NEW YORK - Simon Rattle didn't make a grand entrance at his Metropolitan Opera debut Friday. Unobtrusively, he materialized in the orchestra pit - garnering no applause - and commenced one of the quietest-ever operas, Debussy's

Pelléas et Mélisande

.

That was only the initial tipoff of his uncompromising stance with an opera that insistently inhabits its own world and doesn't leave any wide-open doors for listeners. With a fairy-tale aura that curdles into breathtaking cruelty, the music's mellifluousness is so easily mistaken for dramatic inertia that the opera has a high walkout rate (most notoriously in 1986 at Philadelphia's Academy of Music, where only a smattering of listeners remained at the end of a concert version conducted by Dennis Russell Davies).

How ironic that Rattle is using what has been, in past years, a winter guest-conducting residency in Philadelphia to conduct Pelléas in New York through Jan. 1. His cast is close to ideal: Magdalena Kozena (Rattle's wife) is Mélisande, the woman without a past who is found weeping in the woods. Golaud, who finds and marries her, is perfect for Gerald Finley's vocal weight and dramatic edge. As his brother, Pelléas, who falls in love with Melisande, Stéphane Degout sang beautifully, even if his presence suffered compared to Kozena and Finley.

The Jonathan Miller production is sort of a Jungian version of The Matrix. Though much of the opera takes place outside, the sets are all interiors of an ornate but scantly furnished mansion, suggesting that the characters are possibly imagining their own reality or giving us a tour of their psychic caverns.

Rattle embraced Debussy's quietude. Rather than solving the mysteries, he lived in them. Though few conductors so clearly chart the progression of leitmotifs, Rattle let listeners interpret their meaning. The opening moments did telegraph the profound weariness of Mélisande - even as she's about to be adapted into an exhausted culture that has outlived its own era. From there, Rattle downplayed rhythmic propulsion (in comparison to James Levine) and, rather dangerously, expanded the estimated four-hour running time by 15 minutes.

Rattle has often been a conductor to realize the power of a score while trusting that the music's pace and architectural functions will take care of themselves. That approach didn't fully succeed Friday; the opera wasn't as entrancing as it could be - which may change in later performances.

Luckily, the singers projected such a strong sense of inner life, you couldn't pass them off as mere French symbolist shadows. Mélisande is often played as a serial victim, and in the past Kozena has portrayed her as a Zen-like tabula rasa. Now, her Mélisande is not to be crossed. At the first hint of mistreatment, her unhappiness is articulated as a warning. She goes on to demolish Golaud's world, even if her loss - both she and Pelléas die - is greater.

No matter how assiduously one adds up the pieces of this opera, no wholly coherent picture emerges - a reason why Pelleas maintains its experimental status, even if it's also a grand opera. So how do you know if a revival has been successful? Well, this one was a vivid encounter with the piece. Beyond that? Ask my hypnotist.

Contact music critic David Patrick Stearns at dstearns@phillynews.com.

"Pelléas et Mélisande" repeats Thursday and on Dec. 29 and Jan. 1. Tickets: 1-212-362-6000 or www.metoperafamily.org.