Everything magical is parasitic?

I just finished re-watching Fushigi Yuugi: Eikoden, also known as "Legend of the Eternal Light." I'm sure it would have made a lot more sense in the novel form (assuming I understood the idea that it was based off the Fushigi Yuugi Gaiden novels), but the episodes were long enough to convey a plot and...I'm still a bit confused.

( Kaishen! )

"Eikoden" seems to wrap everything up, but it's only left me with more questions.