I just finished re-reading it. Thanks for flagging it, I had forgotten about it!

I've been interpreting (re-interpreting?) a lot of various myths in terms of the descent of souls, following Sallustius... I intentionally skipped over The Lord of the Rings, as it tells a very different story with a very different vision (e.g. the ascent of the Christian Elect). Leaf by Niggle seems to me to tell the story of that vision, as well.