I think the Sun represents strenght, perhaps needed to unlock our Inner Sun?
In the AL we can read:
Page 97 [2008-12-18 03:22:22 - The Inner Sun - Ren., Am.]
"I channeled all of my energy into the Quill. It was the thing that most closely identified with my mind, you see. When the darkness completely consumed my body, the quill, with my soul and essence, remained glowing. It glowed with the fierceness of the sun, and drove the darkness out. It is here, always, that I wake from the hellish nightmare."
There, the light drove the darkness. And a bit later it says his Inner Sun is unlocked. Perhaps the Sun is there to balance the darkness within? To help each one with his own Inner Sun. (Of course I don't know the exact meaning of Inner Sun, and would love to know more about it, if someone has information to share! I certainly would love to learn more in order to find my own Sun!)
There are a lot of good lines of thought in this topic, mine is maybe a different approach on the main question.
~Aelis