Daniel Christlein:

>A while ago, a thread brought up the topic of the famous first four notes
>in the finale of the Jupiter symphony and their possible cross-references
>throughout the literature.  IIRC, the consensus (or at least the majority
>opinion) was that this motif was a common contrapuntal exercise of the time
>and that most of the alleged quotations (especially those by Beethoven)
>were a bit spurious anyway.

I've come across those four notes so often (another thematic germ that
occurs across composers is the "And with his stripes" motive from Handel's
Messiah) in various composers that I suspect it's probably a trope from
counterpoint exercises.  It also occurs in Mozart's so-called "Credo"
mass, K. V. 192, in (appropriately enough) the Credo movement.

Steve Schwartz