Carl Philipp Emanuel Bach published his 'Fortsetzung' Sonatas, Wq51, in 1761, only one year after the appearance of Six Sonatas with Varied Reprises, Wq50 (released on Volume 21, BIS-1624). Although the new collection contained only one single movement with a written-out varied reprise, Bach and his publisher, George Ludewig Winter, titled it Fortsetzung (continuation or sequel), obviously hoping to capitalize on the success of the set which had preceded it. (The same strategy was used two years later, with Zweite Fortsetzung, Wq52.) Although the ‘Fortsetzung’ Sonatas were not published together with the composer's own variants on them, such alternative versions exist in manuscript, and splitting this set of large-scale works over two discs, Miklós Spányi also includes recordings of these varied or embellished versions, which may represent the composer's revisions but could equally well have been intended as study material for his students. On the disc is also one of the composer's intriguing experiments – a re-composed version of the entire first sonata of the set, in which each movement has the same bass line and harmonic progressions as the original, yet is varied throughout in texture, rhythm and character. A tour de force in the technique of variation, Bach’s achievement becomes all the more impressive when one considers that he went on to compose yet another, entirely different version of the same sonata, which will be included on the next disc in this highly acclaimed series.