Pentecost. “Let your Spirit come upon these gifts to make them holy, so that they may become for us the body and blood of our Lord, Jesus Christ.”
Those familiar words from the Mass accompany the action called the epiclesis, Greek for “to call forth.” The General Instruction of the Roman Missal says more about the understanding of these words, which, by the way, are spoken as the priest extends his hands over the bread and wine being offered.