This site introduces unknown Emanuel Bach (C. P. E. Bach).
C. P. E. Bach Sonata V in E-flat major, Wq 63-5 (H. 74)
1st Movement: Allegro di molto
2nd Movement: Adagio assai
3rd Movement: Allegretto
ChatGPT4o writes as follows (please note that it may not be accurate):
Emanuel Bachʼs Sonata in E-flat major Wq 63-5 (H. 74) is one of the works that showcases his unique musical style. This sonata is structured in three movements, each with a different tempo and atmosphere. The first movement is a lively and energetic beginning, reflecting Bachʼs creativity and technical prowess. The following second movement is characterized by deep emotion and delicate expression, inviting the listener into a world of quiet introspection. The final movement is a light and rhythmic finale, bringing the piece to a bright conclusion. This sonata exemplifies how Emanuel Bach served as a bridge to classical music, embodying the diversity and innovation of his compositions.
According to the commentary by Darrell M. Berg on Miklós Spányi's CD (BIS-CD-1189) (translated by ChatGPT4o):
Allegro di molto - E-flat major - A "perpetual motion" movement (consistent sixteenth-note motion) that highlights the performerʼs technical skills.
Adagio assai, mesto e sostenuto - B-flat minor - A movement that tests the performerʼs expressiveness. After 19 bars of contrasting character, a quiet "recitative" style section ends, concluding with loud "orchestral-style" chords.
Allegretto, arioso ed amoroso - F major - In this binary form movement, it was customary to add improvised embellishments upon repeating each structural part. In this movement, Bach provides the first publicly written "improvisation" (although he may have taught it privately to students before the publication of Probestücke).