THE COMPLETE PROSE OF MARIANNE MOORE <i> edited by Patricia C. Willis (Elisabeth Sifton Books/Viking: $24.95; 816 pp.)</i>

From time to time, Marianne Moore found herself taxed with obscurity, a point she dealt with in a spirit of discriminating fair-mindedness. Sometimes, she allowed, it might seem so. “We must be as clear,” she wrote, “as our natural reticence allows us to be.”

It is one of many flashes of discovery in this impressively and sometimes excessively complete collection of her “Complete Prose.” Moore is saying that to write may be a violation not of the subject’s privacy but of the writer’s.

How unexpected; how exact! What is this reviewer’s disinclination before a blank page? Not a reluctance to invade Marianne Moore who, even were she alive, would hardly care. But a hesitation to reveal himself.

By today’s standards, Moore’s poetry scarcely seems obscure, despite some difficult lines here and there. Although her verbal complexity is comparable to Wallace Stevens, whom she much admired despite his “bearishness”--”America’s chief conjurer,” she called him--she is much clearer than he is.

She would have been able to explain why. Difficult writing “should at least have the air of having meant something to the person who wrote it,” she claimed, explaining why she felt that James Joyce and Gertrude Stein were fundamentally accessible. If you can sense the poet’s attitude and commitment, the poetry will show through the complexity.

Stevens frequently vanished behind his words. It was always clear what Moore was doing. She was noticing and celebrating, whether it was the Verrazzano Bridge (“Enfranchising cable, silvered by the sea”), the universal resourcefulness of Yogi Berra (“He is no feather”), or the infrangible elusiveness of the jelly-fish (“visible, invisible / a fluctuating charm”).

“More than any modern poet she gives us the feeling that life is softly exploding around us, within easy reach,” wrote John Ashbery, one of our more difficult self-concealers.

It is not in her poetry but in some of the critical writing collected here, in fact, that Moore can be hardest to fathom. Perhaps because in this kind of writing, it is clarity we particularly look for.

And we get it. But the clearer Moore is, the more difficult she can be, because what she is clear and exact about is a train of thought so individual that it lacks steps to climb aboard. She is like a person whose vision is so sensitive that she can’t see yellow; what looks to us like different shades of yellow, looks to her like different colors.

When she writes about Jane Austen’s “sandstorm-like propriety of presentation,” I have no doubt at all that it is a precise image--I simply don’t understand it.

There are more than a few such impasses in this collection of prose that goes from early stories in the Bryn Mawr college magazine through her time as critic and editor of “The Dial” and finally to essays and observations written for a wide variety of newspapers and magazines. From Moore’s early “Dial” days, though, her eye and sensibility were acute; as the years went by, her style relaxed without ever losing its individuality.

The editor, Patricia C. Willis, has decided upon inclusiveness. There are long reviews, book notes and even several pages of blurbs. There are interviews, speeches and articles--many of them splendid--written for the leisure sections of The New York Times and other publications.

Had Moore been around to supervise the job, this “might have been a much slimmer volume,” the editor writes. As it is, with certain themes recurring and with certain poets--Stevens, Ezra Pound, T. S. Eliot--written about repeatedly, we sometimes get a sense of undue reiteration. One of her favorite Stevens’ couplets-- “Chieftain Iffacan of Azcan in caftan / of tan with henna hackles halt”-- can be found six times. There are three citations of Dante’s reference to Beatrice walking loftily, like a crane. But we forgive that one, because it so much suggests Moore’s own high, delicate strides and her darting eye.

In short, there is a certain amount of sand in the raspberries. With a little rinsing, it is a feast, a slimming one. Here is a sampling of the mind that chose as its operating standard “concentration and gusto”:

On Victorian writer George Moore: “There is a tinge of misery in his pathological humanitarianism.”

On some children’s stories by A. E. Housman; after conceding crossly that virtue probably has to prevail: “But an appearance of moral insouciance is essential; and in a number of these stories one sees, perhaps too plainly, the wish to bless.”

On Stevens: “an impermeable, profuse magnificence which leaves us exactly where we were.”

On Yeats: “He is overtaken sometimes by the pursuing wave of his own delicacy.”

Of an orchestral passage: “the escorting innuendoes of the bass drum.”

Her literary heroes were Eliot, Pound, Joyce, Stein, Stevens and William Carlos Williams. Perhaps it was the last two who meant the most to her, who especially reinforced her vocation as an American poet of high and concrete style. “Poetry in America has not died so long as these two ‘young sycamores’ are able to stand the winters that we have, and the inhabitants.”

Her heart was nowhere on her sleeve, but it shows. Some of the pride as well as pain of her idiosyncrasy is reflected in these words of advice to young readers in a magazine column: “Fashion can make you ridiculous; style, which is yours to control individually, can make you attractive.” And these: “The cure for loneliness is solitude.”

“The most important influence in my poetry,” she writes late in life, “has been ethical.” Her poetry’s lilt may make this puzzling; but it doesn’t take much reading to make it evident. She is a poet of health, and her curlicues are of an astonishing straightness. “Any writer overwhelmingly honest about pleasing himself is sure to please others,” she writes.