In a chapter entitled ‘Composition as Arrangement and Adaptation’ in The Cambridge Companion to Bach (Cambridge: Cambridge University Press, 1997), Werner Breig observed that Johann Sebastian Bach found delight in exploring ‘the possibilities inherent in a finished work’, noting that ‘at every period of his creative life Bach may be found altering, arranging, and continuing to develop his own and other composers’ works’ (154). Such observations echo the famous account that Carl Philipp Emanuel Bach gave to Forkel that his father, upon hearing the first moments of a fugal exposition, could immediately grasp its full range of contrapuntal possibilities. In his 1802 biography of Bach, Forkel himself devoted a brief chapter to Bach's revisions of his own compositions, particularly the preludes of The Well-Tempered Clavier.

The notion of Bach as incessant tinkerer may seem antithetical to scholars, performers and aficionados influenced by the concept of Werktreue, or to one of many standpoints that have emerged through debates concerning ‘authenticity’ and historically informed performance. However, such views often retrospectively project values of permanence onto musicians who thought more flexibly. This was the world of the baroque musician: improvisation and ornamentation were expected; manuscripts and printed parts presented an array of interpretive possibilities rather than a single, prix fixe directive. These practices, along with other forms of reworking, were customary not only for Bach, but also for his predecessors, his contemporaries and those who have been inspired or influenced by Bach's music through succeeding generations. The techniques and implications of these practices formed the central subject of the twentieth biennial meeting of the American Bach Society in April 2018 at Yale University.

In an opening plenary address entitled ‘Parody Is Overrated’, Daniel R. Melamed (Indiana University) questioned the usefulness of studies of parody that fixate on genesis and source material at the expense of substance and meaning of the finished work, an appeal reminiscent of Joseph Kerman's challenge to forge beyond empiricism and positivism toward more robust criticism (‘How We Got into Analysis, and How to Get Out’, Critical Inquiry 7/2 (1980), 311–331). Drawing on examples from his new book, Listening to Bach: The Mass in B Minor and the Christmas Oratorio (New York: Oxford University Press, 2018), Melamed pointed to several instances in which a source composition such as the chorus ‘Weinen, Klagen, Sorgen, Zagen’, bwv12/ii, offers only a partial understanding of Bach's parody in the ‘Crucifixus’ of the Mass in B minor, bwv232. As Melamed summarizes it in the Preface of his book, parody alone offers ‘a very limited view and one that is largely cut off from the experience of hearing these works either in the eighteenth century or today’ (xviii).

Following the plenary address, several presenters discussed aspects of parody, genesis and transcription, and their respective implications within Bach's oeuvre. Matthew Dirst (University of Houston) traced a network of vocal and instrumental antecedents for some of the 1738 harpsichord concertos, particularly bwv1052, 1053 and 1058, in order to support the notion that some may have begun as organ concertos in the previous decade, perhaps included among the ‘various concertos’ Bach played in Dresden on 19–20 September 1725 (Christoph Wolff, ‘Did J. S. Bach Write Organ Concertos?’, in Bach and the Organ, ed. Matthew Dirst, Bach Perspectives 10 (Champaign: University of Illinois Press, 2016), 60–75). Szymon Paczkowski (Uniwersytet Warszawski) directed attention to various versions of ‘Schwingt freudig euch empor’, bwv36, a birthday-turned-Advent cantata wherein aspects of Polish style, especially the polonaise, are retained throughout its revisions and provide new meanings in each particular context. Even with revisions to text and structure, its style is appropriate not only for the courtly pomp and ceremony that characterized its use for secular celebrations in the cases of bwv36a, 36b and 36c, but also for the royal entry of Christ into Jerusalem as heard in Matthew's gospel on the first Sunday of Advent, for which the 1731 version was fashioned. In a lecture-recital at the Yale Collection of Musical Instruments, Mary Oleskiewicz (University of Massachusetts Boston) and David Schulenberg (Wagner College) compared earlier versions of sources for the ‘triple concerto’, bwv1044, in order to question whether or not Bach himself was responsible for its adaptations. Their conclusions suggested that the work was probably a collaboration from his later years, perhaps carried out by pupils with Bach's permission or under his supervision.

Kayo Murata (Tokyo) and Moira Leanne Hill (New Haven, Connecticut) both directed attention towards the borrowing and reworking that marked Sebastian Bach's early career and Carl Philipp Emanuel Bach's later career respectively. Murata traced the influence of learned contrapuntal techniques that Bach may have studied or copied alongside Johann Gottfried Walther in Weimar, especially in light of Walther's Praecepta der musikalischen Composition, published shortly before Bach's 1708 return to Weimar. Hill surveyed borrowed and reworked movements from two decades’ worth of the Passions that C. P. E. Bach presented in Hamburg's churches, summarizing patterns of reuse that he developed according to genre, style characteristics of the source models and their chronological placement within his tenure. There was, she noted, a marked shift away from baroque idioms in later reworkings.

The conference's central themes were further explored in presentations by researchers from the Bach-Archiv Leipzig, a quintet consisting of Manuel Bärwald, Christine Blanken, Bernd Koska, Michael Maul and Markus Zepf. Through examination of annotations to autograph performance parts, Bärwald hypothesized that an intermediate version of the St John Passion, bwv245, may have existed between its second known performance in 1725 and the third performance, which seems to have taken place some time between 1728 and approximately 1732. Like Kayo Murata, Zepf surveyed fugue archetypes used and adapted by Bach, with special emphasis given to subjects by Johann Caspar Ferdinand Fischer in his Ariadne Musica as well as material therein based on works by Johann Jakob Froberger. Blanken, Koska and Maul offered new findings and questions from the circle of Bach pupils, as well as musicians who came into contact with Bach's music later in the century. Though Bach's students would have been immersed in their teacher's models, the positions they subsequently held and changing tastes meant that some would have followed these tried-and-true models while others, especially court musicians, would have departed from them in order to accommodate the latest musical fashions. Maul noted the case of Augsburg cantor Philipp David Kräuter, who, though a pupil of Bach's for eighteen months in Weimar, later demonstrated a preference for Telemann's cantata cycles, suggesting that taste could eclipse loyalty to a particular pedagogical lineage. Such was the point made by Koska, namely that some of Bach's pupils came to view him as a venerable historical figure rather than a contemporary model. That musicians were obliged to make music fit given circumstances and tastes was further stressed by Blanken's survey of adaptations of Bach's organ music found in a substantial, previously ignored collection of his keyboard music from Nuremberg. For example, the chorale prelude ‘Christ, unser Herr, zum Jordan kam’, bwv684, for two manuals and pedal, was not only shortened but further retrofitted in several ways: its two upper voices were adapted for one manual, the cantus firmus moved from the alto voice (originally played by the feet) to the soprano, and the bass line transposed to account for a lack of 16′ pitch, all perhaps to make the piece playable on a one-manual instrument. The discussions surrounding these presentations frequently emphasized the degree to which scholarship and performance have, as Melamed observed, prioritized sources and documents at the expense of contemporaneous practices.

The concept of ‘Bach Reworked’ was also carried beyond the eighteenth century by presentations that considered, among other matters, reception histories and the use of Bach's themes and baroque styles in jazz, funk and rock. Alannah Rebekah Taylor (Florida State University) examined ways in which Bach's two Passions were adapted for secular performance by nineteenth-century American institutions such as Boston's Handel and Haydn Society and the Bethlehem (Pennsylvania) Choral Union. Ruth Tatlow (Stockholm) hypothesized that Chopin's Préludes, Op. 28, were modelled on numerical relationships in the second book of The Well-Tempered Clavier, while Russell Stinson (Lyon College) used a newly discovered four-hand piano arrangement of Bach chorale settings from the Mendelssohn circle as a point of entry for considering how Mendelssohn and his contemporaries may have understood and adapted Bach's music.

Through a survey of nineteenth-century editions of the Goldberg Variations, bwv988, Erinn Knyt (University of Massachusetts Amherst) contextualized the myriad editing, transcribing and arranging endeavours undertaken by Busoni for his 1915 performing edition. Her discussions of reworking were extended to include a comparison of several recordings of Busoni's version made between 1996 and 2018 that featured individual performers’ own adaptations. Sebastian Wedler (University of Oxford) noted how Webern's Passacaglia, Op. 1, of 1908 adapted structural and contrapuntal ideas from both Bach and Heinrich Isaac, describing how the juxtaposition of historicist and modernist elements not only reflects the aesthetic tensions that characterized turn-of-the-century modernism, but also provides valuable clues about turn-of-the-century Bach reception.

Presentations on topics of ‘Bach as Modern Jazz’ by Stephen Crist (Emory University), ‘Bach Transmogrified: Leonard Bernstein's Cultural Accreditation of Baroque Rock’ by Sara Gulgas (University of Pittsburgh) and ‘Certifying J. S. Bach's Interplanetary Funksmanship: George Clinton, Bernie Worrell, and P-Funk's Baroque Aesthetic’ by Ellen Exner (New England Conservatory) discussed influences and reworkings of Bach's music and baroque style in the second half of the twentieth century. Through pieces, songs and albums such as Lukas Foss's Baroque Variations of 1967, the New York Rock & Roll Ensemble's song ‘Brandenburg’ of 1968, Switched-On Bach (Wendy Carlos, 1968), Cosmic Slop (Funkadelic, 1973), Blues on Bach (Modern Jazz Quartet, 1974) and Let's Take It to the Stage (Funkadelic, 1975), attendees were invited to consider properties of Bach's music that surpass traditional boundaries associated with the concept of genre.

In addition to the thoughtful presentations, conference attendees and members of the local community were treated to memorable performances that reflected the conference theme. On the first evening, student and staff organists offered a potpourri of arrangements, transcriptions and Bach-inspired pieces on the E. M. Skinner (1931, restored 1986) and Taylor and Boody (2007) organs in Marquand Chapel, including Alexandre Guilmant's transcription of the sinfonia from the cantata ‘Wir danken dir, Gott, wir danken dir’, bwv29, one of Robert Schumann's fugues on B-A-C-H from Op. 60, movements from Bach's Memento by Charles-Marie Widor and Bach's own assimilation of French style in the Pièce d'Orgue, bwv572. On the second evening, the Yale Schola Cantorum under the direction of David Hill was joined by the Elm City Girls’ Choir for a complete performance of the St John Passion as arranged by Robert Schumann. Premiered in Dusseldorf in 1851, Schumann's adaptation was, to quote the evening's programme notes, ‘remarkably faithful to Bach's St. John by mid-nineteenth-century standards’. The use of cello and fortepiano in the continuo group was compelling, as were discreet additions of clarinets and the exquisite colour added by girls’ voices (originally scored for fifty boy sopranos) to the melody of each chorale. On the third night, Masaaki Suzuki led a choir of Yale Institute of Sacred Music alumni and Juilliard415, The Juilliard School's primary period-instrument ensemble, in a stirring performance of the Mass in B minor. Before the performance, Suzuki was awarded an honorary membership of the American Bach Society for his accomplishments as a performer and champion of Bach's music.

As demonstrated throughout the papers and performances, concepts of fixity and finality were largely unknown to Bach and his contemporaries. Taken together, their working methods suggest – quite strongly, in fact – that they would have ignored the limitations arising from overzealous interpretation of sources alone, or views that reduce musical works to mere artefacts or museum pieces. Writing about authenticity and Bach in Early Music: A Very Short Introduction (New York: Oxford University Press, 2011), Thomas Forrest Kelly cautions that even ‘if we really did it Bach's way, there would be nothing of ourselves in the matter’, adding, ‘the thing that mattered most to Bach, and probably to almost anybody else, is the presence of a musician’ (88). Such a view offers creative licence for continued engagement with Bach's music through parody, transcription, adaptation and other novel forms of reworking.