This `Moses' commands attention

There are very few landmark works that the Boston Symphony Orchestra has never played in its 125-year history, but this fall it will present one of them, Schoenberg's monumental opera ``Moses und Aron."

On Oct. 26 and 28, James Levine will lead concert performances of the work that promise to be a major highlight of the BSO's ongoing Beethoven/Schoenberg project by simple virtue of what the opera is: a gnarled pillar of 20th-century music, an epic biblical story transformed into a searing modernist parable, and a poignant reminder of Schoenberg's personal journey, doubly scarred by public indifference and political exile.

The opera's plot is taken from the book of Exodus, adapted by Schoenberg to highlight the prohibition against graven images. Moses is commanded to liberate the enslaved Israelites by awakening them to the presence of the one true God. But while Moses understands the monotheistic ideal in its purest form, he cannot communicate it to the Israelite masses. His expressive impotence spills into the music itself, as his part is written in Sprechstimme, a hybrid style that falls between speech and song. By contrast, Aron lacks Moses's pure understanding but sings in a mellifluous tenor that commands the attention of the restless Israelites.

The score features Schoenberg's 12-tone technique at its most urgent and compelling; no special training is required to sense the opera's primal power. In fact, listeners who have written off Schoenberg's dissonant style as too forbidding might find themselves drawn in by the forceful symbolic drama and the sheer visceral intensity of the music. That intensity peaks in the second act with an explosive 12-tone orgy around the Golden Calf. The third and final act, however, was never composed, and therein lie both a tragic story and a great mystery.

Schoenberg had begun the piece between 1930 and 1932 as skies were darkening over Europe and the composer was defiantly re-embracing the Jewish faith he had abandoned. The subject of his opera also clearly resonated on deeper levels, as Schoenberg had for decades cast himself as a Moses figure, possessed of a burning prophetic truth that would liberate music from the shackles of tonality.

But sadly, history fashioned for this Moses a painful wilderness. After rising to one of the leading academic posts in all of Germany, Schoenberg fled the country when the Nazis came to power in 1933, eventually settling in, of all places, Los Angeles. California showed little interest in his music, and so the great atonal revolutionary from Vienna spent his final years living off of Sunset Boulevard, teaching music theory and composition to UCLA undergraduates, among other activities. He died in 1951, his life's work incomplete.

Since Schoenberg's death, the ghost of the unwritten third act has haunted the modernist imagination. Many have wondered whether the difficulties of exile really prevented him from completing the opera, or whether it was perhaps something deeper. One theory holds that Schoenberg was unable to compose the third act because the opera's core tension -- how to express a pure truth that lies beyond the boundaries of any language -- is simply irresolvable. Others have seen the work as perfect in its incompleteness: that is, the unfinished opera embodies the belief that the fragment is the only truthful work of art in a modern world that has lost faith in utopian visions of wholeness and purity. Still others have struggled valiantly to complete the opera, albeit in quixotic ways: The architect Daniel Libeskind once told The New York Times that his design for the Jewish Museum in Berlin was his own attempt to finish ``Moses und Aron."

Whatever theory you choose, this is a challenging yet gripping piece that will be sung next month by two stars from the Metropolitan Opera's past productions: John Tomlinson as Moses and Philip Langridge as Aron, along with a large supporting cast, a full chorus, and a children's choir. And as BSO audiences might guess from last season's programs, this repertoire is hallowed ground for Levine. He believes in it passionately, and conducts it with a fluency and conviction that is unsurpassed.

Symphony Hall, 888-266-1200, www.bso.org.

Jeremy Eichler, the Globe's new classical music critic, begins Sept. 18.