The Church celebrates the Eucharist in obedience to the words of Jesus at the Last Supper: “Do this in remembrance of me” (Luke 22:19). At this time, Jesus gave the Apostles both the command and the power to bring the Eucharist to us.
The celebration of the Eucharist is the Church’s way of doing what Jesus did at the Last Supper. St. Paul wrote, “For I received from the Lord what I also delivered to you, that the Lord Jesus on the night when he was betrayed took bread, and when he had given thanks, he broke it, and said, ‘This is my body which is for you. Do this in remembrance of me.’ In the same way also the cup, after supper, saying, ‘This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me.’ For as often as you eat this bread and drink the cup, you proclaim the Lord’s Death until he comes.” (1 Corinthians 11:23–26).
The Church does this to remember Jesus and to be reunited with Him. At the Last Supper, Jesus gave the Apostles His own Body and Blood, under the appearance of bread and wine. He then asked them to remember Him always by doing this same thing among themselves.