What does Exodus 7:21 mean?
At the Lord's command, Moses and Aaron have confronted Pharaoh (Exodus 7:14–16) and triggered the first of ten great plagues on Egypt (Exodus 3:19–20). The first catastrophe is turning the water of Egypt into blood (Exodus 7:17–20). What follows are the expected consequences of replacing water with bodily fluid. Fish die, everything decomposes and rots, and there is nothing for crops, livestock, or people to drink. This plague affects not only the river, but also the stored water, ponds, and pools throughout the land (Exodus 7:19). This will last long enough to threaten lives (Exodus 7:25).One effect of this plague is Egypt suffering the results of its own evil. When Pharaoh first rejected the command to free Israel (Exodus 5:1–4), he spitefully made the slaves (Exodus 1:11–14) scramble and toil to find the straw which had once been provided (Exodus 5:6–9). Now, the Egyptians must struggle to find water, which was once abundant (Exodus 7:24). Egypt once murdered Israelite children in the Nile (Exodus 1:22), now that blood symbolically comes back against them.