Nicholas J Roberts:

>Can anyone enlighten me as to the music deemed 'masonic' by Mozart,
>Sibelius and Haydn? I'm currently writing a paper on the subject.

OK, but only if you know the secret handshake.  Oh, all right...My quick
research reveals a little information (that is, I had to look most of it
up.) [& please excuse my very poor German.  (Someday we'll be able to do
this with proper accents!!  Imagine!)]:

Sibelius: Musique religieuse, Op. 113

Mozart: Thamos, Koenig in Aegypten (incidental music to Baron von Gebler's
masonic play), K.345/336a

  Maurerisch Trauermusik [Masonic Funeral Music], K.477/479a
  Dir, Seele des Weltalls (cantata), K.429/468a [possibly masonic]
  Die ihr des unsermesslichen Weltalls Schopfer ehrt (cantata), K.619
  Laut verkunde unsre Freude (cantata), K.623
  &  Die Zauberflote (of course), the most masonic of all.

Many other suspected masonic pieces, or pieces used in this manner.

Haydn: Was a mason, but no confirmed masonic music per se, but much has
(apparently) been adopted by practitioners of The Craft.

Grove's has a good article where I got most of this; look up "Masonic
Music".

Hope this helps,

Bob K.