The work consists of fugal Variations planned on the most elaborate scale.(249) The composer’s intention was to show in what a variety of ways the same theme can be treated fugally. The Variations (here called “Contrapunctus”)(250) are complete Fugues upon the same theme. The last Fugue of all has three subjects, in the third of which the composer signs his name, B A C H.(251) Bach was prevented from finishing it by the disorder of his eyes, and as an operation brought no relief the movement was never completed. It is said that Bach intended to introduce four themes into it and to bring it to an impressive conclusion by inverting them all. All the Fugues in the work are equally smooth and melodious.
To make up for the unfinished Fugue Bach concluded the work with a Choral Prelude upon the tune “Wenn wir in höchsten Nöthen sein,” which he dictated to his son-in-law, Altnikol, a few days before his death.(252) Of the extraordinary skill it displays I do not speak, save to remark that even in his last illness it proclaims Bach’s skill undiminished. The pious resignation and devotion that characterise it move me deeply whenever I play it. Nor should I find it easy to say which I had rather had been omitted, the Choral Prelude, or the conclusion of the unfinished Fugue.
9. Lastly, after Bach’s death, his four-part Chorals were collected by his son, Carl Philipp Emmanuel, and were published by Birnstiel (Berlin and Leipzig), Part I. in 1765, Part II. in 1769.(253) Each Part contains one hundred Chorals, mostly taken from the composer’s church Cantatas.
More recently Kirnberger edited, in four volumes, a collection of Bach’s Chorals. They are published by Breitkopf.(254)
Bach’s works, still in MS., consist of compositions for the Clavier, Organ, with and without other instruments, Strings, and the voice. I will enumerate them in that order.
1. _Six Little Preludes far Beginners_.(255) 2. _Fifteen Two-part Inventions_. An Invention is a musical theme so constructed that by imitation and inversion a whole movement can be evolved from it. The subject having been first stated, the rest develops naturally out of it. For the instruction of a young Clavier player these fifteen Inventions are of great value, seeing that the composer has been careful not only to provide exercises for both hands but for every finger as well. They were composed at Cöthen in 1723, with a long title which begins: “An honest Guide, in which lovers of the Clavier are shown a clear method of playing correctly in two parts,” etc.(256)