RONDO, a musical form originally derived from the rondel in verse; as may be seen, long before the development of instru mental forms, in some of the chansons of Orlando di Lasso. The rondeau en couplets of Couperin and his contemporaries shows the same connection with verse. It consists of a single neatly rounded phrase alternating with several episodes (the couplets) without any important change of key. Ex. 1 shows Bach's han dling of this early form. The later rondo is an important member of the sonata forms (q.v.), chiefly found in finales; but rondo form sometimes occurs in slow movements. Ex. 2 is not more elaborate than the adagio of Beethoven's 4th symphony. Philipp Emanuel Bach invented an extraordinary kind of rondo, not part of a sonata, but on a voluminous scale with wildly incoherent episodes and modulations.
The later sonata-style rondo forms may be divided into two main classes: (i.) Sectional rondos; i.e., with little or no development or transition between the episodes and the main theme; very char acteristic of Haydn, who, however, may run away with it in un expected developments. The name rondo implies at least two episodes, and a sectional rondo may have more. Beethoven in his early works shows the influence of Haydn in this type of rondo ; e.g., the finales of sonatas, opp. Io, No. 3, and 14, Nos. 1 and 2 ; and the slow movements of the sonatas, opp. 2, No. 2, and 13 (Pathetique). The sectional rondo last appears on a gigantic scale in the finale of Brahms's G minor pianoforte quartet, op. 25; and it lends itself, like the cognate idea of a dance with several "trios" to Schumann's pianoforte pieces and to some of his finales.
(ii.) Rondos influenced by the form of a first movement (for which see SONATA FORMS). In the normal scheme for this, which is Mozart's favourite rondo-form, the rondo-theme (which may contain several clauses) is followed by a well-organized transition to the key of the first episode, which key is chosen as if for the "complementary key" of a first movement. The return to the rondo-theme may be elaborate or abrupt, and the theme itself may be reduced to its first complete clause (but not to a mere fragment, without loss of the rondo effect). The second episode
will be in a new key and may be followed by wide modulations, or itself be widely modulatory, or it may even be entirely a development of the previous material, as in the rondo of Bee thoven's Sonata Op. 90, given on p. 525. When the rondo-theme returns again it is followed by a recapitulation of the first episode (perhaps preceded by the transitional passage suitably modified) in the tonic; after which the coda may contain a final return of the rondo-theme. When the second episode is concentrated on development the only difference between the rondo and a first movement is the slender fact that the whole first theme returns immediately after the first episode. Yet the rondo style can be recognised from the outset by the tunelike character of the main theme, and also by the fact that, unlike the most tuneful open ings of first movements, it comes to a definite close instead of swinging continuously into the transition passage. A rondo with a development in its middle episode may return to the tonic with an immediate recapitulation of the first episode, omitting the expected second return of the main theme, thus : A, B (new key), A, C (development), B (tonic), A, Coda (where A is the rondo-theme and B and C the episodes). Mozart, Schubert and Brahms have a form, always worked on a very large scale, which consists only of A, B (new key), A, B (tonic), Coda; where a certain amount of development is edged in a propos of the transition-passage on its recapitulation. Only the style of the main theme can distinguish this from a first movement that omits its normal development-section.
In the rondos of classical concertos (q.v.) the orchestra (espe cially in Mozart) finds its opportunity in a series of accessory themes announced as soon as the solo instrument has given out the rondo-theme. These accessories are then held in reserve for the coda.
Two examples of rondo-forms are given on pp. 524-6:—