Need Advice About Bach Chorale Key Signature!

Hi!

New member here so be gentle! :)

I'm trying to analyze the Bach chorale "BWV 254 - Ach Gott, erhör' mein Seufzen und Wehklagen".

The chorale seems to move between F major and D minor, however the key signature has no flats or sharps, so indicates C Major / A minor!

Is this a modal or historical thing? Could anyone explain this to me? Sorry if this is a dumb question, i'm just a beginner really!

Thanks! ..........Dazzer

Okay this is a very tricky one. You've got to look at the cadences. The first cadence occurs in ms.4 on the 3rd beat as an FM chord, however after a change of position it immediately changes to CM it's subdominant. The next cadence on Dm from AM and then again on Dm from AM, and then the final on DM as a picardy third. While the interior progressions are in fact very modal, they do not solidify the tonality at the cadence. If the cadence had been BbM to CM perhaps we whould have placed it in the mixolyidan, but this is not the case.

Baroque composers frequently employed "dorian" key signatures (one "sharper" than it would have been otherwise) in minor mode pieces. It saved ink and made things easier to read (because the 6th degree usually gets sharpened moving to the leading tone)

Thanks for the info!

Here's the chorale analyzed from Christopher Czarnecki's book: