"Intelligence," guest editor Sontag notes in her introduction, "is a literary virtue, not just an energy or aptitude given literary clothing." And she goes on to insist that "it is hard to imagine an important essay that is not, first of all, a display of intelligence. And sheer intelligence of the highest order can in and of itself make a great essay." The choices here leave that assertion open to doubt, though. If smarts were all, then John Guillory's essay on the fallacy of canon formation and Philip Fisher's essay about Shakespeare's radical reinterpretation of the contingency of the passions in Hamlet would be classics. They're not, each written badly in its own way and each without the edge of argumentative flexibility that all great essays, even screeds and fragmenta, manage to lead with. Other things here, in contrast, are all voice, no content--essays by William Gass, Stanley Elkin, Patricia Storace, Elizabeth Hardwick, Leonard Michaels, Anne Carson--esoterica by virtue of their contrarian textures rather than their indwelling mental processes. The exceptions, then, stand out as all the more sterling. Best of all, in its exoteric generosity and clarity, is Joan Didion's devastating essay about New York and its "sentimental narratives"--politically muzzy but coming close to the last word about the city's self-destructive wane. Adam Gopnik's "Audubon's Passions" is a revelation, an invitation to see what we thought we'd seen and known. Sontag is a masterful enough essayist herself to know the real thing--which is why she reprints not one but two John Updike pieces, one on domestic objects in childhood, one on Mickey Mouse: Essays that in their adventurousness both of voice and interim conclusion fit the essentially plastic paradoxicalness of the essay form better than anything else here.