Director Akira Kurosawa's own grapple with old age lends a special poignance to "Ran," his three-hour epic of an ancient Japanese warlord losing his grip. And a certain irony, for Kurosawa is clearly in command of all his powers. "Ran" is a definitive piece of work from one of the world's major directors, perhaps self-consciously so; it's impressive and profound and vaguely dull. But if it's sometimes slow going, it also has moments of cinema so heavenly you'd think Kurosawa already had passed into the next world.

While "Ran" (literally, "chaos") has its resonances with Shakespeare's "King Lear," Kurosawa's departures from that story may be more significant than his attachments. Lord Hidetora (Tatsuya Nakadai), fatigued by the 50 years of war that have united the land under his rule, relinquishes power to his eldest son, Taro (Akira Terao). The second and third castles are deeded to sons Jiro (Jinpachi Nezu) and Saburo (Daisuke Ryu), the youngest, who scoffs at Hidetora's notion that the three, "weaned on strife and chaos," can work together. Saburo calls his father "either senile or mad" and is banished.

Under Hidetora's plan, he retains only his title, his insignia and a small retinue of warriors, but quickly, even these prove too much for Taro and his ambitious, scheming wife, Lady Kaede (Mieko Harada). Humiliated, Hidetora storms off to the second castle, where he is again humiliated. Jiro admits him, but not his warriors. Soon enough, Hidetora is formally banished by Taro. Gulled into occupying the third castle (which Saburo has abandoned), Hidetora's forces are attacked by the united armies of his first two sons and annihilated. Hidetora is alone, accompanied only by his jester Kyoami (Peter) and his faithful retainer, Tango (Masayuki Yui). For the rest of the movie, chaos rules.

Kurosawa's vision has its own geometry, and this pivotal sequence at the third castle is a small textbook of how a battle should be staged. Cavalry slashes in at odd angles, lines of infantry coil like hungry pythons; onto a canvas drab with smoke and dust Kurosawa daubs the bright reds and yellows of the invaders' uniforms, the stylized blood (red as a fire engine), the pink flash of musket fire. From the orchestra of chaos, Kurosawa cuts to solos, the personal horror of battle -- a warrior holding his own hacked-off arm in amazement or Hidetora's concubines committing suicide. At the center is Hidetora himself, inside the castle, face to face with his staggering folly (and, in one of the movie's characteristically artful ironies, unable to commit seppuku because his sword is broken).

Kurosawa's stroke of genius is to present the scene, almost till the end, without any battle sounds; only composer Toru Takemitsu's score is heard. Throughout, that music -- alternately rich and spare, distant and intimate, a tapestry of recurring flute and drum motifs and big, symphonic waves -- is one of the finest film scores in memory, and Kurosawa uses it inventively to shift the perspective. By taking out the war cries and gunshots and drumming hooves, Kurosawa provides a dispassionate, Olympian view of human destructiveness.

This perspective pervades "Ran," and while it lends the movie its grandeur, it also undercuts its sense of excitement. The pace is stately, sometimes oppressively so; the camera (except in the battle scenes) is mostly static. Part of Kurosawa's mastery is the way he can build excitement without moving the camera, simply through the way men are arranged in their environment; even when nothing's happening on screen, he can build pace simply with the sinuous turns of his editing. But when that energy flags, "Ran" can turn leaden.

At times the movie seems addressed to an audience of gods; it feels valedictory from the start, so the tension of the story is diminished, a flaw epitomized in Nakadai's performance. An intense actor whose brows and almond eyes can lock in a Nebuchadnezzar gaze, Nakadai is bowed (literally) from the start -- the old Hidetora, who terrorized the region, is already lost when "Ran" begins. It's as if Kurosawa is so intent on making Hidetora (and his sufferings) puny that he forgets to first make him grand. And Nakadai's Kabuki-style acting doesn't let you inside Hidetora. He exists, always, on the level of symbol.

On the other hand, the movie's never dull so long as Harada is on the screen. Finally, a truly dangerous woman! In her billowing white robes, her slight Lady Kaede seems lost, but she's closer to a razor hidden in an apple. Years earlier, the power-mad Hidetora had murdered her father and brother, and she's a 98-pound vessel of revenge. Harada moves with quick, precise, almost balletic gestures, and her voice shifts soundlessly from sexual cooing to an abominable shriek. Her big scene with her brother-in-law Jiro demands that she jump from obsequiousness to menace to animal lust to sinister manipulation, but Harada might as well be playing hopscotch -- it's that effortless.

"Ran" suffers by comparison with "Lear" -- Kurosawa's visual virtuosity is no substitute for Shakespeare's language. But as Hidetora wanders across the plain, half-naked and half-mad, he encounters, one after another, some vestige of his old cruelty -- a victim, the ruins of a castle. And in the final, striking tableau, one of those victims, a blind man silhouetted against an orange sky, staggers back from a precipice, dropping a scroll of the Buddha that glows at him from below. Kurosawa may not be Shakespeare, but with images like these, he gets at something about the horror -- and hopelessness -- of being a man that is peculiarly his own.

Ran, opening today at the Key Theater, is rated R and contains graphic violence and sexual themes.