THE rondos resemble the song-forms in certain ways. They consist of a chief theme, or main section, which alternates with one or more other sections. The main section, however, is not necessarily a single period. It may be a complete song-form in itself, or may be entirely free in shape. In the old rondos of Haydn and Mozart, and even in those of Beethoven, the themes are usually clean-cut, and each section is in some fairly definite form. Even when this is the case, the rondo differs from the song-forms, for in rondos the first section, or chief theme, is emphasized and made more prominent than in song-forms, all the other sections being brought into definite contrast with it. But in many cases the rondo shows more freedom of shape than the song-forms. When this characteristic is found, it will be seen that a rondo may have its sections blended into a much more unified whole than can be obtained from the song-forms.
The so-called first rondo consists of a main section, a side section, and a return of the main section. The side section and main section may be repeated together, just like the second and third parts of a three-division song-form; and in this case the shape is called first rondo extended by repeats. A coda may always occur at the end of a rondo, or an introduction at the beginning; and the unified character of the rondo often makes transition and returning passages practicable.
As an example of first rondo, the slow movement of Beethoven's first piano sonata (Op. 2, no. 1) may be inspected by the student. It shows a fairly clear structure. The first sixteen measures form a first section. New material makes a clear side section. Then the first section returns, quite clearly, and is prolonged into a coda. Some analysts have called this movement a song-form; but the evidence seems contrary to their verdict. The first sixteen bars seem more like a two-period form than a single period; and if the