HARRISON — The Sebago-Long Lake Music Festival opened its 41st season at Deertrees Theater in Harrison on Tuesday night with a delightful program of Beethoven and the Mendelssohns – Fanny and Felix. It also featured fine performances by newcomers Elizabeth Anderson, cello, and Julie Whitton, viola.

I found the performance of the Beethoven String Quartet in B-Flat Major (Op. 18, No. 6) by Whitton and Anderson, with festival favorites Movses Pogossian and Varty Manouelian, both on violin, to be not only well played but also more interesting than versions by quartets who have been together a long time.

There was a freshness to it, a sense of discovery, that is hard to find, at least in recordings. The contrasts between the “melancholy” opening theme and the dance-like allegretto in the final movement were as striking as Beethoven intended.

The difference between talent and genius was made apparent by the pairing of the Piano Trio in D Minor, Of. 11, of Fanny Mendelssohn Hensel, and her brother Felix Mendelssohn’s String Quintet No. 2 in B-Flat Major, both composed at about the same time.

The Trio could not have received a better reading than that of Pogossian and Anderson, with Stephen Manes at the piano. It was always pleasantly flowing, with a wealth of novel ideas, such as the opening theme set against a spinning-wheel accompaniment on the piano, or its chromatic treatment on the cello.

The following movements, although equally enjoyable, were more derivative, including a boat song, a song without words, and a final pastiche of dances, opening with a series of piano flourishes. It made one wonder if the composer knew the Chopin polonaises.

The Quintet that followed after intermission was a different animal entirely, of an almost otherworldy radiance, moving rather than entertaining. It was played superbly by the quartet, with the addition of violist Laurie Kennedy. Manouelian was outstanding in the virtuosic first violin part, while the all-important cello both sang alone and united all the other parts.

The whimsical Andante scherzando lived up to its name, creating a fairyland even more convincing than that of “A Midsummer Night’s Dream,” with an inexhaustible supply of musical ideas. The melodic Adagio e lento, however, took the quintet to new heights, with some of Mendelssohn’s most beautiful melodies spread against a starkly dotted rhythm. The passages in unison tremulando created a shimmering curtain of sound.

The festival continues every Tuesday night through Aug. 13. If the programs are as enjoyable as the first, it would be well worth the trip to Harrison.

Christopher Hyde’s Classical Beat column appears in the Maine Sunday Telegram. He can be reached at classbeat@netscape.net.