Break out the creepies and the crawlies, the ghosts and the goblins.

And, of course, the history books. According to the Library of Congress, Halloween and its rituals can trace most of their roots back to the Celtic holiday of Samhain, which was celebrated usually around the date we know as Nov. 1. For the Celts, this was the time when crops and livestock were brought in and tucked away for winter.

Oh, and when the ghosts of the dead traveled into the underworld, bumping against some of the living along the way. The Samhain festival included sacrifices to the dead and bonfires to help them on their journey.

The Christians, the library says, co-opted many of the pagan holidays and rituals in an effort to draw more people to Christianity.

The feast of All Saints was assigned Samhain’s holiday of Nov. 1, and while the Christians weren’t entirely successful in replacing Samhain, they did relegate some of the old Celtic gods to a diminished status. The church tried again with All Souls Day on Nov. 2 — a day set aside for the living to pray for the souls of the dead.

Still, Samhain lived on. All Hallows’ Eve, or Halloween, is the day before All Saints Day, and this evening was seen as the time of the most activity, human and otherwise.

People continued to placate wandering spirits by setting out gifts of food and drink. In England, for example, people made cakes for wandering souls and gave them out to groups who were gone “a soulin’. ”

Nowadays, we dress up and wander around for tricks and treats alike, but mostly treats, if we’re honest.