On 7th July 1747 Bach's son, Carl Philipp Emanuel, harpsichordist to King Frederick the Great, presented to his employer, in his father's name, an engraved copy of The Musical Offering. Bach had dedicated the work most submissively to His Royal Majesty of Prussia, after having been prompted to compose it by his visit to Potsdam. The 'royal theme', which, on that occasion, 'would not work out properly' had now been 'worked out with greater perfection' and Bach now wanted to make it known to the world through this publication.

To the dedicatory copy Bach also added the title: Regis Iussu Cantio Et Reliqua Canonica Arte Resoluta (By command of the King, the theme and the rest worked out in canonic style). The first letters spell the word Ricercare, and this acrostic denotes the main feature of the work, the 'continual seeking out' of the royal theme, in all conceivable forms of the art of variation.

The composer left little in the way of instructions as to the order of the thirteen movements of the work or their instrumentation.

The ten canons fall into two groups. In the first the theme appears as a canto fermo, an independent canon, in two parts in each case, developing in combination with it. In the Canon perpetuus super Thema Regium, the canto fermo lies, abridged, in the middle voice, entrusted to the violas, entwined in canon at the double octave with oboe and bassoon; the canto fermo then appears in its normal form in the lower voice in the next canon, and again changes in shortened form to the upper part, given here to the flute, in the third canon, accompanied by a canon in contrary motion. The next two are characterized by remarks that Bach himself adds in explanation: Notulis crescentibus crescat Fortuna Regis (As the note-values increase so may the fortune of the King) is added to the Canon 4. a 2 per Augmentationem, contrario Motu (Canon for two voices in augmentation and contrary motion). The theme is ornamented and embedded in augmented form in a mirror canon. This is followed by an even more complicated circle canon: Ascendente Modulatione ascendat Gloria Regis (As the modulation moves upward, so may the King's glory).

In the second group of canons the canonic melody develops from the royal theme itself. The number or voices varies; the Canon a 4 is a particularly fine-sounding four-part canon; in the Fuga canonica in Epidiapente (Canonic Fugue at the Upper Fifth) a two-part canon appears, extended, as it were, into a three-part fugue. After these displays of contrapuntal skill, there follows a puzzle canon, noted in one part only. Qul Erendo invenietis (Seek and ye shall find), writes Bach, over the Canon, contrarium stricte reversum (Canon in strict retrograde), leaving the performer to find for himself the correct point of entry for the second voice. Our recording proposes four distinct possibilities. Of these the common interpretation, here with cor anglais and bassoon, comes last; this is preceded by aversion with the strictly reversed canon in the violas; in our first version, which is similar to the last, the first voice, the cello, starts one octave lower, while the following voice, the harpsichord, is played one octave higher, thus changing the soprano voice into a bass and the 'strictly reversed' bass into a soprano. In the second version these two voices exchange entries, the soprano, in the violas, one octave higher, begins and the bass, one octave lower in the cellos, follows. After this comes a two-part Canon cancrizans and, ending the group, the Canon perpetuus, where the flute and violin playa canon in contrary motion with continuo accompaniment.

The central place in The Musical Offering is occupied by the Trio Sonata, for which Bach, probably with the King in view, specified the instruments Flauto traverso. Violinoe Basso continuo (Violoncello o Viola da gamba col Cembalo). In four movements, Largo-Allegro-Andante-Allegro, the royal theme is presented in a variety of guises.

Writer: Keith Anderson