The passage tomb at Newgrange in Ireland may be the most impressive winter solstice monument on Earth.

Constructed about 5,200 years ago, before the Egyptian pyramids and even Stonehenge, the site covers an acre in the Boyne Valley north of Dublin. While it surely functioned as a tomb, the massive amount of stonework involved, as for the pyramids or the medieval cathedrals of Christianity, implies that it was the work of generations and served similar religious/ceremonial functions.

The key design feature is a 62-foot stone tunnel to the center of the circular structure, with an entranceway so carefully constructed that only for five days around the winter solstice can sunlight shine over the capstone and penetrate all the way to the core.

There it illuminates a triple-spiral engraving that many associate with Celtic culture, except that Newgrange predates arrival of Celtic people in Ireland by about 2,500 years. Although we cannot know the full cultural significance of the solstice to the Stone Age builders, to say it was “important” is, well, a monumental understatement. My wife and I can testify to the power of the place, though our visit came in the summer, not during the magical mornings around the winter solstice.

Preliterate societies relied on the solstices and equinoxes, together with the regular cycle of the moon, to reliably judge times for migration or for planting. Consequently, ancient calendars of various levels of sophistication existed universally. In the southwestern U.S., solstice markers include Calendar Wall at Wuptaki National Monument near Flagstaff, Arizona, for the winter solstice, and the more famous Sun Dagger at Chaco Canyon for the summer solstice.

As autumn progresses toward winter, the directions to sunrise and sunset gradually shift farther south and days grow shorter and shorter. At the winter solstice, the progression stops and for several days the direction to sunrise or sunset scarcely moves. Thereafter each day brings more daylight. Even though it comes relatively early in meteorological winter, the solstice promises longer days and the eventual coming of spring.

Cultures around the world, but especially in the populous northern mid-latitudes and in the Arctic, celebrate the return of the light. Examples of winter solstice festivals are Dongzhi in China, Inti Raymi in Andean South America (a legacy of the Incas) and Saturnalia in the Roman Empire. Christianity aligned the major religious celebration of Jesus’ birth in winter – its own coming of the Light – with the Roman solstice festival.

My own earliest memories of Christmas center around the religious observance (though I am sure that at first Santa Claus took precedence). Christmas Day began with mass, with gift unwrapping deferred until after we returned from church. What followed was a nice brunch, but the main event always was the turkey dinner, with as many of the family as could come to our house. These were warm and happy occasions.

After I went away to school and then work, I almost always returned home for Christmas, though the scale of the celebration diminished as we lost family members. Since my mother’s passing, my wife and I have rarely had opportunities to celebrate Christmas with family, though “found family” usually fill the gap, and we always mark the return of the light on the winter solstice.

Whatever your religious or secular traditions, may the joyful spirit of this season fill your life with light and the warmth of family and friends.