In addition to choral and orchestral music, Bach wrote for organ, which can change dynamics by changing the number of ranks. I don't recall that he had access to any instruments with a swell organ, but he may have known about them. He also had at home instruments which did change dynamics, including two many harpsichords, which at least have mf and f available for the player.

To assume that Bach would not use dynamics is, I believe, the height of arrogance and condescension, if not outright stupidity. Everything we know about Bach's writing, especially for the big works, were expressive in the extreme. His music, especially the sacred, was full of emotion and emotive music is most certainly not monotone in nature.

I suspect that the idea of not using dynamics stems from a period when performers were thinking of imitating the harpsichord on the piano. An idea which has hopefully died out completely.

Then the question becomes, when to use dynamics. It is certainly not marked, just as ornamentation isn't marked. Musicians were expected to know when to use both and how to use both. Following a formula such as your friend suggested is better than nothing, but I think it's best to carefully analyze the music and perform accordingly.

Huh? Ornamentation isn't marked? It certainly is. Bach, owned instruments which DID change dynamics? His estate lists several harpsichords (which could have included virginals, or spinets, though it's not known WHICH keyboards he owned, nor their makers), though the only change in dynamics one would hear from a harpsichord would be that of a dual keyboard instrument. "MF" and "F" would not be the only dynamics available to some larger harpsichords as some of them employ lute stops as well. There are some works, though few, in which Bach DID indicate dynamics, however. The Italian Concerto, is just one example.

Out of curiosity, on the piano what would you do if there are no dynamic marking on a certain part of a Bach keyboard work. Would do get louder as the melody goes up and get softer as it goes down etc?

Actually, Bach's favorite keyboard instrument was the clavichord. This instrument IS capable of dynamic variation, albeit subtle.

My approach to Bach (generally) is to drive to the cadences. Build it gradually to each cadential point, then drop off and start again. A generalization, I realize, but one which often works.

It is of utmost important to think about voicing as well.

Actually, Bach's favorite keyboard instrument was the clavichord. This instrument IS capable of dynamic variation, albeit subtle.

My approach to Bach (generally) is to drive to the cadences. Build it gradually to each cadential point, then drop off and start again. A generalization, I realize, but one which often works.

It is of utmost important to think about voicing as well.

Huh? Ornamentation isn't marked? It certainly is.

There are some works, though few, in which Bach DID indicate dynamics, however. The Italian Concerto, is just one example.

You play as you would sing. All Bach's kids (and himself) were singers, violinists and keyboard players.

With very few exceptions, ornamentation isn't marked. If your edition has ornamentation markings, it's been added by the editor. Get your hands on a good Urtext.

The major exception, such as it is, are pieces noted by his students with ornamentation added. Even those are not comprehensive. Much more can be tastefully added.

Actually, Urtext editions of the Italian have very few dynamic markings, just forte and piano as I recall.

Bach also used forte and piano in some parts of French Overture. I think the last movement (Echo) had dynamic markings; however, they are very "terraced."

When I play Bach, I use all that's available on a modern piano--una corda, sostenuto pedal, damper pedal, crescendo, diminuendo, and all kinds of dynamic shadings.

My students still run into judges who write nonsense comments to them. Seriously, one judge wrote something to the effect of "you need to make the piano sound more like a harpsichord for Bach." Huh??? I guess there are still some folks leftover from the "no pedal in Bach" school of piano playing.

I believe that there are basically two valid ways to approach Bach on the piano. First, imagine that Bach had a modern instrument available and think about how he might have played his works on it - dynamics, pedal, etc, and probably fairly sparse ornamentation.

Second, try for "historic accuracy" and strive to imitate the harpsichord. Lots of ornamentation, very minor dynamic change and pedaling.

I find myself vascillating between the two. Neither, to me, is "right". In fact, playing a piece with both approaches seems to me to be bring some insight to the piece.

it's your OWN idea and wouldn't, as a result, stem from Bach, himself.

Some of the fugues would sound awesome in SATB arrangement. However, what do you do when you encounter passages that are not "singable"?