The first five books of the Bible are called the Pentateuch, which comes from the Greek words for five and for scroll; together these books are called the Law, particularly in the Jewish religion. The last of these five books is called Deuteronomy, which come from the Greek words for second and for law, because this book is like a summing up of the laws and experiences of the previous books of the Law. It is chiefly a story of the relationship between God and the people; He saves and looks after them time and again in wonderful ways, they repeatedly complain and let Him down – it’s the story of our lives too, perhaps. The verses we have today focus on the manna, which they received as a gift from God when they found themselves in the desert with no knowledge of how to survive there and hence made a complaint against God for leading them there through Moses. Manna was seen as miraculous food that was the gift of life for them from God even though they were not deserving. From this it is clear how this is related to the sacrament of Communion.
The second reading is just a couple of verses from a letter of Paul to the Corinthians written about the year 54 AD. The selection follows on well after the first reading where the wanderers in the desert formed a community chosen by God, protected by Him and often failing to please Him. The Corinthians are living in a pagan setting and can easily fall into the pagan ways; so two verses earlier, Paul writes to them, “my dear friends, flee from idolatry!” Then, like a good teacher or caring and tactful parent, he tells them to be sensible – as they are – and asks them to think carefully about what he is going to say (“I am speaking as to sensible people: judge for yourselves what I say”); this is what precedes our reading. The Christians in Corinth would come together, probably weekly, to share a meal; it was a custom imported from Jewish practice to have a prayer of thanks during the drinking of a cup of wine, and also to break and share bread to symbolise their fellowship. The Christian Eucharist (the Lord’s Supper) developed from this. But here Paul is thinking of the Blood of Christ as the life He led and the death He met for the sake of others – including the Corinthians and us today; he makes it quite clear that for the sharing of bread he is thinking of the body of Christians gathered together who now live out the life of Christ in their lives. The more specific beliefs that the feast of Corpus Christi celebrates developed gradually in the churches and can differ across the denominations.
What we read for today’s gospel is a section of a lengthy discourse in Chapter 6 of John’s gospel, after his telling of the miraculous feeding of the multitude. The discourse has already referred to the manna in the desert (vv32f) which links with today’s first reading. In the discourse the use of “living bread” is similar to the “living water” in the story of the Samaritan Woman at the well (John 4:7-15), both are to do with eternal life. Jesus has already said in this speech that believing is what leads to this special life, but in our reading He is clearly referring to the Eucharist, for his phrases mirror those of the Last Supper as told elsewhere in the New Testament. Here, however, the word ‘flesh’ replaces the more usual ‘body.’ John has used this word when describing how God came to be one of us (“the Word was made flesh and dwelt amongst us” John 1:14). Some recent (adventurous) translations have replaced ‘flesh’ in this verse with ‘human,’ but the word, even in English today, has other connotations in phrases like ‘in the flesh’, ‘it makes my flesh creep’ and ‘she’s my own flesh and blood.’) Here together with ‘blood,’ it clearly refers to the Eucharist especially the sacrificial aspect of Jesus’ whole life and death – this is what offers us eternal life, and what we celebrate this day!
See Jeffs Jottings – The body of Christ