Essays prove most vigorous and involving in this year's anthology. The standouts: Oscar Mendel's personal, truly provocative argument for Jewish non-identity--a strongly written (if dubiously reasoned) essay; Wayne Booth's discussion of the inconsequence of movies compared to fiction; a fine Clark Blaise memoir (much superior to Lincoln Kirstein's tedious grapple with an early-life misappreciation of Hart Crane); Robert Bly's didactic piece on translating Rilke; and Cynthia Ozick's ""What Literature Means."" Prose fiction is led in quality by William Gass' ""Uncle Bait and the Nature of Being""--less showy but no less weighty than his earlier works; by Bobble Ann Mason's wonderfully casual ""Graveyard Day""; and--almost as impressively--by Kate Wheeler's ""Judgment."" And the poetry, as usual, is on a lower level--with poems by Jorie Graham, James Baker Hall, Andrew Hudgins, Heather McHugh, and Amy Clampitt the best exceptions. Not among the most exciting Pushcart gatherings, then, but with enough mind-challenging, distinctive work to be required browsing for serious literary readers.