Today being Holy Thursday, it seem appropriate to re-read the Bread of Life discourse in John 6:22-71. Jesus makes his message as clear as possible. He starts by saying, "I am the bread of life; whoever comes to me will never hunger, and whoever believes in me will never thirst." (v.35) The crowds murmur at this, so Jesus ups the ante by proclaiming, "I am the living bread that came down from heaven; whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world." (v.51) Once again the crowds debated his meaning, so finally Jesus is explicit: "Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you. Whoever eats my flesh and drinks my blood has eternal life, and I will raise him on the last day. For my flesh is true food, and my blood is true drink. Whoever eats my flesh and drinks my blood remains in me and I in him." (vv.53-56)
Jesus lost many of his disciples over these words: "many of his disciples returned to their former way of life and no longer accompanied him." (v.66) The twelve remained, even, oddly enough, Judas -- who would later betray Jesus. Why didn't Judas leave at this time? Could he have actually believed that Jesus's flesh was true food and his blood true drink? When Jesus asks why the twelve don't go, Peter tells him, "Master, to whom shall we go? You have the words of eternal life. We have come to believe and are convinced that you are the Holy One of God." (vv.68-69) None of the others dispute this, even at at time when it would have been incredibly easy to walk away, which indicates that all the apostles concurred with what Peter said. Judas must have accepted both Jesus's words and Peter's statement.
At the Last Supper, Jesus again proclaims that his flesh and blood are meant to be eaten. "While they were eating, Jesus took bread, said the blessing, broke it, and giving it to his disciples said, 'Take and eat; this is my body.' Then he took a cup, gave thanks, and gave it to them, saying, 'Drink from it, all of you, for this is my blood of the covenant, which will be shed on behalf of many for the forgiveness of sins." (Mt. 26:26-28). This time there are no doubters in the room -- no one grumbles about these being hard words to accept. Judas rushes out, preparing to betray him, but all the rest of the disciples echo Peter's words: "Even though I should have to die with you, I will not deny you." (Mt. 26:35)
Yet all but one of the disciples did leave Jesus, much as the crowds did in John 6. Despite having just witnessed the first Mass and having given assent and partaken of Jesus's flesh at the Last Supper, there are none who come to his aid, or who can even stay awake at the garden of Gethsemane. Not even the first Eucharist bolstered the courage of the disciples, even though they truly believed.
Jesus knew that his followers would need an extra dose of grace and stamina, because he promiseed them the Holy Spirit after he departs. It's not until after Pentecost that the disciples are willing to lay down their lives for Jesus. Until then, even those who have received the Eucharist do not publicly acknowledge him.
Interesting footnote: John is the only gospel that doesn't mention the institution of the Eucharist during the last supper. Perhaps that's because he had such a strong Eucharistic discourse earlier in chapter 6.