"The chalice of benediction which we bless, is it not the communion of the blood of Christ? And the bread which we break, is it not the partaking of the body of the Lord? For we, being many, are one bread, one body: all that partake of one bread." (1 Cor 10:16-17)
I found this amazing piece from Ignatius Insight, which includes excerpts from Joseph Cardinal Ratzinger's "Truth, faith and tolerance" -- written before he became Pope Benedict XVI. It's great reading.