Gustav Mahler's Seventh Symphony seems to belie traditional notions of symphonic unity in that it progresses from E minor in the first movement to C major in the Finale. The repertoire of eighteenth and nineteenth century composers such as Haydn, Beethoven, and Brahms indicates that tonal holism is a significant factor for the symphonic genre. In order to reconcile Mahler's adventurous key scheme, this dissertation explores a multidimensional harmonic model that expands upon other concepts like Robert Bailey's double-tonic complex and transformation theory. A multidimensional musical object is a nexus of several interconnected chords that occupy the same functional space (tonic, dominant, or subdominant) and can be integrated into a Schenkerian reading. Mahler's Seventh is governed by a three-dimensional tonic object that encompasses the major and minor versions of C, E, and A-flat and the augmented triad that is formed between them. The nature of this multidimensional harmony allows unusual formal procedures to unfold, most notably in the first movement's sonata form. To navigate this particular sonata design, I have incorporated my own analytical terminology, the identity narrative, to track the background harmonic events. The location of these events (identity schism, identity crisis, and identity reclamation) is critical to the entire structure of the Seventh.