A spell in essence corresponds to a code, or set of instructions, inserted into the sensorium of an entity which is able and not unwilling to alter the environment in accordance with the message conveyed by the spell.Vance likewise states that "Magic is a practical science, or, more properly, a craft, since emphasis is placed on utility, rather than basic understanding." Taken together, these comments provide additional fuel for the fire of discussion regarding the meaning of "Vancian" spellcasting and its relationship (or not) to D&D's magic rules.
The second reason gamers might be interested in this book is the third story in this collection -- and the best, in my opinion -- is the origin of Ioun Stones. The story in question, "Morreion," was originally published in 1973, in a collection called Flashing Swords! 1, edited by Lin Carter and enjoyed by Gary Gygax. By his own admission, he was so taken with both the story and the magical stones it described (which Vance always spells in all capital letters as "IOUN stones") that he imported them into Dungeons & Dragons, an importation to which Vance in fact gave his kind permission.
The first story of Rhialto the Marvellous is entitled "The Murthe" and concerns a powerful female magic-user from the past, after whose title the story is named. In the past, there was a "War of Wizards and Witches," in which the witches were victorious. However, a few surviving wizards created a cabal to strike back against their feminine foes. In this endeavor they succeeded and the Murthe was exiled "to a far star." Alas for the wizards, the Murthe proved wilier than expected and, rather than go in peace, she discovered a means to travel into the future, which is to say, Rhialto's present to exact her revenge by transforming her enemies into women under her own control. Only Rhialto and his friend Ildefonse escape the Murthe's magic and, together, they must find a means to stop her and reverse her spells.
The second story, "Fader's Waft," is lengthy and could easily stand on its own as a novella. Its plot centers on Rhialto's censure by his fellow wizards, the penalty for which is being stripped of most of his magical possessions, including his collection of IOUN stones. Rhialto becomes convinced that the events that led to his reprimand are the result of a nefarious plot against him by agents unknown and, with the aid of an unruly sandestin (are there any other kind?), he travels back in time to unravel the mystery of just what has transpired and why. Of course, things aren't as simple as that and, through the course of the story, Rhialto must contend with several temporally-based plots and counter-plots in order to get to the bottom of it all.
The final story, the aforementioned "Morreion," is a terrific story that involves the journey of Rhialto and his fellows to the literal edge of the universe in search of a former colleague who disappeared some time ago while seeking out the source of the much-coveted IOUN stones. Though a good story in itself, what makes it stand out is Vance's fanciful conception of magical space travel, in which the wizards use their powers to transport an entire palace into the outer dark. Part whimsy, part brilliance, the third story of Rhialto the Marvellous presents a vision of extraterrestrial exploration that I find very compelling and one that I can't help but wish D&D had adopted more fully. You can see glimmers of it in Gygax's conception of the Astral Plane, I think, and there's even a touch of it in -- believe it or not -- Spelljammer but neither really quite does justice to what Vance has concocted in "Morreion."
Overall, I have mixed feelings about Rhialto the Marvellous. There's no doubt that it contains some of Vance's best and most humorous prose. The interactions between the immensely powerful and self-absorbed wizards is priceless and almost worth the price of admission alone. With the exception of "Morreion," though, I can't say that the stories themselves particularly engaged me, with "Fader's Waft" being notably tedious at times. But perhaps the stories themselves aren't the point so much as Vance's luxurious prose and skill in producing dialog at once beautiful and vapid. If nothing else, the book is great inspiration for a campaign involving powerful magic-users in a decadent and dying world.