In his work, The Man Well-Anchored (374 A.D.), St. Epiphanius of Salamis wrote about the Eucharist:
We see that the Savior took [something] in His hands, as it is in the Gospel, when He was reclining at supper; and He took this, and giving thanks, He said: "This is really Me." And He gave to His disciples and said: "This is really Me." And we see that it is not equal nor similar, not to the incarnate image, not to the invisible divinity, not to the outline of His limbs. For It is round of shape, and devoid of feeling. As to Its power, He means to say even of Its grace, "This is really Me"; and none disbelieves His word. For anyone who does not believe the truth in what He says is deprived of grace and of Savior. (The Faith of the Early Fathers, Vol. 2, by William A. Jurgens, p. 69.)
I love so many things about this passage. First, Epiphanius' title, The Man Well-Anchored, is a good reminder to us to be conscious of what we make our anchor in life: is it God, or is it some idol, some created thing, such as money, fame, power, lust, sports, TV, control, etc.? Second, Epiphanius uses the phrase "This is really Me" to make immediate and penetrating the Lord's "This is my body" and "This is my blood" as we try to grapple with how what appears to be bread and wine can "really" be the body and blood of Christ. But we are called to believe that Jesus cannot lie to us; we are called to trust that he is as good as his word.