Iacobus Leodiensis [Iacobus de Montibus, Iacobus de Oudenaerde]

(ix) Complete pieces.

Improvisation of complete pieces of music was not new to the Baroque period, but some of the great composer-performers of the era achieved new heights of virtuosity. In the 17th century the organ improvisations of Sweelinck, Frescobaldi and Buxtehude won the admiration of crowds who were attracted from far and wide. Bach is known to have improvised a prelude and fugue, an organ trio in three obbligato parts, a chorale prelude and a final fugue, all on a single hymn tune. Forkel remarked on Wilhelm Friedemann’s impressions of his father’s improvisations at the organ, saying that his organ compositions were indeed

full of the expression of devotion, solemnity and dignity; but his unpremeditated organ playing, in which nothing was lost in the process of writing down but everything came directly to life out of his imagination, is said to have been still more devout, solemn, dignified and sublime.

A famous story that hardly needs repeating tells how in 1747, while visiting Frederick the Great, Bach extemporized a fugue on a ‘royal theme’ given him by the king that he later worked out in his Musical Offering. Two of the rare places in music by (or attributed to) Bach where the performer is allowed some freedom to improvise are seen in the bars of minim chords in the Chromatic Fantasia bwv903 and the semibreve chords that constitute the entire prelude of the keyboard fugue in A minor bwv895.

Handel was equally famous for his improvising, as is attested by Hawkins’s description of his playing of his own organ concertos:

His amazing command of the instrument, the grandeur and dignity of his style, the copiousness of his imagination, and the fertility of his invention were qualities that absorbed every inferior attainment. When he gave a concerto, his method in general was to introduce it with a voluntary movement on the diapasons, which stole on the ear in a slow and solemn progression; the harmony close wrought, and as full as could possibly be expressed; the passages concatenated with stupendous art, the whole at the same time being perfectly intelligible, and carrying the appearance of great simplicity. This kind of prelude was succeeded by the concerto itself, which he executed with a degree of spirit and firmness that no one ever pretended to equal.

Indeed, in the scores of the opp.4 and 7 organ concertos the soloist is frequently directed to play an ‘Adagio ad lib’ or ‘Fuga ad lib’. While Handel’s own improvisatory skills must have been prodigious, the publication of such instructions indicates that he expected no less from his colleagues.

A new type of improvisatory piece called a partimento arose in the Baroque period with the inception of the thoroughbass. In thoroughbass practice both the bass line and the melody are given, while in the partimento only the bass line with figures is given, over which it was the performer’s responsibility to improvise self-contained pieces, character-pieces often called toccatas, and even fugues. Practised mostly in Italy, the partimento is closely related to the English practice of making divisions on a ground (see §(ii) above). Partimento improvisations were cultivated extensively as pedagogical exercises in the later Baroque period, when numerous collections were published by Gaetano Greco, Francesco Durante, Carlo Contumacci, Gaetano Franzaroli and Giuseppe Saratelli.

The art of improvisation flourished to the very end of the Baroque era in the free fantasia. J.S. Petri, in his Anleitung zur practischen Musik (1767), claimed that the fantasia was ‘the highest degree of composition … where meditation and execution are directly bound up with one another’. The whole final chapter of C.P.E. Bach’s Versuch (1753) is devoted to the improvisation of fantasias. A free fantasia is given at the end both in written-out form and as a partimento. The absence of bar-lines emphasizes the freedom of such a composition.

Beyond the feats of the 17th- and 18th-century virtuosos, improvisation was certainly a customary skill among competent, less renowned musicians. Extemporizing over ground basses, for instance, was an essential part of any musician’s training, and the extemporization of dances, suites and even more complex forms was not considered unusual. The incomplete scoring of 17th-century Italian operas seems to indicate that much of the instrumental music was improvised: at many junctures, one finds simply a bass line with two to four cleffed blank staves above it. It is clear that five-part texture (either two violins and two violas with bass, or one violin and three violas of differing sizes with bass) was usual in music throughout Europe, yet few viola parts or viola lines in scores can be found. There is little doubt that these were improvised, particularly given the more aural and less page-orientated training of most musicians of the period; unquestionably musical literacy was not a critical requirement for a practising musician of the day.

Improvisation, §II: Western art music.

4. The Classical period.

(i) Instrumental music.

(ii) Vocal music.

Improvisation, §II, 4: Western art music: The Classical period

(i) Instrumental music.

Performers and composers of the Classical period perpetuated three types of Baroque improvisation: embellishment, free fantasies and cadenzas. (The present article treats the two former; for discussion of the latter see Cadenza.) Although all three practices gradually declined, the universality of their use is confirmed in contemporary reports of concert performances (Burney), in treatises (e.g. by C.P.E. Bach, Manfredini and Türk – who in turn drew from earlier treatises e.g. by Marpurg and Quantz), and in composers' written-out embellishments of their own and others' musical texts. It seems likely also that soloists performing keyboard concertos improvised during orchestral ritornellos.

Reports and histories of the period inveigh against excessive amount and length of improvisation and embellishment. Such polemics confirm that these practices were widespread. Their aesthetic prescriptions are best evaluated in comparison with written-out embellishments, for example those by Haydn and Mozart, and the pseudo-improvised modulating preludes Mozart wrote for the use of his sister Nannerl; such documents show what was actually done (as opposed to what some observers would like to have heard). Of the authors whose treatises contain detailed descriptions of the use and methods of improvisation, C.P.E. Bach is the only one whose music elicits the same respect as his writings; the disparity in proficiency between composers and performers of Haydn's or Beethoven's level and those of, for example, Türk's cannot be overlooked. Nor can the fact that exhaustive treatises often tend to the categorical and pedantic. While writers and composers of the period may have agreed generally on the decisive role of taste, that of the master Classical composers is not necessarily identical with that of their writer contemporaries.