The Scottish composer James MacMillan writes music of high moral seriousness and unabashed complexity. So it's no surprise that he and Osmo Vänskä hit it off when Vänskä was leading Glasgow's BBC Scottish Symphony, or that Vänskä would commission MacMillan after moving on to the Minnesota Orchestra.

The fruit of that commission -- MacMillan's Piano Concerto No. 3, unveiled Thursday in the composer's presence -- has been long in coming. According to the score, it commemorates the orchestra's centennial, celebrated in 2003. But then MacMillan, whose art often takes its impetus from his Catholic faith, has an expansive view of time. What's a year or two against the backdrop of eternity?

Subtitled "The Mysteries of Light," the concerto revives the tradition of writing music rooted in the structure of the rosary. (So say the composer's lucid notes, reduced to hash in the printed program.) And if the idea of rosary-based music prompts a yawn, prepare to change your tune: The work, all 25 minutes of it, is a wild ride, overflowing with color and incident -- turbulent, incantatory and, at moments, luminous.

MacMillan's keyboard writing calls for a dramatist and a poet, and it has both in Jean-Yves Thibaudet, whose playing spans the extremes of forcefulness and delicacy. Yet he doesn't convince me that the new piece is best understood as a concerto. It's better seen, as the composer half-acknowledges, as an orchestral piece with an exceptionally prominent piano part. But that label will hardly lure soloists of Thibaudet's class, so "concerto" it is likely to remain.

Led by a tipsy conductor, the 1897 premiere of Sergei Rachmaninoff's First Symphony was a very different affair -- a fiasco from which the work has never recovered. "My most agonizing hour," Rachmaninoff later called the premiere, conceding that parts of the piece were "weak, childish, strained and bombastic."

Still, the symphony deserves an occasional airing. Tchaikovskyan echoes notwithstanding, it offers an individual take on Russian melancholia. Thursday's performance, a thing of fierce energy, could have drawn more deeply from the well of late-romantic performance practice: Tempos might have been stretchier, the strings might have swooned more. And a few cuts would not have gone amiss.

The concert began with George Enescu's earthy "Romanian Rhapsody" No. 1, played for thrills by Vänskä and the band.

Spectators may be startled to see Ruggero Allifranchini, a mainstay of the St. Paul Chamber Orchestra, in the concertmaster's chair for these concerts. He's a candidate for the position, vacant for nearly two years. His solo playing in the Rachmaninoff was characteristically delectable.

Larry Fuchsberg writes frequently about music.