WHERE THE STRESS FALLS: Essays, by Susan Sontag. Farrar Straus Giroux. 351 pp.

Anyone who admires the work of Susan Sontag can only greet the publication of a new volume of her essays with mixed emotions, a blend of hope and worry. Her last collection appeared in 1980. That same year, she told an interviewer in Poland that there were no really great writers in America but that the country did have "ten extremely good prose writers, of which," she helpfully noted, "I am one." During this same period she began announcing that she would henceforth spend less time writing criticism, in order to concentrate on fiction -- a promise she has, unfortunately, kept.

In other words, Where the Stress Falls was written during a period of Sontag's waning commitment to the work for which she has a real gift. Over the past 20 years, I have worn out a few copies of Against Interpretation (1966) and subsequent collections. The authority of that voice, the sensuousness of mind that it evoked, the intellectual restlessness and energy, the knack for the adamantine aphorism -- these made for essays in an almost classical vein. In ber best writing on literature, film and ideas, Sontag captures the intrinsic drama of moral and aesthetic questions.

But in Sontag's fiction, by contrast, mere will does the work of the imagination. At its worst, the effect is that of an unintentional parody of Borges, lacking the wit or grace of the original. With The Volcano Lover (1992), she overcame the narrative anemia of her previous novels through a transfusion of full-blooded historical drama. But this was temporary. Last year, In America recycled her bestselling formula (adulterous romance among sophisticated emigres in an exotic setting) while also revealing a formidable gift for the platitude. The book was sprinkled with dozens of passages in which her wandering band of Polish intellectuals ponder the American way of life as a ceaseless abolition of history, responsibility, complexity, etc. The line between profundity and triteness has seldom been drawn more finely.

Where the Stress Falls reprints more than 40 essays written while Sontag has been trying to reconfigure herself as novelist -- or rather, perhaps, as Nobelist. (With her regular invocation of "the idea of literary greatness" and the frequent suggestion that she is among the last defenders of "seriousness," she sounds as if she has her eyes on the prize.) The volume includes one of her very best essays, "Writing Itself: On Roland Barthes" (1982), plus a half-dozen or so other pieces that bear up to more than one reading. As her own remarks over the years have indicated, rereading is indeed the test. A durable literary work cannot be exhausted the first time through; returning to it is a curious process of defamiliarization, of renegotiating an understanding with something you have already experienced.

A few of Sontag's essays from the past two decades can induce that experience. Most don't. Several essays written as prefaces to collections of photographs read like indifferent paraphrases of the densely textured argument of her book On Photography (1978). The items on dance and opera are pleasantly effusive, but not much else. Her comments on Robert Walser and Danilo Kis sent me scrambling to the library when she first published them years ago; they leave you wishing she would write critical essays on their work, instead of brief introductions.

A short item titled "DQ" is not, alas, about a visit to the Dairy Queen. Rather, it offers five paragraphs about Don Quixote that are both unexceptionable and remarkably uninteresting: She writes that "Cervantes's book is the very image of that glorious mise-en-abime which is literature, and of that fragile delirium that is authorship, its manic expressiveness." The staleness of that thought has scarcely been forgotten when (two pages later, in an essay on Borges) she denies that reading is escapism: "Books are much more. They are a way of being fully human." A bold thought, to be sure -- though nothing can quite compare to this one, in an essay on Adam Zagajewski: "From a great Polish writer we expect Slavic intensities."

What gives? The early Sontag was ruthless about cultural cliches. Her favorite term of scorn was "philistine," and her essays embodied, as she says about Barthes, "an ideology of taste which makes of the familiar something vulgar and facile." Her manner now is virtually indistinguishable from that of George Steiner in his lugubrious moments as Last Intellectual, striking that solemn pose as embodiment of high seriousness while perched atop the Nintendo ruins of Western Civilization. Of course, this attitude can itself be something "familiar . . . vulgar and facile" -- not to mention self-aggrandizing.

Eagerness to mount one's portable pedestal is a definite liability to a writer. For one thing, you can see only so much from that great height. Instead of writing and speaking to her fellow American citizens on behalf of military action against Serbian aggression in Bosnia, Sontag gave another well-rehearsed performance of her contempt for the people who would actually do the fighting. (She has never been shy about expressing her belief that the butt-ugly aesthetics of our mass society is no better than its inhabitants deserve.) Nor has her writing on the arts exactly benefited from her proclamation that she is ultimately responsible to "the republic of letters" -- the self-selected cosmopolitan elite of self-regulating excellence. Her essays were better in the early '60s, when she was hanging around with the methamphetaminized drag queens and Eurotrash sponges at Andy Warhol's studio.

The habit of high disdain has its own rewards, of course. But the long-term effect, to judge by Where the Stress Falls, is ultimately impoverishing. At several points, Sontag evokes the idea that a great artist's goal is "wisdom." That belief is honorable. But what about the belief that one is among the great? It seems the better part of wisdom to keep such thoughts to oneself.