This is the main theme from a piece for wind ensemble, Divertimento, originally thought to be written by Franz Joseph Haydn (1732- 1809), though in recent years had been attributed to French composer Ignaz Pleyel (1757- 1831).  The simple but elegant theme has been made famous in the orchestral work, Variations on a Theme by Haydn, by Johannes Brahms (1833- 1897).