To what extent can a piece of music reveal the character or state of mind of its composer? Music is such an abstract way to express emotions or ideas. One must interpret what one hears and arrive at conclusions based on the sound itself and the circumstances that led to its creation.

And so it is with Tchaikovsky's Symphony No. 6, the penultimate score penned by the tortured Russian composer and the last piece he conducted before his death just nine days later.

He nicknamed his great symphony the "Passionate," which ended up in its French translation as the "Pathetique." Both passion and pathos are present in abundance, and the Charleston Symphony Orchestra, under the decisive direction of guest conductor and music director candidate Lawrence Loh, offered a vigorous and thoughtful rendition of this audience favorite Friday night at the Sottile Theatre.

It was impossible for me to disassociate the heart-rending final movement from its composer. Surely something that sad and moving could only have been the last cry of a man on the brink of oblivion.

It is said Tchaikovsky died of cholera, and it's true that the nasty bacterium was prevalent in the water supply of St. Petersburg at the time. Tchaikovsky's mother died of it, and his father once fell ill with cholera but recovered. Perhaps the composer forgot to boil the water before he drank it.

Or perhaps his death was a suicide, as some scholars have speculated. He was embroiled in a controversy concerning his liaison with Duke Stenbock-Thurmor's nephew. The Duke was mad and wrote a letter of protest to the Czar, threatening Tchaikovsky with a national scandal.

Maybe he ingested arsenic at the prompting of a hastily assembled "court of honor" comprised of old classmates. Arsenic can produce symptoms - dehydration, vomiting - similar to cholera's.

We know that Tchaikovsky was ashamed of his homosexuality and always trying to hide it. We know that his childhood was miserable and he was prone to lifelong bouts of depression, experiences that surely informed his hyper-romantic music.

Whatever the truth might be, the Passionate Symphony is one of those great gifts to humanity, full of soaring melodies, innovative orchestration and moments of glory for most of the players in the band. Loh, who comes from the batonless Kurt Masur school of conducting, approached the piece with an obvious commitment to, and appreciation for, the score. His dynamic direction was crystal clear and often avoided the use of standard gestures.

He reminded me a little of Tom Cruise in the movie "Minority Report" in which the actor manipulates virtual computer images projected in the air with firm swipes of his hands. Loh used his hands in ways that seemed to maximize both the symphony's subtleties (of which there aren't many, frankly) and its heart-on-the-sleeve poignancy.

It was evident that Loh had a clear vision for the piece and that he succeeded in getting the orchestra players to realize it. That vision included making the most out of the inherent emotions without allowing the symphony to gush over the brim. And it involved making sense of the many elements, bringing it all together into a cohesive whole, while at the same time encouraging the solo lines and sectional blasts.

What's more, Loh and the orchestra achieved a remarkable sonic balance that lent real oomph to this interpretation. The conductor was acutely sensitive both to the individual lines and their combined effect.

Tchaikovsky is not afraid to go from gracious romanticism to heart-pounding angst, from descending lines in the strings that might represent falling tears to horn fanfares. His perverse waltz, in 5/4 time, came across Friday night as if the dancers were dressed like clowns, miserable under their makeup, staggering to the exit.

And the final movement, an adagio lamentoso, was so heart-rending and beautiful that all of Tchaikovsky's tendencies toward exaggerated sentimentality were forgiven. The piece ended on such a sad note it took a few moments for the audience to respond with its applause.

Symphonic cohesiveness and balance were equally on display during a terrific performance of Samuel Barber's Violin Concerto, played by former CSO concertmaster Alexander Kerr.

Kerr has gone onto great things since his days in Charleston a decade ago. He is concertmaster of the Dallas Symphony Orchestra now, after a stint as concertmaster of the Royal Concertgebouw Orchestra in Amsterdam. He teaches at the prestigious Indiana University Jacobs School of Music and performs regularly as a soloist and chamber musician.

Kerr plays on a 1715 Stradivarius with a sound at once sweet and robust. He has a gorgeous tone and an admirable tendency to express phrases fully, with long bow strokes and an appealing, moderate vibrato. It was clear that the orchestra embraced the chance to play this difficult but utterly endearing 20th century masterpiece, with its lush harmonies and bursts of Americanisms. They were feelin' it.

It was a perfect marriage of soloist and symphony; Kerr and his fellow players were listening hard to one another, guided by the firm hands of Loh. Kerr managed to sing as a soloist while at the same time embedding his part in the larger texture of the piece.

The gracious second movement showed the orchestra at its best, offering opportunities to highlight its various players. The last movement was an exciting, precisely executed flurry of notes, in moto perpetuo (perpetual motion), a showy display of ensemble virtuosity and a great way to finish the first half of the concert.

It all began on an optimistic note with a performance of Beethoven's Fidelio Overture, deftly managed by Loh and played with gusto.