The significance of this miracle was to expose the true nature of the Egyptian living, i.e., that the fallen life in Egypt was under Satan the serpent’s usurping hand (cf. Eph. 2:2; 1 John 5:19).

The significance of this miracle was to expose the true nature of the Egyptian living, i.e., that the fallen life in Egypt was under Satan the serpent’s usurping hand (cf. Eph. 2:2; 1 John 5:19).
A prophet is not mainly one who predicts the future but one who speaks for another, as Aaron spoke for Moses (v. 2). On prophesying, see 1 Cor. 14:1, 3-5, 24-25, 31 and note 1 Cor. 14:13e, note 1 Cor. 14:241a, note 1 Cor. 14:251, and note 1 Cor. 14:311.
After the first two conflicts with Pharaoh, God used ten plagues to punish the Egyptians so that they might release His people, and to educate both the Egyptians and His people concerning the nature of the life in the world that they might be willing to forsake the worldly life. The ten plagues can be grouped into four categories. The first group includes the plagues of blood, frogs, and lice (Exo. 7:15-25; 8:1-19); the second group, the plagues of flies, pestilence, and boils (Exo. 8:20-32; 9:1-12); the third group, the plagues of hail, locusts, and darkness (Exo. 9:13-35; 10:1-29); and the fourth group, the plague of the killing of the firstborn (Exo. 11:1-10; 12:29-30). The plagues in the first group were troublesome but not injurious; the plagues in the second group caused harm both to beasts and to men; the plagues in the third group destroyed the environment; and the last plague terminated the worldly life. By means of the ten plagues God was able to accomplish the exodus of His chosen people from Egypt and fully expose the nature and result of the life in the world (cf. Rev. 16:1-21).
The magicians of Egypt can be compared to the philosophers of the world. The worldly philosophers may teach things similar to what is preached in the gospel and may also expose that life in the world issues in death (v. 22 see note Exo. 7:171b), but they are not able to remove the death; only the gospel can do this (cf. Exo. 8:8-13). Just as Aaron’s staff swallowed up the magicians’ staffs (v. 12), the gospel swallows up all the philosophies of the world.
cf. 2 Tim. 3:8
The waters of Egypt signify the worldly supply and enjoyment, and blood represents death, the issue of a life of sin (Rom. 6:23a). The significance of this first plague is that under the wrath of God’s judgment the life of Egypt, i.e., the life of the world, issues in nothing but death. The death signified by the blood exposes the nature and significance of the life in the world.