"The great wheel has four points. At its base, chaos, absolute and total. At its height, order, stillness, perfection. In times past, the wheel would turn, and chaos would rise. It would turn again, and order would emerge."

"Like a crystal growing from random interactions?"

"Somewhat."

"But if Discord is chaos and you're order—"

"Twilight, I did not say we are order. Order is... order is that same crystal. It is perfection, but it is unchanging, cold, empty perfection. It is absolute, just as chaos is absolute. I have never met order, or any being incarnating order, and I pray I never shall, for absolute order is as destructive to our existence as absolute chaos."

"Then... what are you?"

"We are harmony. We stand between order and chaos. We are order and chaos. We balance the wheel so that neither one nor the other shall become ascendant. This is what true harmony means, Twilight; to be in between, to be all things. We are each in one another, my sister and I. My light shines upon Luna's face, and the dark of her night is buried within my heart. We are order and chaos in equal amount." Celestia raised her wing and peered under it at Twilight. "Is this the answer you sought?"

Author's Notes:

Just a little dialogue.