WHAT ONE FIRST notices in the work of Jack Vance is the style. The sentences are processional -- richly ornamented, courtly, measured, slightly ironic. The syntax is never fancy, but the vocabulary possesses a faintly archaic flavor, the result of a flair for naming things and a historian's desire for precision. The polite diction suggests a civilized observer, a kind of galactic Saint-Simon, who analyzes in detail the social structures of alien worlds while describing the doings and misadventures of various outsiders, misfits and rebels.

Vance's opening sentences establish this carefully pitched tone: The world-weary "Ixax at the best of times was a dreary planet"; the quiet crescendo of "Toward the end of a stormy summer afternoon, with the sun finally breaking out under ragged black rain-clouds, Castle Janeil was overwhelmed and its population destroyed." In his descriptions, though, Vance lets his taste for gilt and brocade dominate:

"Such was Mazirian's garden -- three terraces growing with strange and wonderful vegetations. Certain plants swam with changing iridescences; others held up blooms pulsing like sea-anemones, purple, green, lilac, pink, yellow. Here grew trees like feather parasols, trees with transparent trunks threaded with red and yellow veins, trees with foliage like metal foil, each leaf a different metal -- copper, silver, blue tantalum, bronze, green iridium. Here blooms like bubbles tugged gently upward from glazed green leaves, there a shrub bore a thousand pipe-shaped blossoms, each whistling softly to make music of the ancient Earth, of the ruby-red sunlight, water seeping through black soil, the languid winds."

Such a sensuous, elevated style, at times reminiscent of the art-prose of Ruskin or Huysmans, can easily cloy or become mere bejeweled description, gaudy but insubstantial. Vance skirts this danger by fixing on traditional adventure plots: the revenge sage, the picaresque journey or marvel-filled odyssey, the murder mystery, the novel of education (his most common form), sword-and-laser battle epics (chiefly The Dragon Masters and The Last Castle, both Hugo winners). All these strong story lines prevent the novels from bogging down in the merely evocative; unfortunately, though, Vance seems content to adopt them whole without transforming them into anything uniquely his own -- none of his plots tick with the clockwork-precision of Robert Heinlein's, nor do his characters possess the complexity and realness of Philip K. Dick's.

This last criticism results largely from Vance's historical perspective, one which conveys a feeling of sympathetic observation rather than of close involvement with his characters. His heroes themselves often possess this same detachment: Kirth Gersen, the single-minded revenger of "The Demon Princes" saga, may occasionally indulge in uncertainty about his lifelong manhunt for the five super-villains who destroyed his planet and family, but for the most part he regards himself and his actions with the impersonality of a chessplayer. What gives Gersen's adventures their baroque richness -- and Vance has spent his best years on them -- are the subsidiary figures, the detailed variety and intricate coherence of the planets, organizations and peoples that make up the Oikumene, and the grandiose Venetian character of the Demon Princes themselves.

For in Vance's work description itself becomes epic. From any of his novels the reader will learn, unobtrusively, how a world is governed, its history, the values of the citizens (including their religious beliefs, social aspirations and general character traits), the forms of technology available, the games people play, what the night sky looks like.

In The Face, for example, Vance creates the desert world of Dar Sai, half-Arab, half Australian, where the Darsh people are brutish, and sexual contact results only through culturally-condoned violence."Procreation," to quote the Tourist Guide to the Coranne, by Jane Szantho, "is accomplished . . . during nocturnal promenades across the desert, especially when Mirassou-shine is in the sky. The system is simple in outline but complicated in detail. Both men and women aggressively seek out young sexual partners. The men waylay girls barely adolescent; women seize upon boys not much older. To lure boys out upon the desert, the women ruthlessly send out the pubescent girls and so it goes." The Darsh live under huge gossamer "shades," structured to trap and preserve moisture. The whip is the preferred weapon, their food ("chatowsies, pourrian, ahagaree") revolting, the great sport hadaul, a kind of free-for-all played on a tri-colored circular court.

Such zestful creativity reflects Vance's liking for marvels, spectacle and Grand Guignol -- for games. In Emphyrio, for instance, young Ghyl Tarvoke views a puppet show, part of Framtrees Peripatezic Entercationers ("Wonders of the Universe: a magnificent tour without danger, inconvenience or expense, depicting spectacles of sixteen enthralling worlds, arranged in tasteful and edifying sequence"). What seems at first a mere childhood incident gradually becomes the ruling metaphor of the whole novel, as Ghyl uncovers ever more sophisticated levels of puppetry in his world. Similarly, the anything-goes resort Carnevalle in To Live Forever counterpoints and eventually overwhelms the grade-card prestige system of Clarges, just as the image of the formal masque, playing against Dionysiac surrender, gives structure to The Palace of Love. Many of the novels also depict elaborate caste systems, with precise and absure requirements; in "The Moon Moth" people communicate with bizarre musical instruments, wear finely-worked masks (revealing a naked face is unthinkable), and value social esteem above all else. The plot here is elegantly simple: How does one identify a murderer in a society where everyone goes about in disguise?

Readers new to Jack Vance may be surprised at the number of books he has written (40 or so novels since 1950) and by the range of their subject matter and flavor. The stories of The Dying Earth, set on our planet some 20 million years in the future, convey an elegiac mood, the sad magic of mankind's twilight; but the Cugel tales (in The Eyes of the Overworld,) take place at the same time and possess a sardonic trickster humor, suggestive of Dunsany. (Who could forget the elegant Spell of Forlorn Encystment?) The five novels of the Demon Princes -- the spooky last volume, The Book of Dreams, is just out -- constitute a kind of spaghetti western in space, while The Last Castle depicts the most wondrously refined and delicate of societies, as ordered as a Japanese tea ceremony. Nopalgarth, by contrast, is an hallucinatory, paranoiac novel, picturing human beings as the playthings of rival alien beings -- a mixture of Lovecraft and Vonnegut; and Emphyrio studies the deep affections and sympathies that spring up between a father and his son.

Like a few other genre writers -- Wodehouse or le Carre come to mind -- Jack Vance is a craftsman of an unusual order, whose books show all the signs of being a true oeuvre, the products of a single, inventive intelligence. In anything he writes one hears that refined, inimitable, addictive voice -- there is his triumph. NOTE ON AVAILABILITY

Much of Jack Vance's work is available from DAW Books at $2.25 a volume; Pocket Books, however, has the logical introductory collection: The Best of Jack Vance (also $2.25). Don't be put off by garish covers; they are a convention in science fiction publishing. Some of the novels are still available in sedate hardcovers and Gregg Press has reprinted three -- including my favorite, The Eyes of the Overworld ($11) -- in sturdy library bindings on acid-free paper. Those wishing to learn more about Vance's work should consult the excellent collection of essays, Jack Vance, edited by Tim Underwood and Chuck Miller (Taplinger, $12.95), who also publish fine limited editions of their favorite writer.