Rondo, a musical form originally derived from the rondel in verse; as may be seen, long before the development of instrumental forms, in some of the chansons of Orlando di Lasso. The rondeau en couplets of Couperin and his contemporaries shows both in name and form the same connexion with verse. It consists of the alternation between a single neatly rounded phrase and several slightly contrasted episodes (the couplets) without any important change of key. Bach enriched it with his wealth of epigram, but did not expand its range.
The later sense of the term covers an important series of the sonata forms, chiefly found in finales; but rondo-form sometimes occurs in slow movements (e.g. Mozart, Haffner Serenade, String Quintet in E flat; Beethoven, Fourth Symphony; Quartet, Op. 74, &c.). The single-phrase ritornello and short couplets of the old form are in the sonata style replaced by a broadly designed melody and well-contrasted episodes in different keys.
If the form of a Bach or Couperin rondo may be represented by A B A C A D A, &c., the various forms of the later rondo may be represented somewhat as follows: placing on a horizontal line those parts that are in the main key, and representing other keys by differences of level: (i) Sectional rondos; i.e. with little or no development or transition between episode and main theme; very characteristic of Haydn, who, however, often gives it more organization B than appears on the surface - A A A coda; very rarely C with no change of key except between tonic major and minor, as in Haydn's famous Gipsy Rondo. Frequently the episodes are increased in number or made to recur. Beethoven most clearly shows the influence of Haydn in his frequent use of modifications of this type of rondo in his earlier works, e.g. finales of Sonatas, Op. so, No. 3, Op. 14, Nos. 1 and 2. He also applied it very successfully to his early slow movements, as in the Sonatas, Op. 2, No. 2, and Op. 1 3 (Pathetique). The sectional rondo was modernized on a gigantic scale by Brahms in the finale of his G minor Pianoforte Quartet, Op. 25; and Schumann's favourite art-forms are various compounds between it and the cognate idea of the dance-tune with one or more "trios," as in the Novellettes, the Arabeske, and the Romance in B major.
(ii) Rondos influenced by the form of a first movement (for which see Sonata Forms). The normal scheme for this, which B is Mozart's favourite rondo-form, is A A A B A coda, C and it is easy to see how it may be applied to sectional rondos, as in the finale of Beethoven's Sonata, Op. 13. But it normally implies longer and weightier themes and a higher degree of organization. If the second episode (C) is transformed into an elaborate development of previous material in various keys, the resemblance to first-movement form is increased; the only external difference being the recurrence of A in full after the first episode B (which is treated exactly like the "second subject" of a first movement). As, however, many first movements that do not repeat their exposition (corresponding to A+ B in the above rondo-scheme) make a feint of so doing before beginning the development, it is obvious that the blending of rondo and first-movement form may become very. complete. In fact, the true criterion of a rondo is, as with all real art-forms, a matter of style rather than of external shape. The well rounded-off, self-repeating, tune-like character of the main theme, and a sense of pleasure and importance in the mere fact of its return (without absolute necessity for dramatic effect) are the distinctive evidences of rondo form and style. This rule is well proved by the case most frequently cited as an exception, the rondo of Beethoven's Sonata in D, Op. 10, No. 3; for nothing can be more significant than the way in which its fragmentary opening figure is built up into a self-contained musical epigram and ended with a full close, as contrasted with the way in which the most tuneful of first-movement beginnings (e.g. Beethoven's Quartet in F major, Op. 59, No. 1, Trio in B flat, O. 97; Brahms's String Quintet in F major, Op. 88) expand gradually into their further course.
The following are some of the more important of many modifications and applications of this form (a) Omission of return of main theme before recapitulation of B episode - A A development - in various keys, B A coda - as in Beethoven's G major Concerto, where, however, much happens between the recapitulation of B and the following return of A, and the coda is nearly as long as all that has gone before.
B (b) A A B (A) like a first movement without a development. Here A will be very large and the transition to B important, while B will consist of a considerable number of themes. See the finales of Mozart's E flat String Quartet and C major Quintet, most of his greater slow movements, and many of Beethoven's.
In concertos the only modifying influence the balance between solo and orchestra shows in rondo-form is in the tendency to give the orchestra a large number of subsidiary themes at the outset, which perhaps do not reappear until the coda, where, with the aid of the solo, they can round off the design very effectively. Mozart's use of this device is not confined to concertos. (D. F. T.)
