I am a raven.
I cannot speak.
Though I carry words
of great matters.
I'm just a raven
I cannot read.
Though I can tell
what kind of letters
I deliver.
I can't sort out
the words they say,
but all they do
before they send me
is a clue
to my assignment.
They say my news
are seldom good--
as dark as both
my bustling wings.
They hate me
but
they need me
and
they cannot stand the thought I might
get lost or hunted down and fail.
source
With so much guilt, I post this messed up combination of words. It must have come from "Game Of Throne". That's the only "world" I know of where they use ravens as messengers.