passacaglia

A continuous variation form, principally of the Baroque, whose basso obstinate formulas originally derived from *ritornellos to early 17th-century songs. The passacaglias or ritornellos were played on the guitar between stanzas or at the ends of songs, where they were repeated many times, probably with improvised variations; the practice began in Spain [Sp. pasacalle] and then quickly moved to Italy and France. The passacaglia then developed in a way quite similar to the *chaconne. Its four-bar *ostinato became the basis for long sets of continuous variations as well as vocal pieces (e.g., Frescobaldi, Partite sopra passacagli and Aria di passacaglia). Early differences between chaconne and passacaglia were the particular chord progressions; the passacaglia tended to be in minor, with a I-IV-V or I-IV-V-I pattern. The bass lines themselves might change in successive phrases, or extra harmonies might be inserted, but these variants fell within a limited set of formulas. One of these formulas is the descending tetrachord used in so many operatic laments but appearing as well in pieces titled passacaglia (e.g., Biber, Passacaglia in G minor for solo violin, Mw 11). Bach’s Passacaglia in C minor for organ BWV 582 is perhaps the best-known 18th-century passacaglia and was used as a model by many later composers; its eight-bar obstinate appears in the bass for the first eight and last five variations, but in the ninth through fifteenth it is decorated, ascends in register, and even disappears.