As the days grow shorter and the leaves turn from green to shades of yellow, orange, and red, we know that autumn is upon us. It's a time of change, both in the natural world and in our lives. Many modern cultures celebrate Halloween at this time of year, but the roots of this holiday go much deeper — all the way back to the ancient Celtic festival of Samhain.

Interestingly, multiple modern-day Halloween traditions that we take for granted, such as pumpkin carving and wearing costumes, can be traced back to Samhain. Traditionally, the Celts regarded Samhain (pronounced "SAH-win") as one of the most important holidays of the year, one that marked the end of the harvest season and the beginning of winter, or the "darker half" of the year, as they called it.