This Bitter Language
I know your streets, sweet city,
I know the demons and angels that flock
And roost in your boughs like birds.
I know you, river, as if you flowed through my heart.
I am your warrior daughter.
There are letters made of your body
As a fountain is made of water.
There are languages
Of which you are the blueprint
And as we speak them
The city rises.
I believe I am in Hell, therefore I am.
Before me things created were none, save things
Eternal, and eternal I endure.
All hope abandon, ye who enter here.
Day of wrath, that day of burning,
Seer and Sibyl speak concerning,
All the world to ashes turning.
What's up with the epigraph?
This poem feels like it was written just for this book. We have a reference to a "sweet city," which could be New York City, where Clary and pals live. There are "demons and angels" and a "river," which is where Valentine docks his scary boat. "I am your warrior daughter" could alert us to the fact that Clary is the narrator here, although she's being a little generous calling herself a warrior. "Klutzy" isn't as poetic. "Letters made of your body" refers to the Marks, runes written on a person's body.
In addition the main epigraph, each part begins with a little quote, usually about hell. Considering Valentine wants to summon a horde of demons, thereby creating a temporary hell on Earth these epigraphs do a nice job building tension as the story progresses. Also, the reference to "ashes" in a book called City of Ashes is a nice touch.