A short piece composed solely of a series of arpeggiated runs. It is positioned early in Bach's creative history and is noteworthy as one of his earliest works to employ B minor. Multiple manuscripts accompany the Fugue on a Theme by Albinoni, BWV 951. Although this pairing was not made by Bach himself, it is effective and convincing due to the shared key and the well-matched musical atmosphere. (Even today, published editions combining BWV 923 and BWV 951 into a single piece are widely used.)

What is striking is the succession of half-note chords in the latter half. This is likely an unfinished sketch. When Bach used such abbreviations, he invariably provided a "solution." The right-hand figuration shown in the latter half of measures 8-9, respectively, might be considered a "solution" to the abbreviation in measures 6-10. (Examples of "solutions" can also be seen in the Chromatic Fantasy, BWV 903/1. Furthermore, the Fantasy, BWV 944/1, is also a work consisting solely of half-note chords and is likely unfinished.) In the first place, it is highly unbalanced for such a section to occupy more than half of the total measures. Additionally, the harmonic connections, especially towards the conclusion, do not seem to work very well. In any case, this type of abbreviation would require the performer to supplement the music with their free imagination. Note that an alternative version, BWV 923a, exists, which supplements the latter part; this is considered an adaptation by someone close to Bach.

On the other hand, the first half is impeccably crafted, being both improvisatory and meticulously detailed, and is nothing short of magnificent. It skillfully employs ascending and descending motion, sixteenth notes and thirty-second notes, and freely manipulates range and tempo. In the middle section, the motive is developed equally between both hands, and just as the ear becomes accustomed to the eighth-note pulsation, runs are again scattered across the full width of the keyboard, soaring beyond the world of meter.