Celebrants believe that the barriers between the physical world and the spirit world break down during Samhain, allowing more interaction between humans and denizens of the Otherworld.
Ancient Celts marked Samhain as the most significant of the four quarterly fire festivals, taking place at the midpoint between the fall equinox and the winter solstice. During this time of year, hearth fires in family homes were left to burn out while the harvest was gathered.
After the harvest work was complete, celebrants joined with Druid priests to light a community fire using a wheel that would cause friction and spark flames. The wheel was considered a representation of the sun and used along with prayers. Cattle were sacrificed, and participants took a flame from the communal bonfire back to their home to relight the hearth.
Early texts present Samhain as a mandatory celebration lasting three days and three nights where the community was required to show themselves to local kings or chieftains. Failure to participate was believed to result in punishment from the gods, usually illness or death.
There was also a military aspect to Samhain in Ireland, with holiday thrones prepared for commanders of soldiers. Anyone who committed a crime or used their weapons during the celebration faced a death sentence.
Some documents mention six days of drinking alcohol to excess, typically mead or beer, along with gluttonous feasts.