The Annunciation, 25 March

The Annunciation falls on the twenty fifth of March, the date this rule records, set exactly nine months before Christmas on the twenty fifth of December by straightforward calendar counting, since the feast commemorates the angel Gabriel's announcement to Mary of Christ's conception rather than his birth. The specific choice of March the twenty fifth is older and more deliberate than the arithmetic alone suggests, since early Christian writers, including figures such as Augustine, connected the date to a belief, current in some patristic circles, that the spring equinox marked the world's creation and that great events in salvation history clustered around it, with some traditions further holding that Christ's conception and his eventual death fell on the same calendar date.

The feast is kept on the identical Gregorian date by new-calendar Orthodox churches, while old-calendar Orthodox churches keep the twenty fifth of March by the Julian calendar, which falls on the seventh of April Gregorian, the same thirteen day drift that separates their Christmas from the twenty fifth of December. The date's position creates a recurring calendar tension, since it frequently falls within Lent and occasionally within Holy Week itself, a joyful feast landing inside the year's most penitential season, and various traditions have developed their own rules for transferring the observance in years when the two collide directly.