In "Hugh Selwyn Mauberley," Ezra Pound set out to condense an entire Flaubertian novel into the confines of a single poem; in "Ellen West," Frank Bidart has reduced a book-length case study of an anorexic woman into 15 pages of a tormented soul. "Ellen West" is one of the five poems that make up Bidart's second volume of poetry, The Book of the Body , and it is work that displays Bidart's talents at their most exacting, their most insistent.

In order to free her spirit, Ellen has determined to diet away the material flesh with which she has been burdened. She pursues her suicidal goal with the relentlessness of a great artist. Indeed, her ambitions are those of a sculptor seeking to release the beautiful figure latent within the block of uncut marble. Like all true artists, she loathes nature, the slow, narcotic fall of gravity, the slower dissolution of a life, and she declares: "I shall defeat 'nature.' "In the central section of the poem she meditates on the career of Maria Callas, another hunger artist who lost her voice when she lost weight, a woman who disliked belonging to a particular artistic era and recognized (or so Ellen believes) that "the only way / to escape / the History of Styles / is not to have a body."

Ellen's anorexia is both a clinical and a universal condition. Her fasting is a philosophical quest after a self anterior to matter. It is also the passionate assertion of an ideal image of herself, not as she is but as she would be, "all profile / and effortless gestures . . ." In reading this masterful poem I was reminded of a strange document I stumbled across years ago, the record of one of the first sex-change operations in the 1930s. Man Into Woman. In that book a middle-aged male Dutch painter underwent painful surgery in order to become not only a woman (complete with a new name, a husband, a new style of painting, even a new handwriting) but also a new person; she was fiercely indignant when the authorities refused to grant her a new birth certificate that would date her birth to the day of the operation. Like Ellen West, the transsexual was determined to defeat nature, to replace its cruel laws with the force of will.

And that is the drama that Bidart enacts upon the page - the tragedy of will. No poet can capture quite so well as he the speaking voice raised to protest the inevitable. Obsessed and baffled, his characters (Ellen, an amputee, the poet's mother, the poet himself) do not submit to the humble dignity of resignation. Rather, they call out in a flat American accent as they object to loss, death, sex - to the body itself. (Farrar, Straus & Giroux, $7.95)