The first movement of Beethoven’s Sonata No. 15, Op. 28, is an expansive Allegro in D major and three-quarter time. A quiet repeated bass note supports a broad melody in the upper voices. This steady pulse remains a recognizable feature even as the music moves into busier passages, stronger accents, and changing harmonies. The movement follows a large opening section, a contrasting development, a return of the principal ideas, and a quiet coda.

Opening theme: The left hand begins alone on a low D before the melody enters above it. The upper line is often part of a chord, with longer notes stretched over the bass’s regular quarter-note motion. Small rising figures interrupt the sustained melody, and short crescendos lead to accented arrivals. Later phrases shift the bass and add quicker notes without losing the opening’s measured tread.

Contrasting themes and repeat: The texture grows more active through running notes and brief triplet flourishes. A quieter theme appears in sustained right-hand chords, then develops into continuous eighth-note motion shared between the hands. Held melody notes stand above this moving inner texture. The closing material uses short, lightly detached phrases and chordal accompaniment. First and second endings direct the player either back through the opening section or onward into the development.

Development and return: The middle pages break the earlier ideas into smaller exchanges. Running figures pass between the hands, accents interrupt the pulse, and the bass reaches into a lower register. Repeated upper gestures build over changing bass notes before a broad slowing and sustained chords suspend the motion. After a brief Adagio indication, the original tempo and the low repeated bass return. The main themes reappear with changes of harmony and register, including the busy inner-note texture and the detached closing phrases.

Coda and ending: The marked coda brings back the opening melody over repeated low D notes. Short rising gestures add several final accents, but the texture gradually becomes quieter and more spacious. A slowing indication leads into separated soft chords, and the movement closes with a held final sonority.

Interesting fact: In this score, the very first bar belongs to the bass alone; the forward repeat sign appears only when the upper melody enters.