The twelve days are a magical, liminal time which may once have been celebrated between the new moon and the full moon (or, like this year, between the full moon and the new moon). In ancient Babylon, the twelve days were a time of chaos between the ending of the old year and the beginning of the new one. This has always been a time to abstain from work, to throw off your normal schedule and roles.
http://www.schooloftheseasons.com/pdfdocs/midwtrcelebrate.pdf
http://www.candlegrove.com/solstice.html
UJIMA
Ujima (ooh-GEE-mah) is the third day of Kwanzaa and means "collective work
and responsibility". On this day we celebrate working together in the community to
help others. For Ujima, we pledge to rebuild our communities and to help our people
solve our own problems by working together to do it.
http://www.schooloftheseasons.com/pdfdocs/midwtrcelebrate.pdf
http://www.candlegrove.com/solstice.html
UJIMA
Ujima (ooh-GEE-mah) is the third day of Kwanzaa and means "collective work
and responsibility". On this day we celebrate working together in the community to
help others. For Ujima, we pledge to rebuild our communities and to help our people
solve our own problems by working together to do it.