Our analysis of the diminished seventh chord sequence (such as in the Coda of Bach's Chromatic Fantasy, in Mozart's Piano Sonata K533/i mm. 213-218, or in Chopin's E-minor Prelude Op. 28 No. 4) involves at least three levels of the scalar hierarchy: structural, diatonic and chromatic. Most puzzling is the ambivalence of the minor third along these levels. At the structural level it embodies the ‘augmented prime’, i.e. the difference between the large step (P4) and the small step (M2). This circumstance is relevant for investigation of fundament progressions. At the diatonic level, the minor third embodies the dual concept of that of the diazeuxis (sum of M2 and m2 as the dual construct to the difference between P5 and P4). The circumstance is closely related to the fact that the difference between the tonics of major and relative minor modes, is a minor third. At the chromatic level the minor third is a generator of the diminished seventh chord, and thereby it exemplifies a violation of the CV-property for chords (cardinality equals variety). In our paper we explore the relevance of these distinguished properties in analytical situations.