John tells a pair of miracle stories familiar from the Synoptic gospels: Jesus feeds a hungry crowd with few loaves of bread and a few fish. Then, in crossing over the Sea of Galilee, he stills a sudden storm, showing a divine mastery over the elements. These deeds evoke among some bystanders an expectation about the royal role of Jesus, something that he assiduously avoids. In telling that tale of the miracles and the reaction of people to them, the evangelist seems to suggest a critical attitude toward “signs” of the Messianic status of Jesus. The miracles attributed to him can easily be construed as proofs or tokens of a belief about Jesus that is not true. The “signs” that point to the significance of Jesus need to be properly understood.
These stories, apparently well known and loved by early Christians, had already suggested deeper layers of meaning. The account of Jesus’ action in multiplying the loaves in Mark already evokes the ritual actions of Christians in their common meal, at which they remembered the death of the Lord until he returned again (See 1 Corinthians 11). John therefore builds on what probably was already a way of reading the stories by turning the first into a discourse by Jesus on true “bread from heaven.”
Jesus remarks begin, like a Jewish homily, with a citation from scripture (Ps 78:24), each element of which receives a new interpretation. Not “bread from heaven” but Jesus himself is the “bread of life.” It is not Moses, but God who gives, and it is not a past act, but something in the present, in the here and now in which true sustenance is to be found. As often in the Jewish interpretation of scripture, another scriptural text plays a role in finding new meaning in a text. Isaiah 54:13, cited at John 6:45 helps to build the case that “eating” the “bread from heaven” is really a matter of being taught the truth.
The discourse takes an unexpected turn when in v 51 and following the focus shifts to the “bread” that is to be eaten in a physical sense and the “blood” that is to be drunk. The allusion seems to be at once to the Christian practice of the eucharist and to the death of Jesus, which that eucharist memorialized and celebrated.