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.

Be that as it may, hunting that motif down is a lot of fun, if only
because you get to hear a lot of Mozart in the process.  It was also
noted correctly that the motif makes an (unexpected and quite prominent)
appearance in the Symphony No.  33 in Bb, KV 319, albeit in the first
movement and not, as claimed, in the finale.  And list members also
spotted it in an early Mozart mass and a Haydn symphony.

I'm bringing this up again only because I recently acquired a document
that references yet another sighting of that motif in quite a prominent
place in Mozart's own symphonic oeuvre, and by no-one less than Robert
Volkmann himself!  I believe that one had not been spotted by the sharp
eyes and ears of the list members when the topic came up - but correct me
if I missed a post.

Here's the account, from an article written by Ilka Horovitz-Barnay, one
of the students in Volkmann's introductory theory class at the Hungarian
National Academy of Music, from "Neue Freie Presse", April 26th 1903.
That incident must have taken place in the 1870s or early 1880s.

"Only once did I see him in a somewhat agitated mood.  He wrote the first
four measures from the last movement of Mozart's Jupiter Symphony, which,
as one knows, consist of four whole notes:  c, d, f, e, onto the blackboard
to have them harmonized.  'Do you know where these four measures are from?'
he asked.  When I wanted to answer his question, he indicated to me to keep
silent.  No-one knew the answer.  'Well, you know, if you have to drum up
all those virtuoso pieces on the piano[*], you should at least know
Mozart's _first_ symphony.  That really wouldn't hurt you.' "

 [*]That class consisted of female students never intending to become
composers, but heading for careers as piano virtuosas under the auspices
of Liszt, who was in charge of the piano class, instead.  Volkmann had
relatively little regard for Liszt and his music, and no more for any kind
of pretentiousness in music in general; his heart, as he used to say,
belonged to Mozart and Beethoven ("and each of them possesses all of it").

Assuming that KV 16 was already being regarded as No.  1 at the time,
I was surprised, never having noticed that occurrence.  I went back and
listened to it.  Nothing in the first movement.  But then it was right
there, clear for all to hear, right at the beginning of (and throughout)
the second movement, played by the horns in Eb (I think).  Anyone got a a
score and could confirm this?

 From such small-number statistics and without a control sample, it
is impossible to conclude whether Mozart might have had any particular
preference for this combination, or whether he even intentionally quoted
himself, or whether we are just calibrated towards recognizing this motif
because of its association with the Jupiter, and it may not occur more
frequently or prominently in his output than comparable motifs.  Still,
coincidence or not, it is a nice pattern formed by the appearances of
this motif - KV 16, KV 319, KV 551, near the beginning, middle, and
end of Mozart's symphonic oeuvre (although he was hardly aware of these
proportions when he wrote them).  Is there a similar distribution in works
other than symphonies?

Ah, let's pour some oil on the (already extinguished?) fire.  Here's what
Egon Kenton says about these four notes in the liner notes for Vol.  2 of
a Mozart Symphony cycle with Guenter Kehr and the Mainz Chamber Orchestra
on VoxBox, regarding their appearance in KV 319:

"At the risk of being called a fantast, this writer could suggest that the
famous four notes that suddenly appear in the development section are also
a hint to Mozart's conscious return to his native German musical language.
These four notes [were] frequently used as a fugal subject (in this form
or slightly changed) [...] In fact it took Beethoven three of his late
quartets to develop this motif, the germ-motif of all three quartets, with
a psychological meaning attributed to them by Paul Bekker in his monograph
on Beethoven.  [...] Beethoven knew the famous four notes.  But he surely
knew Mozart's G Major Quartet (dedicated to Haydn) and the 'Jupiter'
Symphony as well, in addition to Haydn's Quartet Fugue in F Minor and his
'Drum-roll' Symphony."

Daniel Christlein
(who reserves judgement)