Blood represents life and death, and so does the Nile for all of Egypt. At some point in their history, Egyptians associated the Nile with their gods—Hapi, Sobek, and Osiris—and relied on them to bring fertility to the soil for farming through the natural cycle of the Nile River. Without the Nile, Egyptians would die. They tried to invoke gods to ensure the Nile flowed and flooded at the appropriate times. But, God—the I am—cannot be invoked.
Yahweh shows true mastery over the Nile, and every other body of water in Egypt, by doing something that is not part of their natural cycles. The river is turned to blood, putting Hapi, Sobek, and Osiris to shame. After turning to the religious magicians of Egypt, who also turn water to blood by their secret arts, Pharaoh’s heart is hardened again. He refuses to let the people go just as Yahweh predicted he would. Pharaoh increased Israel’s labors. God increased Egypt’s labors—causing them to have to dig wells to get water to drink.
In the Gospels, when Jesus turns water to wine, the image of water turning to blood in Egypt comes to mind. The Gospels have many parallels with the Exodus account. Like blood, wine symbolizes life. Like water, wine symbolizes cleansing. Jesus took water meant for cleansing and made it wine with cleansing and flavor qualities that brought life to the party in Cana. He is Lord of life and death. Those who are against God find themselves working and working and working to merely sustain themselves in this life—having to dig their own wells because their water turns to blood. Those who are in Christ, who are God’s chosen people, experience the purity and flavor symbolized by the wine at Cana—new life that gets better with time.