Magic is the easiest way to come to terms with the work that goes into art. The untrained eye doesn't know how. It knows only what. Art happens. Process is often a secondary consideration. But on occasion the question arises: How, indeed?

The great, tireless filmmaker Frederick Wiseman spent a recent season with the Paris Opera Ballet. The result is "La Danse," a unique kind of magic: a documentary about the work in art that is itself a work of art.

For long stretches, the camera watches rehearsals: dancers doing pas de deux and pas de trois. There are no title cards, no introductions. We're simply dropped off for 153 grand minutes. We see the ways in which a dance is constructed and polished. It includes both intricate classical ballet (Rudolf Nureyev's "The Nutcracker") and thrillingly, gruelingly modern dance (Pina Bausch, Wayne McGregor, Mats Ek).

We come to appreciate the degree to which some dancers are athletes and others, the exceptional ones, are stars. You can see the difference for yourself. Some of these men and women can take the corporeal calculus of choreography and turn it into body song or drama.

The asides are also illuminating. Two instructors bicker about how the art form has evolved. One recalls that Maria Tallchief had "something of a heavy butt," then suggests to a dancer that she rethink her développé (the unfolding of the leg in the air). "You'll think you are late, but it will be beautiful," she promises.

As an exclusive glimpse into one of the world's finest dance companies, the film would be a treat. But the meticulously immersive "La Danse" is altogether more fascinating as a consideration of the Paris Opera Ballet as a kind of organism. With deceptive rhythm (a shot of a stairwell, a shot down a hallway, a look at two dancers passing through a door), we move from the rehearsals to the building's cafeteria, to the costume department where sequins are being threaded onto skirts, to the grand theater where lighting cues and hectic dress rehearsals are underway, to the live performances themselves. The institution is very much alive.

As he did in 1995's "Ballet" (about the American Ballet Theater) and 1996's "La Comédie-Française," Wiseman finds deep pleasure in the application and development of talent. You get the sense that the quest for perfection never rests. There's something heartening about the way in which the dancers focus on the honing of their craft as opposed to some whimsical wish for stardom. He never shows us a civilian audience, only other dancers regarding their peers from the wings.

It's an honor to watch. At one point we learn that a few donors who have given more than $25,000 want a peek at rehearsals. Wiseman offers us the same gratifying privilege at a steep discount.