progression, Zug. A linear progression is a stepwise
progression of a third or greater connecting structural notes of
one or more harmonies. The fundamental line
is a linear progression at the background
level. Where two or more voices exhibit parallel linear progressions
(in thirds or sixths), the linear progression that relates most
directly to the underlying harmonic context, or to the fundamental
line, is considered the leader.
The example, mm. 83-86 of the fugue, illustrates several
linear progressions. The uppermost slur indicates a descending octave
from f in m. 83 to f in m. 87 (not shown). The next series of slurs indicate
fourth progressions that expand the motion f-c of mm. 83-86, which itself
is a descending fourth-progression. More descending fourth-progressions
are also found in the lower voice.