4b. Parallelism

The Parallelism is a voiceleading model which was popular in late Renaissance music. Here we discuss the basic 3-voice version, where 5-3 chords alter with 3-8-chords. The upper two voices ascend in parallel thirds and the bass is folded into ascending fourths, followed by descending steps.

There seems to be an incorruptible mechanics behind of this progression. But what would be the next chord in the example above? Due to the odd cardinality 7 of the diatonic scale it happens that the alternating 5-3 and 3-8 chords necessarily exchange roles. The notes C-E in the upper voices of the first chord appear over the bass A (3 and 5), while in the last chord they appear over the bass C (8 and 3). With the next chord the progression either would run into a diminished triad B-D-F or it would require an alteration B-D-F# of the fifth of the triad and thereby of the governing diatonic scale.

The video explores the second option and traces the progression with overlapping charts of 8 chords each. The overlaps between neighboring charts contain always 4 chords.