The Variations are models of what such compositions ought to be, though no one has been so rash as to attempt to follow Bach’s footsteps. We owe them to Count Kaiserling, formerly Russian Ambassador at the Saxon Electoral Court, who frequently visited Leipzig with Goldberg, already mentioned(238) among Bach’s pupils. The Count was a great invalid and suffered from insomnia. Goldberg lived in the Ambassador’s house, and slept in an adjoining room, to be ready to play to him when he was wakeful. One day the Count asked Bach to write for Goldberg some Clavier music of a soothing and cheerful character, that would relieve the tedium of sleepless nights. Bach thought a set of Variations most likely to fulfil the Count’s needs, though, on account of the recurrence of the same basic harmony throughout, it was a form to which he had hitherto paid little attention. Like all his compositions at this period, however, the Variations are a masterpiece, and are the only example he has left us of this form.(239) The Count always called them “my Variations” and was never weary of hearing them. For long afterwards, when he could not sleep, he would say, “Play me one of my Variations, Goldberg.” Perhaps Bach was never so well rewarded for any composition as for this. The Count gave him a golden goblet containing one hundred louis d’ors, though, as a work of art, Bach would not have been overpaid had the present been a thousand times as large. It may be observed, that in the engraved copy of the Variations there are serious mistakes, which the composer has corrected in his own copy.(240)
6. _Einige kanonische Verdäderungen,_ “Canonic Variations on the Christmas Hymn ‘Vom Himmel hoch da komm ich her,’ for an Organ with two manuals and pedal. Published at Nürnberg by Balthasar Schmidt.” The work contains five canonic variations of the utmost ingenuity.(241) 7. _Musikalisches Opfer_, or “A Musical Offering,” dedicated to Frederick II., King of Prussia. The theme received by Bach from the King(242) is treated first as a three-part Fugue under the acrostic title “Ricercare” (Regis iussu cantio et reliqua canonica arte resoluta). There follows a six-part “Ricercare” and Thematis regii elaborationes canonicae of various kinds.(243) The work includes a Trio for Flute, Violin, and Clavier upon the same subject.(244) 8. _Die Kunst der Fuge_, or “The Art of Fugue.” This work, unique of its kind, did not appear till about 1752, after Bach’s death, though the greater part of it had been engraved by his sons during his lifetime.(245) Marpurg,(246) the leading German musical critic of that day, contributed a preface to this edition which contains many just observations on the value and utility of such treatises.(247) But, being too good for the general public, the work found only a small circulation among those who discerned its merit and eagerly bought copies. The plates were never used again and eventually were sold(248) by Bach’s heirs at the price of old copper. Written by a man of Bach’s transcendent genius, and commended as a masterpiece by a critic so highly regarded as Marpurg, a work of this kind, if published in any other country than Germany, would have passed through at least ten editions by now, if only at the bidding of patriotism. But in Germany not a sufficient number of copies was sold to pay for the plates used in engraving the work!