"Bethany: Is your house on fire, Clark?
Clark: No, Aunt Bethany, those are the Christmas lights." -National Lampoon's Christmas Vacation
Ahh, Christmas. It's easy to forget how much the invention of the light bulb in 1879 reduced the number of tree fires in people's homes. It was a mere three years later that people began decorating Christmas trees with strings of lights instead of candle flames, and as you can imagine, the reduction in open flames atop fresh kindling had its benefits, and caught on like wildfire. Trees now routinely sport previously unfathomable numbers of lights, limited…