Level-analysis in the field of music theory today is rarely hierarchical, at least in the strict sense of the term. Most current musical theories view levels systemically. One problem with this approach is that it usually does not distinguish compositional structures from perceptual structures. Another is its failure to recognize that in an artifactual phenomenon the inherence of idiostructures is as crucial to the identity of an artwork as the inherence of style structures. But can the singularity of an idiostructure be captured in the generality of an analytical symbol? In music analysis, it would seem possible provided closure and nonclosure are admitted as simultaneous properties potentially present at all hierarchical levels. One complication of this assumption, however, is that both network and tree relationships result. Another is that such relationships span in both "horizontal" (temporal) and "vertical" (structural) directions. Still another complication is the emergence of transient levels. In this paper, a tentative solution to these problems is offered by invoking a hypothetical theory that relies on the cognitive concepts of return, reversal, and continuation (i.e., similarity) as regards the parameters of melody, harmony, and duration. Applied to the theme of Mozart's Piano Sonata, K. 331, this analytical theory is contrasted with several systemic analyses of the same theme by the theorists DeVoto, Lester, Schenker, and Meyer. In conclusion, the hierarchical analysis of the Mozart theme gives way to a synthesis as the melody's various levels are rendered into rankings of pitch shown on one level only.