Bachian Variations

Speaking of variations, Bach did a really interesting variation piece that follows the French clavicinist model of doing "doubles" on a dance movement. A "double" follows the basic harmonic and metric structure of the original with varied figuration. A famous example is by Rameau where he does six doubles on a simple gavotte in A minor:

Bach's Violin Partita no. 1 in B minor is a tour de force in which each movement is followed by its double. Shunseke Sato performs it for the Netherlands Bach Society:

Compare this kind of variation with what Beethoven did with the form.