The beginning of the "Prague" sounds almost like a very slow beginning
of the "Jupiter", but in D. The beginning is mainly a call and response
between the woodwinds and strings.  The reason as to why there is the slow
introduction could be the fact that Mozart wanted a dramatic contrast from
the syncopations in the violins to commence the allegro.  To start the
symphony there would be a little awkward.

Aaron Lofaro