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.
"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!"