That Mozart left a nearly-completed Adagio for unspecified instruments has left a happy opening for Mozart scholars and arrangers and a still-happier opening for players of the Cor Anglais. It’s not clear what the instrumentation of this work (from the most masterful period of Mozart’s life) was intended to be, since it exists in manuscript only as a fragment. The melodic line was completely written out, but the three accompanying voices were only partially written out, and only the words corno anglais, written in the hand of Georg Nikolaus Nissen (biographer of Mozart and Constanze Mozart’s second husband) give any indication of an intended instrumentation. Whether this instrument was Mozart’s intended bearer of melody for 580a is lost to history, but the instrument does suit very well. The work is simple and beautiful and very warm on the low reed instrument. The version we give today was set by an anonymous arranger for English Horn and String Quartet around 1900.