Johann Sebastian Bach's Concerto for solo keyboard No. 4 in G minor (BWV 975) is one of several solo concertos, all from 1713-1714, that Bach based on concertos by Antonio Vivaldi. These transcriptions were undertaken during Bach's Weimar period, at the behest of Prince Johann Ernst. The Prince, having been impressed by the keyboard realizations of Italian concertos by organist Jan Jacob de Graaf, commissioned several concerto transcriptions from Bach as well as the composer's cousin John Walther, providing them with manuscripts and publications he had collected during his travels. Vivaldi is the most well-represented composer of Bach's concerto transcriptions, but the 16 works in this collection also include keyboard realizations of works by Torelli, Marcello, and Prince Johann Ernst himself. The solo concerto BWV 975 is unique among the collection, however, in that the Vivaldi concerto upon which it is based, Op. 4/6 (RV 316), no longer exists in the form from which Bach adapted it. A later version of Vivaldi's original (RV 316a) survives, but with a different third movement. Bach's transcription of the piece is thus the only remnant of the Vivaldi work as it was originally structured. (Three other of the 16 concertos are of unknown provenance and attribution.) As in the other works in this collection drawn from violin concertos, the solo concerto BWV 975 makes certain idiomatic adjustments in rendering the solo lines. The obvious textural contrasts of tutti vs. solo passages are rendered through contrasts between more chordal and more economical voicings. There are certain passages whose physical contours suggest their emerging from an instrument other than the one playing them; after the second tutti section of the first movement, for example, the right hand enters with a sequence of downward skips that are subsequently filled in with quick thirty-second notes in a manner suggesting nimble fingerboard work, germane to violin virtuosity and slightly out of place on the keyboard. On the other hand, in translating from one instrument to another, Bach widens the keyboard's palette of textures and contours. Likewise, in striving for the fluid emotional intensity of the violin in the second movement, Bach's transcription lends the harpsichord an unusually poignancy. The third movement (the one not surviving in Vivaldi's original), rides along on an extrovert and nearly unbroken stream of rapid eighth notes in a quick and delightful "Giga."

© Jeremy Grimshaw, All Music Guide