By Nikki Giovanni

Morrow. 167 pp. $12.95

THE ESSAY is quite often like the poem in intent, and in the expectations readers bring to the contemplation of both literary forms. At its best, the poem is a moment, a revelation captured in language that, while brief, informs, startles and sets the imagination on edge. The essay analyzes and critiques ideas or events with a conciseness that depends for its success on an unexpected vision of the world and a respect for the technical discipline demanded of so compact a structure.

In Sacred Cows and Other Edibles, Nikki Giovanni -- poet, personality, social critic, iconoclast and raconteur -- exhibits the best and the worst uses of the essay as a vehicle for expression, verbal performance and exploration of the mundane and the special. The articles that make up this collection have previously been published in publications as varied as the Boston Globe, Essence, and USA Today. The topics Giovanni submits to her unique brand of analysis are as different as the stances she assumes. Tennis, termites, game shows, black political leaders, literary politics, the profession of writing, odes to fellow writers and the proper celebration of national holidays are some of the subjects Giovanni explores with humor that is street and worldly wise, and with occasional insights that, in the best Giovanni style, turn a neat phrase too.

The problem with Sacred Cows and Other Edibles, however, is that it falls short precisely because Giovanni's glib, wise-cracking overly conversational style (which has made her poetry so popular) is ill-suited to the intellectual requirements of the essay. These pieces mildly entertain more than they probe; more often than not, the reader is merely reminded of what is obvious rather than introduced to another way of seeing things.

Giovanni is at her best in the selection titled "Reflections on My Profession" and "Four Introductions" -- pieces dedicated to writers, among them Paule Marshall and Mari Evans. In "An Answer to Some Questions on How I Write" Giovanni asserts, "I don't have a lifestyle. I have a life," which made me want to cheer this hearty refutation of categories and oversimplification of the human equation. And puncturing the vague pomposity of the current hot cliche', the "role model," Giovanni says: "When people do not want to do what history requires, they say they have no role models. I'm glad Phillis Wheatley did not know she had no role model and wrote her poetry anyway." And she sums up the job of the writer with a feisty confidence saying, "We write because we believe that the human spirit cannot be tamed and should not be trained." This is Giovanni at her best -- sparkling and thoughtful.

But the overall quality of this collection is marred by the author's penchant for digression. Several pieces cry out loudly for editing. In one essay ostensibly on the writer's profession, Giovanni wanders over an unruly terrain that detours to a discussion of Vanessa Williams, the Miss America Pageant, Bob Guccione, her son Tom and her dog Bruno. She apologizes for the "tendency to digress" without much conviction, blaming it on having passed her 40th birthday. The longer the essay, the more Giovanni seems to glory in her ability to free-form associate a host of incompatible ideas and examples so that it becomes like reading a conversation with someone who has 100 opinions on a single topic.

Politically, Giovanni adopts a neo-black conservatism -- knocking special privileges, and racial and sexual quotas. I've no problem with her political views, but whatever Giovanni's political beliefs or how long they last, they deserve stronger justification than "Life seems so unfair lately to those of us who are ordinary."

Black conspicuous consumption, buppies and materially successful blacks come in for special praise. Giovanni long ago decided she was a winner and so she has spun gold in most of her career endeavors, exhibiting little patience with those too busy complaining to hustle up some luck. She criticizes black political and social leaders for promoting a perception of the black community as weak, fragmented and hopelessly mired in despair, all she asserts quite convincingly, for the sake of their corporate and foundation-supported bread and butter.

Sacred Cows and Other Edibles is quintessential Nikki Giovanni -- sometimes funny, nervy and unnerving with flashes of wisdom. But this collection will be appreciated most by those already among the converted, rather than those searching for someone to follow. ::

Marita Golden is the author of "Migrations of the Heart" and "A Woman's Place."