By Patricia A. McKillip. (Dunno where the 'A.' came from.)
This is my second time reading this book, so either it's worth reading twice or you sort of have to, to understand what's going on. Well... I noticed more reading it this time than last time, but I still don't feel like I know everything that happened. This must be the ambiguity my sister hated about Alphabet of Thorn that made her not read any of the rest of McKillip's books.
Part of the book is pretty obvious: It's framed as Lydea's story: the first and last chapters are about Lydea, and she's even on the cover, along with a couple of unidentifiable people. But, in the end, it seems more like it's about the sorceress who learned she had a heart, and the daughter she loved.
McKillip's prose is hard to describe, but her style is distinctive and dreamlike. I definitely enjoyed this book both times, but if you hate ambiguity and want to know the answers to all the questions (In the end, who knows what? What did the sorceress know all along? Was she ever human? What is it to be human? What happened to the shadow city? What is the relation between Ducon's parents and Mag's parents? What stops the sorceress from doing whatever she wants to everyone? She certainly seems powerful enough, so the frightening answer is that just she doesn't care enough to.), then you may hate the way everything is resolved.
I would advise not skipping the words you don't know: they may mean more than you think. Not that there are very many of them (at least for me), but I still found at least one wordplay I definitely didn't notice the first time.