Fantasia in D minor, K. 397 (385g)

Wolfgang Amadeus Mozart (1756-1791) composed three fantasias (K. 396, K. 475, and K. 397). Among them, the Fantasia in D minor, K. 397 (385g), remains the most enigmatic, partly due to the absence of an autograph manuscript and its unfinished state. While its composition is generally attributed to 1782, the precise period and the motivation behind its creation are unknown.

The first edition, published posthumously in 1804, bore the inscription "Fantasia as an introduction, a detached piece," and concluded at measure 97 with a fermata on a D major dominant seventh chord. Consequently, it is presumed to have served as a prelude to other works, such as sonatas or fugues, similar to K. 475 in C minor. Currently, it is customary to perform the 10-measure completion that was added when Breitkopf & Härtel published the work in 1806. The author of this completion is unknown, but it is widely believed to be August Eberhard Müller (1767-1817), who also composed the cadenza for Mozart's Piano Concerto No. 23.

Structure

Broadly speaking, the form of the piece consists of three main sections:

• Andante: Serving an introductory role.
• Adagio–Presto: The central expressive section.
• Allegro: The climactic conclusion.

The Andante features arpeggiated chords played by both hands, creating an improvisatory atmosphere as if wandering in search of something. The harmony is fundamentally composed of simple I-IV-V degrees, but borrowed chords inserted at the end of phrases create an effect like light piercing through darkness.

The Adagio, resembling a lamenting arietta, effectively uses chromaticism and rests, gradually intensifying a sense of urgency. It finally reaches a Presto, culminating in a descending figuration cadenza.

After the Adagio and Presto are repeated, the piece transitions to an Allegretto section in D major. This section, reminiscent of an operatic finale, presents a completely different character from the preceding parts. However, by focusing on the melodic figures, it can be seen as a development of the Adagio's figures, making it a unified work despite its free form.