CONCERTO, in music, a term which appears as early as the beginning of the i7th century, at first with vague meanings, but soon acquiring a sense justified by its etymology (Lat. concertus, from certare, to strive ; also confused with concentus), being ap plied chiefly to compositions in which unequal instrumental or vocal forces are brought into opposition.
Although by Bach's time the concerto as a purely instrumental form was thoroughly established, the term frequently appears in the autograph title-pages of his church cantatas, even when the cantata contains no instrumental prelude. Indeed, so entirely does the actual concerto form, as Bach understands it, depend upon the opposition of masses of tone unequal in volume, with a com pensating inequality in power of commanding attention, that Bach is able to rewrite an instrumental movement as a chorus without the least incongruity of style. The very title of his secular cantata, Vereinigte Zwietracht der wechselnden Saiten ("united contest of turn-about strings"), is a perfect definition of the earlier form of concerto grosso, in which the chief mass of the orchestra was opposed, not to a mere solo instrument, but to a small group called the concertino; unless, indeed, the whole work was for a large orchestral mass in which tutti passages alternate with passages in which the whole orchestra is dispersed in every possible kind of grouping.
But the special significance of this cantata is that its first chorus is arranged from the second movement of the first Brandenburg concerto and that, while the orchestral material is merely trans posed and arranged for larger forces, the whole four part chorus has been evolved from the solo part for a kit-violin (violino piccolo). This shows that the true relation between the opposed factors in a concerto depends not on volume of sound, but on power to command attention.
A convenientiy isolated individual will command more attention than the crowd, whether in real life, drama, or instru mental music. But in music the human voice, with human words, will thrust any orchestral force into the background, whether the voice be individual or choral. The full chorus is the equivalent of the kit-violin and the kit-violin is the equivalent of the full chorus because both assert personality against the orchestra.
Hence the polyphonic concerto is fundamentally identical with the vocal aria, as matured by Alessandro Scarlatti. The orchestra is entrusted with a short pregnant summary or ritornello of the main contents of the movement, and the solo, or the groups cor responding thereto, will either take up this material or first intro duce new themes to be combined with it, and, in short, enter into relations with the orchestra very like those between the actor and the chorus in Greek drama. The polyphonic concerto, the vocal aria, and the forms of many of Bach's choruses, even including some that contain fugues, ought to be classed under the head of ritornello forms. (See ARIA.) Many of Bach's larger movements for solo instruments without orchestra will at once reveal the proper lines of their interpretation in the light of ritornello form. The harpsichord, no less than the organ, can obviously imitate contrasts between solos and tuttis with excellent effect.
In slow movements of concertos Bach uses the ground bass (see VARIATIONS), diversified by changes of key (klavier concerto in D minor), the more melodic types of binary form, sometimes with the repeats ornamentally varied or inverted (con certo for 3 klaviers in D minor, concerto for klavier, flute, and violin in A minor), are found besides aria-form on the aria scale. In finales the rondo form (violin concerto in E major, klaviec concerto in F minor) and the binary form (3rd Brandenburg con certo) may be fourid.
When musical forms changed to those of the dramatic sonata style the problems of the concerto proved ridiculously easy to ordinary musicians and the tasks of the highest interest to the greatest composers. Bach's sons took important new steps. Philipp Emanuel Bach developed a romantic rhetoric. Johann Christian, the "London" Bach, initiated the all-important method of empha sizing a change of key so that it became a dramatic event irrevers ible except by other dramatic developments. Mozart, as a boy, modelled himself closely on Johann Christian Bach, and by the time he was 20 was able to write concerto ritornellos that gave the orchestra admirable opportunity for asserting itself by the statement, in charmingly epigrammatic style, of some five or six sharply contrasted themes, afterwards to be worked out with additions by the solo, with the orchestra's co-operation and inter vention.
The problem changes rapidly as the scale of the composition grows. On a large scale a too-facile alternation between solo and tutti produces forms too sectional for the high organization re quired in first movements; yet frequent alternation is evidently necessary, as the solo is audible only above a very subdued or chestral accompaniment, and it would be inartistic to confine the orchestra to that function. Hence in the classical concerto the ritornello is never in spite of the enormous dimensions to which the sonata style expanded it. Mendelssohn and most later composers evidently see in it only a conventional impediment easily abandoned. Yet its absence reduces the whole style to a more theatrical and lighter art-form. Hence it is restored to its place not only by Brahms in his four magnificent examples, but by Joachim in his Hungalrian concerto and by Elgar in his violin concerto. The danger in so long an orchestral prelude is that the work may for some minutes be indistinguishable from a symphony and thus the entry of the solo may be unexpected without being inevitable. This will happen if the composer treats his tutti so like the exposition of a sonata movement as to make a deliberate transition from his first group of themes to a second group in a complementary key, even if the transition be only temporary— as in Beethoven's C minor concerto. But Beethoven's C minor concerto is the one which Spohr and Hummel and even Joachim took as their model, and thus the true solution of the problem remained for Brahms to rediscover.
Mozart keeps his whole tutti in the tonic, relieved only by his mastery of sudden subsidiary modulation. Beethoven, in turn, after the C minor concerto, grasped the true function of the opening tutti and enlarged it to his new purposes. With an inter esting experiment of Mozart's before him, he, in his G major concerto, Op. 58, allowed the solo player to state the opening theme, making the orchestra enter pianissimo in a foreign key. In this concerto he also gave variety of key to the opening tutti by means of an important theme which modulates widely, an entirely different thing from a deliberate modulation from ma terial in one key to material in another. His fifth and last piano forte concerto in E flat begins with a rhapsodical introduction for the solo player, followed by a long tutti confined to the tonic major and minor with a strictness explained by the gorgeous modulations with which the solo subsequently treats the second subject. In this concerto Beethoven also organizes the only un digested convention of the form, namely, the cadenza, a custom elaborated from the operatic aria, in which the singer was allowed to extemporize a flourish on a pause near the end. A similar pause was made in the final ritornello of a concerto, and the soloist was supposed to extemporize what should be equivalent to a symphonic coda. Cadenzas are, to this day, a form of musical appendicitis, since the player (or cadenza-writer) cannot be the composer himself and is rarely so capable of entering into his intentions as Joachim, whose written cadenzas for classical violin concertos are unsurpassable.
Brahms's first concerto in D minor, Op. 15, was the outcome of many changes and, though on a mass of material originally intended for a symphony, was nevertheless so perfectly assimilated into concerto form that in his next essay, the violin concerto, Op. 77, he had no more to learn and was free to continue making true innovations. He found out how to include wide key contrasts in the opening tutti, thus giving the form a wider range in def initely functional key than any other instrumental music. Further, it may be noted that in this work Brahms develops a counter plot in the opposition between solo and orchestra; giving not only the development by the solo of material stated by the orchestra, but also a counter-development by the orchestra of material stated by the solo. This concerto is, on the other hand, remarkable as being the last in which a blank space is left for a cadenza ; a testimony of confidence in Joachim. In the pianoforte concerto in B flat, and in the double concerto, Op. 102, the idea of an introductory statement in which the solo takes part before the opening tutti is carried out on a large scale, and in the double concerto both first and second subjects are thus suggested.
The forms of slow movements and finales in classical concertos, though often treated in special ways, present no general principles peculiar to the concerto ; for a sectional opposition between solo and tutti is not of great disadvantage to slow movements and finales. The scherzo, on the other hand, is normally too sectional for successful adaptation to classical concerto style, and the solitary great example of its use is the second movement of Brahms' B flat pianoforte concerto, a movement in a very special form.
The post-classical concertos, in which the first movement dis penses with the opening tutti, began with Mendelssohn, whose violin concerto dominates the whole subsequent history of the form. The happy idea of putting a cadenza at the dramatic crisis of the return after development instead of in the coda has almost become a convention. The other movements of concertos have not been affected by Mendelssohn's changes, nor does the linking of all three movements uninterruptedly together make any essen tial difference to the scheme. But there is no limit to the expansion or reduction of the first movement. Spohr reduces it to an accom panied recitative in his Gesangs-scene, a work in which he dis covered that a concerto could be an aria, which astonished him as the swimming of ducklings astonishes the fostering hen. Bruch's famous G minor concerto (not his only interesting experiment in new concerto-forms) also reduced the first movement to dra matic gestures without dramatic action. On the other hand, the huge first movement of Schumann's pianoforte concerto was originally intended to stand alone under the title of Fantasia. This example would cover the case of most first movements of this size in modern concertos, whether like Schumann's they have "second subjects" and recapitulations or not.
The case where the concerto as a whole is a fantasia (as with Liszt) needs no discussion. Another line has been struck out by Saint-Saens, most neatly in his first violoncello concerto; namely, that the whole work is one movement, but that after an exposition comprising a "first" and "second" subject the development drifts into a slow movement (or scherzo), and this is followed by a finale of which the matter is partly independent and partly a re capitulation completing the first movement. In his C minor pianoforte concerto Saint-Saens begins with a theme with vari ations and proceeds with a slow second theme, followed by a scherzo and finale which transform their own and the previous materials in various effective ways. But really the term Fantasia would adequately cover all post-classical forms of concerto. The only modern meaning of the word is "composition for one or more solo players with orchestra"; and no special aesthetic or formal questions remain to be considered within the limits of this article.
(D. F. T.)