the Illuminati, which were once a real organization, got their start (and, in my opinion, end) in 1770's Bavaria. they may have used the symbol, but Mozart used a lot of Masonic symbolism in The Magic Flute, and you never hear that he was part of some Masonic conspiracy, just the ones who had money.
I suggest using The Straight Dope, at http://www.straightdope.com, to search out a lot of this stuff.
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Gillian
"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"
"You can't erase icing."
"I can't believe it doesn't work! I found it on the internet, man!"