Today is the winter solstice in the Northern Hemisphere; the day when the earth reaches its maximum tilt away from the sun. So it is when we have the shortest day and the longest night of the year. Not surprisingly, the winter solstice has been a significant time of year in many cultures, since prehistoric times; and has been marked by festivals and rituals celebrating the symbolic death and rebirth of the sun.
Prior to the arrival of Christianity, the Celtic people of Britain celebrated Yule. The word Yule, has several suggested origins: the Old English word, geõla; the Old Norse word jõl, a pagan festival celebrated at the winter solstice; or the Anglo-Saxon word for the festival of the Winter Solstice, 'Iul' meaning 'wheel'. In old almanacs Yule was represented by the symbol of a wheel, conveying the idea of the year turning like a wheel, The Wheel of Life. The spokes of the wheel, were the old festivals of the year, the solstices and equinoxes.
It is thought that Celtic Druids began the tradition of the Yule log, with the intention of driving out darkness, evil spirits, and poor luck in the following year. The Yule Log was intended to be kept alight over the entire solstice period, twelve days over which the sun was believed to stand still. If the fire died, this symbolised bad luck in the following year. Additionally, evergreen plants were used in decoration. Of key significance were holly and ivy, which were used in decoration; and mistletoe, which was suspended over a doorway in a token gesture of goodwill to all who passed under it.
Because the sun is at its lowest elevation in the sky on the winter solstice, it is the day when one has the longest shadow of the year.