Long before there was a Christmas, humans celebrated the winter solstice. Agrarian people were in touch with, and controlled by, the natural cycles of the earth. For those in the Northern hemisphere, the longest night and shortest day of the year meant that Winter had achieved its depth and now began the slow wait for spring. Across cultures, festivals were common to celebrate the returning light. The best food and drink, stored from the fall harvest, were brought out to share with family and friends as the tribes saw the light begin to defeat the darkness.
Sometime in the 4th century, Christians began to celebrate the birth of Christ at this time (even though most biblical scholars agree that Christ was actually born in the spring) as an opposition to the Roman feast of Saturnalia (which looks like it was a hell of a lot of fun. I could get into that kind of partying). Not to disparage Christmas, but the urge to celebrate the winter solstice is an instinctive part of the cycle of life on this planet. We are of this earth, and, thanks to a tilted axis, subject to its seasons.
The Winter Solstice is unique among days of the year — the time of the longest night and the shortest day. The dark triumphs but only briefly. For the Solstice is also a turning point. From now on (until the Summer Solstice, at any rate), the nights grow shorter and the days grow longer, the dark wanes and the Sun waxes in power. From the dark womb of the night, the light is born.
Many of the customs associated with the Winter Solstice (and therefore with other midwinter festivals such as St Lucy’s Day, Saturnalia, Hanukkah, New Years and Twelfth Night) derive from stories of a mighty battle between the dark and the light, which is won, naturally, by the light. Other traditions record this as the time a savior (the Sun-Child) is born to a virgin mother.
Happy Winter Solstice to you all. Let's celebrate the coming of the light.