Tchaikovsky’s Violin Concerto in D major, Op. 35 is generally accepted to be one of the most difficult pieces in the violin repertoire. Apparently, when the Russian composer premiered it in Vienna in 1879, the violin virtuoso picked to perform it backed out, saying it was unplayable.

Time brought willing musicians to tackle the composition, though, and critical opinion has come around to embrace it as a demanding but satisfyingly musical piece. And it’s a testament to her prodigious skills that 17-year-old violinist Heather Thomas, a high school senior from Belgrade and winner of the 2007 Maine High School Concerto Competition, performed it with the Bangor Symphony Orchestra last weekend, with seemingly effortless ease.

Eye-catching in her pink gown, Thomas plucked, double-bowed and slid up and down the neck of her violin, moving involuntarily with the music. She found the happy medium between technical dexterity and musicality, capitalizing on the passionate, colorful shades found in most of Tchaikovsky’s work. She was rewarded with a standing ovation, during which she stopped looking like a seasoned pro, and started looking like the kid she is. A kid with talent bursting from each fingertip.

The BSO began Sunday’s program with Edward Elgar’s Introduction and Allegro, Op. 47, a warm, buttery, deeply evocative piece composed just for strings. It’s full of rich, dynamic textures, from torrents of descending melodies to a variation on a Welsh folk tune that weaves in and out of the whole composition. Maestro Xiao-Lu Li conducted with just his hands, giving the performance an intimate feeling. It was like watching someone knead bread, or paint a portrait, and it made Peakes Auditorium feel a lot smaller, in a good way.

The last performance of the concert was Brahms’ Symphony No. 2, Op. 73 in D major, another difficult composition, in line with Li’s choices so far this season to tackle works many other orchestras find too daunting to play. While it’s a gentle, playful piece, typically known as Brahms’ “peaceful” symphony, it contrasted a little awkwardly with the exotic technicality of the Tchaikovsky and the intoxicating warmth of the Elgar. It’s also 40 minutes long, which, in the case of other long pieces, seems to fly by; here, it overstayed its welcome.