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Donning costumes and begging for candy is, perhaps, no stranger than leaving cookies for a man you expect will climb down your chimney -- or hunting for colorful eggs hidden by a rabbit. Yet unlike with Christmas and Easter, the origins of Halloween are seldom discussed. While Oct. 31 may seem like one of the more secular dates on the calendar, it is a holiday deeply rooted in Christian tradition.

Unbeknownst to many trick-or-treaters, Halloween is thought to have originated around the time of Christ. More than 2,000 years ago, tribes in Ireland, Great Britain, and northern France celebrated the completion of the harvest with a festival called "Samhain." In Celtic tradition, Samhain was held on Oct. 31 to mark the end of their calendar year and the beginning of the long, dark winter.

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The passing of the summer season has often been associated with death. During Samhain, it was believed the barrier between the human and spirit world was worn thin -- that faeries, demons, and the dead slipped through the gaps and wandered through the rolling countryside.

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The Celts feared the spirits' mischief, and sought to appease them by placing cakes, milk, and other treats outside their cottage doors. They lined the road with candles -- precursors to the modern-day "jack-o-lantern" -- to guide their departed relatives back to the spirit world. As darkness fell, the Celtic community gathered around magnificent bonfires; later, when the ceremony ended, each villager took some of the sacred embers to rekindle their own hearth fires. These practices continued for hundreds of years, even after the Roman Empire had extended its power as far north as Scotland.

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Enter Christianity. In the seventh century A.D., Pope Boniface IV instituted the Feast of All Martyrs. One hundred years later, Pope Gregory III expanded the holy day to include all saints and moved the feast to Nov. 1. As the Christianity of Rome spread northward, the new holiday merged with that of ancient Celtic tradition. The day following the "Feast of All Saints" was designated the "Feast of All Souls," a day set aside for prayer and commemoration of deceased friends and family.

In this way, the church sought to peacefully wed the Celtic understanding of the afterlife with the Catholic teachings on death and resurrection, heaven and hell. All Saints Day became known as "The Feast of All Hallows," and Oct. 31 was transformed to "All Hallows' Eve," or "Hallowe'en."

Centuries passed -- and the time-honored tradition of All Hallows' Eve crossed the Atlantic to settle with immigrants in the United States. The holiday gained popularity, first in immigrant communities, then among the general public.

Poor Catholics from Europe continued to observe the Feast of All Saints with the Holy Mass, processions, and parish parties, but by the mid-20th century, Halloween had become the more widely known celebration. Children were decked out in costumes and porches were decorated with grinning jack-o-lanterns, activities that hearkened back to the superstitions of the Celts. Over time, many forgot that Halloween was only a prelude to a more significant feast day.

Although the customs of Halloween have metamorphosed, the holiday's spiritual symbolism should not be overlooked. Centuries before the light of Christianity reached northern Europe, Celtic society was already publicly acknowledging the link between the physical and the spiritual world.

As the dark, death-bearing winter approached, people sought comfort in community and signs from their ancestors. They carried the flames of the sacred bonfire into their own homes, becoming the living representation of Christian communion. The fire they bore became a symbol of the Catholic faith, the source of spiritual life welcomed into the Christian home.

All Hallows Eve and the days that follow are a celebration of communion with the Body of Christ. When the church embraced and transformed the tradition of Samhain, Christians and Celts together celebrated the bond between the church militant (Christians still on earth), the church suffering in purgatory, and the church triumphant in heaven. The church did not abolish the ancient tradition of the Celts, but enriched it by placing it within the context of Christian teaching. At last, the hope that the barbarian tribes were searching for was realized in the death and resurrection of Jesus Christ.

This year, as happy-go-lucky trick-or-treaters begin their twilight rounds, remember the day's Christian origin. This holiday of ghouls and goblin masks, candy and chaos, is only a prelude to a greater celebration -- the celebration of our communion with the Body of Christ.