thumb|right|350px|Development in [[Joseph Haydn|Haydn's sonata in G major, Hob. XVI:G1, I, mm. 29–53 .]]
In music, development is a process by which a musical idea is transformed and restated in the course of a composition. Certain central ideas are repeated in different contexts or in altered form so that the listener can consciously or unconsciously compare the various statements of the idea, often in surprising or ironic manners. This practice has its roots in counterpoint, where a theme or subject might create an impression of a pleasing or affective sort, but delight the mind further as its contrapuntal capabilities are gradually unveiled in a fugal development.
Development is often contrasted with musical variation, which is a slightly different means to the same end. Development is carried out upon portions of material treated in different presentations and combinations at a time, while variation depends upon type of presentation at a time.
The development is the middle section of the sonata form, between the exposition and the recapitulation.
Methods of development
According to The Oxford Companion to Music there are several ways of developing a theme. These include:
- The division of a theme into parts, each of which can be developed in any of the above ways or recombined in a new way. Similarly, two or more themes can be developed in combination; in some cases, themes are composed with this possibility in mind.
- Alteration of pitch intervals while retaining the original rhythm.
- Rhythmic displacement, so that the metrical stress occurs at a different point in the otherwise unchanged theme.
- Sequence, either diatonically within a key or through a succession of keys.
The Scherzo movement from Beethoven's Piano Sonata No. 15 in D major, Op 28 (the "Pastoral" Sonata) shows a number of these processes at work on a small scale. Charles Rosen (2002) marvels at the simplicity of the musical material: "The opening theme consists of nothing but four F sharps in descending octaves, followed by a light and simple I/ii/V7/I cadence with a quirky motif repeated four times." These opening eight bars provide all the material Beethoven needs to furnish his development, which takes place in bars 33-48:
thumb|center|500px| Beethoven Pastoral Sonata Op. 28 Scherzo
Division of a theme into parts
The falling octave in the first two bars and the repeated staccato chord in the left hand in bars 5-8 are the two fragments that Beethoven later develops:thumb|center|500px|Beethoven Scherzo from Piano Sonata 15, thematic fragments used later in the development
Alteration of pitch intervals
The somewhat bald falling octave idea in the first four bars is transformed in bars 33-36 into an elegant shape ending with an upward-curving semitone:thumb|center|500px|Transformation of opening idea
Rhythmic displacement
In this movement, the repeated left hand chords in bar 5 are displaced so that in bar 33 onwards, they fall on the 2nd and 3rd beats:thumb|center|500px|Rhythmic displacement
Sequence and the development of two or more themes in combination
In bars 33-48, the two fragments combine and the development goes through a modulating sequence that touches on a succession of keys;
thumb|center|500px|Beethoven, Scherzo from Sonata No 15, development section
The following outline demonstrates Beethoven's strategic planning, which he applied on a larger scale in the development sections of some of his major works. The bass line traces a decisive progression through a rising chromatic scale:
thumb|center|500px|Harmonic outline of bars 33–49
To quote Rosen again, writing about this movement: "As Beethoven's contemporary, the painter John Constable, said, making something out of nothing is the true work of the artist." that forms the main body of the overture to Mozart's opera Don Giovanni announces the following theme during the initial exposition. It consists of two contrasting phrases: "first determined, then soft and conspiratorial". developing it through repetition in a modulating sequence. The steady plod of the bass line against the sequential repetitions of the "soft and conspiratorial"