Heaney's flight to 'more poetic spheres'; Sweeney Astray: a version from the Irish, by Seamus Heaney. New York: Farrar, Straus & Giroux. 85 pp. $13.95.

Seamus Heaney's Sweeney resembles Daedalus and the Little Prince. In each, the exile of the artist is at one with the flight of the imagination. Sweeney, a legendary king of 7th-century Ireland, connects the contemporary Irish poet Heaney to a world of tragic dimension.

In Heaney's new poem, a translation of an early Irish poem, we see Ronan, a Christian priest, curse and bless Sweeney for throwing the psalter into the water. The curse gives Sweeney the ability to fly; he is transformed into a bird. As we watch the comic and brutal nature of Sweeney's fate, we hear his lament, for he feels betrayed by a world that once appeared good.

Although we never hear about Sweeney's faith, we can infer that it bears a resemblance to that of the Little Prince and to Heaney, for it is the poet who gives music to that nature we cannot see.

With the Little Prince, you may recall, the reader visits the magical presence of animals and flowers; with Sweeney, too, we are led, this time by songs, through the flowers and trees. Sweeney and the Little Prince express how the imagination takes flight, lifting the reader to more poetic spheres. How to show these dimensions and still be true to the historical, or legendary, line of the story is one of the challenges Heaney meets here.

In his earlier poem ''Song,'' he describes the bird's attentiveness to sound and tells of that ''moment when the bird sings very close/ To the music of what happens.'' Heaney regain this precarious balance, this time in a book-length poem. Translating the pristine quality of a landscape he knows by ear, he has us flying above the housetops, eating watercress, singing. And we are not certain whether society has betrayed Sweeney or that Sweeney's poetic imagination has traveled too far. We feel the vertigo.

Sweeney alternates between the extremes of the natural and human world. In one scene, he has flown to the center of a natural landscape. In another, he visits a tree near the place he once inhabited; there, he is taunted by his old neighbors, who give a cruel account of his son's death. Sweeney swoons and falls from his tree. Thinking of his family, he says:

My faithful hound, my faithful nephew

No bribe could buy their love of me

But you've unstitched the rent of sorrow

The heart's needle is an only daughter.

What had seemed whole had been undone.

But the rent of sorrow begins to heal as Sweeney focuses on his particular landscape. As he flies about, growing more plumage, he celebrates his life in nature and for a short time even rejects those he loved.

I prefer the elusive

rhapsody of blackbirds

to the garrulous blather

of men and women.

Obviously, this can't last. The first turning point comes when a madman comforts him. Like Sweeney, the man had been cursed. Through him, Sweeney begins to understand his fate. Driven only by the need for survival, but still guileless, Sweeney feels alone. The madman leads him to a woman who helps him and nourishes him, a bird come out of the storm. But when her husband sees the feathered creature, he shoots him. Returning to the church, Sweeney swoons in the doorway.

The story is ancient and compelling. Readers will recall, too, William Butler Yeats's ''Sailing to Byzantium,'' the Grecian goldsmiths, hammered gold and gold enameling. But Sweeney is no icon: One feels that, whereas art was a consolation for Yeats, Heaney - sometimes discussed as his great successor - feels the hurt of rejection and alienation that the Romantic poet must endure.

Because it is so accessible, Sweeney Astray provides a provocative introduction to Seamus Heaney's poetry. Like the Little Prince, Sweeney reminds us of the ways society can censor what we love if we do not honor its expression in art.

Indeed, Heaney's poem bears witness to that moment when history, like a tree, becomes a sanctuary for the creative imagination.