The Last Supper that Jesus and His disciples had in the Bible was not a new invention at the time. The practice was from a feast called the Passover, and what they did was in remembrance of that day, when God made death pass over the children of Israel. 

Jesus explains the meaning of the Passover meal using figures of speech. The bread signifies His body, which came back to life, as the Passover was fulfilled in his death. 

The Lord’s Supper does not stop at being a mere symbol. What we celebrate now is reinstituted as the new Passover in remembrance of Him- Christ,