ROBERT SILVERBERG, one of science fiction's more erudite and accomplished practitioners, has said of science fiction that among its important values is "its inventiveness: the putting forth of some new notion, or the recombination of old ideas into dramatically vivid form." It may be the harder task to come up with a genuinely new idea. But it's always a delight, for writer and reader alike, to discover that concepts we thought stale still have the power to move and to challenge.

Wild Seed, by Octavia Butler (Doubleday, $10) provides an admirable example. Wild Seed is Butler's fifth novel, the prequel to Mind of My Mind, Patternmaster and Survivor , the other books in her "Patternist" series. (Kindred , her fourth book, is not part of the "Patternist" sequence and, though it contains fantasy elements, it is not being marketed as science fiction.) Wild Seed begins in Africa in 1690 and ends in the New World just before the Civil War. Its thematic core explores the question of what it means to be human, expressed through the experiences and emotions of Doro, a 4,000-year-old mutant whose sense of brotherhood in the human race has been changed and largely obliterated by his powers, and Anyanwu, a younger but also specially gifted immoral.

Immortality, shape-changing, psychic powers, the passing of one mind into many bodies: these are not new ideas to the science fiction canon, and the theme of what it means to be human has fascinated sf writers since Mary Shelley wrote Frankenstein . Doro's existence is obsessively dedicated to breeding a line of people with various psychic gifts, and for his people he is God. Anyanwu is forced to join the gene pool, to pass on her abilities of healing, shape-changing and great physical strength to Doro's people. But Anyanwu is an intelligent, resolute and powerful woman, and her dedication to those of her own genetic line equals Doro's: again and again she tests, thwarts and escapes his control, forcing him to confront his own weaknesses and to adjust his plans to her choices and to her moral concerns.

Butler's prose is spare and sure, and even in moments of great tension she never loses control over her pacing or over her sense of story. Her writing is staccato rather than lyrical. Her use of history as a backdrop to the struggles of her immortal protagonists provides a texture of realism that an imagined future, no matter how plausible, would have difficulty achieving; the novel is often grim, but it is never casually brutal.

Suzy McKee Charnas' novel The Vampire Tapestry (Simon and Schuster, $11.95) is also concerned with defining what it means to be (or not be) human. But don't let the title fool you: this is not another weary novel about Dracula, his imitators, or his heirs. Dr. Edward Weyland is no Transylvanian count, he is an anthropology professor, an explorer of comparative cultures; he is also that most ultimate of predators, a vampire, immortal, feeding on human blood, the pinnacle of the food chain, and utterly alone in a net of human relationships of which he cannot be a part. Unlike Doro and Anyanwu he has no counterparts and descendants (he cannot, like Dracula, make new vampires), and whatever bonds he forms with others are transitory, unreliable, and, for him and for his prey, fraught with treachery and danger.

The book is neatly divided into five sections, each section dramatically bringing us closer and closer to Weyland's mind. The first is told by Katje de Groot, a South African immigrant who recognizes Weyland for what he is and whose relationship whith him is mutually one of hunted to hunter. The second section is told by an adolescent in the jungle of New York, who watches Weyland being captured by human predators and is instrumental in his release, and the third (and most devastingly powerful) is from the point of view of a therapist from whom Weyland learns (or, as we come to understand later, relearns) the degree of his kinship with the human race. A lesser writer might have chosen to draw the sentimental moral, and stop. But Charnas' view of her protagonist is unswervingly unsentimental, and she goes on to delineate precisely what Weyland can and cannot do with this knowledge. Her denouement is savage and intense and brilliantly satisfying.

Charnas' writing is also rich and impressive; she seems equally at home on a college campus, in the office of a professional therapist, in the emotions of a 14-year-old boy, and in the music and story of Tosca . The novel works on many levels -- as pure adventure, as social description, as psychological drama, and as a passionate exploration of the web that links instinct, morality, and culture. It is a serious, startling, and revolutionary work, and I recommend it to all comers.

Barry B. Longyear won two major science fiction awards this year -- the Hugo and the Nebula -- for his novella "Enemy Mine." He also won the John W. Campbell Award for the Best New Writer. City of Baraboo (Berkley/Putman, $10.95) is a collection of stories, some of which appeared first in Isaac Asimov's Science Fiction Magazine and Asimov's SF Adventure Magazine . It is being marketed as a novel, which is misleading, since the separate sections are devoid of thematic or character development and are ordered only by the requirements of plot.

Baraboo is the town in Wisconsin from which the original Ringling Brothers circus sprang, and this designed as a circus novel. Plenty of science fiction writers have used the circus as setting, including Leigh Brackett, Ray Bradbury, and, in The Dreaming Jewels , Theodor Sturgeon. In City of Baraboo we follow the adventures of John J. O'Hara's Greatest Show On Earth from Earth to space. Longyear clearly is fascinated by the circus, and the stories are testooned with carnival lore and language. But the characters in the book are pure cardboard; their interactions with the "aliens" -- who are not much more than human armadillos or frogs -- are trivial beyond hope, and their adventures are painfully predictable. The plot structure is, at best, loose: a vilain, an enemy of O'Hara's whose motives are never sufficiently plumbed, chases the circut from planet to planet, conveniently engineering disasters which the circus always manages to survive. The best of the tales concerns a girl who desires to run away and join the circus, and illegal act on a planet where a revolution against a brutal and capricious regime has resulted in the rigid enforcement of the rule of law. The idea is not new but it is interesting. But Longyear's resolution of the conflict depends entirely on coincidence, and the story ends with everybody happy and the presentation of a moral lecture. The science, when it appears, has no more relevance to the story than it does to reality, and the various galactic cultures have neither economic nor political substnace: the stores read as if they had been culled from (and might have been better left to) the pulp magazines of the 1940s.

Those magazines are gone, or have metamorphosed into such modern publications as Analog, Omni and Fantasy & Science Ficition . But their legacy remains: the science fiction field is one the few which not only makes room for but actively supports the writing of short stories. This is due in large part to the acumen and persistence of its editors, and also to the (occasionally puzzling) willingness of major publishers to bring out original anthologies. One of these is Universe , now in its 10th year. It is edited by Terry Carr, an influential figure in science fiction; he has edited numerous anthologies, both original and reprint, and as an editor of Ace Books in the 1960s was responsible, with Don Wollheim (publisher and editor of the extremely successful DAW science fiction line), for the discovery of such current notables as Ursula K. Le Guin, Roger Zelazny, Thomas Disch and Joanna Russ.

Universe 10 (Doubleday, $8.95) contains eight short stories and two "non-fact articles"; as usual, Carr has taken care to blend well-known writers (Michael Bishop, James Tiptree Jr., R.A. Lafferty, F. m. bUsby) with the lesser and the little know. I found the "non-fact articles" dull, but the stories are well-crafted and polished presentations, especially "Saving Face" by Michael Bishop, in which a man is forced to undergo plastic surgery because he resembles a famous actor, and "The Ugly Chickens" by Howard Waldrop, a zany story about the rediscovery of the dodo.

But I have a complaint about the volume, one which I realize I may be alone in making. Unlike the volumes from the previous years, (and with the exception of the Waldrop story, which is wacko) the anthology as a whole seems curiously passionless. It may have something to do with the texture of Doubleday books -- whose pages always make me feel as if I have been groping Cream Wheat -- but none of the stories shocked, enchanted, or terrified me. Even "Bete et Noir" by Lee Killough, in which murder is done, reads as if it had been written through cellophane, and the entire volume left me with a bland emotional taste, as if I had eaten a full course dinner in which all the food -- fish, roast and strawberry shortcake -- had been cleverly molded out of avocado. I longed for a salted peanut, or the bite of a chili peper. but . . . de gustibus non est disputandum .