ostinato bass

A repeating bass pattern over which upper voices construct variations — the structural principle of the chaconne and passacaglia. In Buxtehude's three ostinato works (BuxWV 159–161) the bass repeats without interruption while harmony and texture above it evolve through continuous variation.

The bass must be steady and clear — it is the spine of the piece. Every variation should feel like a logical consequence of the last while introducing something new. Plan a long-range dynamic and registral arc. In the Passacaglia BuxWV 161, the central section in the relative major is the emotional high point and should feel like arrival.