Forkel, the author of the first significant Bach monograph, tells the story of the origin of the composition. According to him, the great Johann Sebastian was commissioned by a certain Count Keyserlinck to compose the Goldberg Variations. The Count suffered from insomnia, therefore he asked the composer whom he had known from earlier to compose some music which his court harpsichordist, Johann Gottlieb Goldberg, could play for him from time to time in the tormenting hours of the night. Bach believed that a series of variations would best suit the purpose so that Goldberg could play different movements each night. Keyserlinck received the score and paid an appreciable sum for the work, handing over a golden plate with a hundred double Louis d’or.
The 27th variation continues the method only partially: it is a canon on the ninth but there are only two parts. Variation 30 is a Quodlibet of well-known folksongs instead of the expected canon on the tenth. Variations 4, 7, 10, and some others are character pieces (No. 7 is a gigue, No.10 is a fugato, but No. 16, the French overture, also belongs to this group), others (from Variation 5) are virtuoso pieces utilising the technical possibilities of the two-manual harpsichord and are rather dif?cult to play on the piano, since the two hands always cross owing to the lack of the other manual. It remains an unanswered question of how Goldberg could cope with the task. Because, even if not at the age of 15, he probably played these movements for the sleepless Count at some time.