Lexicon Urthus is an alphabetical dictionary for the complete Urth Cycle by Gene Wolfe: The Shadow of the Torturer; The Claw of the Conciliator; The Sword of the Lictor; The Citadel of the Autarch; the sequel Urth of the New Sun; the novella Empires of Foliage and Flower; the short stories "The Cat," "The Map," and "The Old Woman Whose Rolling Pin Is the Sun"; and Gene Wolfe's own commentaries in The Castle of the Otter. The first edition was nominated for a World Fantasy Award. This second edition includes over 1,200 entries. When the first edition was published, Science Fiction Age said: "Lexicon Urthus makes a perfect gift for any fan of [Wolfe's] work, and from the way his words sell, it appears that there are many deserving readers out there waiting." Gary K. Wolfe, in Locus, said: "A convenient and well researched glossary of names and terms. . . . It provides enough of a gloss on the novels that it almost evokes Wolfe's distant future all by itself. . . . It can provide both a useful reference and a good deal of fun." Donald Keller said, in the New York Review of Science Fiction: "A fruitful product of obsession, this is a thorough . . . dictionary of the Urth Cycle. . . . Andre-Driussi's research has been exhaustive, and he has discovered many fascinating things . . . [it is] head-spinning to confront a myriad of small and large details, some merely interesting, others jawdropping."

In this companion guide, Michael Andre-Driussi illuminates Gene Wolfe's Book of the Long Sun and Book of the Short Sun science fiction series through dictionary-style entries on the characters, gods, locations, themes, and timelines of the novels. Gate of Horn, Book of Silk, is organized in two parts, with the first half covering the Long Sun series (Nightside the Long Sun, Lake of the Long Sun, Calde of the Long Sun, and Exodus from the Long Sun) and the second half covering the Short Sun series (On Blue's Waters, In Green's Jungles, and Return to the Whorl) half covering one of the two series. "Languages of the Whorl," a section between the two parts, covers all the dialect, slang, and foreign terms used in the books--thieves' cant, flier language, Tick's talk, and more. Ten maps and diagrams are included. This is Michael Andre-Driussi's third guidebook to the rich tapestries of Gene Wolfe's worlds. As fans of of Lexicon Urthus and The Wizard Knight Companion have noted, that each book is both a convenient tool for a question while re-reading the novels but also an enjoyable read in its own right, from A to Z.