It is said that in 1830, while staying in Weimar, Mendelssohn visited Goethe and performed, among other pieces, this Fantasia in F-sharp minor, 'Scottish Sonata'. Mendelssohn began composing a piece titled Scottish Sonata in 1828, and continued to revise it for the next five years. The work published in 1834 was this Fantasia in F-sharp minor, 'Scottish Sonata'. It consists of three movements, performed continuously.

First Movement: F-sharp minor, 2/4 time, Con moto agitato – Andante

It begins with an 8-measure arpeggiated introduction (Con moto agitato). Following the Andante main section, the recurring arpeggiated passages gradually increase in intensity and volume, forming a climax. After a significantly altered recapitulation is played, the arpeggios from the introduction reappear, bringing the piece to a fantastical close.

Second Movement: A major, 2/2 time, Allegro con moto

It is roughly in A-B-A form and has a scherzo-like character. A short movement employing contrapuntal techniques.

Third Movement: F-sharp minor, 6/8 time, Presto

Although strongly improvisatory in character, it is roughly in sonata form. The first theme consists of a descending sextuplet figure, moving with dizzying speed. The second theme is sung broadly in octaves. The sextuplets permeate the entire piece, and variations in their figuration create a wide range of expressions. A passionate finale.