`Mahabharata': Brook's dazzling stage epic. L.A. Festival audiences are getting America's first look at Peter Brook's 9-hour adaptation of the national epic of India (review below), while elsewhere at the festival John Cage, the grand old man of the musical avant-garde, is confounding listeners with his celebration of `purposeful purposelessness' (story Page 24).

It was the most anticipated theatrical event of the year: the world's longest book staged by the world's foremost director. When Peter Brook's adaptation of ``The Mahabharata'' received its American premi`ere at the Los Angeles Festival last week, all 9 hours of it (well, nearly all 9 hours) lived up to - if not surpassed - those great expectations. It was epic theater in the extreme. At 12,000 pages ``The Mahabharata'' is thought to be the world's longest prose poem, 15 times the length of the Bible, written some 30 centuries ago. Mr. Brook and his collaborator, Jean-Claude Carri`ere, labored 12 years to adapt the work for the stage. The result is the transformation of the national epic of India into a marathon dramatized trilogy that defies Western conceptions of theater.

For underneath the crushing statistical weight of this $1.2 million production beats the heart of an exceptional artistic vision.

``It captures, in the same breath, mankind at its best and at its worst, [at] its most mysterious and its most destructive,'' said Brook just prior to the debut here. ``That's why we immediately felt that [the book] was important.'' Although the story, in its simplest terms, concerns two feuding Hindu clans, the Pandavas and the Kauravas, the ``Mahabharata'' is actually a mythic chronicling of mankind's fall from innocence - the transformation of a family of human beings into a family of enemies.

In the staging, Brook and Mr. Carri`ere have emphasized the universal. The poem's humanistic essence has been expanded by Brook's vision, which spans pre-Christian myth, Biblical allusion, Greek tragedy, and Shakespearean drama and achieves an eerily contemporary post-nuclear resonance.

The story - one initiated by a feud not unlike that of Jacob and Esau or even the Soviets and Americans - becomes a spiritual probing of humanity's capacity for self destruction or survival. Where will ``the war take place - on a battlefield or in my heart?'' asks one of the play's protagonists. ``I don't see a real difference,'' comes the answer.

The production encompasses a vast panorama of moods from savagery to comedy, sensuality to spirituality. One of Brook's finest accomplishments is that he concretizes this range and does so with razor-sharp theatricality - a precise and judicious use of imagery that suggests rather than illustrates, evokes rather than decorates. For his set Brook turns a Hollywood studio into a vast swath of packed red earth, complete with flowing streams, pools of water, and fires. We hear armies splash upriver in retreat, see bonfires being lit, smell their acrid smoke.

At times, movement and mime do the work. A brace of dancing actors becomes two cavorting gazelles; soldiers are wounded by arrows hand carried in slow-motion to their targets. Chloe Obolensky's magnificent costumes and a gifted quintet of musicians evoke an atmosphere sumptuous with mystery and magic.

There's little to quibble about. The third part of the trilogy, ``The War,'' goes on too long at the same fevered pitch. And, overall, the production, which can be viewed on three consecutive evenings or in one marathon sitting, could be trimmed by an hour or two.

Nonetheless, Brook has created a dazzlingly evocative land, across which he sends an equally impressive international cast, many of whom are re-creating their roles from the original production at last year's Avignon Festival. Collectively, their lyrical accents - French, English, Polish, German, West Indian, African - produce a barrage of sounds that cross the barriers of nationality that this masterful tale transcends.

In Los Angeles through Oct. 3; reopening at the Brooklyn Academy of Music Oct. 13 for a three-month run.