Music Box is an artistic implementation of emergent behavior and its use to create music. Music Box employs Craig Reynold's flocking algorithm to display animated notes that rise from a written score, then move to create a distinctive flock-lead musical arrangement. The result is emergent sound; a musical arrangement directed by the visual representation of flocking. The goal of this creative exploration is to free the musical score from the prevalent model of composer, performer and listener supported by standard models. Instead the experience is more democratic. Here the composer suggests, the performer follows a few loose rules, and the listener plays with the composition. This is accomplished through the development of artificial intelligence software that applies the visual rules of flocking behaviors to the algorithmic arrangement of musical pitches. Importantly, these visual rules are manipulated by the software user resulting in a dual performance and composition. The result is musical authoring based on the user model of computer video games.