… (sometimes also known as First-movement Form) is characterised by the following features:
1. It is divided into two distinct sections. The first section (the EXPOSITION) is usually repeated (on the linked recording this is from 0’00’ – 2’58”) . The second section (DEVELOPMENT+ RECAPITULATION) may be repeated. On the linked recording the development of from 2’59”- 3’54”; the recapitulation from3’54”- 5’30”)
2. The first or exposition section is characterized by a substantial passage to establish the tonic key (FIRST SUBJECT), a passage modulating to the dominant (V) key (or to the relative major (III) key, if the music started a minor key) known as the TRANSITION, a passage in the new key (SECOND SUBJECT) and closing with a short cadential phrase (the CODETTA), often emphasising the I and the V chords of the new (dominant) key.
Each of the two “subjects” may include more than one musical “theme” (or melodic idea). However, more than three “themes” to one “subject” is very rare. In the first subject of Mozart’s Sonata KV309 there is a fanfare-like theme, a more lyrical theme and a more powerful theme. In the second subject, both the first theme and the second theme are quite short.
3. The second section is characterized by being in two “halves”. The first – and usually shorter – “half” is known as the DEVELOPMENT. The second – and usually longer – “half” is known as the RECAPITULATION.
In the development the music usually becomes more dramatic by freely modulating through a range of new keys. The musical ideas are nearly always taken from the ideas used in the exposition. The dramatic high-point of the movement often occurs at the end of this part, when the music prepares for a return to the opening key (“tonic”) by emphasising the V7 chord again.
In the recapitulation the music of the exposition section returns, usually with the same succession of musical ideas, i.e first subject – transition – second subject – coda. There are, however, three very important differences to the exposition:
- the music of the second subject is presented in the original tonic (I) key – NOT in the dominant (V) or relative major (III) as before;
- to enable the second subject to be presented in the tonic key, the transition is altered to lead us from (keep us in) the tonic key of the 1st subject to the tonic key ot the 2nd subject!!
- to extend the codetta of the exposition (often by alternating I and V7 chords of the tonic (I) key to produce an impressive ending to the music – the CODA.
Other changes, which reflect the way the music has evolved beforehand, may also occur a little unexpectedly. For example, if the development has used many minor keys for dramatic effect, it might be appropriate to bring back one theme in the recapitulation in the minor mode, when it had been heard in the major mode in the exposition, so as not to lose the more intense mood of the development as the music progresses to its conclusion. Which themes of the first subject come back in the recapitulation in the minor mode?