245 The statement is inaccurate. The work was written for the most part in 1749 and the greater part of it was prepared for engraving by Bach himself during his last illness. None of his elder sons was with him at his death, and the blunders that disfigure the engraved copy show that they clumsily finished their father’s work. It is in P. bk. 218.
246 Friedrich Wilhelm Marpurg, b. 1718, d. 1795.
247 The work was published shortly after Bach’s death, but had no sale. C. P. E. Bach then commissioned Marpurg to write a preface, and the new edition was published at the Leipzig Fair, Easter, 1762. In four years only about thirty copies were sold. See Spitta, iii. 197 ff. and Schweitzer, i. 423 ff.
248 In 1756. See C. P. E. Bach’s advertisement in Felix Grenier, p. 232.
249 The work contains six Fugues and four canons upon the same theme; an unfinished Fugue “a tre soggetti,” the first four notes of the third of which spell B A C H; and the Choral Prelude “Wenn wir in höchsten Nöthen sein.”
250 Schweitzer explains: “His purpose in this work being a purely theoretical one, Bach writes the Fugues out in score, and calls them ‘counterpoints’ ”
[ 251 B A C H in German musical notation]
252 Supra, p. 27. The movement is in N. bk. 17 p. 85. It is not certain that Bach intended the Prelude or the unfinished Fugue to be included.
253 C. P. E. Bach was only concerned with the first volume. Erk, in his edition of the _Choralgesänge,_ conjectures that Kirnberger was responsible for the second.
254 The four volumes were published at Leipzig between 1784-87. Spitta states that C. P. E. Bach was the editor. Erk joins Kirnberger with him in that position. As C. P. E. Bach died in 1788 Kirnberger’s association with the work is probable, especially if he had already been responsible for the 1769 volume.
255 Bach’s Clavier school consisted of eighteen Preludes for beginners (all in B.G. XXXVI.); the two-part and three-part Inventions; and the _Well-tempered Clavier._ The six Preludes mentioned by Forkel, and which alone he knew, were published by him for the first time. Seven more are found in Wilhelm Friedemann’s _Clavierbüchlein_ (B.G. XLV. (1)), and the remaining five have survived in texts handed down by others of Bach’s pupils. The eighteen are in P. bk. 200.