A definition of Communion is:
1. the act of sharing or holding in common; participation|
2. interchange of thoughts or interests; communication; intimate talk
3. the celebration of the Lord's Supper; (also known as) the "Eucharist".
JESUS, during the Last Supper in the Upper Room gave the first "communion" or first Lord's
Supper. (Mark 14:22-26, Matthew 26:26-30, Luke 22:14-20).
The significance of the bread and wine was familiar to the disciples. They knew about the
miracle of manna in the desert which God provided for the children of Israel (Exodus 16:15, John 6:31)
There was even some kept in the Ark of the Covenant (Hebrews 9:4).
In John 6:31-35, 48-59 we read how Jesus taught his disciples He was the Bread of Life.
For some it was a mystery difficult to grasp but Jesus spoke of the things of the spirit (verse 63).
In John 1:14 we learn that Jesus was the Word made flesh but verse 1 says "In the beginning was the Word, and the Word was with God and the Word was God." (This mystery points to
the Godhead of Father, Son and Holy Ghost to be considered elsewhere) Jesus said when He took the bread, gave thanks, broke it and gave it to the disciples "This is my body which is given for you: this do in remembrance of me." (Luke 22:19).
Jesus signified that the wine was a symbol of His blood. The disciples knew that the priest does not enter into Holy of Holies in the temple without a blood sacrifice. It was a sign of the covenant. Hebrews 9 explains the old and new covenants.
The second or new covenant was made by the blood of Jesus, (verses 12). If under the old covenant most things are by the law purged with blood for remission of sins annually then the power of the blood of Jesus brought into the most holy place in heaven was for the remission of sins forever.
Hebrews chapter 10 explains this further so we learn to come before God knowing our sins are forgiven if we continue in the faith. The wine of the Lord's Supper reminds us of this.
Jesus said he would not drink "of the fruit of the vine, until the kingdom of God shall come."
(Luke 22:18) He said also about the cup of wine "This cup is the new testament in my blood,
which is shed for you." (Luke 22:20).