And when they had sung a hymn, they went out to the Mount of Olives.31 Then Jesus said to them, “All of you will be made to stumble because of Me this night, for it is written:‘I will strike the Shepherd, And the sheep of the flock will be scattered.’32 But after I have been raised, I will go before you to Galilee.”33 Peter answered and said to Him, “Even if all are made to stumble because of You, I will never be made to stumble.”34 Jesus said to him, “Assuredly, I say to you that this night, before the rooster crows, you will deny Me three times.”35 Peter said to Him, “Even if I have to die with You, I will not deny You!”And so said all the disciples.

By saying, “This is My Body,” He shows that the bread which is sanctified on the altar is the Lord’s Body Itself, and not a symbolic type. For He did not say, “This is a type,” but “This is My Body.” By an ineffable action it is changed, although it may appear to us as bread. Since we are weak and could not endure to eat raw meat, much less human flesh, it appears as bread to us although it is indeed flesh.

(St Theophylact)