What Is the Eucharist?

The Eucharist is in the Synoptic Gospel so it's in Mark 14, 22 to 25-ish, Matthew 26, 26 to 29-ish and Luke 22, 15 to 20-ish. It's also in 1 Corinthians 11, 23 to 26. There was quite a lot of debate about what the Eucharist should consist of in terms of food and drink. John 6 doesn't seem to be aware of any of that conversation in the first and second century.