|Supposedly an image of Saturnalia, but I can't find a source|
On December 17th, the ancient Romans celebrated Saturnalia. It was the festival of Saturn, the god of agriculture and was held after the harvest and after the autumnal planting was completed. The celebration in Saturn's honor was meant to evoke an earlier idealized time when Saturn ruled the earth. By all accounts this was one of the most popular holidays of the Roman calendar and was celebrated by a cessation of work and governmental administration, public gambling, relaxed formality and reversed social order; masters waited upon their slaves, who were often seen in distinct peaked caps symbolizing that they were freed slaves. The festival was marked by sacrifice (of the human variety), gift giving and continual partying. Of course, this was only temporary; a liminal "time between times" where social hierarchies were temporarily dissolved or reversed and societal norms relaxed.
A popular interpretation of this holiday is that it was a festival of light leading up to the winter solstice, the supposed darkest days of the year. In the later days of the Roman Empire, the solstice and new year were celebrated in the dies natalis of sol invictus, or the birth of the unconquerable sun, which was held on the 25th of December.
It is believed that the festivities of Saturnalia were later incorporated into the Christian celebration of Christmas and the Jewish Hanukkah celebrations which occur around the same time of year and have a lot of the same imagery and ritual.
My source for some of this information is Wikipedia, in which I'm always hesitant to put full stock, and the whole idea of projecting modern cultural phenomena on ancient practices often leaves a lot of room for inaccuracy, but it makes sense logically that some cultures, especially those which can trace a direct line to Rome, would light up the darkest days of the year and then celebrate when that threshold was passed and the days once again became longer. It's also likely that this celebration did not spring from the minds of Rome, but it is probably a deeper and even more primal celebration of light over darkness, from a time long before we were able to electrically light our days and nights. I thought that this was just a little something to ponder at a time which seems to be taken for granted these days.