Once upon a time, Christmas didn't end on December 26, it was only just getting started. It would run for twelve days into January, ending on January 5 and followed by Epiphany on January 6. This is also the eve of Little Christmas or Orthodox Christmas, when the Nativity of Christ is celebrated under the Julian Calendar on January 7.
As I remarked in my entry on the Winter Solstice, these Christian feasts and festivals are intimately bound up with the astronomical facts of seasonal change. It shouldn't be a surprise, therefore, that a little digging reveals that the culture has traditional astrological dimensions to the feasts as well. Wiki:
Astrologically, on the night when the sun commences the visible northward journey, to save the northern hemisphere of the globe from a perpetual winter and consequent extermination of life should the sun remain always in the south, the zodiacal sign Virgo, the Celestial Virgin (the "Queen of Heaven"), stands upon the eastern horizon at midnight; thus the Savior is "born of a virgin" without other intermediary, hence, "immaculately conceived." Every year, on December 25 the Christ Spirit enters the heart of Earth and the planet is swept by powerful solstitial radiations, becoming enveloped by the light of the archangelic Christ and therefore Christmas is considered the most Holy Day of the year. From December 26 to January 6, Epiphany or the "Twelf Day", the twelve zodiacal hierarquies work upon the Earth and its life forms, along with the Christ light which continues throughout the twelve holy days. As also defined in the liturgical calendar, the eve of January 6 is seen as the Twelfth Night, the time when the "Rite of Baptism" was performed in early Christianity. This period of twelve-day interval, initiating after Christmas Day and culminating with the Feast of the Epiphany, is regarded as the spiritual heart of the year to follow and is termed the year's "Holy of Holies".
It's odd to see astrology overlapping so intimately with Christian worship. But since astology was once the principal Western system of cosmology, and the astrological signs were considered to be symbolic measures of time, we can see how that would evolve. According to Wiki, each of the twelve days of Christmas was considered to be ruled by a different astrological sign, and a different central focus for celebration:
December 26 - Aries - "Behold, I make all things new.-Revelation 21:5"
December 27 - Taurus - "He that dwelleth in love dwelleth in God.-I John 4: 16"
December 28 - Gemini - "Be still, and know that I am God. -Psalms 46:10"
December 29 - Cancer - "But if we walk in the light, as he is in the light, we have fellowship one with another.-I John 1:7
December 30 - Leo - "Love is the fulfilling of the law.-Romans 13: 10"
December 31 - Virgo - "But he that is greatest among you shall be your servant. Matthew 23:11"
January 1 - Libra - "Ye shall know the truth, and the truth shall make you free.-John 8: 32"
January 2 - Scorpio - "Blessed are the pure in heart: for they shall see God.-Matthew 5:8"
January 3 - Sagittarius - "Ye, are the light -of the world.-Matthew 5:14"
January 4 - Capricorn - "Let the Christ be formed in you.-Galatians 4:19"
January 5 - Aquarius - "Ye are my friends.-John 15:4"
January 6 - Pisces - "So God created man in his own image. Genesis 1: 27"
I'll be covering what the twelve days of Christmas mean now, at the turn of the Millennium, on this blog.