Published: Oct. 30, 2012

Contrary to contemporary beliefs that the spooky holiday originated with vampires and werewolves -- or even more sinister, candy and costume companies -- CU associate professor of history Scott Bruce notes that Halloween's origins lie in ancient Pagan harvest festivals practiced by the Celts, and Christian traditions.

Bruce explained that Salann, a celebratory Celtic festival during the Roman period, took place at the end of harvest season and before the cold weeks of winter began. However, the Romans cast Celtic food preparations, which included practices such as animal slaughter, in a very negative light.

The Romans had 鈥渘o interest in portraying barbarian peoples in a positive way,鈥 explained Bruce, an expert in medieval history, 鈥渟o, we have to understand that a lot of our understanding of the Pagan ritual is mediated through a hostile source.鈥

Not all conceptions of Halloween, however, are quite so insidious. The timing of the autumnal holiday comes when days shorten and nightfall arrives sooner.

Another influence on the holiday鈥檚 present day identity comes from Christian celebrations, the Feast of All Saints and the Feast of All Souls.

鈥淭he poor people at the time of All Saints and All Souls would go from house to house to house and there they could expect to receive an offering of food and this was called souling,鈥 said Bruce. 鈥淚n popular tradition, the giving of the soul cake鈥 -- which Bruce explains is a wafer-like sweet that was handed out to those house-to-house travelers -- 鈥渨as good for the soul of the giver.鈥 The consumption of a soul cake, Bruce explains, represents a soul that will be released from purgatory.

Public misbehavior in the late 19th century also plays a part in the holiday's mordern practices.

鈥淵oung people, especially young boys, began to perform pranks and to engage in minor acts of vandalism,鈥 said Bruce. Many individuals opposed this behavior and in response, attempted to 鈥渟anitize the rowdiness of individuals who in the late 19th century took it as an opportunity to go a little wild.鈥 These sanitation attempts led to the commercialization of the holiday.

Bruce concluded that though there are not concrete connections between the Pagan and Christian traditions, there are legends that have persisted across time.

鈥淲hat pre-modern people may have shared is this sensibility that as the days got shorter and as the night encroached upon their lives, the membrane between the world of the living and the dead was thinner,鈥 said Bruce. This explains our modern fascination with haunting and fantastical entertainment during the days leading up to Halloween.

By the 1920鈥檚, the holiday began to resemble the Halloween we celebrate today. Trick-or-treaters visiting the doorsteps of neighboring houses today still receive sweets -- even if the meaning of the tradition has changed -- and movies and haunted houses continue to feature plots with lost souls and interactions between the living and the dead.

Today, the festive holiday generates more than $3 billion every year -- one of the highest grossing holidays, second only to Christmas.