passacaglia

A compositional form built on a repeating bass line or harmonic progression, over which the upper voices vary freely. One of the most important structural forms in Baroque keyboard music, the passacaglia evolved from the early 17th-century Spanish and Italian dance tradition into a vehicle for large-scale variations. Frescobaldi's Cento partite sopra passacaglio (100 variations on a passacaglia bass, from the 1637 Aggiunta to Toccate I) is one of the longest and most ambitious keyboard works of the entire Baroque period, lasting approximately 30 minutes in performance. His Passacagli e Ciaccona (from Toccate II) pairs the passacaglia with its close relative the chaconne.

In a passacaglia, the bass is the skeleton and the constant point of reference. Every variation must be understood in relation to both the bass pattern (which rarely changes) and the previous variation (from which each new one should feel like a natural development or contrast). Practise the bass alone until it is completely internalised; then the variations will feel like improvisations above a known foundation. In Frescobaldi's Cento partite, organise the performance into sections by character (lively, melancholy, dance-like, chromatic) to give the work perceptible shape over its great length.