why the symphony does not use a piano...

[Preston]

I have wondered this for quite sometime, why is the piano not used in the symphony?

I imagine that it is incorrect form and style of writing the symphony, but why?

Kind Regards,
Preston

[Peter]

It has to do with the origins of the form, developing from the old Italian overture. At the time of the first symphonies in the early 18th century by Monn and Sammartini, the piano was a very new instrument and not very powerful (don't forget that the piano concerto itself wasn't developed until later in the century with J.C.Bach and ultimately Mozart.)
So the Harpsichord was the main keybord instrument of choice and in orchestral music it served the function of underlining the harmony and bass (basso continuo). This is a typical feature of Baroque orchestral music and even Beethoven's piano concertos in their original form continued this tradition with the solo piano underlining the orchestral parts during the tutti (this practice is never observed in performance of Beethoven today, except in some HIP).
Gradually the basso continuo became obsolete and as the piano developed it was the concerto where its uses were considered best as a means of virtuoso display and contrast.

During the 19th century and 20th centuries the piano did become used as an integral part of a symphony orchestra (as opposed to a solo concerto), Saint-Saens Carnival of the Animals, his Organ symphony or Stravinsky's Symphony in 3 movements are just a few examples.

[Ateach Asc]

I have wondered this for quite sometime, why is the piano not used in the symphony?

Preston

Well that's not quite entirely correct... Vincent D'Indy's Symphony On A French Mountain Air uses the piano... and that instrument is very prominent in the last movement...

Mahler also uses the piano in some of his symphonies... if memory serves me right...