Imbolc, 1 February

Imbolc falls on the first of February and runs two days by this rule's reckoning, one of the four traditional quarter days of the medieval Gaelic calendar, marking the turn of the year roughly midway between the winter solstice and the spring equinox. The earliest textual references come from medieval Irish literature, including the saga Tochmarc Emire and the glossary Sanas Cormaic, which associate the day with the goddess, and later the Christian saint, Brigid, and describe practices connected to the beginning of the lambing season, ewes coming into milk being one traditional explanation offered for the name itself.

The day passed into the Christian calendar as the feast of Saint Brigid of Kildare, a figure whose own historical existence is debated separately from the festival's, and it survived in that Christianized form across Ireland and parts of Scotland through the medieval and early modern periods. Its modern life as Imbolc, one of the eight sabbats of the neopagan Wheel of the Year, is a twentieth century construction associated with the Wiccan revival rather than a continuous unbroken practice reaching back to the medieval sources, and the historical case for a direct line from the earlier pre Christian festival implied by the medieval texts through to the modern Wiccan observance is considerably weaker than popular accounts of Imbolc's ancient pedigree generally suggest.