"You know the place where the old fort used to be, in bygone days before they built the bridge?"
"I know it well," said the Mole.  "But why should Otter choose to watch there?"
--epigraph to The Castle of the Otter, from The Wind in the Willows by Kenneth Grahame

Gene Wolfe is a head case.  I mean this in a nice way.

The title of this slim, out-of-print volume comes (inadvertently) from the science-fiction review magazine Locus, which in one issue told its readers that the upcoming final volume in The Book of the New Sun was going to be called The Castle of the Otter (the correct title, we know, is The Citadel of the Autarch).  The book consists of a series of essays by Wolfe about the creative process that led up to the writing of his masterpiece.  Among other things, we learn that the idea began as a novella titled "The Feast of St. Katherine", which Wolfe was encouraged to expand (and did he ever!).  There's a handy glossary of a few (but by no means all) of the ultra-esoteric Greek and Latin words used in The Book of the New Sun to create the impression of an ancient and dying world.  There's also a few of Wolfe's reflections on the art and craft of writing.

From most other writers, this would seem like masturbatory self-aggrandizement at its worst.  Wolfe, however, is such a profoundly illuminating intellect that reading the book is like snatching M&M's from God's personal candy jar.  Essays on writing become, for him, merely a jumping-off point for all sorts of discussions philosophical and philological.  One of my favorite bits is a chapter where, after noting that his son complained he wasn't being funny enough, he features the main characters from The Book of the New Sun--the gloomy torturers, countesses, eunuchs, cyborgs, and the rest--telling jokes.  All in character, too; Wolfe's world is so realized, so three-dimensional, that he can write about it from any angle, even for the sake of pure silliness.

This is a wonderful companion volume to The Book of the New Sun; I recommend it heartily for anyone who plowed through the tetralogy.  Thankfully, the book has been reprinted in its entirety, along with Gene Wolfe's Book of Days, in the hefty collection Castle of Days.  Go.  Buy.