The strings , playing from behind the stage , play very slow , chorale-like music throughout the piece while several times the trumpet ( playing from behind the audience ) plays a short group of notes that Ives described as `` the eternal question of existence '' . The strings ( located offstage ) play very slow , chorale-like music throughout the piece while on several occasions the trumpet ( positioned behind the audience ) plays a short motif that Ives described as `` the eternal question of existence '' .