The Musical Offering

The Ricercar a 6, a six-voice fugue which is regarded as the high point of the entire work, was put forward by the musicologist Charles Rosen as the most significant piano composition in history (partly because it is one of the first).

The meeting, taking place at the king's residence in Potsdam, came about because Bach's son Carl Philipp Emanuel was employed there as court musician.

[citation needed] Bach instead chose a different theme and, again completely extempore, executed a six-voice fugue on it with the same virtuosity as he had done the three-voice one, greatly impressing all in attendance.

[6] Bach inscribed the piece "Regis Iussu Cantio Et Reliqua Canonica Arte Resoluta" (the theme given by the king, with additions, resolved in the canonic style), the first letters of which spell out the word ricercar, a well-known genre of the time.

Sassoon notes that "Handel's theme is much shorter than the King's, but its musical 'architecture' is uncannily similar: jumps followed by a descending chromatic scale."

[8] In its finished form, The Musical Offering comprises: Apart from the trio sonata, which is written for flute, violin and basso continuo, the pieces have few indications of which instruments are meant to play them, although there is now significant support for the idea that they are for solo keyboard, like most of Bach's other published works.

The ricercars are more frequently performed on keyboard than the canons, which are often played by an ensemble of chamber musicians, with instrumentation comparable to that of the trio sonata.

One of these riddle canons, "in augmentationem" (i.e. augmentation, the length of the notes gets longer), is inscribed "Notulis crescentibus crescat Fortuna Regis" (may the fortunes of the king increase like the length of the notes), while a modulating canon which ends a tone higher than it starts is inscribed "Ascendenteque Modulatione ascendat Gloria Regis" (as the modulation rises, so may the king's glory).

The main title, Opfer (“offering”), makes it possible for the cycle to be viewed as an Offertory in the religious sense of the word.

Ursula Kirkendale[11] argued for a close connection with the twelve-volume rhetorical manual Institutio Oratoria of the Roman orator Quintilian, whom Frederick the Great admired.

[13] Igor Markevitch produced a realization for three orchestral groups and, for the sonata movements, solo quartet (violin, flute, cello, and harpsichord), written in 1949–50.

The Modern Jazz Quartet used one of the canons (originally "for two violins at the unison") as an introduction to their performance of the standard song "Softly, as in a Morning Sunrise", on their album Concorde (1955).