When members of the now defunct Theater Chamber Players formed the Left Bank Concert Society in 2004, they took on the worthy mission of bringing chamber music, especially modern repertory, to new audiences. On Saturday night in the Kennedy Center’s Terrace Theater, the Left Bank String Quartet shared the stage with a young string quartet called the Dionysian Quartet, made up of University of Maryland students. Most of the Left Bank’s core members (all but second violinist Sally McLain) are teacher-performers on faculty at Maryland, and they sometimes perform with their best students.

There was a good reason to attend this concert, the chance to hear a live performance of Mendelssohn’s Octet in E-Flat Major, op. 20. Because of the forces required, it is a piece that you are more likely to hear in an academic setting or played informally at a party of string players. In an anecdote related by Peter Schickele, at a performance of the Octet in Itzhak Perlman’s home where there were only seven music stands, David Finckel placed his music in another player’s suspenders and sat behind him.

Mendelssohn was only 16 years old when he composed the Octet, and the mind boggles at the young man’s compositional maturity. The piece combines the fruits of a fecund melodic genius with an advanced understanding of the forms of the sonata, enlightened by a daring willingness to stretch them in new directions. The lead-up to the recapitulation in the first movement is so protracted that the tension Mendelssohn creates with repeated false starts is both humorous, as the players exchange knowing glances, and desperate, not unlike trying to find one’s way out of a maze. The famous third movement, based on a passage from Goethe’s Faust, is a brilliant evocation of a landscape buzzing hazily with insects.