All this musical variety is built into the exposition. The following section, the development, heightens the tensions set up by the contrasting themes and keys of the exposition. The themes are “developed” by being broken up, recombined, reorchestrated, extended, and in general shown in unexpected and often exciting new contexts. Most development sections use counterpoint to create a sense of breakup and turmoil.

This section moves around restlessly from key to key. Its modulations can often be easily heard. The music sounds unstable and less clearly oriented than in the exposition.

After considerable tension has been built up, the last modulation of the development section returns to the first key. The passage that accomplishes this, called the retransition, has the function of relieving the tension and creating a sense of expectancy for the recapitulation to come. Classical composers were amazingly inventive in finding ways to make this crucial juncture of the form seem fresh, logical, and inevitable.