Lord Valentine's Castle owes as much to the modern tradition of fantasy as to predecessors in science fiction: the work of J. R. R. Tolkien and his imitators is clearly an influence. Unlike Tolkien, however, Silverberg shows little indebtedness to medieval heroic saga or to Norse mythology. Moreover, the planet Majipoor with its three continents, diverse cultures, and history is supposed to exist in a science fiction continuum. It has been colonized by humans and exists several thousand years in the future, although the various indigenous beings of the planet are Silverberg's own invention — including Skandars, sea dragons, and shape shifters. For this thoughtful and detailed construction of an imaginary planet, the most influential model is probably Frank Herbert's Dune (1965) and its sequels, although earlier writers, including even the much maligned Edgar Rice Burroughs, had constructed some elaborate cultures on other...