I'm rewatching Mushishi on DVD and blogging it. Previous post here. First post here. You can watch this episode and the rest of the series legally (and free) on Youtube. For those looking for a brief refresher, there's a list of brief episode descriptions here.
Thus far in the series, there have been two essential categories of mushi: those whom Ginko can control, and those who are so untouchable and powerful that he can't even attempt a cure. In other words, either beasts or gods. And some do take on the form of gods, literally: they command humans' worship (episode 6), control their dreams (episode 7), establish their taboos (episode 9), and even have dominion over the nature of their lives (episode 1). But if the mushi are gods, what does that make the mushishi?
Why, they're the priests, of course.