Chopin’s Prelude in F-sharp minor has a specific harmonic feature: the lack of a concluding cadence at the end of the first section of the ternary form, this being also tonally open, modulating from the tonic to the minor mediant, A minor.
The contrapuntal structure of the prelude will be analysed on the base of a five-part voice-leading matrix, rather than the two-part Schenkerian Ursatz, as the high-level structure of tonal counterpoint. The gradual generation of the contrapuntal structure will be shown in the form of five structural levels.
The harmonic development in the first two sections seems to be based on a system of interval progressions 5–6, in the form of a sequence moving up by half step, with two chords in each leg. This system, contrapuntal in essence, follows its own linear logic and has its own hierarchy, independent of that of the overall contrapuntal structure.
There are seven tonicised triads whose roots, along with the tonic, make up three cycles of thirds: one ascending minor-third cycle and two descending major-third cycles a semitone apart. The roots of triads of the major-third cycles, taken together, constitute a hexatonic scale. Like the system of interval progressions 5–6, the cycles of thirds are independent of the overall contrapuntal structure.
Each section of the prelude has a very clear phrase-structural design. In particular, the grouping structure of the first eight bars, typical of a parallel period, is sufficient enough for demarcation of the first section, despite of the lack of the concluding cadence. Therefore it seems that harmony has here another, more interesting task beyond that of the articulation of form – the task of individualisation of the tonal structure. The aforementioned characteristic features of harmony serve, to use Yurij Cholopow’s notion, as an additional constructive element of the pitch structure.