The singers of the forest had no books. No ink, no parchment, no
written language. Instead they had the trees, and the weirwoods above
all. When they died, they went into the wood, into leaf and limb and
root, and the trees remembered. All their songs and spells, their
histories and prayers, everything they knew about this world.
Maesters
will tell you that the weirwoods are sacred to the old
gods.
The singers believe they are the old gods. When singers die they become
part of that godhood.
-Jojen Reed to Bran Stark
