A Dictionary of Music and Musicians/Ground Bass
GROUND BASS [App. p.658 "(Ital. Basso ostinato)"]. The most obvious and easily realisable means of arriving at symmetry and proportion in musical works is by repetition, and a large proportion of the earliest attempts in this direction took the safe side of making the symmetry absolute by repeating the same thing over and over again in the form of variations; and of this order of form a Ground Bass, which consisted of constant repetition of a phrase in the Bass with varied figures and harmonies above it, is a sub-order. At an early period of Modern Music this was a very popular device, resorted to alike by Italians, such as Carissimi and Astorga, and by our English Purcell. In the works of Purcell there are a great number of examples, both in his songs in the Orpheus Britannicus, and in his dramatic works, as in the Dido and Æneas, in which, though not a lengthy work, there are three songs on a Ground Bass; the best of which 'When I am laid in earth,' has often been pointed out as a fine example. An expansion of the idea was also adopted by him in the 'Music before the play' of King Arthur, in which the figure after being repeated many times in the bass is transferred to the upper parts, and also treated by inversion. Bach and Handel both made use of the same device; the former in his Passacaglia for Clavier with Pedals, and the 'Crucifixus' of his Mass in B minor; and the latter in his Choruses 'Envy eldest-born of Hell' in Saul, and 'O Baal monarch of the skies' in Deborah. In modern times Brahms has produced a fine example in the Finale to the Variations on a Theme of Haydn in B♭ for Orchestra.
At the latter part of the 17th century Ground Basses were known by the names of their authors, as 'Farinell's Ground,' 'Purcell's Ground,' etc., and extemporising on a Ground Bass was a very popular amusement with musicians. Christopher Simpson's 'Chelys Minuritionum, or Division Viol' (1665), was intended to teach the practice, which he describes as follows—'Diminution or division to a Ground is the breaking either of the bass or of any higher part that is applicable thereto. The manner of expressing it is thus:—
'A Ground, subject, or bass, call it what you please, is pricked down in two several papers; one for him who is to play the ground upon an organ, harpsichord, or what other instrument may be apt for that purpose; the other for him that plays upon the viol, who having the said ground before his eyes as his theme or subject, plays such variety of descant or division in concordance thereto as his skill and present invention do then suggest unto him.'
A long extract and a specimen of a 'Division, on a Ground' are given in Hawkins's History, chap. 149. [App. p.658 "See an example of a ground bass of four minims only, accompanying a canon 7 in 1, by Bach, in Spitta's Life, iii. 404."][ C. H. H. P. ]