The end of the exposition in an aria and concerto, however, has an inescapable ambiguity, which arises from the character of an inner frame: does the enterance of the tutti end the exposition, or begin the development? This is not a quibble about terminology, as there are two ways of starting the second ritornello, one of which faces forward, the other backward: it can start either with the opening theme or with the closing paragraph of the first tutti, now played at the dominant.The former is the older tradition and gives to each of the ritornelli a symmetrical opening. Mozart uses this form in the piano concerto's only once, in K.415; otherwise, he uses the more modern form, and the tutti at this point replays either the closing themes of the first ritornello or the end of the first group (in K.459 the tutti starts, not with the first theme, but with a variant of it in the solo exposition).To open the second ritornello with the first heme at the dominant implies a new beginning: when, on the other hand, the orchestra enters with the closing themes (the more modern technique, developed in the 1760s), it rounds off the solo expotion. In that case, however, one expects a firm cadence on the dominant. If the cadence is withheld, the ambiguity reappears; the apparent rounding-off was a new beginning after all, a beginning underlined by the change from solo to orchestral texture. We can see Mozart rounding off the exposition off in most of the concertos, and Beethoven in his first two.
Topic: Cramer sonatas 