It was in the synagogue at Capernaum that Jesus first proclaimed the doctrinal mystery of His Living Presence in the Sacred Consecrated Eucharistic Species of Bread and Wine. (Read John 6:22-71) Later, at the Last Supper with His apostles, in the course of the Jewish Passover celebratory meal, Jesus, "The (Sacrificial) Lamb of God Who takes away the sins of the world," (John 1:29) instituted the Holy Eucharist commanding His apostles to, "Do this in remembrance of Me." (Luke 22:19)
Just as the blood of the sacrificed lambs was used to save the Jews from the Avenging Angel who killed only the first-born of the Egyptians (Exodus 11:1-10), so now, the Precious Blood of the Lamb of God, Christ, the only-begotten Son of the Father, was sacrificed and shed on the Cross for all mankind to save us from the death our sins deserve. Just as the Avenging Angel was enabled to 'pass over' the Jews because of the shedding of the blood of the sacrificial victims, so now too, by the sacrifice and shedding of the Saviour's Most Precious Blood, the Father now 'passes over' the just consequences of our sins and we are enabled, to pass from death to share in the wonder of His own Divine Life.
And just as the Jews ate the flesh of the sacrificial lambs on the night of the first 'Passover' (Paschal) meal, so we now eat the Sacred Flesh of The Sacrificial Lamb of God given for us and made present for us daily in the perpetual Holy Sacrifice of the Mass. Every day, the same Living Paschal (Passover) Victim continues to be offered and eaten throughout the world. It is the same Christ, The same Living Bread which came from heaven to give life to the world, (John 6:33) still giving Himself to us in The Holy Sacrifice of the Mass to nourish, strengthen and sustain us on our way to meet Him face to face (1 Corinthians 13:12) in His Heavenly Kingdom where we are all called to enter, share in, and behold the glory He had with the Father in the Holy Spirit, "before ever the world was." (John 17:5).
Now as they were eating, Jesus took some bread, and when He had said the blessing He broke it and gave it to the disciples. "Take and eat;" He said, "This is My Body". Then He took a cup, and when He had returned thanks He gave it to them. "Drink all of you from this," He said, "for this is My Blood, the Blood of the Covenant, which is to be poured out for many for the forgiveness of sins." (Matthew 26:26-28)
"For this is what I received from the Lord, and in turn passed on to you: that on the night He was betrayed, the Lord Jesus took some bread, and thanked God for it and broke it, and He said, "This is My Body, which is for you; do this as a memorial of Me." In the same way He took the cup after supper, and said, "This cup is the New Covenant in My Blood. Whenever you drink It, do this as a memorial of Me."
Until the Lord comes, therefore, every time you eat this Bread and drink this Cup, you are proclaiming His death; and so anyone who eats the Bread and drinks the Cup of the Lord unworthily will be guilty of the Body and the Blood of the Lord.
Everyone is to recollect himself before eating this Bread and drinking this Cup; because a person who eats and drinks without discerning the Body is eating and drinking his own condemnation." (1 Corinthians 11:23-29).
Jesus said to the Jews at Capernaum;
"I am the bread of life.
Your fathers ate the manna in the desert and they are dead;
but this is the bread which comes down from heaven,
so that a man may eat it and not die.
I am the living bread which has come down from heaven.
Anyone who eats this bread will live forever;
and the bread that I shall give is my flesh,
for the life of the world."
Then the Jews started arguing with one another:
"How can this man give us his flesh to eat?" they said.
Jesus replied: "I tell you solemnly,
if you do not eat the flesh of the Son of Man and drink his blood,
you will not have life in you.
Anyone who does eat my flesh and drink my blood has eternal life,
and I shall raise him up on the last day.
For my flesh is real food and my blood is real drink.
He who eats my flesh and drinks my blood lives in me
and I live in him.
As I, who am sent by the living Father,
myself draw life from the Father,
so whoever eats Me will draw life from me.
This is the Bread come down from heaven;
not like the bread our ancestors ate: they are dead,
but anyone who eats this Bread will live forever."
"It is the Spirit which gives life,
the flesh has nothing to offer.
The words I have spoken to you are spirit
and they are life."
"God is spirit,
and those who worship
must worship in spirit and truth." (John 4:24)
O Sacrament Most Holy,
O Sacrament Divine,
All praise and all thanksgiving,
be every moment Thine
(See also: Eucharistic Miracle beheld by Pope Francis)