A symphony should contain the entire world, said Austrain composer Gustav Mahler. And the enormous world of his Symphonie No. 5 took shape last night when the Bangor Symphony Orchestra began its 96th season. From the first lonesome sound of a bellowing horn to the chilling fullness of the last thunderous movement, the BSO triumphantly moved through Mahler’s gigantic symphony.

With special training in the works of Mahler, Maestro Werner Torkanowsky was at his best. His curled and trembling hand rose high, beckoning to the musicians and summoning the music to fill the Maine Center for the Arts. The largeness of the piece and Torkanowsky’s keen understanding of its multi-texture made for a smashing opening performance. The symphony moves through many peaks and valleys that, indeed, require sharp focus to perform effectively. Torkanowsky traversed the landscape with polish and refinement, and turned each tricky curve with grace and style.

The opening Funeral March was tough and carnivalesque, rather than overly emotional, and sounded like the theme music to an old black-and-white film about passion and intrigue. Even in the symphony’s centerpiece, when the string section wails with sweet sentimentality, the BSO avoided the sugary possibilities of this colossal work. It was no small feat that these musicians captured an entire world — with all its dark tragedy and lovely tenderness.

The 70-minute Mahler piece was preceded by two Bach concertos for three pianos. Joined by the string section of the orchestra, pianists Robert Bahr, Kathryn Ann Foley, and Lillian Garwood gave lively performances of Bach’s Concerto for three pianos in C major and Concerto for three pianos and orchestra in D minor.

These delicate melodies were reputedly written by Bach to be performed with his sons, and the keyboardists seemed, also, to work as a family unit, trilling smoothly through the harmonies and rhythms of tricky arrangements. With basses and cellos humming in the background, the pianists offered a particularly lovely rendition of the concerto in D minor. The cadences were steady and stormy without becoming boring or overdone. At the end, the three joined hands for a bow, and the two women were given bouquets of flowers. What an unfortunate oversight that Bahr was not equally commended for his performance.