This inaugural volume in an annual collection of best American essays features 17 selections and is edited by the estimable Elizabeth Hardwick. Among the best here are Donald Barthelme's ""Not-Knowing"" from The Georgia Review, a defense of postmodern writing exampled by Barthelme's showing of a short story in the making. Says Barthelme: ""Flannery O'Connor, an artist of the first rank, famously disliked anything that looked funny on the page, and her distaste has widely been taken as a tough-minded put-down of puerile experimentalism. But did she also dislike anything that looked funny on the wall? If so, a severe deprivation. Art cannot remain in one place. A certain amount of movement, up, down, across, even a gallop toward the past, is a necessary precondition."" Gore Vidal is represented here by a memorial essay, ""On Italo Calvino,"" that is both prickly and moving. Gerald Early writes about ""The Passing of Jazz's Old Guard: Remembering Charles Mingus, Thelonius Monk, and Sonny Stitt."" Others include the late Robert Fitzgerald, Joyce Carol Oates, William Gass, Cynthia Ozick, Anne Hollander and Julian Barnes. Ever-interesting but rarely passionate. Even so, a welcome book.