The bass imitates the motif in a freely augmented way:

In bars 3 and 4, the upper voice transforms the motive by means of inversion:

The bass takes it up again, inverted and augmented. The key of E flat major is confirmed:

From bar 7, the bass uses the first notes of the motive to create an ascending progression that leads to B flat major:

In measure 13 we find the motive in ascending form in the upper voice and in descending and varied form in the lower voice. The key of B flat major is confirmed, and the motive appears in its original form in the upper voice (bar 19):

Once the key of B flat major is established, a recapitulation presents the thematic material similar to the opening bars:

• A coda concludes Section A.
• Its first 5 notes form a new variant of the motif that will be reused to start the B section.
• From bar 28 on, the upper voice seems to split into two: the upper voice with the ascending motive, the lower voice insisting on the first two notes.

The variation of the motif in bar 27 (Bb - A - Bb) gives the entire work its motivic unity.

We find the motive in the prelude:

And in the fugue:

The motif will reappear in the B section of the Allegro.

The numerous transformations of the motive throughout the Allegro are summarized below:

Original motive (bar 1):

Augmentation:

Inversion:

Inversion and augmentation:

The first few notes of the motif form an ascending progression:

A note is added to reach each note (C for D, B for C, ...):

The motive begins with a neighboring note. From bar 28, two voices are separated. The upper voice has the ascending motive, the lower voice insists on the first notes:

Similar to bar 27:

Descending motive with octave rhythmic play:

A descending motive splits from the notes:

Eighth notes are added to reinforce the climax:

An ascending motive splits from the notes:

Entire section A: