The exposition ends at the beginning of the seventh bar. The two bars that follow have hardly enough distinct character to constitute an episode; they are rather a kind of codetta—a prolongation of the exposition, leading up to a half close, to introduce the counter-exposition. Here we see (§ 207) that the voices which before had the subject (the bass and alto) now have the answer, while the tenor and treble have the subject; we also see the entries in a rather close stretto. It looks at first as if the introduction of a close stretto so early in the fugue were premature; but Bach has other devices in reserve for the later part of this fugue, as we shall see presently.
270. In the 31st fugue of the same work, the counter-exposition contains a canonic imitation in stretto, first between tenor and bass, and then between alto and treble. We quote the passage; the subject and answer of the fugue were given in § 88.
J. S. Bach. Wohltemperirtes Clavier, Fugue 31.