I think it's a book that somehow slipped through the dimensional void between our plane of existence and that of our counterselves.
(BTW, I really do believe in more than one universe and plane of existence, and that creatures beyond human fathoming exist in each.)
I find that book strangely familiar, but considering the number of modern works that mention it I've probably heard about it in passing somewhere.
Have you ever looked at the paintings by Brian Froud, Xion? He's best known for character and world designs in
The Dark Crystal and
The Labyrinth films, but he's also published a couple of books that you might find interesting. Mr. Froud paints faeries, but not the stereotypical 6" pixies with shiny wings and sparklies--he touches on higher planes of thought and feeling repeatedly.
Good Faeries, Bad Faeries is a great coffee table book with all sorts of descriptions of everything that's in it; another one to look for is the
Faeries' Oracle. It's similar to a tarot deck if you're in to that kind of thing, but I've found it to be a very profound source of inspiration and insight.