The emphasis thus at first seems to be upon conventional ostinato variation: upon the original ground bass
(periods 1-3, 6, 8), or upon the varied ground (periods 4, 9, 10-12, 17-18; see 'Ground bass
' level in table 1).
The opening movement of the Sonata in B[flat] Major, BuxWV 255, is a prime example of Buxtehude's variations on a ground bass
. Over a pulsating bass line in quarter notes, the violin presents improvisatory-like material while at the same time introducing a descending triadic figure that will subtly unify the entire movement.
In the first part, Bach's Organ Passacaglia in C Minor is accompanied by musicologist Robert Greenberg announcing tire variations on a ground bass
. In the second section, we hear the Passacaglia and appended fugue without commentary.