Christian Liturgical Year

The Christian liturgical year is built on two fixed points that move at different speeds. Christmas stands still, kept on 25 December wherever the Gregorian reckoning is followed; Easter moves, set each year by the moon, falling on the first Sunday after the first full moon on or after the spring equinox. Around these two anchors the year arranges itself into seasons.

Advent opens the cycle, four Sundays of preparation before Christmas; Christmastide flows from the feast itself; a first stretch of Ordinary Time follows; Lent then leads through forty days of penitence to Holy Week and the Paschal Triduum, the three days at the summit of the year; Eastertide keeps the fifty festal days to Pentecost; and a long second stretch of Ordinary Time carries the year back around to Advent. Each season has its own character, marked in readings, music and colour: violet for the preparatory seasons, white and gold for the great feasts, red for Pentecost and the passion, green for the ordered weeks between. The structure means no two years are identical, since the movable Easter cycle slides back and forth across the fixed calendar, shortening one stretch of Ordinary Time and lengthening the other, which is why the church's year has always needed its own tables and its own arithmetic.

The liturgical year was not designed; it accreted, and the layers can be dated. The oldest observance is the Pascha itself, attested by the second century, when churches already disputed whether it should follow the Jewish fourteenth of Nisan or always fall on a Sunday. The fifty days of rejoicing that follow it are nearly as old, kept as a single feast called Pentecost before the day of Pentecost took the name for itself.

The Nativity is a later layer: the earliest secure record of Christmas on 25 December is the Roman Chronography of 354, and from Rome the feast spread east while Epiphany, the older feast of the incarnation in the East, travelled west. Lent took recognisable shape after the Council of Nicaea, its forty days converging out of varied older fasts; Advent appears in Gaul and Spain between the fifth and sixth centuries and settled at Rome later. The assembled cycle has never been fully uniform.

The Eastern churches reckon the paschal moon by the older Julian tables, so Easter and Pascha coincide only in some years, and the calendars of feasts diverge further. The 1969 reform of the Roman calendar reorganised the Western structure, naming Ordinary Time and restoring the Triduum's primacy. The year as kept today is therefore a working archaeological site, every era of the church's history still visible in it.