Gene Wolfe's collection CASTLE OF DAYS is a must for fans, especially those who enjoyed his four-volume great work the Book of the New Sun. It consists of three parts, "Gene Wolfe's Book of Days", "The Castle of the Otter", and "Castle of Days."
"Gene Wolfe's Book of Days" is a collection of some of Wolfe's short stories, each representing a particular holiday. While these pieces are generally lighter and less substantial than Wolfe's other short stories of the late 70's and earlier 80's, there are several stories that are highly worthy. "Forlesen", representing Labor Day, is a clever jab at life in a corporation and it shows that the Dilbertesque workplace is nothing new. "The Changeling" represents Homecoming Day. A chilling and haunting piece, it takes place in the same town as Wolfe's early novel PEACE and illuminates a cryptic reference made there. This story alone makes CASTLE OF DAYS worth getting for fans of PEACE.
The second part of the book is "Castle of the Otter", named in jest after the mispelling of THE CITADEL OF THE AUTARCH which appeared in a 1982 issue of Locus. Subtitled "a book about the Book of the New Sun", it is a collection of essays about Wolfe's best-known work and can greatly expand one's knowledge of that world. "Words Weird and Wonderful", for example, defines all the archaic words in THE SHADOW OF THE TORTURER. "These Are the Jokes" is a collection of witty jokes, each told by a different character from the Book of the New Sun. "Onomastics" explains the names of many characters. "Castle of the Otter" was written when two of the four volumes of the series had been published, so it is a bit light on detail from THE CITADEL OF THE AUTARCH. Nonetheless, if you loved the Book of the New Sun, this part makes CASTLE OF DAYS the next Wolfe work worth getting.
The final section is "Castle of Days", which is a collection of diverse essays from the late 1980's. I found this the least interesting section, as much deals with science fiction fandom and a few pieces are rather quaint. However, there is the highly interesting essay "The Secret of the Greeks" which explains some of Wolfe's work on the Soldier series and why classical languages and literature are a worthwhile pastime.
All in all, CASTLE OF DAYS is an essential purchase for fans of Gene Wolfe. I didn't pick it up until six years after I read and was fascinated by the Book of the New Sun, and I instantly regretted missing out on such an illuminating collection. I can't recommend this collection enough.