On the night of October 31st, people across the United States fire up their finest jack-o’-lanterns, dress up as ghosts or ghouls, and set off to “trick or treat” their neighbors for sweets. But the true story behind “All Hallows’ Eve” goes deeper than costumes and candy.

The ancient tradition of Halloween dates back to the Celts; a tribe of people that first inhabited parts of Europe a few centuries “B.C.” The Celts believed that on one day of the year, the dead could rise from their graves and dwell among the living. They called this day “Samhain”, and it simultaneously marked the end of the harvest season.

This spooky celebration of life and death went paired with druids, bonfires, and disguise. As the druids performed rituals to predict the following year’s crop, the ordinary people would light bonfires and disguise themselves so as to confuse the frightening phantoms out and about that day.

The arrival of Christianity to the European mainland caused the tradition to slowly peter out there, as the celebration of All Saints’ Day took precedence. It was not until the mid-nineteenth century that Halloween started to take on it’s more conventional contemporary form.

Irish immigrants, who had continued to celebrate certain Halloween traditions throughout the ages, arrived in the United States. There (in New York City), they were encountered with an entirely new lifestyle that no longer permitted them to engage in their customary Halloween activities, such as lighting massive bonfires.

Unwilling to fully abandon their cultural heritage, the Irish relied on various newer traditions to create a more friendly version of their original harvest feast. A sort of “Halloween-Light”, if you will. The bonfires became jack-o’-lanterns, the frightening disguises became increasingly playful, and the poor people’s “songs for alms” evolved into children screaming “trick-or-treat!” in exchange for candy.

So now you know that Halloween is not just some modern marketing stunt, but rather a tradition that goes back thousands of years to a time when people actually believed that spirits from the afterlife dwelt among us. Who knows, perhaps the Celts actually right about Halloween’s eerie origins. So before you head off to your Halloween party this weekend just remember that you may be doing so in the company of… a ghost!