Dark days can mean dark moods. This natural turn of the seasons helps explain the timing of Christmas. It is the festival of light, the return of the sun and longer periods of daylight. It’s a time of renewal and hope, sentiments we feel as we watch the skies and see faint signs of the sun returning. What happens in December in the northern hemisphere is a natural symbol. You don’t need a dictionary or an encyclopedia to know that the dark sky parallels your darkened heart. You feel it in your body and then in your emotions. The sky mirrors your feelings, and your pulse beats with the special rhythms of night and day. The turn of the sun on the day of solstice may well coincide with a turn in your spirits.
— from the book The Soul of Christmas