Two separate publications of C. P. E. Bach’s keyboard works appeared during the 19th century in the edition of Hans von Bülow: Sechs Sonaten (Leipzig, Peters, 1862), and the ‘Concertvortrag’ version of a rondo movement in the Anthologie Classique (Berlin, Schlesinger, 1860). Both editions alter the original text heavily, by dressing it up in the raiment of the flamboyant and virtuosic style of their own time. The long Preface to the Sechs Sonaten, in which Bülow explains the necessity of a ‘revision’, but, at the same time, betrays his uneasiness about his procedures, is an extremely important document of the historical/artistic thinking of Bülow’s generation.Bülow’s revisions are examined in the following aspects of the music: enrichment of the keyboard texture; change of harmony; obliteration of the fantasia character; performance indications and tempo changes; abolishment of the aposiopesis. Differences between the original and the revised text are illustrated with several musical examples.Although Bülow was a true son of the nineteenth century, his attitude to textual fidelity was stricter than that of his colleagues. His troubled conscience about the revision of the C. P. E. Bach sonatas shows a fundamentally ethical principle, independent from the artistic disposition of his age.