If you were to make two piles, one with books and articles and poems written by Sylvia Plath, and another with books and articles and poems written about her – well, you’d have yourself two very different-sized stacks.

Which is just one way of saying this: Five decades after her death, Plath remains a figure of deep cultural fascination.

The Boston-born Plath died 50 years ago this month, in the middle of a bitterly cold February in London, at age 30. She had been struggling on and off all of her adult life with serious depression.

At her death, Plath left two slim collections of poems – only one, “The Colossus,” had been published – and a novel about mental breakdown and recovery, “The Bell Jar.” She also left two children, Frieda, almost 3, and Nicholas, 1.

Since that moment in February 1963, Plath has been the subject of intense scrutiny, even controversy, both in the United States and in England, where the poet lived the final years of her life, as the wife of British poet Ted Hughes. (Their marriage had ended badly the year before Plath’s suicide, and Hughes had taken up with another woman, the wife of a poet.)

Critics call Plath an overrated writer who couldn’t best her demons. Her fans charge that she was the brilliant one in her marriage to Hughes – and claim that her work will only grow in stature with the passage of time. Some fans have gone so far as to chisel the name “Hughes” off of Plath’s grave marker in Yorkshire.

“American Isis,” a new and largely sympathetic biography of Plath, will do nothing to calm the debate.

Biographer Carl Rollyson presents Plath as a woman of her singular time and place – a changing, but still in many ways repressive, America of the 1950s and 1960s, as well as England.

Rollyson’s biography is significant because it is the first to make use of new materials – including dozens of unpublished letters between Plath and Hughes – that have been made available to scholars in the archive of Ted Hughes, who was named poet laureate of England before his death in 1998.

During the past five decades, books and articles written about the American poet (or “poetess,” as Hughes used to call her, with pride and consternation) and novelist – and her marriage – have been seemingly endless. This one is journalistic in approach, with voluminous amounts of research and interviews undergirding the text. Rollyson interviewed Smith College alumnae, old friends of Plath and Hughes, and others; he also cites liberally from many of the other published accounts of the couple, from the 1950s to the present day.

Rollyson sets his book apart, amid others released to coincide with the half-century anniversary, by likening Plath to an unconventional parallel: Marilyn Monroe.

“Plath is a genre breaker and a cross-cultural heroine,” writes Rollyson, whose other biographical subjects have included Lillian Hellman, Martha Gellhorn, Rebecca West, Marilyn Monroe and Dana Andrews.

As much as Plath tried to escape from her New England home and her strong mother, Aurelia, and to become a part of the English literary landscape, Rollyson argues, she couldn’t change the fact that she was American to her core: talented, ambitious, outgoing, passionate, and – until her final struggle with depression – almost preternaturally buoyant.

Witness her academic successes in high school and at Smith College, her magazine short story-writing from a young age, her early efforts at poetry, and her junket to New York City one summer with other top-drawer American female students (fictionalized in “The Bell Jar”) to serve as a guest editor on a women’s magazine.

“American Isis” makes two correlations of Plath’s life to symbolic cultural “twins”: Isis – a figure from mythology, representing fertility and maternity – and Monroe, the tragic Hollywood sex symbol.

Rollyson’s argument here is simple: “Sylvia Plath is the Marilyn Monroe of modern literature.”

To support his point, Rollyson describes in vivid detail a dream that Plath had, in which Monroe was painting Plath’s fingernails and chatting with her. Rollyson draws numerous points of comparison and contrast between the two women – both lost powerful husbands they loved, Ted Hughes and Arthur Miller; both were blond and stunningly attractive; both died young; both pretended to be something they were not in order to put on a pleasing public face.

Whether Rollyson’s case succeeds is up to each reader to decide. One thing can safely be said: the final word has not come close to being written yet.