The second is the quite different symbolism the first two plagues were meant to have for the Israelites – and for us. As with the tenth plague, these were no mere miracles intended – as it were – to demonstrate the power of the G-d of Israel, as if religion were a gladiatorial arena in which the strongest god wins.
Their meaning was moral. They represented the most fundamental of all ethical principles, stated in the Noahide covenant in the words “He who sheds the blood of man, by man shall his blood be shed.” This is the rule of retributive justice, measure for measure: As you do, so shall you be done to.
By first ordering the midwives to kill all male Israelite babies and then, when that failed, by commanding “Every boy who is born must be cast into the Nile” (Exodus 1: 22), Pharaoh had turned what should have been symbols of life (the Nile, which fed Egyptian agriculture, and midwives) into agents of death. The river that turned to blood and the Heket-like frogs that infested the land were not afflictions as such, but rather coded communications, as if to say to the Egyptians: see what it feels like when the gods you turned against the Israelites turn on you.
Hence the tenth plague, to which all the others was a mere prelude. Unlike all the other plagues, its significance was disclosed to Moses even before he set out on his mission, while he was still living with Jethro in Midian:
You shall say to Pharaoh: This is what the Lord says. “Israel is My son, My firstborn. I have told you to let My son go, that he may worship Me. If you refuse to let him go, I will kill your own firstborn son” (Exodus 4:22-23).
Whereas the first two plagues were symbolic representations of the Egyptian murder of Israelite children, the tenth plague was the enactment of retributive justice, as if heaven was saying to the Egyptians, You committed, or supported, or passively accepted the murder of innocent children. There is only one way you will ever realize the wrong you did, namely, if the same thing happens to you.
This too helps explain the difference between the two words the Torah regularly uses to describe what G-d did in Egypt: “otot u’moftim – signs and wonders.” These two words are not two ways of describing the same thing – miracles. They describe quite different things. A mofet, a wonder, is indeed a miracle. An ot, a sign, is something else. It is a symbol (like tefillin or circumcision, both of which are called ot). That is to say, it is a coded communication, a message.
The significance of the ninth plague is now obvious. The greatest god in the Egyptian pantheon was Ra or Re, the sun god. The name of the Pharaoh often associated with the exodus, Ramses II, means meses, “son of” (as in the name Moses) Ra, the god of the sun. Egypt, its people believed, was ruled by the sun. Its human ruler, or Pharaoh, was semi-divine, the child of the sun god.
In the beginning of time, according to Egyptian myth, the sun god ruled together with Nun, the primeval waters. Eventually there were many deities. Ra then created human beings from his tears. Seeing, however, that they were deceitful, he sent the goddess Hathor to destroy them. Only a few survived.
The plague of darkness was not a mofet, but an ot. The obliteration of the sun signaled that there is a power greater than Ra. Yet what the plague represented was less the power of G-d over the sun, but the rejection by G-d of a civilization that turned one man, Pharaoh, into an absolute ruler with the ability to enslave other human beings – and of a culture that could tolerate the murder of children, because that is what Ra himself did.