Plenty famous piano composers plaid them as they were practicing and also wrote about them and their important impact on piano composition, even Beethoven used them to practice and wrote in a letter about the importance to know them well.
Little is known about Johann Sebastian Bach's early youth. One thing we do know is that he started on keyboards before he went to school, working at the organ under the supervision of his second cousin Johann Christoph. It marked the beginning of a life-long devotion to the keyboard for Johann Sebastian.
There are several events that chronicle Bach's relationship to the family of keyboard instruments. After his parents died, the ten-year-old went to live with his older brother, a church organist in the small German town of Ohrdruf. There, as a teen-ager, Johann Sebastian observed the construction of a new organ at his brother's church with great interest. Johann Sebastian would be renowned during his lifetime not as a composer, but as an expert on organs and keyboard playing in general.
In 1700, Bach went to Lüneburg, a larger city southwest of Hamburg, as a student. There, he heard and got to know one of the leading organists of the previous generation, Georg Böhm. Bach also went to Hamburg to hear another leading keyboardist, Johann Adam Reincken; Bach owned manuscript copies of Reincken's variations and arranged pieces from Reincken's Hortus musicus, a chamber work, for keyboard. In 1705, Bach made the 230-mile trip from the southwest German town of Arnstadt, where he was employed as organist at the Neue Kirche, to Lübeck, a port city on the Baltic Sea, to hear another renowned player of an earlier generation, Dietrich Buxtehude. This interest in the music of his baroque predecessors served the young Bach well, as he set out on a compositional career that marked the pinnacle of the baroque era and would have a profound influence on generations of composers to come.
The Aria mit verschiedenen Veränderungen comes from the last decade of Bach's life. It was the fourth and final part of Bach's Clavier-Übung, a series of works for various instruments that are both some of the finest examples of his keyboard writing and outstanding didactic works. Clavier-Übung I (Leipzig, 1731) consisted of Bach's six French Suites; part II (Leipzig, 1735) brought together his Concerto nach italiänischem Gusto and his Overtüre nach französischer Art (the Italian Concerto and French Overture, both of which still turn up with some frequency on the music stands of keyboard students today); and part III (Leipzig, 1739) offered a German organ mass, with an opening Kyrie followed by a series of preludes and fugues on the most famous chorales of the Lutheran service, all framed by the majestic "St. Anne" Prelude and Fugue.
Bach composed his Variations in 1741 for a pupil, Johann Gottlieb Goldberg (which explains the work's common title). Goldberg was in the service of Count Hermann Carl von Kaiserling, a diplomat Bach probably met during a visit to Dresden in 1733. (He had been to Dresden once before, for a keyboard contest with the French virtuoso Louis Marchand, who left secretly by carriage under cover of darkness the night before, fearing Bach would trounce him.) During the time leading up to the Goldberg Variations, Kaiserling was frequently resident in Leipzig and Goldberg with him.
According to Johann Nikolaus Forkel's biography of Bach, published in 1802, "The Count was often sickly, and then had sleepless nights. At these times Goldberg, who lived in the house with him, had to pass the night in an adjoining room to play something when the Count could not sleep. The Count once said to Bach that he should like to have some clavier pieces for his Goldberg, which should be of such a soft and somewhat lively character that he might be a little cheered up by them in his sleepless nights. Bach thought he could best fulfill this wish by variations, the composition of which, on account of the constant sameness of the fundamental harmony, he had hitherto considered an ungrateful task. But as at this time all his works were models of art, these variations also became such under his hand. This is, indeed, the only model of the kind that he has left us. The Count thereafter called them nothing but his variations. He was never tired of hearing them, and, for a long time, when the sleepless nights came, he used to say, 'Dear Goldberg, do play me one of my variations.' Bach was, perhaps, never as well-rewarded for any work as for this: the Count made him a present of a golden goblet, filled with 100 Louis d'ors."
Forkel was off about Bach's experience writing variations. An Aria variata from sometime before 1710 and an Air with Variations in C minor from the Clavierbüchlein (Little Keyboard Book) he assembled in the 1720s for his wife Anna Magdalena both predate the Goldberg Variations in Bach's output, but do not offer overwhelming evidence of a fondness for the form, so on that point, Forkel was right. But the sheer variety of the Goldberg Variations could easily fool the listener into believing that Bach had been writing variations all his life, and that this set marked the culmination of his work in the genre.
Bach composed the Variations with a two-manual harpsichord in mind, but many artists choose to play them on modern pianos. The modern piano expands on the possibilities of the two-manual harpsichord, which allowed the player to differentiate between soft and loud.
The form of the Goldberg Variations seems to be governed by numbers derived from three and eight. The starting-point for the 30 variations is the opening Aria. It's 32 bars long, divided into two 16-bar halves, each of which Bach marks to be repeated. The Aria is also divided into four eight-bar sections harmonically (G major-D major-E minor-G major). A slow saraband, the Aria presents the basic thematic material, as well as the bass line, on which Bach elaborates in each of the subsequent variations.
The variations take their cue from the proportions of the Aria and are all either 16 or 32 bars in length. The variations can be grouped into ten sets of three, with the third variation in each set being a canon, the strictest form of contrapuntal imitation, where one voice imitates another at a set interval. In addition to these subdivisions, the variations are split into two halves, mirroring the structure of the Aria, with the grandiose gestures of the 16th variation, a French overture, marking the beginning of the work's figurative second half. If you count the opening Aria and its repeat at the close, the Goldberg Variations is in 32 sections, mirroring the 32 bars of the Aria itself.
(There has been speculation about Bach's interest in numerology to explain these mathematical divisions and subdivisions. At the very least, the work's careful layout reflects the rigorous nature of Bach's musicianship and compositional technique, but he may not have viewed the Variations as an "integral" work.
The title page of the Goldberg Variations is inscribed: "Composed for music lovers, to refresh their spirits, by Johann Sebastian Bach." It is a charmingly modest explanation of their purpose, for, in terms of their importance with respect to Bach's compositional output, the Variations brought together everything he'd learned in a lifetime of keyboard-playing, with echoes of his youthful experiences of Böhm, Buxtehude, and Reincken in the canons and traces of the latest Italian and French music in some of the other sections. They richly demonstrate his mastery of keyboard music both as a performer and as a composer.
Each of the variations is extraordinary in its own way. Some show the influence of dance, as with the gigue of Variation 7. Others, such as the elegant Variation 13 or the darker, more inward world of Variation 25.
With each subsequent variation driving the music toward the final Quodlibet. Here, Bach combines the melodies of two folk and "Kraut und Rüben" - developing them majestically over an elaboration of the bass line from the Aria. The work closes with a return of that initial Aria, reminding the listener of just how miraculous the stream of invention that has flowed from it over the past hour or so has been.
Glenn Gould was told that he was a reincarnation of Bach, when he was playing the Variations at the piano with such mastery and command; I too feel to have some kind of connection with Gould’s soul as I listen to his playing, I actually own every single movie on DVD ever made to portray this pianist, together with his entire recorded production of piano music from Bach he ever recorded, now available on CD.