Bach Prelude and Fugue in G minor

I originally learnt the G minor prelude and fugue in 2011, eight years ago. The prelude features long trills and a semiquaver demisemiquaver rhythm in which variants are suggested; I adopted a couple of these suggestions when I first studied the piece and have kept them this time round. The fugue is another in 4 parts, the characteristic subject appearing many times until its final iteration in the last two bars.