Robert Hart on the Trinity in Bach
(We prostrate ourselves with tears
The art of the fugue lies in the development of the piece, with its subject always being repeated, as it modulates into different keys and keeps the lines of melody moving with good harmonic flavor throughout. Sometimes the subject disappears very briefly and we are treated to what is called an “episode.” The purpose of the “episode” is to lead us into the next statement of the subject.
The “St. Anne” Fugue is a triple fugue. Each of the three sections, which I will identify as A, B, and C, is part of the fugue and yet is at the same time itself a complete fugue. The opening notes of the hymn “O God, Our Help in Ages Past” are clearly stated as the subject for A. It develops as all fugues do, as each voice comes in and the fugue modulates from key to key, but then it resolves rather quickly in an unsatisfying conclusion. This is because we are not done, and are meant to anticipate more.
Bach Against Arius