Shortest day of the year, and longest night.
Christmas rituals are sometimes based on or originate from Celtic, Roman, or Viking rituals for the Winter Solstice. We can thank the Romans and Celts for most of our modern day Christmas traditions.
The festival of Saturnalia, an ancient pagan holiday which honoured the Roman God Saturn, took place every year between the 17th and 24th December. This was basically a week of eating, drinking and giving presents during the Northern Hemisphere’s winter solstice.
Likewise, the Celts celebrated the fact that the winter solstice had arrived and rejoiced at the fact that the nights were once more getting lighter and spring was only just around the corner.