Near the end of his long and illustrious career, a weary Brahms told his publisher that it was “finally time to quit composing.” And then, he met the clarinetist Richar Mühlfeld, whose dark, woody sound and stellar musicianship inspired a quartet of new chamber works, including the trio for clarinet, cello, and piano. Also on the program are a pair of French gems: Poulenc’s graceful and ironic flute sonata and Ravel’s Introduction and Allegro for Harp, Flute, Clarinet, and String Quartet, a work that so enchanted audiences that the musicians immediately played it a second time at the premiere.