The first and last movements are in the same rapid tempo and both are treated contrapuntally throughout. Their internal structure is fundamentally tri-partite, like the fugues and the preludes in the English suites, the opening and closing sections being the same. The middle section brings out new material, but also retains suggestions of that already announced; the new material tending to take on an episodic character, like the couplets in Couperin’s rondos. This is unusually clear in the middle section of the last movement of the Italian Concerto, in which there are three very distinct episodes, one of which appears twice, quite after the manner of the Beethoven rondo. But one feature, which Bach probably acquired from Vivaldi, makes the whole procedure different from Couperin’s. This is that the main theme, either the short or long part of it which may be restated between the episodes, appears in different keys. The same feature is evident in the preludes to the English suites. The slow movements in both the D minor and the Italian concertos are written upon a favorite plan of Bach’s. The bass repeats a certain form or ground over and over again, above which the treble spins an ever varied, rhapsodical melody, highly ornate in character. The plan is an exceedingly simple and a very old one. It may be traced in the old motets of the mensuralists of the thirteenth century, with their droning _ordines_; and in the favorite ‘divisions’ of the early English composers. The Chaconne and the Passacaglia are but variants from the same root. It is, of course, a simple form of variations. This leads us, at last, to a brief consideration of what is perhaps from the point of view of the pianist, if not indeed from that of the musician, the most astonishing of Bach’s harpsichord music,--the Goldberg Variations. The story of their origin will bear repetition for the light it throws on the mood in which they were written. A certain Count Kaiserling, at one time Russian ambassador to the court of Saxony, supposedly suffered from insomnia and nervous depression. He had in attendance a clavecinist named Goldberg, a pupil of Bach’s, who, among other duties, had by his playing to wile away the miserable night hours of his unhappy patron. Hearing of the great Bach through Goldberg, Kaiserling requested him to write some harpsichord music of pleasant, cheerful character especially for these weary vigils. Bach composed and sent back a theme and thirty variations, which so pleased the count that he presented Bach with a goblet filled with one hundred Louis d’or.