Johann Sebastian Bach composed this piece around 1725 at the beginning of his Leipzig years. The character of the "Fantasia" is serious and grave. Even the interludes, despite their lighter texture, maintain an overall contemplative character. The four-part double fugue is an example of Bach's unique contrapuntal craftsmanship. He combines two notably contrasting themes: the first is diatonic, rhythmic and agile while the second consists of a descending chromatic line.