And he took bread, and gave thanks, and brake it, and gave unto them, saying, This is my body, which is given for you; this do in remembrance of me. Likewise also the cup after supper, saying, This cup is the new testament in my blood, which is shed for you.
1 Cor 10.16
The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread we break, is it not the communion of the body of Christ?