 The difficulty for Mozart with the typical rondo structure is that it is naturally strophic; i.e., the structure is divided into a series of highly differentiated and distinct sections.However, such a structure does not lend itself to creating an overall unity in the movement, and Mozart thus attempts various ways (with greater or lesser success) of overcoming this problem.For example, he may have complex first themes (K. 595), contrapuntal treatment (K. 459), or rhythmic and other variation of the theme itself (K. 449).