with a cadence featuring a final chord in the major: In his book Music and Sentiment, Charles Rosen shows how Bach makes use of the fluctuations between minor and major to convey feeling in his music. Rosen singles out the Allemande from the keyboard Partita No. 1 in B-flat, BWV 825 to exemplify "the range of expression then possible, the subtle variety of inflections of sentiment contained with a well-defined framework". The following passage from the first half of the piece starts in F major, but then, in bar 15, "Turning to the minor mode with a chromatic bass and then back to the major for the cadence adds still new intensity." Many passages in Bach's religious works follow a similar expressive trajectory involving major and minor keys that may sometimes take on a symbolic significance. For example, David Humphreys (1983, p. 23) sees the "languishing chromatic inflections, syncopations and appoggiaturas" of the following episode from the St Anne Prelude for organ, BWV 552 from Clavier-Übung III as "showing Christ in his human aspect. Moreover the poignant angularity of the melody, and in particular the sudden turn to the minor, are obvious expressions of pathos, introduced as a portrayal of his Passion and crucifixion": Notably, Bach's two books of The Well-Tempered Clavier, composed in 1722 and 1744 respectively, differ considerably in their application of Picardy thirds, which occur unambiguously at the end of all of the minor-mode preludes and all but one of the minor-mode fugues in the first book. In the second book, however, fourteen of the minor-mode movements end on a minor chord, or occasionally, on a unison. Manuscripts vary in many of these cases. While the device was used less frequently during the Classical era, examples can be found in works by Haydn and Mozart, such as the slow movement of Mozart's Piano Concerto 21, K. 467: Philip Radcliffe says that the dissonant harmonies here "have a vivid foretaste of Schumann and the way they gently melt into the major key is equally prophetic of Schubert". At the end of his opera Don Giovanni, Mozart uses the switch from minor to major to considerable dramatic effect: "As the Don disappears, screaming in agony, the orchestra settles in on a chord of D major. The change of mode offers no consolation, though: it is more like the tierce de Picardie, the 'Picardy third' (a famous misnomer derived from