In the First Reading, from the Book of Genesis, we have a story about Melchizedek, King of Salem (early name for Jerusalem) who comes to greet Abram by returning from a victorious battle. Melchizedek, who is also a priest, blesses Abram with bread and wine. The bread and wine are taken to prefigure the bread and wine of the Eucharistic sacrifice that celebrate Jesus’ victory over death, evil and sin, and enable us to remember our union with Jesus.
The Second Reading is taken from St. Paul's First letter to the Corinthians. This is the most ancient text we have on the origin of the Eucharistic sacrifice of Christ. Since Paul was not present at the Last Supper, he is passing on what he himself received. Jesus gave us the Eucharist and the command to continue the practice of participating in the Eucharist to nourish our souls and spirit, but also to give our bodies in loving service and example just as Jesus did. This is what "Do this in remembrance of me" means.
The Gospel Reading is from the Gospel of St. Luke. This is the only miracle story recorded in all four Gospels. Jesus is out in the desert with a large crowd of people, teaching them about the reign of God and healing their sick. Jesus is feeding the multitude with a few loaves of bread and a few fish with more than enough for everyone and much left over. It is a prelude to His institution of the Eucharist at the Last Supper. “All are satisfied” and there are 12 baskets left over. “Give them something to eat yourselves” is a challenge to the Church to feed the physical and soul-hungers of people.