From Fulton Sheen’s Life of Christ (McGraw-Hill, 1958)
The Last Supper and the Crucifixion took place during the Passover, when the Eternal Son of the Father mediated a New Testament or Covenant, as the Old Testament or Covenant was mediated through Moses. As Moses ratified the Old Testament with the blood of animals so Christ now ratified the New Testament with His own Blood, He who is the true Pascal Lamb. “This is My Blood, of the New Testament.” Matthew 26:28
He wanted men not to be readers about His Redemption, but actors in it, offering up their body and blood with His in the re-enactment of Calvary, saying with him, “This is my body and this is my blood;” dying to their lower natures to live to grace; saying that they cared not for the appearance or species of their lives…but that their intellects, their wills, their substance — all that they truly were — would be changed into Christ; that the Heavenly Father looking down on them would see them in His Son, see their sacrifices massed in His sacrifice, their mortifications incorporated with His death, so that eventually they might share in His glory.