The Celtic Feast of Imbolc
Throughout the UK
Imbolc was the second of the four great fire festivals. At Imbolc, Brighid, the daughter of Daga, was pregnant with the seed of the Sun. She was ripe with the promise of new life, as the seeds of the earth deep within its soil begin to awaken at this time, thus signaling the return of spring.
Imbolc, which literally means "in milk", traditionally has marked the lactation period of ewes and cows. Ewes are unable to produce milk until after they bear their young, which occurs at this time. Since milk was very important to the basic survival of the tribes, this was a time of great joy. It meant that the end of a long winter was in sight, and green pastures were only a few months away.
During the Imbolc ritual it was customary to pour milk (or cream) onto the earth.
http://www.historic-uk.com/CultureUK/FolkloreYear-Feb.htm