In Charles Rosen's landmark analysis of Beethoven's "Hammerklavier" Sonata, Opus 106, Rosen revealed Beethoven as the progenitor of a type of musical structure that may be described as "form-content relationship." In the case of the Opus 106 it is the pervasive use of chains of melodic descending-thirds that organizes the motivic and melodic content as well as the larger structural elements of the work, resulting in an unprecedented organicism. This phenomenon of form-content relationship can be found in the Piano Sonata Opus 110 and reaches its furthest development in the String Quartet in C-sharp Minor, Opus 131. Whereas the Hammerklavier's structure is derived from a short motive, that of the Opus 131 may be said to be based on an idea, the Urphanomen (primal phenomenon), although at one important point in the work this idea is manifested in terms of a specific musical motif. This study is a detailed explication of the structure of Beethoven's Opus 131 and also explores the possible genesis of the work in terms of Goethe's morphological theories and Schelling's transcendental idealism."