BRUNSWICK — At 7:30 p.m. Friday, Dec. 19, at the Unitarian Universalist Church, Maine’s premier Celtic duo, Castlebay, will “drive cold winter away” with joyous and mysterious seasonal songs and tunes from the Ireland, Scotland and British Isles as well as their native New England. The lilting sound of Irish flute, Celtic harp, fiddle and guitar will mingle revelry and lusty wassails with vibrant songs of mystery and wonder.

The duo will be joined by a motley crowd of mummers who will perform a traditional play about the seasonal battle of Light and Dark. Audience members may also be recruited to fill roles in the play.

For the ancient people of the British Isles and Ireland, the celebration of the winter solstice was one of the most important in the calendar. The word “yule” means “wheel” and symbolizes the turning of the sun-wheel. Many of the enigmatic circles of standing stones that rise from the wind-swept landscape are oriented to the solstice.

The music of these people is filled with the symbolism of light conquering darkness, rebirth and the evergreen power of life. Legends and lore abound featuring the affirmation of life-force in the form of the Green Knight, and power animals such as the stag and the wild boar.

In addition to these ancient stories and symbols, the lore and music of Celtic Christianity are mysterious and beautiful. Deep in the most desperate darkness the hope that came with the coming of Christ sustained those people of faith. Miracles and magic abound as the sun returns and the joy of a child’s birth remind us of the light in our lives.

Here in the New World, the crisp, cold starlit nights, and brilliant crystalline days brought ruddy-cheeked family and friends gathering around a crackling wood fire, to share convivial songs with roots in the old country.

Castlebay will include some of this homegrown fare honoring new traditions. Come celebrate, sing along and experience a little old and new Celtic yuletide enchantment.

The newly reconstructed church is at One Middle Street just opposite the Curtis Memorial Library. Doors open at 7 p.m. Tickets are $10 at the door. For more information, visit www.uubrunswick.org/church-activities/side-door-coffee-house/ or email sidedoorcoffeehouse1@hotmail.com.

Now Christmas comes, ’tis fit that we,

Should feast and sing and merry be.

Keep open house, let fiddlers play

A fig for cold, sing care away!

From “Poor Robin’s Almanac,” 1715