The Emerson String Quartet has amassed an unparalleled list of achievements over four decades. In this new program, the Emerson explores three famous quartets written as elegies: Barber’s Adagio, probably the most famous elegy ever written; Britten’s third quartet and final work, completed on his death bed; and Beethoven’sOpus 59, No.1, on whose last sketch he wrote, “A weeping willow or acadia tree on my brother’s grave,” a reference to the Freemasons and their philosophies of mourning and resurrection.