49 St. John Chrysostom insists upon the same point with these words: "It is not man who makes what is put before him the Body and Blood of Christ, but Christ Himself who was crucified for us. The priest standing there in the place of Christ says these words, but their power and grace are from God. This is my Body, he says, and these words transform what lies before him." (53)
Source: Mysterium Fidei (Vatican.va)