Plath journals offer new insights;

The Journals of Sylvia Plath, edited by Ted Hughes and Frances McCullough. New York: The Dial Press. 384 pp. $16.95.

Among the photographs included in ''The Journals of Sylvia Plath'' is a picture taken of Plath and her poet husband, Ted Hughes, in Yorkshire in 1956. The picture was taken after their long Spanish honeymoon, and it's the kind of photograph every couple should have. Both are looking into the distance with confident smiles. Sylvia's hair is cheerfully windblown, and her hands cradle Hughes's arm with commanding grace.

The picture is proof that Sylvia Plath - remembered too often only as a poet who committed suicide - had moments in her life when her head was triumphantly above the waters of depression and confusion.

''Someday,'' she wrote in her journal in 1952, when she was 20, ''. . . I will stop this absurd, self-pitying, idle, futile despair.''

These journals are a record of her efforts to stop. Though they don't provide any final explanation of her life or suicide (Hughes made the decision to destroy the last of her notebooks which recorded her experience up to three days before she took her life), they do give an X-ray vision of the struggle to become an artist in a society that Plath believed was quite happy to let its struggling artists drown.

The journals obviously lack the characteristic compression of Plath's poetry, but they may ultimately become the way a wider public - unwilling to puzzle out her many difficult poems - will come to understand and appreciate Sylvia Plath.

This, understandably, would infuriate her. From her early success, with an award-winning story published when she was 20 by Mademoiselle magazine, Plath branded herself as a writer. It was an all-or-nothing arrangement. Her contract with herself seemed to be based on a self-made theory: ''I write therefore I am.'' ''I cannot live for life itself,'' she wrote in her journal in 1957, ''but for the words which stay the flux.''

But later in life, Plath had the intelligence to examine more closely this severe arrangement. She concludes that though her desire to be a writer was real , the compulsion in this desire was to win the recognition that would bring her love and approval from her family, her husband, and also from herself.

Ironically, it was when she had fulfilled her desire for literary success - after she had published her novel ''The Bell Jar'' and her well-received volume of poems, ''The Colussus'' - that she committed suicide. She had separated from her husband four months before and was living in London with their two children.

The journals show how much happiness and support she gained from her marriage to Hughes. When professional success coalesced with closeness to him, she was in ecstasy. When her first poem was accepted by The New Yorker magazine in 1958, she writes: ''I ran yipping upstairs to Ted and jumping about like a Mexican bean (sic.).''

It is difficult to read Plath's journals without feeling the impulse of wanting to interfere after the fact. Many will find her excess of emotion just too messy: She's like an overboiling pot that needs the heat turned down under it. Little things obsess and upset her. She finds bobby pins revolting, an example of her general disgust with the human body. But Plath nearly always had the capacity to observe herself and would have agreed that she was frequently excessive. The problem was that she couldn't seem to help it.

The stereotype of Plath's poetry as sad and intense, appealing most directly to an adolescent sensibility, is partly true. Her journals show how hard she tried to find joy in life, and how frequently she found it despite her problems - like the moment caught by the camera in 1956 when Ted Hughes was by her side and her head seemed held so proudly above the waters.