the former tended to employ distinctly harmonic methods in the building up of strong chord-series without conspicuous thematic detail, and the latter often passed over into the homophonic presentation of a melody with accompaniment. Both of these methods offered opportunities not presented by set or strict forms like the suite or the fugue.
The 'sonata' had already passed through several stages before 1700. Of these that of the later 17th century, when the 'sonata da chiesa' was distinguished from the 'sonata da camera,' is specially important. This 'church' sonata, as perfected by Corelli and his contemporaries, was usually written for from one to three solo stringed instruments, with an accompaniment on a figured bass, the material distributed in four movements (sometimes three), alternately slow and quick. Just before 1700 the type was used for the harpsichord as well, so that in the early 18th century sonatas were written either for a solo instrument, especially the violin, or for a very small group of such instruments, or for the clavier alone, the details of treatment differing considerably according to the vehicle adopted. The order of movements, if there were four, was slow, quick, slow, quick, or, if three, quick, slow, quick, and, as a rule, the first quick movement was chief in intrinsic interest. Within the movements, the material was generally presented either in two sections, progressing from tonic to dominant and back again, as in dance-forms, or in three stages of exposition, development and recapitulation, but with no such schematic regularity as in the fugue. The treatment was predominantly thematic, but with a constant tendency to escape from the comparative formality and learning of polyphony and to utilize methods that were homophonic or harmonic. In all this are to be seen premonitions of the method of the later and modern sonata, though the importance of a second subject was not yet generally recognized, nor the need of a comprehensive harmonic plan controlling the process of development (see sec. 146). The total unity was sometimes increased by having some relation between the subjects proposed for treatment in the different movements. But in many cases dance-forms or fugues or variations were used as movements without evident connection with the rest.
The 'concerto' was not sharply distinguishable from the sonata, except in the vehicles of expression used. Originally, concertos were instrumental pieces in which different orchestral instruments or groups of such instruments were employed successively in combination or contrast (whence the name concerto, a working together). Later, the term was limited to works in which a solo instrument, especially a violin, appeared in successive contrasts with a concerted accompaniment, the part of each element being elaborated. In the early 18th century, the name was also given to extended works for either the clavier or the organ alone, or for all sorts of ensembles of orchestral instruments. The number of movements was variable, but tended to be three or four. In the plan and treatment of these there was no constant distinction from the sonata. It was not until the next period that the concerto in precisely its modern sense was undertaken. Yet experiments with the form were contributing to the establishment of the modern type.
