In Circe Bloom thinks of Georgina Simpson's
housewarming party, sixteen years earlier, on "Old Christmas
night." This is another name for January 6, more commonly
called Twelfth Night or the Epiphany. The expression endures
in parts of England, Ireland, the maritime provinces of
Canada, and Appalachian America.
Although there is an older history from the reign of
Constantine in the 4th century, the modern duel between
December 25 and January 6 dates from 1582, when Pope Gregory
XIII instituted a new calendar to correct the ongoing drift
between a 365-day calendar and a slightly longer astronomical
year. The non-integral mismatch between earthly days and
earthly years meant that, with each passing calendrical year,
dates diverged a little further from the equinoxes. The
Gregorian solution initiated our practice of "leap years,"
whereby one day is added to the calendar every four years.
(The reality is in fact slightly more complicated. Since the
earth takes 365.2422 days to orbit the sun, rather than
365.25, leap years are defined as years divisible by 4, not
including most years divisible by 100, but including years
divisible by 400.)
Some Catholic countries adopted the new calendar immediately,
but other countries came on board decades or centuries later,
having drifted yet further from their appropriate solar
positions. In Britain, legislation called the Calendar Act
was passed in 1751, by which time the drift was approximately
twelve days, so twelve days were dropped from the old Julian
calendar. The result was that in 1752 Christmas was celebrated
on December 25, but purists clung to the old date of January
6. For readers interested in what Ithaca calls the
"parallactic drift of socalled fixed stars, in reality
evermoving wanderers," the inexactitude of human calendars
provides an additional, temporal way to contemplate the
concept of parallax.
