The Last Supper & Sacrament of the Holy Eucharist
 
The Eucharist or Body of Christ is a Sacrament instituted by Christ Himself at the Last Supper, where under the appearances of bread and wine and after the Words of Consecration by a Catholic Priest, the Body, Blood, Soul, and Divinity of Our Lord Jesus Christ are Truly Present.
 
In John Chapter 6, Jesus said, "I am the bread of life. Your fathers ate the manna in the wilderness, and they died. This is the bread which comes down from heaven, that a man may eat of it and not die. I am the living bread which came down from heaven, if any one eats of this bread, he will live for ever, and the bread which I shall give for the life of the world is my flesh." (John 6:48-51)
 
Jesus said again, "Truly, truly, I say to you, unless you eat the flesh of the Son of man and drink his blood, you have no life in you. He who eats my flesh and drinks my blood has eternal life, and I will raise him up at the last day. For my flesh is food indeed, and my blood is drink indeed. He who eats my flesh and drinks my blood abides in me and I in him. As the living Father sent me, and I live because of the Father, so he who eats me will live because of me. This is the bread which came down from heaven, not such as the fathers ate and died, he who eats this bread will live forever." (John 6:53-58)
 
After hearing this teaching, many of Jesus's disciples left Him, for they knew He was not talking symbolically, but that He would literally and truly be present as the Eucharist, the living bread from Heaven. 
 
At the Last Supper, Jesus took bread, blessed, and broke it, and gave it to the disciples saying, "Take, eat; this is my body." And he took a cup, and when he had given thanks he gave it to them, saying, "Drink of it, all of you, for this is my blood of the covenant, which is poured out for many for the forgiveness of sins." (Matthew 26:26-28) 
 
At Calvary, Jesus was both High Priest and Victim, where He offered up Himself, His Body, as a Sacrifice to His Heavenly Father.
 
Therefore, at the Mass, the Priest is acting on earth "in the place of Christ" or "In Persona Christi", he pronounces the Words of Consecration over the bread and wine calling down from Heaven, Jesus's Body, Bloody, Soul, and Divinity, thus maintaining the same Perfect "Unbloody" Sacrifice to Almighty God as the Highest form of Worship.
 
Image Explanation
 
The Center Scene is the Last Supper or Institution of the Sacrament of the Eucharist.
 
The Bottom Scene is the Sacrament of the Eucharist for present day. 
 
The Top Right Scene is a foreshadowing of the Eucharist, for Elijah or Elias ate bread from an angel and was able to be strengthened for forty days and forty nights. However, the Eucharist strengthens our soul on its journey to Heaven. 
 
The Top Left Scene is the traitor Judas who hanged himself after despairing of his betrayal of Jesus and incurring of Mortal Sin for not discerning the Body of the Jesus in the bread at the Last Supper. For St. Paul says, "For any one who eats and drinks without discerning the body, eats and drinks judgment upon himself." (1 Corinthians 11:29)