00:00 — No.1, C minor. A set of variations on two themes, even though you’ll notice that the second theme is based on the first, with more widely-spaced intervals.
09:06 — No.2, E-flat major. The link between the first E-flat major and B minor themes is especially ingenious, and strangely obvious once you’ve spotted it: the second B minor theme is based rhythmically on the implied accents in the structure of the A section (1!231!231!2!3!1!23).
13:55 — No.3, G-flat major. A study in muted and utterly compelling lyricism.
20:16 — No.4, A-flat major. A dialogue between gently cascading arpeggios and murmuring chordal responses. The richly brooding middle section ventures into the major mode towards its conclusion, but dramatically reverts to the minor.