Themes are simple, and tonal centers were rarely out of reach.

All its movements have D as their tonal center.

The gestures belong to a music rooted in tonal centers.

The first movement begins in D major, and sets the tonal center with a strong introduction.

Its tonal center is slightly ambiguous, due to the large number of half steps.

Thus diversity is achieved within a stable and fixed tonal center.

They both end on a note other than the tonal centre of the first four phrases.

However, the strong presence of G in the movement also points to another tonal center.

The result lands the tonal center back to C major at measure 11.

It has something to do with the bass lines not quite connected to the tonal center.