Prelude in A-flat major (Rachmaninoff)  The Prelude in A-flat major, Op. 23, No. 8, is a 1903 composition by Sergei Rachmaninoff. It is part of Rachmaninoff's Ten Preludes, Op. 23. The work is three-part ternary; however, it assumes monothematic characteristics. The first occurrence Section A comprises measures 1–19, Section B of 19–43, Section A returns from measures 43–70, and the coda is placed at measures 70–78. A right hand figuration extends over a descending quarter-note melody in the first two bars, outlining the A flat chord. This motive repeats, and then is varied in measures 5–8, in succession. From measures 9–18, the section is restated though a transient modulation to E major (at measure 15). An imperfect cadence in the tonic bridges the transitory gap in measure 18 to the B section in E flat. Measures 19–20 introduce a variant of the main motive. Now in a new key, the bass melody changes, descending chromatically in an eighth-note figure. Measure 19  A transition section comes together though the combination of ascending and descending chromatic scale fragments at measures 31–41. Vertiginous modulations swing through E flat – G – C – F – A flat and B flat, before settling into E flat at measures 39–41. Measures 31 and 32  The original statement occurs beginning at measure 42, and then a progression at measures 54–62 through F- B flat – D flat and F minor provides a link to measures 61–70, where the harmonies become vague and undistinguishable: Measures 61 and 62  The coda exhibits a gradual breakdown of the forward motion, and, with a quarter-note progression in the final three bars, the A flat tonality is reestablished. Measures 76–78  Some critics of this Prelude, such as John Culshaw, believe that the relentless, florid nature of the sixteenth-note figures extinguishes any expressive quality of the work.