The other day, someone was telling me that why have a Maundy Thursday service without serving Communion since that was the day of the last supper.

Help me out here. I realize that the last supper was when Jesus instituted the Lord's Supper (Communion), yet how does the last supper relate to the Passover? It has always been said in talking about the sacraments that baptism and circumcision goes together, and Communion and Passover goes together. Please tell me the connection between Passover and the last supper? It is probably an easy explanation, but I am drawing blanks.