 Sometimes the exposition starts with one of these new themes (in piano concertos Nos.9, 20, 22, 24, and 25), but the exposition can also start by restating one of the prelude themes.In addition to the preludial and expositional themes, the exposition typically contains various free sections that show off the piano; but, contrary to the popular conception of the piano concerto, and to how it developed in the nineteenth century, these sections are not merely empty displays, but rather, short sections that fit into the overall scheme.