The origins of “The Musical Offering” are closely connected with Bach’s memorable visit to the court of Frederick II of Prussia in Potsdam. This event is one of the few outstanding highlights of Bach’s biography, which is not exactly rich in spectacular happenings. Undoubtedly it was also the culminating point of Bach’s public recognition when several North German newspapers published an identical detailed report on the Thomas cantor’s meeting with the king on 7th May, 1747: “In the evening, at about the time when chamber music was usually want to be played in the royal apartments, His Majesty was informed that Kapellmeister Bach had arrived in Potsdam and was now waiting in the ante-chamber for gracious permission to be allowed to listen to the music. His Majesty personally gave immediate orders for him to be admitted, and when he had entered, crossed to the so-called Forte and Piano and without any preparation condescended to play a theme to the Kapellmeister which the latter was to play in extemporised fugal form. This was performed by the aforementioned Kapellmeister in such a wonderful manner that not only His Majesty was gracious enough to express his pleasure, but also all the others present were amazed. Herr Bach considered the theme set to him such a paragon of beauty that he intends to write it as a proper fugue and afterwards to have it engraved in copperplate.” The newspaper report describes here in terse, but impressively descriptive phrases the beginning of the history of Bach’s last chamber music work in a manner which has never remotely been achieved with regard to his other compositions. The nucleus is formed by the theme drafted by the king, which as a combination of two traditional soggetto models was consciously chosen as a difficult piece and was assuredly taken up by Bach without any substantial change. To be sure, the “Thema regium” in its musical diction bears the unmistakable Bach hallmark. It is not hard to imagine how the theme provided by the king might have sounded in its original form: Music example No. 1. The ascending minor triad with descending diminished seventh chord leap (a) as well as the chromatic tetrachord (b) are not original inventions, but were common musical knowledge since the 17th century. The king was therefore able without any preparation to revert to this material, with which he must have been acquainted. The organic assembly of the two heterogeneous elements, however, was probably Bach’s idea, whereby the joining seam between the two soggetti is rhythmically rearranged (x) and by the extended insertion (y) of the thematic conclusion takes on dynamic contours (music example No. 2). To what specific extent Bach edited the theme, however, is beyond speculation, although it is worth considering what actually lends the “Thema regium” Bachian significance and flavour.

This theme, considered such a “paragon of beauty”, saw its first development in the improvised fugue as it probably existed in the ternary form ricercar in the subsequently elaborated shape; traces of the free paraphrasing between the less concentrated exposition parts of the fugue movement can still be clearly seen from the ricercar. Immediately following the Potsdam improvisation Bach will also have conceived the plan of submitting at least this fugue in print. The expanded project in the sense of a several-part monothematic instrumental work must have taken on firm outlines afier Bach’s return from the journey. The Potsdam events still have a lasting effect in the wider concept of the work; for the six-part ricercar is nothing else but the subsequently delivered “fugue with six obbligato parts” requested by the king at that time, the improvision of which Bach (according to the report of the obituary writer in 1754) felt capable of approaching only with a self-chosen theme. The trio sonata is understood as a special gift to the flute-playing monarch to enrich his chamber music repertoire. The ten canons are exemplary samples of Bach’s contrapuntal craftmanship which had apparently called forth the king’s admiration. Bach completed the entire opus in a comparatively short time, for as early as the end of September, 1774 he was in a position to insert a publisher’s advertisement in the newspapers: “Since the ... promised Royal Prussian fugue theme is now being printed; it is hereby announced that it can be obtained at the impending St. Michaels fair as well as from the author, Kapellmeister Bach, as well as from his two sons in Halle and Berlin... The elaboration consists 1.) of two fugues, one with 3 the other with 6 obligato parts; 2.) of a sonata, à traversa, violin e continuo; 3.) in various canons, one being a canonic fugue.”
The complete work therefore comprises various solo and ensemble pieces, with each individual setting based upon the “Thema regium.” It was Bach’s aim to treat this theme in the most varied manner, from the free setting to the strictest contrapuntal entity without regard to a unified tonal medium. This diversity is also reflected in the external appearance of the original printing in 1747, made up of three fascicles and consisting of single pages and sheets, presenting the musical contents in varying notation styles: piano notation (ricercar a 3), open score (ricercar a 6), additional parts (sonata) and encoded mystery notations (canons). Bach evidently did not place any importance upon an overall order or binding movement sequence, since he did not intend to conceive the work as a cyclic grand form. Modern performances of the collection therefore have to find their own solutions.
As can be assumed from the advertisement previously referred to, three groups of arrangements of the “Thema regium” can be distinguished.
(1) The two fugues: these are called “ricercar” (an exception in Bach’s fugal works) because the term, which had a double meaning in the 18th century, effectively characterises the difference in the two pieces. According to the definition in J. G. Walther’s “Musicalisches Lexicon” (Leipzig, 1732), a distinction has to be made between an improvisational type of ricercar (wherein it appears as if the composer were seeking the harmonious passages or drafts”) and a processed type of fugue (“artistically composed after strong reflection”). Bach produces this stylistic contrast in the two fugues. Furthermore, with an ingenious acrostic he dedicates the ricercar a 6 in the third fascicle of the original printing: “Regis Iussu Cantio Et Reliqua Canonica Arte Resoluta”, which means “Upon the King’s Demand, the Theme and Additions Resolved in Canonic Style.”
(2) The four-movement “Sonata sopr’ il Soggetto Reale”: In formal scheme this centrepiece of the Musical Offering accords with Bach’s preferred type of the Italian sonata da chiesa with the movement sequence slow-quick-slow-quick. The third movement is of particular interest. In this instance Bach clearly follows the mannerisms of the sensitive fashionable style of King Frederick’s court orchestra, of which he is said to have remarked with biting irony in allusion to his son Carl Philipp Emanuel: “it’s Berlin blue! It fades”, (according to Cramer, 1792). However, in this adroitly written movement with its enormously dynamic shading and harmonious surprises, he provides an example which must have completely outclassed the Berlin musicans. The trio sonata, as a whole and in particular, shows how the elderly Bach by no means just dreamily followed esoteric arts, but was still the brilliant virtuoso musician dominating all musical methods.
(3) The ten canonic movements: Taken together, these two to four-part movements represent a small compendium of the canonic art, and with a strong leaning towards that series of 14 canons which between 1742 and 1746 Bach had entered in his personal copy (not discovered until 1975) of the Goldberg Variations (BWV 1087). In five movements each the “Thema regium” is led canonically or serves as the foundation for canonic counterpoint, at the same time undergoing manifold metamorphoses. All essential canon techniques are introduced: canons in unison or in octave intervals in two, three and four parts (No. 1), crabwise canon for two parts (No. 2), canons in counter-motion (No. 3) or with mirroring of the main part (No. 4), canon with various rhythmic value sizes by doubling the note values with simultaneous reversion (No. 5), modulating canon, with each circular canon rising by a whole tone (No. 6), and finally canonic fugue, in which the free imitation principle is replaced by the strictly canonic (No. 7). Even in these canonic movements recollections of the visit to Potsdam are still noticeable, when Bach in the dedication specimen for the king added the following allegorical notes to the extending and modulation canon: “Notulis crescentibus crescat Fortuna Regis, Ascendenteque Modulatione ascendat Gloria Regis”, i. e. “May the king’s happiness grow with the augmenting notes, and with the rising modulation may the king’s fame increase.” Thus in the two small canon movements Bach incorporated a personal wish to the king, just as in the overall work of the Musical Offering he conceals his own musical self-portrait: the picture of the composer in his capacity as master of the fugue and keyboard virtuoso, Kapellmeister and chamber musician, contrapuntalist and musical scholar.

The three sonatas for viola da gamba and obbligato harpsichord, like the flute sonatas, as opposed to the violin sonatas, have not come down to us as integrated groups of works from the point of view of the sources. It is not even certain whether perhaps the three works might simply be what has been retained of a once larger repertoire. In Bach’s case there is no viola da gamba solo literature going beyond these sonatas, although he frequently has recourse to this instrument in his vocal works. They were probably composed during the Kapellmeister period in Köthen, a result of cooperation with Christian Ferdinand Abel, the chamber viola da gamba player there. The highly developed use of the harpsichord, and particularly the consistent use of the full keyboard volume as far as D3 rather indicates a date after 1720. The sonatas are not original works for the viola da gamba, but without exception transcriptions of trio sonatas for two violins and continuo. (Admittedly the only documentary evidence extant is the later trio version of the G major sonata for two flutes and continuo, BWV 1039, which - as with BWV 1027 - goes back to a missing trio for violins and basso continuo). This situation explains the less idiomatic setting of the viola da gamba part. Double stopping and polyphonic playing, which is so characteristic of contemporary French viola da gamba music by Marais and Forqueray (and as Bach also effectively applies it, for instance in the viola da gamba aria of the St. Matthew Passion), is lacking in the sonatas except for the triadic formations of the final chords.
The G major work, BWV 1027, comes closest to the normal type of a four-movement Bach trio sonata. This is shown especially in the traditional fugal design of the allegro movements, where free concertante and strict imitative elements maintain the balance. (Note the scarcely perceptible derivation of the intermediate movement theme in the first allegro from the reversion of the main theme, a contrapuntal device almost outmanoeuvred by the emphasis on the lighter movement style). - The special element of the Sonata in D major, BWV 1028 consists mainly of renunciation of through- formation of the quick movements. Instead cantabile elements are preferred in the melody and movement design, and homophonic textures emphasised (also for example in the lombardic rhythm of the theme in the second movement). - Whereas the two sonatas bear unmistakable traits of the concertante principle in the play of heterogeneous musical concepts, the third sonata in G minor, BWV 1029, is of straight concerto-style design. In its abnormal three-movement typeit represents that genre of “Sonaten auf Concertenart” - sonatas in concerto-style, as described by J. A. Scheibe in 1745. The marked concertante construction of the composition is already revealed in the pithy formulation of the themes (especially the theme heads) and culminates in the permanent contrasting of tutti and solo material. Especially impressive here is for instance the confrontation of the pulsating rhythmic main themes with the melodically soft (“cantabile”) subsidiary theme.