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Cup of Blessing
BLESSING, CUP OF (τὸ ποτήριον τη̂ς εὐλογίας). This expression is found only in
Borrowing this expression from Judaism, Paul applied it to the cup of the. He meant by it, therefore, not the cup which imparts blessing, but that over which the Christian gives his thanks to God for the death of Christ, and by which he sets apart the entire eucharistic meal (the Christian’s Passover?) as spiritual food for his soul.
International Standard Bible Encyclopedia (1915)
A technical term from the Jewish liturgy transferred to the, and signifying the cup of wine upon which a blessing was pronounced. The suggestion that it carries with it a higher significance, as a cup that brings blessing, is not without force. The succeeding words, "we bless," are equivalent to "for which we give thanks." It was consecrated by thanksgiving and prayer.
See also CUP.