When the composer completed it in 1749, he was a year from his death, so it stands as the kind of late-in-life crowning achievement any artist would love to have.

This astounding farewell to the world also served as a cap to the baroque era. After the Mass in B Minor was written, nothing further needed to be said in that style. In fact, many regard it as the peak of all classical compositions, the magnum opus of the art form's ultimate genius.

It also provided the beginning of the Bach Society of Minnesota. A group of University of Minnesota music students discovered the mass amid the Great Depression in 1932 (a mere 32 years after its U.S. premiere), and set out to perform it with the assistance of professor Donald Ferguson. After they opened auditions to the public, the Bach Society was born.

Saturday night, the Bach Society celebrated its 90th birthday with a performance of the Mass in B Minor at St. Paul's Ordway Concert Hall, the centerpiece of the month-long Minnesota Bach Festival. Conducted by the society's artistic director, Matthias Maute, it was one of those particularly rewarding instances when a tall task becomes a triumph, leaving the audience to bask in the glow of this masterpiece's many gifts.

Performed by a skilled 16-voice choir, four vocal soloists and a 22-member orchestra devoted to the sonorities of 1749, it overflowed with beauty and hummed with energy, aided by Maute's spirited leadership. Splendid solos abounded, the arias delivered with sensitivity and confidence, the choir bringing conviction and contrast to the 27 movements.

The B-Minor Mass is, at root, a choral work, and the chamber choir had many an impressive moment, hitting its stride on a buoyant, booming "Gloria," and reaching its peak of intricate interplay on the "Cum Sancto" that closed the concert's first half.

Speaking of interplay, the vocal soloists created several wonderful instances of collaboration with instrumentalists. On the "Domine Deus," soprano Sarah Brailey and tenor Nicholas Chalmers engaged in a dance of delight with flutist Immanuel Davis. And oboist Curtis Foster lent rich-toned enhancements to mezzo Victoria Vargas' "Qui Sedes."

It was a concert that grew stronger as it went, Brailey and Vargas finding another level of beauty while echoing one another's lines on the "Et in unum" before the final five movements provided an extraordinary climax. The choir split in two for an antiphonal "Osanna" before outdoing it in enthusiasm on a reprise. Chalmers and flutist Davis made something arrestingly mournful of the "Benedictus," and Vargas proved to have the ideal dark shadings (and the orchestra the more subdued and solemn tones that "historically informed" instruments can bring) on a sad lullaby of an "Agnus Dei."

The dark-toned strings proved an ideal complement to the choir's comforting harmonies on the closing "Dona nobis pacem," inspiring me to join most of the Ordway audience on its feet for a performance that took on a monumental challenge and gave J.S. Bach's genius all the devotion it deserves.

And, if you're sorry you missed it, you can view a video stream of the concert at bachsocietymn.org. Think about donating, if you do.

Rob Hubbard is a Twin Cities freelance classical music writer. wordhub@yahoo.com