Corelli, Arcangelo Concerto Grosso, Op. 3, No. 1 (Arr. by Shelley Collins) The concerto grosso of Corelli's day was often a trio sonata with extra voices  used to emphasize various aspects of the music.  This piece has can be played as a trio but has also been arranged for 4 C flutes, 2 altos and 1 bass.  Alternate parts have been added to use all C flutes as well.