1.1b.3 End of Egypt
The slavery of Israel in Egypt was a judgement. They did not worship God, but the gods of Egypt.
First they were given manna, a kind of bread to eat. Jesus is the bread from heaven. It represents the cross; his body given for us. While we were still sinners, Christ died for us.
They then thirsted. This signifies the end of judgement. They lacked the word of God. This parallels the church right after his resurrection. All of the doctrine hidden in the OT was still hidden.
One might use the term 'sanctification' to describe the death of Israel in the desert. We must die to self. They were given a flood of water from the rock. After the cross, there was a flood of doctrine as all the OT was revealed to speak of Christ.
The rock 'tsur' צור is the exchange of sin and righteousness צ made clear ו by revelation ר. Christ was
