Bach himself is known to have executed it in a very polyphonic style, and this for the excellent reason that plain chords would have contrasted so strongly with the real instrumental parts that they could not fail to attract attention even in the softest tones of the harpsichord or the organ, while light polyphony in these tones would elude the ear and at the same time perfectly bridge over the gap in the harmony.
There seems no good reason why in modern performances the pianoforte should not be used for the purpose; if only accompanists can be trained to acquire the necessary delicacy of touch, and can be made to understand that, if they cannot extemporize the necessary polyphony, and so have to play something definitely written for them, it is not a mass of interesting detail which they are to bring to the public ear.
The invention of the damper-pedal in the pianoforte epitomizes the difference between polyphony and symphonic art, for it is the earliest device by which sounds are produced and prolonged in a way contrary to the spirit of "real" part-writing.
The pianoforte trios of Haydn are perhaps the only-works of first-rate artistic importance in which there is no doubt that the earlier stages of the new art do not admit of sufficient polyphony to give the instruments fair play.
Where the orchestra shows that Parsifal is becoming half-conscious of his quest while Kundry is beguiling him with memories of his mother, - and also during the two changes of scene to the Hall of the Grail, where the orchestra mingles the agony of Amfortas and the sorrow of the knights with the tolling of the great bells, - the polyphony is almost as dramatic as in Tristan; while the prelude and the Charfreitagszauber are among the clearest examples of the sublime since Beethoven.
In the development of instrumental polyphony Haydn's work was almost as important as that of Mozart.
The polyphony of Beethoven was unquestionably influenced by it and, even in his latest sonatas and quartets, may be regarded as its logical outcome.
In the choral numbers of the five masses, and in the oratorios Die Heilige Elisabeth and Christus, the rarity of fugal polyphony acts as a drawback.