This fugue states its subject 169 times over the course of 39 pages. It the first 13 pages states the subject 13 times per hand in a matter of 5 expositions and 5 episodes. (Note that double-barlines mark the start of an episode while subsequent exhibitions are marked by a thicker barline.)
Page 14-26 consists of the first 13 pages inverted. (Please note that from this point forward, double-bar lines serve their normal function of indicating key changes.) Page 27-39 reprise the first 13 pages but realized in different octaves.
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