If anyone has harbored doubts that Gary Sheldon has the making of a major conductor, last night provided ample evidence for the optimists among conductor watchers.

The music director of the Marin Symphony transcended the limitations of working with a part-time orchestra; he more than met the challenges of an utterly complex, impossibly difficult, truly great work of music.

Gustav Mahler’s Fifth Symphony is a towering windmill in the path of quixotic conductors.

Well over an hour long, requiring a huge orchestra, presenting cross-rhythms and balances that not even two conductors could control at times, the challenge of the Fifth is way beyond those practical considerations.

It is a universe of sounds, a complete catalog of human emotions, a whole far greater than the sum of its parts. It is big in every way: in its size, requirements, depth of despair, exultation in spite of it all, in the surpassing sheer beauty of its famous adagietto.

But the Marin Symphony, under Sheldon’s secure, knowing, effective leadership, succeeded in giving an excellent performance, virtually untroubled not only by errors, but even by mediocre passages that often creep into readings of the Fifth by some big-name orchestras.

First violins, cellos and basses played their hearts out, often reaching the “critical mass” of Mahler’s fortissimos that pound against Fate with far more angst than that other famous Fifth.

Woodwinds were fine and, in a welcome surprise considering the challenge, the brass excellent. Those great horn calls soared high from Glen Swarts and Katie Poeck, Carole Klein’s trumpet work was at her considerable best. The percussion section did very well.

There was a little problem with the entire second-violin section for a while, but it didn’t last long enough to take away from the total impression of a “personal best” for orchestra and conductor.

It is a memorable Fifth, setting a clear standard the orchestra to reach for in the future.