"When we speak of the reality of Christ's nature being in us, we would be speaking foolishly and impiously -- had we not learned it from Him. For He Himself says: "My Flesh is truly Food, and My Blood is truly Drink. He that eats My Flesh and drinks My Blood will remain in Me and I in Him." As to the reality of His Flesh and Blood, there is no room left for doubt, because now, both by the declaration of the Lord Himself and by our own faith, it is truly Flesh and it is truly Blood. And These Elements bring it about, when taken and consumed, that we are in Christ and Christ is in us. Is this not true? Let those who deny that Jesus Christ is true God be free to find these things untrue. But He Himself is in us through the flesh and we are in Him, while that which we are with Him is in God." ST. HILARY OF POITIERS (c. 315 - 368 A.D.) (The Trinity 8:14)
St. Ignatius became the third bishop of Antioch, succeeding St. Evodius, who was the immediate successor of St. Peter. He heard St. John preach when he was a boy and knew St. Polycarp, Bishop of Smyrna. Seven of his letters written to various Christian communities have been preserved. Eventually, he received the martyr's crown as he was thrown to wild beasts in the arena.
"Take care, then who belong to God and to Jesus Christ - they are with the bishop. And those who repent and come to the unity of the Church - they too shall be of God, and will be living according to Jesus Christ. Do not err, my brethren: if anyone follow a schismatic, he will not inherit the Kingdom of God. If any man walk about with strange doctrine, he cannot lie down with the passion. Take care, then, to use one Eucharist, so that whatever you do, you do according to God: for there is one Flesh of our Lord Jesus Christ, and one cup in the union of His Blood; one altar, as there is one bishop with the presbytery and my fellow servants, the deacons."
-Epistle to the Philadelphians, 3:2-4:1, 110 A.D.
I understand the Blood to be the Blood of the New Covenant. The reception of which seals one's bond to the covenant member. When tempted to turn stones into bread for bodily consumption, our Lord and Savior responded, Man doesn't live by bread alone, but by every word that proceeds from the mouth of God. How much greater might the consumption of bible doctrine on a daily basis be understood as that bread which is also the body of Christ, inculcated in our thinking processes, which thereby provides us His life.