Over the course of the past 2,000 or so years, 31 October has transformed from a celebration of the last day of the Celtic calendar (marking the point where the nights grew long, the days grew cold, and people began to die) and a spooky, fun, and fanciful celebration of creative costumes, neighbourly candy exchange, and self-induced terror.
The Celts believed that on the 31 October, the boundary between the world of the living and the world of the dead became blurred and the dead could return to earth. That sounds completely terrifying, and because humans inexplicably like to be scared (actually, it’s apparently because our ability to determine the fear of actual danger versus low-risk danger transforms our perceived fear into excitement), it has become a day to celebrate fear.
In addition to blurred lines between worlds, 31 October has also become a time to blur the lines between reality and fantasy. Thanks to the tradition of dressing in costumes, it is the one night of the year when people can publicly masquerade as someone or something else. And this year, there will probably also be a lot of blurred lines between good and bad versions of Miley Cyrus and Robin Thicke costumes.