Giles: These letters contain references to a, a, an ancient power known as The First.
Buffy: First what?
Giles: Evil. Absolute evil, older than man, than demons. It could have had the power to bring Angel back.
Buffy: These guys, (picks up one of the letters with sketches of the eyeless priest) I-I saw them in my dream. I, I fell asleep up there.
Giles: You had another dream? With Angel? (Buffy nods) What happened?
Buffy: (evasively) Oh, we don't need to get sidetracked. Who are these guys?
Giles: Um, they're known as the, uh, (sits) as the Bringers o-o-or Harbingers. They're high priests of The First. They, uh, they can conjure spirit manifestations and set them on people, influence them, haunt them.
Jenny/The First: Hmm. You think you can fight me? I'm not a demon, little girl. I am something that you can't even conceive. The First Evil. Beyond sin, beyond death. I am the thing the darkness fears. You'll never see me, but I am everywhere. Every being, every thought, every drop of hate.
I find that last bit interesting given the Buffy/Spike dialogue tonight regarding (self-)hate.