Mike Leghorn wrote:

>Oops, I forgot!  Btw, did you know that Beethoven took the dah dee
>daahhh, duh dah dah dee deeeeeee theme (without modification) ...

Actually, the themes are not entirely identical.

>...from a Mozart overture.

No, he didn't.  That's a myth.

>I don't remember the name of the overture,

You are thinking of Bastien und Bastienne.

>but I did hear it once, and that theme stuck out as clear as day.

Nope, because a theme like that is one of the most natural one to come with
in tonal music.

Mozart's little singspiel was written when he was 12 and it was soon
forgotten.  There is no chance that Beethoven could see or hear it or
see the score of it (it wasn't published until later).  Most certainly,
he didn't even know this work existed.

This claim that Eroica's theme is taken from Bastien is often repeated,
but it's simply false.  People often mistake coincidental similarity for
quotation, not knowing the context.

-Margaret Mikulska