Term, short for ‘basso continuo’, to denote the continuous bass part - hence the term - that runs through a concerted work of the Baroque period (also the late Renaissance and the early Classical period) and serves as a basis for harmonies. The term ‘thoroughbass’ (or ‘throughbass’) has the same meaning. Continuo parts may be figured to indicate to the player what harmonies might appropriately be added above; often they are unfigured and the choice of harmonies is clear to a capable player. The practice of continuo playing arose at a time when music was coming increasingly to be conceived in terms of harmonic progression, with a melody line or lines underpinned by a bass line and supporting harmony.
The term probably came into use because of its coining by one of the early exponents of the practice, Viadana, in the title of his Cento concerti ecclesiastici ... con il basso continuo (1602). The practice of continuo playing was closely linked with the growth of recitative and certain kinds of solo music, both vocal (monodies, arias) and instrumental (violin sonatas etc).
A continuo accompaniment may be ‘realized’ (the term for its interpretation and performance) in many different ways, depending on the kind of work and the context of its performance. Many theorists and composers of the Baroque period discussed in treatises and instructions books the ways in which accompaniments should be played: whether in full chords or more slender ones, whether in a contrapuntal style with imitation, in what register etc. The instrumental forces were often indicated by the composer. For sacred music, the use of an organ was often presumed. For chamber or orchestral music, a harpsichord was usually considered appropriate, though for small-scale ensembles, especially early in the period, and for the accompaniment of songs, a lute-type instrument (theorbo, chitarrone, archlute) would usually be preferred. In music where the bass part plays an active role in tile contrapuntal texture, a sustaining instrument (particularly if an organ was not in use) would be appropriate - a cello, bass viol, violone or a bassoon, for example, depending on the instruments used in the upper voices. Often more than one instrument capable of realizing the harmony would be used, particularly in a larger ensemble (e.g. a harpsichord and a theorbo together). The most famous example of a multiple ensemble is in Monteverdi's Orfeo (1607), where the composer specified two harpsichords, three chitarroni, harp, regals and two organs: this selection would allow the players to choose at any point instruments appropriate to the dramatic context. In a concerto of the late Baroque period, separate continuo instruments would generally be used for the ripieno and the concertino, for example an organ and a harpsichord or a harpsichord and a lute; the choice would be dictated by local traditions and circumstances.
The system of figures placed above (usually; sometimes below) the bass notes told a player, in general terms, what harmonies to play. These were indicated in terms of the intervals above the bass note. The absence of figures implied a root-position chord (which could be indicated &sup5; &sub3;); the figure 6 (or &sup6; &sub3;) meant a first inversion. Figures above 9 were used in the early Baroque period but were later abandoned in favour of their equivalents an octave lower (e.g. 4 would replace 11). Notes were realized diatonically unless otherwise indicated: this could be done with a flat or sharp sign, or sharpening could be specified by a stroke through part of a figure. Horizontal dashes meant that the last indicated harmony should be sustained. A simple flat or sharp sign meant that the 3rd above the bass should be flattened or sharpened.
By the mid-18th century, treatises indicated that continuo parts should generally be realized in four-part harmony; and the study of thoroughbass began to be used as a method of studying harmony (as it still is). With the increasing elaboration of orchestral and chamber writing during the Classical period, all the notes necessary for the harmony and the texture were written into the music and continuo playing became less important - though it should be noted that Mozart expected the pianist to play in the orchestral sections of his piano concertos, and Haydn directed his later symphonies (in the 1790s) from the piano. As late as 1849 Bruckner wrote figures to the organ part in his Requiem.
The Concise Grove Dictionary of Music. Copyright © 1994 by Oxford University Press, Inc.. All rights reserved.
