General Observations

Pace

According to tradition, Bach interpreted his harpsichord music as a true fleet-fingered virtuoso, very rapidly; as for his organ music, we do not know anything about it. But even if an instrument of the time no longer remained to us, and there was no longer any evidence of what one could require of an organ, there cannot be any doubt in this regard: he did not play fast, on the one hand from the quest for polyphonic clarity and the need to emphasize the least contrapuntal detail, and on the other hand because the slowness of the sound wave would not permit it.

Now we still have quite a number of instruments from the middle of the eighteenth century, those of Silbermann among others (in Saxony and Alsace), whose depth of the key dip forbids all velocity, all pace faster than the modern Moderato… .

Can one specify metronomically the interpretation of organ music?

No. It is the resonance of the building that determines the pace. The course of a sound wave in a cathedral of 120 meters in length requires more than two-thirds of a second, whereas it seems instantaneous in a room of 20 or so meters. How are the same tempi kept in the two places? How under the same vaults would one not adapt the beat to the size of the crowd, according to the greater or lesser resonance of the room?

Nothing is more profitable to an organist than to listen at a distance to a piece played in a tempo agreed on in advance and inscribed metronomically: “Too fast, much too fast, you will think; my colleague is mistaken, his values marked at 92, I hear at 116.” And your colleague answers: “I followed the beats of the metronome set at 92, which reproduce with the most rigorous exactness your own performance when you are at the keyboard, although I also met with the impression you just experienced.” Long years of experience are necessary to succeed in hearing oneself independently from all mechanical preoccupation, as if one were one's own audience.