Christmas Day and still room for a saint! The reason for the date is that the Church of St. Anastasia in Rome (opposite the Circus Maximus and just below the Palatine Hill) was where the Pope, having said the midnight Mass at St. Mary Major's (which contains relics of the Crib), came to say the Mass of the Dawn. The church was convenient for the courtiers who lived nearby - the site of the ancient Palace of the Caesars was very close; they liked their Christmas Mass at a time to suit them [old habits die hard!]. After that, papal stamina being what it is/was, the Pope returned to St. Mary Major's for the Day Mass. The church in question was founded by a 'Lady Anastasia' - the name means 'Resurrection' and very possibly refers not to a person but to Christ's Rising from the Dead. The St. Anastasia of history was a martyr of Sirmium -an ancient Balkan centre of Christianity, now Sremska Mitrovica in Serbia. So who exactly is the 'Anastasia' mentioned in the Roman Canon of the Mass [Eucharistic Prayer 1] and who exactly is honoured in the church of St. Anastasia in Rome are enigmas you must contemplate as you munch your Christmas sprouts.