Bach then proceeds to juxtapose passages in the key of D minor with passages in A minor: in the first movement this concerns the first 27 bars; and in the last the first 41 bars. These somewhat abrupt changes in tonality convey the spirit of a more ancient modal type of music. In both movements the "A" sections are fairly closely tied to the ritornello material which is interspersed with brief episodes for the harpsichord. The central "B" sections of both movements are freely developed and highly virtuosic; they are filled with violinistic figurations including keyboard reworkings of bariolage, a technique that relies on the use of the violin's open strings. The "B" section in the first movement starts with repeated note bariolage figures: