The plagues came one after another: the waters of the Nile turned to blood, then frogs, lice, swarms of flies, the death of Egypt's livestock, boils, hail, locusts and thick darkness. Egypt worshiped the Nile, the sun and many animal gods. Each plague showed that the LORD alone is God, ruling over the river, the land, the animals and the sky.
After the third plague, Pharaoh's own magicians could not copy what God did. They said, “This is the finger of God.” Yet Pharaoh's heart remained hard. Again and again he promised to let the people go when the plague pressed him, and again and again he went back on his word once relief came. A hard heart is often a heart that bargains with God but never truly surrenders.
God also made a difference between His people and Egypt. Of the flies He said, “I will make a difference between My people and your people.” The hail did not fall in the land of Goshen, and during the darkness “all the children of Israel had light in their dwellings.” The same God who judged Egypt sheltered Israel.
Before the last plague, God said He would bring one more judgment on Pharaoh and Egypt: the death of the firstborn. Pharaoh had once ordered Israel's baby boys thrown into the Nile; now judgment would fall on Egypt's firstborn. Through it all, God's purpose was mercy as well as justice — “that My name may be declared in all the earth.”