Arnold Schoenberg's theory of musical coherence is used as a point of departure to explore how aspects of a musical motive can be explained by recent research into categorization. Categorization can account for the coherence produced by repeated statements of a motive, for the role of motive as a starting place for higher level cognitive processes, and for relationships among diverse motive forms. The first section of the essay reviews recent research into categorization, with applications to music. The second section presents an analysis of a principal motive from Mozart's String Quartet K. 465. This analysis demonstrates how the structure of a motivic category is realized over the course of an entire movement.