Ghosts don't have to be scary. I think that ghosts are more likely to be scared themselves than scary.
-- Jean (chapter 3)

Importance: Jean says this to Eliza shortly after they visit the morgue and see one of the dead women that has turned up around Monterey. Eliza and Jean differ when they think about the supernatural. To this point, Eliza's view on ghosts is that they are always malevolent and frightening, perhaps informed by her Christian upbringing. Jean, however, teaches her eventually that oftentimes, ghosts and spirits can be benevolent. When she sees ghosts, they often have some tie to the history of the place she saw them in or are just trying to make themselves known.

It was easy enough to imagine someone like that, out of control, seeing his own sin in the face of a girl, and also easy to imagine the girl doing the wrong thing, and the fellow...
-- Narrator (chapter 4)