Betty,

The stones encouraged the Israelites and drove fear into the hearts of the Canaanites because God miraculously stopped the waters of the Jordan for the Israelites so they could cross over.

The stones were a reminder (4:7) of the very place (4:9) where God performed the miracle. The miracle proved that God was on the Israelite's side and that he had power that the Canaanites did not have.

• Does that make sense?

In Luke 22:19 and 1 Corinthians 11:24, the Christian's memorial is the Eucharist, which Jesus discusses also in John 6:25-71 at length. The Eucharist, or Lord's Supper, is when, in Catholic and Orthodox churches and certain other churches, bread and wine is offered up to God as a memorial sacrifice and transformed into the Body and Blood of Christ for us to eat (John 6:53-58).

Through the Eucharist (the word from the Greek for "thanksgiving"), we enter into the one sacrifice of Christ on the Cross and partake of the flesh of the Paschal Lamb sacrificed for our sins.  Christ spoke of a "New Covenant" in His Blood.  In the Biblical perspective, a covenant relationship is sealed with a ritual — often involving blood. Christ died once for all on the Cross to free us from sin as the Lamb of God (John 1:29), the Passover Sacrifice that delivered us from bondage to the slavery of sin.  When God led the Jews out of slavery in Egypt, he first had them celebrate the Passover: The lamb was sacrificed, its blood smeared on the doorway, and its flesh eaten in the Passover ritual.  Examine the Passover ritual in Exodus closely.  Without doing all three of these things, the Angel of Death would strike down their firstborn.  The Paschal feast also fed the Jews through their journey in the desert, as did the Manna, into the Promised Land of milk and honey.

Jesus's death on the Cross fulfills the sacrifice.  Christ, as Scripture says (1 Corinthians 5:7), is our Passover: The Lamb of God, who was sacrificed for our sins, of whom the Exodus lamb was a type. But unless each one of us partakes of the flesh of the sacrificed lamb (cf. 1 Corinthians 10:16-18, Exodus 12:8), as the Israelites did, we do not truly participate in the sacrifice.

So the Eucharist is the central act of Christian worship. Consuming it has several effects:

• It makes us partakers of the divine nature (2 Peter 1:4), making us more and more like Christ.
• It frees us from sin.
• Through it, we abide in Christ (John 6:56).
• It is the source of spiritual life (John 6:57).

The Jews, when they were in the desert, were fed by God by manna from Heaven (Numbers 11; John 6:31).

Jews believed that the Messiah would bring a new manna, this is hinted at in John 6:30 (it's explicit in the Second Temple work 2 Baruch 29:8 <thefirmament.org/carm.org>). The Eucharist is the new manna (John 6:50); it feeds us spiritually. It is supernatural food (1 Corinthians 10:3) of the New Covenant.

St. Ignatius of Antioch, martyred in the year 107, called it the "medicine of immortality and the antidote to death". The Eucharist applies the saving effects of the sacrifice of the Cross to our sins and saves us from the angel of death.

Let me know if you have any questions!