Background
A new kind of orchestral composition, the concerto, appeared in the last two decades of the 17th century, and became the most important type of Baroque orchestral music after 1700. The concerto was the synthesis in purely instrumental music of four fundamental Baroque practices: the concertato principle; the texture of a firm bass and florid treble; musical organization based on the major-minor key system; and the building of a long work out of separate autonomous movements.The concerto grosso is probably the most important type of baroque concerto, characterized by the use of a small group of solo instruments, called "concertino" or "principale", against the full orchestra, called "concerto", "tutti" or "ripieni." The concertino usually consists of two violins and continuo (the same ensemble that constitutes the Baroque trio sonatas). The ripieni are a small string orchestra, later occasionally including wind instruments (trumpets, oboes, flutes, horns).
"Concerto grosso" originally signified the "large consort," that is, the orchestra, as opposed to the "concertino" or "little consort," the group of solo instruments. Later, the term "concerto grosso" was applied to the composition which used these opposed groups.
The practice of contrasting solo instruments against full orchestra had been introduced into Baroque music long before the concerto as such made its appearance. A predecessor of the concerto was the sinfonia or sonata for one or two solo trumpets with string orchestra, which was cultivated especially at Venice and Bologna. Various elements of the concerto also may be found in the Venetian opera overtures, which were occasionally played outside the opera house as independent instrumental sonatas.
The circumstances under which orchestral church music was presented were often such as to encourage the concerto style. The church of San Petronio in Bologna, for instance, maintained a small orchestra of expert instrumentalists; when large numbers of extra players were brought in for special occasions, the contrast between the modest technique of the outsiders and the accomplished virtuosity of the regular performers strongly suggested writing that could take advantage of the situation by providing an appropriately different kind of music for each group within the framework of a single composition -- easy parts for the ripieno, more difficult parts for the soloists when heard alone. Concertos, like sonatas and sinfonias, were played in church as "overtures" before Mass or at certain moments in the ceremony.
The earliest known examples of the concerto grosso principle occur in two "Sinfonie a piu instrumenti" by A. Stradella (1653-1713). Some concerti grossi by Corelli, although published much later, would seem to be of a date close to Stradella's, because they show the patchwork structure of the earlier canzona with quick changes of a considerable number of short "movements."
Composers
Arcangelo Corelli - The concerti grossi of Corelli, which are among the earliest examples of the form, employ the principle of solo-tutti contrast; but he did not differentiate in style between the solos and the tutti portions, and these concertos are in effect merely church sonatas or chamber sonatas divided between a small and a larger group of instruments. The "Concerti grossi" op.6 of Corelli, some of which probably date from the 1680s, resemble amplified trio sonatas and could be played by as few as three or four players or by orchestras of over 100. They were imitated by his pupils in Italy and by composers in Germany and England.Giuseppe Torelli - The composer who contributed most to the development of the concerto around the turn of the century was Torelli, the leading figure in the last years of the Bologna school. The most important achievement is the form of his Allegro movements (see Processes below). With his collection, op. 8, the concerto acquires a distinctive style. Published after his death in 1709, the twelve concerti of op. 8 constitute one of the great achievements of the Baroque period. The principle traits that mark the mature concerto are displayed here (see Processes below).
Antonio Vivaldi - The most prolific of the concerto composers, he wrote over 450 various types of concertos. A new trend in concerto grosso style was inaugurated by Vivaldi, who consistently used the three-movement scheme allegro-adagio-allegro and largely discarded the contrapuntal treatment of the earlier masters in favor of a novel style of rhythmic precision and dynamic drive. It was the three-movement solo concerto of the Vivaldi type, with the quick movements usually in ritornello form, that survived the Baroque period and developed into the Classical concerto.
George Frederick Handel - In his Grand Concertos op. 6 (1740), although incorporating elements of Vivaldi's style, retained, like Corelli, the larger number of movements.
Johann Sebastian Bach - In his original works in the concerto medium, Bach leaned greatly upon Vivaldi for the forms and types of opening and slow movements, while he enlarged upon the fugal allegro of the earlier Italians for his last movement. The six Brandenburg Concertos of Bach derive from the type of ripieno and solo concertos composed by Torelli and others at Bologna and by Vivaldi and others at Venice. There are three concerti grossi in the set of six Brandenburg Concertos -- numbers 2, 4, and 5. In vastness of conception and complexity of thematic and contrapuntal relationships they surpass the work of any of the Italians.
This first movements of numbers 2 and 5 follow the Vivaldi model -- the opening tutti present a series of thematic segments from which subsequent tutti are drawn, while the first soli announce an idea that will remain the exclusive property of the soli.
The concertino of number 2, consisting of trumpet, recorder, oboe, and violin, does not merely double the ripieno parts in the tutti but bears its share of thematic content. In Brandenburg number 5, on the other hand, Bach followed the more common practice of letting the concertino of flute, violin, and harpsichord be submerged in the ripieno group during the tutti, the flute remaining silent, the violin joining the first violins, and the harpsichord returning to its normal chordal filling.
Bach's perennial quest for fully integrated designs is everywhere in evidence. The patchy effect risked by having many disparate thematic segments is avoided by keeping a steady rhythmic figure in the bass or by having the parts interchange rhythmic motives.
As Vivaldi was accustomed to do, Bach reduces the orchestra for the slow movement. While number 2 lacks tutti-solo contrast, number 5 is ingenious in using concertato orchestration and contrasting styles (fugal vs. episodic) to preserve the concerto impression.
The final movements of the Brandenburg numbers 2, 4, and 5 are all fugues. As was common in Italy, the tutti play the expositions while the soli are mainly active in the episodes. The most unusual of the fugues is number 5 which is a combination of fugal method, gigue rhythms, concerto contrast, and da-capo-aria form.
Formal Processes
The typical Allegro movement of the concerto was established primarily by Torelli. Each begins with a complete exposition of the theme by the full orchestra; alternating with solo/concertino episodes, the material of the tutti exposition recurs once or twice, slightly modified and in different keys; the movement is rounded off and brought to a close with a final tonic tutti practically identical with the opening one. A tutti which recurs in this way in a concerto is called ritornello; this structure is typical for all first and last movements of late Baroque concertos. The form is something like that of the rondeau, with the important exception that in a concerto all the ritornellos except the first and last are in different keys. The concerto therefore combines the principle of recurrence with the equally important principle of key relationships.Typical traits that mark the mature concerto form of the Baroque are: 1) the fast-slow-fast sequence of movements (allegro-adagio-allegro); 2) the ritornello form; and 3) virtuoso flights of the soloists. An occasional adagio introductory movement might precede the first Allegro movement. Generally, except in the case of Vivaldi, the fast movements are based on the fugal principle. A typical pattern of key-related cadences in an Allegro movement might be: tonic; dominant; tonic; relative minor or major or other related key; subdominant or dominant; and finally, tonic.