So, I’m curious–anybody know the origin of drawing a lightbulb over someones head when they have a “Bright Idea”? I’m thinking it must be Twentieth Century, because of the bulb, but I guess it could have been a candle at one time! Editorial cartoons go way back. Is the idea specific to one person? 
Anyone?
WAG: Thomas Edison, perhaps?
Definitely Edison. The impact on that society was truely immense, so Thomas Edison with a thought-balloon containing a light bulb was the icon of the age. Don’t miss the symbology of a “light dawning in your mind.”
If Nikola Tesla had beat out Edison, then our symbol for having an idea would’ve been a little coil of wire suddenly appearing over your head? 
Or more likely a lightning bolt. The Tesla icons still live on in modern society: to do a REAL science experiment you have to open the big doors on your roof and crank the huge coil into the sky. Igor, throw the Big Switch! Yeassss Neeeekola!