Beethoven's piano sonatas have been studied from different aspects. While many previous studies have investigated the internal coherence within individual Beethoven sonatas, this book provides a broad analytic overview of the connections that exist between the sonatas revealing the composer's approach to the idea of an opus as a unified set of several organically coherent works. The study identifies the related opuses, and adduces the ways in which cohesion operates on the macro-level by the investigation of formal design, harmonic and melodic language, affective key characteristics, thematic and rhythmic interrelationships, dramatic character, stylistic congruence, and other methods employed by Beethoven to unify individual sonatas into cohesive sets. Given the remarkable individuality and originality of singular sonatas, it is easy to mistake the "forest for the trees," so to speak. It is only when one begins to draw back and see a broader vista that the many interconnections between the disparate sonatas become more visible, allowing us to grasp and to understand the individual trees as part of the forest. The analysis should be useful to both performers as well as scholars.