S13.15. Subjects from (a) Fugue in E-flat, BWV 552/2; (b) Hurlebusch, Composizioni musicali, part 2, Fuga in D (no. 4); (c) Buxtehude, Praeludium in E, BuxWV 141; (d) “Keiser,” St. Mark Passion, “Seht, Menschenkinder” (no. 24), mm. 5–7