Parallel octaves and 5ths in BWV 552a (St. Anne, Prelude)

May 09, 2023

BWV 552 is the great St. Anne Prelude and Fugue found at the opening and closing of Bach's Clavierübung III, published 1739.

In case you don't already know, the nickname St. Anne wasn't used by Bach. It comes from the similarity of the fugue subject with the tune known in the English-speaking world as St. Anne, written by William Croft (1678-1727), to the text O God, Our Help in Ages Past, by Isaac Watts (1674-1748). Researchers believe it's unlikely Bach knew of the tune. The fugue subject is also related to one Bach had used earlier in his career, in the Prelude in E-Flat Major (same key) in the WTC, Book 1. Today we're looking at the prelude, which Bach marks Präludium pro Organo pleno, a large work — in fact the longest prelude for organ that Bach ever wrote — which has multiple themes.

There are some voice-leading anomalies in this piece. The most striking of these is found in bar 67, where Bach writes a real parallel unison (and / or octave, depending on how you want to interpret the pedal part).

The thing about this is, nobody listening is ever going to hear a parallel octave or unison there. Organ registration is in fact based on adding parallel octaves and 5ths. The indication organo pleno means that many octave doublings and mixtures (which include 5ths) are expected to be used in the organ registration. When the pedal part moves here in a parallel unison with the tenor, the relationship between the voices simply can't be heard as such. It's even likely that the pedal will be sounding (in part) exactly the same pipes as the tenor, since the pedal is often coupled to the manual in organo pleno which again has been deliberately specified in the title of the work.

But it doesn't stop there. Bach also wrote implied parallel octaves in this piece, in measures 137, 146, and 150.

And if that's not enough rule-bending for you, in bars 133, 142 and 158, Bach also writes implied parallel 5ths with this same material.

So students take note: Bach gets away with writing real parallel octaves / unisons when it's something nobody will ever hear, and he shows how these kinds of implied parallels can in fact be used, and will not sound wrong. But keep in mind that it takes a master to work magic like this. Chances are we're not quite on the same level as Bach. Like so many other things in this art, there are a great many more ways to do it wrong than there are to do it right. That's why students are simply told: "don't do it".

Next time we'll continue looking at this monumental work, taking a very close look at one particular passage — in fact it will be another episode of "Passages that bother me".

Until then,
AAH