Fractious music for fractious times.

Such was the milieu of Leonard Bernstein's Mass: A Theatre Piece for Singers, Players and Dancers when it first appeared in 1971, in all of its confrontational clangor, commissioned by Jacqueline Kennedy but quietly boycotted by Richard Nixon.

Some 40-plus years later, the piece unfolded at the Kimmel Center on Thursday, performed by the Philadelphia Orchestra for the first time, hours after Baltimore-related protests took place down the street at City Hall.

Pure coincidence, of course. But for all its pageantry and spectacle, Bernstein's Mass made a statement by bringing together at least eight musical organizations from the larger community - from Mummers to the Temple University Diamond Marching Band - for a two-hour piece that charts the cycle of idealism, disillusionment, and peaceful resolution.

Different kinds of music (pop and classical) arrive at each stage of the journey that's ostensibly Roman Catholic, though with an Old Testament sensibility. The rock-concert reception at the packed Verizon Hall was such that music director Yannick Nézet-Séguin had to stop choruses from leaving before the cheering was over.

The occasion would be special no matter what was happening outside. For the first time in its history, the Verizon Hall orchestra pit was utilized - did anyone know there was one? - while the stage was filled with choruses (Westminster Symphonic Choir, American Boychoir, and Temple University Concert Choir), dancers (Rock School for Dance Education) and two flanks of orchestra musicians.

The stage was lined in neon-like light and framed by series of vertical and horizontal lights so attractive that, in the post-concert talk with the audience, Nézet-Séguin and orchestra president Allison Vulgamore toyed with the idea of leaving them up after the run of performances (which go through Sunday afternoon).

Though Mass played Philadelphia in a post-premiere 1970s tour, its longtime absence isn't hard to explain. The piece isn't just big; it's fearsome. With key portions pre-taped (such as the opening Tower of Babel-like voices), the huge live-music forces require tricky coordination. And then with a marching band and whirling-dervish mummers in the main-floor aisles? Also Mass elicits mixed opinion more than any other Bernstein piece and goes in and out of fashion like the phases of the moon.

The scenario involves a religious leader - named The Celebrant - dealing with the existential questions of early adulthood, both within himself and in those around him. The no-expense-apparently-spared production, directed by Kevin Newbury, had a saturated blue-and-red color scheme onstage, plus the unusually youthful casting of Broadway tenor Kevin Vortmann, often wearing a priest collar, in a staging that put him face-to-face with a cross-section of humanity, from a glamor girl in spike heels to a gay male couple.

Islands of tranquility emerge from music written for boy soprano (beautifully sung on Thursday by Douglas Butler), amid myriad questions, voiced by an aggressive collection of street singers that begins looking and sounding like the Jets and the Sharks in West Side Story.

The power of the music, however, had to be in the heart of the beholder - more than in typical Philadelphia Orchestra concert circumstances. As a piece of visceral musical theater, Mass completely worked. Yet the score goes in so many possible directions, few listeners are likely to love it 100 percent. For me, it was more like 40 percent - and who knows why? My Catholic upbringing? My close relationship with late-1960s pop music that Bernstein drew on? My love for other Bernstein works that he fell back on while creating Mass? (Long passages nearly quote "Somewhere" from West Side Story and "Make Our Garden Grow" from Candide.)

Much of the first two thirds of Mass are, to my ears, rambunctious incidental music that's there to support the drama but doesn't stand up on its own. Often Bernstein makes a point and hammers away at it in numerous verses. But the power of the complete package can't be denied. So if Bernstein's Mass returns in future seasons, it needs to live large. Very large.

Additional performances:   8 p.m. Saturday,and 2 p.m. Sunday at the Kimmel Center, Broad and Spruce Streets. Information: 215-893-1999 or