WE SO FIRMLY believe that stories for children should be accompanied by lots of pictures that we've invented all sorts of silly justifications for it. We say, for instance, that children like pictures (and forget that some don't, and that even though many adults do, there's not much illustrated adult fiction being published). Or we say that children watch so much television that they are "visually oriented" and therefore need pictures before they can understand words (and forget that TV is a richly verbal experience; turn off the sound and you'll soon learn how little sense the pictures make on their own). We even try to justify the pictures in children's books by combining some misunderstood physiological research and some mangled Zen Buddhism into a mystical mumbo-jumbo about how the right hemisphere of the brain does something called "visual thinking" -- a half-brained idea if there ever was one, for luckily, few of us ever have the opportunity to use the separate parts of our brain independently of each other.

The real reason picture books form the bulk of children's literature is a lot more practical than that: picture books are nothing more or less than a convention of publishing. Children's books are supposed to have pictures, so they do; we wouldn't buy them if they didn't.

Consequently, a lot of stories get published as picture books that really don't need pictures at all. For those of us, both adults and children, who like pictures, that may make these books fun to look at -- a pleasant visual experience. But the pleasure may disappear as soon as we actually start thinking. Because a picture inevitably adds meaning to the words it accompanies -- the meaning provided by visual information about how things look, by mood and atmosphere, by the dynamics of the picture's organization -- pictures produced to accompany words that don't particularly need them can easily add the wrong meaning, and undermine a story. Even good pictures can make for a bad book -- a book whose words and pictures so poorly relate to each other that it can be enjoyed by only one half of the brain at a time.

There's really no reason why the old tale of Chicken Licken needs to be illustrated at all; there's not much potential for visual excitement in this story of how a dumb cluck is beaned by an acorn, thinks the sky is falling, and talks her equally bird-brained friends into apocalyptic hysteria. Jan Ormerod obviously realized that; instead of providing straightforward pictures of frenzied birds, she makes The Story of Chicken Licken (Lothrop, Lee & Shepard, $13; ages 3-6) a school play, with children in bird costumes on a stage in the top half of the pictures and an audience of adults in silhouette in the bottom half. This is so static and uninteresting that a quite unrelated subplot Ormerod provides about a baby from the audience wandering onto the stage easily becomes the center of attention. Ormerod's unsuccessful attempt to salvage a simple story by making it less simple merely makes obvious how little it needed illustration in the first place.

Yet even simple stories can be illustrated meaningfully -- by those with the courage to accept their simplicity. Jeanette Winter reveals the amusing absurdity of the simple nursery rhyme she illustrates in Come Out to Play (Knopf, $12.95; ages 3-6) just by taking it literally. For instance, she shows that a large number of children are indeed all served by one "halfpenny loaf," just as the rhyme says; the magic is that it looks prosaically like Wonder Bread. The jacket copy says that the setting of this book is Winter's own neighborhood in Chicago; but her mysteriously literal pictures make these ordinary apartments look like rows of romantic castles, and the local park a fit scene for some decidedly un-Chicagoish forms of revelry.

THE LUMINOUS water colors Helme Heine has made for One Day in Paradise (Atheneum, $12.95; ages 3-6) create the right atmosphere; they work with the words to provide an unusual but persuasive interpretation of what might have happened when God created Adam and Eve. Heine's God is an old man with a beard, of course; but He wears an unpretentious straw hat and a serviceable lab coat, and is clearly a hardworking fellow, for we see Him in his divinely messy workroom using a saw to cut stars out of plywood and modeling Adam and Eve in clay. Adam and Eve fit right into the playful paradise Heine provides for them, for they are not the naked adult fugitives from aerobics classes that are usually depicted in children's Bible stories; they come to life at the age of 5 or 6 -- just in time to enjoy riding bareback (and bare naked) on panthers. One Day in Paradise is not just a convincing depiction of innocence, but a throroughly charming one.

The God Beverly Brodsky depicts in The Story of Job (Braziller, $14.95; ages 3-6) is anything but charming, but just as persuasive. This God has left his straw hat and his kindness back home in the workroom; He speaks out of any angry vortex of powerful swirling lines. But then the God of the Book of Job is not exactly going out of his way to express his gentle kindness, and Brodsky wonderfully captures His intensity, in pictures that combine rich blocks of color with energetic lines and crosshatchings in deep black. These pictures are something like Tiepolo on LSD -- a visual equivalent of the strong emotions of Job.

But good illustrations don't necessarily have to mirror what the words say, as these pictures by Brodsky so brilliantly do. Rather than amplify the dark message of the serious fable they illustrate, the happy cartoons that accompany Wolf Harranth and Winfried Opgenoorth's Isn't It a Beautiful Meadow? (Oxford University Press, $10.95; ages 3-6) cleverly undercut its solemnity, and turn what might have been a boring moral tract into a funny satire. The town-dwellers of this book enjoy the fresh air and sunshine of a meadow so much that they build roads to it, erect fences and houses, and even start a factory. Finally, of course, the place is so crowded that they have no choice but to find another meadow; we are left guessing about how they will treat this one. When Virginia Lee Burton told a similar story decades ago in The Little House, her gently warm pictures of the country and broodingly melancholy pictures of the city made the seriousness of her message clear; but when urban blight takes over the meadow in this book, the brightly contrasting colors and what seems like hundreds of different people doing hundreds of different things all in one picture imply a delight in complexity and confusion that balances the Crunchy Granola sentiment.

JUST AS clever but far more powerful are Charles Mikolaycak's brooding pictures for Zilpha Snyder's The Changing Maze (Macmillan, $12.95; ages 3-6). While they look enough like important work by Trina Schart Hyman and Maurice Sendak to fit squarely within a tradition of great picture book art, these pictures are startlingly different from anything ever done before in a picture book. The difference is rhythm: like the maze of the story, these pictures are constantly changing. There are scenes from a distance, scenes in closeup, scenes viewed from below, scenes viewed from above. While most of the pictures conventionally depict the main character doing what the words say, one picture of a particularly intense moment contains three different images of him, looking as if he were afraid of his other selves. All the pictures strikingly use white space, and all are in a stark palette of browns and somber greens that establishes a particularly eerie atmosphere; each is also suffused with a differing tone of yellow or green that matches the locale and emotion of the accompanying text. Mikolaycak fills the maze of the title with what appear to be marble statues of mostly unclothed male figures that always seem to be moving malevolently toward the young boy who intrudes on their space -- or is it that he is as fixed by his fear as they are?

Throughout the book, the text is on blocks of pale yellow in the center of one side of each opening, and the pictures seem to continue underneath the block. When Hyman used this technique in her brilliant Snow White, she arranged the pictures so that nothing of significance fell under the text; quite differently, Mikolaycak constantly implies that mysterious things might be understood, if only that yellow block didn't block our view of them.

All of this evokes an unsettlingly eerie world that perfectly matches both Snyder's eerie story and the half-buried poetry of the prose she tells it in. Her description of the maze captures the effect of the book as a whole: ''So twisting, curving, turning, bending, crammed with corners and dead endings. So full of mystery and treasure.'' Equally eccentric, Snyder's words and Mikolaycak's pictures perfectly suit each other and the story they tell. That the story is exciting, the words a pleasure to speak and the pictures a pleasure to look at makes The Changing Maze much more than just an example of clever technique; it is a fine picture book.

The pictures in The Changing Maze and Isn't It a Beautiful Meadow?, in Come Out to Play and One Day in Paradise and The Story of Job, are different from each other in style, in tone, and in purpose. What they have in common is not merely that the stories they illustrate would be different without them, for that's true of all illustrations in picture books; rather, these fine pictures all persuade us that they are right -- that without them, the words alone would tell much less interesting stories. They are good picture books because their pictures play an essential part in the stories they tell; and that's why children (and adults) who like pictures will like them -- presumably with both sides of their brains.