(1) I am much indebted to Mrs Jephta Drachman of Maryland, USA, the present owner of the autograph manuscript of KV 405, who has assisted me in preparation of this paper by painstakingly compiling a list containing both errors in Kirkendale's editions in Mozart Jahrbuch (1962/63), pp. 140-155, and corrections by Mozart in his manuscript. Her work, in extract, is given in Appendix.
(2) Warren Kirkendale's detailed study on his expanded second edition of Fugue and Fugato in Rococo and Classical Chamber Music (Duke Univ. Press, 1979), p.156, lists a selected letters and documents associated with Mozart, Bach and fugues.
(3) Daines Barrington, p.61f, London 1764/5, quoted from Warren Kirkendale's Fugue and Fugato, p.156.
(4) According to Kirkendale's Fugue and Fugato, p.155, Nissen once reported that Thomas Attwood, who was one of Mozart's piano pupils in the years 1785-86, "remembered that this volume of fugues [WTC] was always lying open on his pianoforte" in 1786.
(5) Reinhold Bernhardt, "Aus der Umwelt der Wiener Klassiker. Freiherr Gottfried van Swieten (1734-1803)," Der Bär (1929-30), p.107.
(6) The Letters of Mozart and His Family. Chronologically arranged, translated and edited with an Introduction, Notes and Indexes by Emily Anderson (3re revised, 1985) p.800.
(7) ibid. p. 801
(8) According to the letter to his father on 12 March 1783, we can learn to some extent who were among the circle and how the session was like.
(9) ibid.
(10) This view is shared by Warren Kirkendale's article, "More Slow Introductions by Mozart to Fugues of J. S. Bach?" Journal of the American Musicological Society, Vol. 17, No. 1 (1964), p.44, fn.8; Alan Tyson in his Mozart: Studies of the Autograph Scores (Harvard Univ, Press, 1987), p.81; and The Letters of Mozart and His Family (op.cit), p. 862, fn.3.
(11) Kirkendale, Fugue and Fugato, p.154.
(12) The description of this MS and other related sources are discussed in Kirkendale, "More Slow Introduction", pp. 45-46, Holschneider, p.52, and Kirkendale, Fugue and Fugato, p.333.
(13) Alfred Einstein: "Mozart's Four String Trio Preludes to Fugues of Bach", The Musical Times, Vol. 77, No. 1117 (March 1936), 209-216.
(14) Walther Vetter: "Mozart und Bach". Bericht über die Internationale Konferenz über das Leben und Werk W. A. Mozarts, Praha, 27.-31. Mai, 1956 (Prague, n.d.) 61-69; also In: Mythos-Melos-Musica. Ausgewählte Aufsätze zur Musikgeschichte II (Leipzig 1961), pp.333-345.
(15) The MS is described by Kirkendale's article, "KV 405: Ein unveröffentlichtes Mozart-Autograph." Mozart Jahrbuch 1962/63, pp. 140-155; and Gerhard Herz, Bach Sources in America (Bärenreiter, 1984) 256-265.
(16) Gerhard Croll: "Eine Neuentdeckte Bach-Fuge für Streichquartett von Mozart", Österreichsches Musikzeitung Vol. 21 (1966) 12-18. Croll considers that this manuscript, currently held at Schloßarchiv Kremsier, did not belong to the set of 5 fugues on the evidence of its physical size.
(17) They are described in Kirkendale's "More Slow Introduction", pp. 46-47.
(18) Kirkendale, "More Slow Introduction" p.65, also cautions the earlier approach by Einstein, and changes his view in Appendix IV, p.334, in his Fugue and Fugato (1976) that KV 404a "should be removed from the canon of the authentic works [of Mozart]".
(19) Alfred Einstein: "Mozart's Four String Trio Preludes to Fugues of Bach", p.210.
(20) The original sentence reads "Immerhin bleiben von den in beiden Berliner Handschriften gleichzeitig vorkommenden Abweichungen noch hinlänglich zahlreiche, die beweisen, daß es Mozart ferngelegen hat, eine mechanische Streicher-Kopie des originalen Klaviersatzes zu geben." p.335.
(21) "Er hat vielmehr eine ganze Reihe von Änderungen angebracht, die verdeutlichen, daß er, teils bewußt und planvoll, teils wohl auch rein instinktiv, seine Individualität durchsetzte." ibid.
(22) The MS is first studied by Aldreas Holschneider in his paper "Die musikalische Bibliothek Gottfried van Swietens" read at the Internationaler Musikwissenschaftlicher Kongress, Kassel, 1962. The facsimile of this manuscript is published by Riemenschneider Bach Institute, Baldwin-Wallace College in 1985 as Book III and IV of "Riemenschneider Bach Facsimiles" series.
(23) Kirkendale, "More Slow Introduction", p.49.
(24) This quotation is by Kirkendale, "More Slow Introduction", p.48. Equivalent statement is also made by Croll.
(25) In fact, Kirkendale has occasionally shown his cautious approach in referring to it as "the one most probably used by Mozart", in "Slow Introduction", p.48, but he does not mention in his article the negative' information contained in the Berea manuscript. Later scholars quote his view as being definite: in the introduction to the facsimile edition (op. cit., p.35), the editor writes "Warren Kirkendale has presented conclusive evidence linking this manuscript to the copy of Bach Fugues that Mozart borrowed from Baron van Sweiten in 1782"; Gerhard Herz in Bach Sources in America (Bärenreiter, 1984, p.252) also says "... Furthermore, Mozart's own transcriptions of the Well-Tempered Clavier prove by identical and otherwise inexplicable deviations that the Berea manuscript was the model from which Mozart copied."
(26) Werner Breckoff, Zur Entstehungsgeschichte des zweiten Wohltemperierten Klaviers von Johann Sebastian Bach. PhD diss., Tübingen 1965. 101p.
(27) More detailed physical and philological information about these sources is expected to be covered in Dürr's forthcoming "Kritischer Bericht" to the Neue Bach Ausgabe. The information about the text from text-critical viewpoint is covered fully in my second volume of J. S. Bach's Das Wohltemperierte Clavier II' A Critical Commentary (Leeds, Household World, 1995). I am most grateful to Dr Alfred Dürr for his information on sources 1, 2, 4 and 5 in our private communication in July 1991. Source 6 is discovered by myself in July 1995.
(28) See Tomita (1995), pp. ix-xi.
(29) The manuscript shows no sign that the original gathering is now in different shape. Thus I believe the collection was originally planned as is. The philosophy behind selection and transpositions seems to be of the following: (1) exclusion of the preludes apart from the purely contrapuntal piece (Pr.a = 2 part invention); (2) exclusion of the fugues of quick tempi, which are particularly suited for harpsichord and not for organ or string arrangement (such as Fg.C, C#, c#, F, G and a); (3) avoidance of keys with more than three flats or sharps in the key-signature. The collection is then rearranged, and at the end, Albrechtsberger wrote "Fine" to mark the end of the collection. This inscription is later changed to "Sieg Nro 17 in C natural | 2/4" implying that the original Fg.C is to follow this collection. Probably it is at this stage that the title to the manuscript in the top margin of Fg.B (transposed to C major) on page 1 was modified to "XXIV. Fugæ del Seg: Seb: Bach. Liber I." from "XVI ...." (but this reconstruction of the erasure may not be accurate). Thus there once had been an accompanying "Liber II", now lost, which contained the remaining 8 fugues of WTC II.
(30) This manuscript has been misquoted previously as Q 10728. The title page reads "24. Fughe. | per il | Clavi Cembalo. | o per | l' Organo | Del: Sig: S: Bach". It is worth noting that the title was modified later in different shade of ink: "Fughe" from "Fuge" and two lines, "o per | l' Organo", were added.
(31) For example, I have identified 16 areas of pitch corrections in (transposed to A minor) which can be considered to be related to the transposition at copying stage.
(32) Kirkendale, "More Slow Introduction", p.49, and Andreas Holschneider, "Zu Mozarts Bearbeitungen Bachscher Fugen", Die Musikforschung Vol. 17 (1964), p. 177, however, did not study Source 1, although Kirkendale in fact mentions the manuscript in his article, p.58.
(33) They are listed in Appendix B of the author's Das Wohltemperierte Clavier II': A Critical Commentary, Vol.2 (Leeds, Household World, 1995), p. xxix.
(34) At the end of each piece that is edited, the reviser wrote an inscription with a date, e.g., "Coll. C. Füg. 18 24/8 43." (collated by C. Fügerl [?], 24 August 1843).
(35) Warren Kirkendale: "KV 405", pp. 142-143.
(36) The Letters of Mozart and His Family, p.801.