There also stands the gloomy house of Night;
ghastly clouds shroud it in darkness.
Before it Atlas stands erect and on his head
and unwearying arms firmly supports the broad sky,
where Night and Day cross a bronze threshold
and then come close and greet each other.
(Hesiod, Theogony, 744 ff.)
What's up with the epigraph?
Okay, so there's no mention of Hesiod in the book itself. That's fine, maybe Zoey just hasn't signed up for "Ancient Greek Dudes 101" at the House of Night just yet.
What this quote—taken from Hesiod's poem, Theogony—does for us, though, is establish that Nyx worship goes back a long time, like, millennia, and that Nyx has always been associated with the House of Night. Just like Zoey, we're new to that particular tidbit of information, so it's helpful to know going in.
We also get that darkness and light will be explored in the book, and that religious references may happen, and that what's considered dark or gloomy may be a matter of perspective. After all, Hesiod doesn't sound too thrilled about the House of Night, but when we see it from Zoey's eyes, it seems pretty cool (if also a bit intimidating because it's so new). So in a lot of ways, this epigraph sets us up to have a more complex understanding of some of the issues explored in the book—and also to keep our eyes peeled for mythological references.