A diffuse light spread through the universe. God saw that the universe though, no longer chaotic, was too undifferentiated. God concentrated the light in the sun, the stars and the moon, and restored enough darkness to make the heavenly bodies stand out. The rest of the darkness was kept in reserve for later use.
Pharoah was a god to the Egyptians, who refused to let the Israelites go. Some of the plagues God sent were attacks on Egyptian gods. For the first plague, God turned the water of the Nile into blood. This was an assault on the god Hapi, an incarnation of the Nile’s life force, and Osiris the god of the underworld, a god of regeneration and rebirth also associated with the Nile. After seven more plagues that demonstrated God’s control over nature it was time for the ninth plague - darkness. This thick daytime darkness annihilated the sun, a god to the Egyptians, the god Aten proclaimed by the pharaoh Akhenaten to be the only God.
Hashem said to Moses: “stretch out your hand toward the heaven, that there may be darkness over the land of Egypt, even darkness which may be felt” (Exod. 10:21). R. Nehemiah (midrash Tanchuma, Bo 2) argued that it ascended from the darkness of Gehonim, the netherworld, as it is stated: “A land of thick darkness, as darkness itself, a land of the shadow of death, without any order, and where the light is as darkness” (Job 10:22). This midrash holds that Hashem drew from remaining darkness that had been locked up at the beginning of creation.
This was a pure concentrated darkness. At first Egyptians perceived what might have been an ordinary darkness, but when they lit a candle they could see nothing (Nachmanides). Even outdoors they couldn’t see anything. Then movement became difficult. Those who were standing could not sit down and those who were sitting could not stand up (Midrash Rabbah). Total darkness was new and frightening. At night there was usually enough light from the stars and the moon to perceive the outline of nearby objects. They called to one another in their plight, but the darkness thickened, and no sounds reached their ears. They wondered if this was dream - their legs couldn’t walk, there was no way home. But real nightmares end when most unbearable, and this experience seemed endless.
Only thoughts flowed. Perhaps this was a punishment, like the preceding plagues. If only Pharoah had let the Hebrews go. Some people bargained with their gods, then in desperation called on the unknown Hebrew God. Taskmasters vowed to drop their whips if they were granted the freedom to walk in light again. Egyptians who stood by when Hebrew boys were thrown into rivers, prayed for an end to their parents’ pain. This was a collective decision to change, we call it tshuvah. They dedicated themselves to act differently, accept Hebrews as fellow human beings who should not be enslaved.
What happened next requires a brief digression on quantum mechanics. The standard interpretation of quantum mechanics holds that just before the box holding Schrodinger's cat is opened there exists a superposition of an alive cat and a dead cat, and that opening the box forces it to be dead or alive. But the “many worlds” interpretation holds that when the box is opened the universe splits in two. In one universe the cat is dead, in another universe the cat is alive. In this midrash the everyday Egyptian people all do tshuvah, but then there is a split with Pharaoh fully repentant in one universe, while in the other universe as God slowly puts the darkness back into its box Pharaoh’s resolve to change weakens and he does not repent. In this latter universe God removes all the darkness but hardens Pharaoh’s heart. Because the people repented, the tenth plague brings only the death of Pharoah’s son. In the first universe the repentance of Pharoah and the Egyptian people make darkness the final plague. The Israelites leave unpursued carrying goods freely bestowed as reparations for their enslavement.
Sadly, in our universe outside the midrash “in the middle of the night יהוה struck down all the [male] first-born in the land of Egypt, from the first-born of Pharaoh who sat on the throne to the first-born of the captive who was in the dungeon, and all the first-born of the cattle.” (Exodos 12:29). In this universe Pharaoh pursued the Israelites, his army drowned and Israel was ultimately exiled. Perhaps someday, through the power of tshuvah and tikkun olam, we draw we can draw closer to that universe in which the thick darkness had true healing power.