Light/Darkness: Good/Evil.
Water below/above: ???
Land/Water: Humanity; God's work of removing wickedness & chaos from us.
I'm wrestling with the firmament: a vault God put in the water to shove half the sea into the sky. This is what the Hebrews understood. Why?
The ancient people believed that earth had a dome over it, where an uncrossable sky-sea existed, beyond which was God's realm. The flood waters involved the dome opening and allowing water to fall.
That's the mythology.
But what is the symbolism? And why is it not "good?"
The dividing of the sea into the "waters below" and "waters above" is on day 2 of the creation story, and it's the only day where God does not say that He "saw that it was good."
Is it not good? Is it bad? Does it point to the grief of the Flood story? I don't know.