One of the great cultural traditions of modern American Christmas observance is the use of lights. Everything that doesn’t move is decorated with lights. Christmas trees are recognizable by their lights, and indeed as more and more types of trees are used as Christmas trees, the more it is the presence of the lights that identifies them as such. Lights are put around lampposts. We hang lights from the eaves and awnings of our homes, and around windows and doorframes. Lighted fixtures and images are arrayed in front yards, and those that are not self-lighted are bathed in spotlights. Without a moment’s embarrassment at the brazen self-interest, electrical power companies promote contests for the best and most elaborate seasonal displays. Terms like “Sparkle Christmas” are entering the vocab…