Samhain (pronounced Sah-wen) began as a Celtic festival marking the end of the harvest season and the beginning of winter or the darker half of the year. However, it is thought that Samhain had its beginnings in an ancient, pre-Christian Celtic festival of the dead. It is celebrated from sunset on 31 October to sunset on 1 November, which is nearly halfway between the autumn equinox and the winter solstice.
According to the ancient Celtic calendar, the year began on a day corresponding to November 1st on our present calendar. Since the Celts were a pastoral people, it was a time when cattle and sheep had to be moved to closer pastures and all livestock had to be secured for the winter months. Crops were harvested and stored. The date marked both an ending and a beginning in an eternal cycle.
The Celtic peoples, who were once found all over Europe, divided the year by four major holidays – Imbolc, Beltane and Lughnasadh and Samhain. It was observed in Ireland, Scotland and the Isle of Man. Kindred festivals were held at the same time of year in other Celtic lands; for example the Brythonic Calan Gaeaf (in Wales), Kalan Gwav (in Cornwall) and Kalan Goañv (in Brittany).
Irish mythology was originally a spoken tradition, but the tales were eventually written down by Christian monks in the Middle Ages. According to Irish mythology, Samhain (like Beltane) was a time when the doorways to the Otherworld opened enough for fairies and the dead to communicate with us; but while Beltane was a summer festival for the living, Samhain "was essentially a festival for the dead".
The Boyhood Deeds of Fionn says that the sídhe doorways (fairy mounds or portals to the fairy world) "were always open at Samhain". Like Beltane, Lughnasadh and Imbolc, Samhain also involved great feasts. Mythology suggests that drinking alcohol was part of the feast, and it is noteworthy that every tale that features drunkenness is said to take place at Samhain.
Many important events in Irish mythology happen or begin on Samhain. The Second Battle of Maighe Tuireadh beganon Samhain. In the days of the Tuatha Dé Danann, the Morrígan and the Dagda meet and have sex before the battle against the Fomorians; in this way the Morrígan acts as a sovereignty figure and gives the victory to the Dagda’s people, the Tuatha Dé Danann. The Morrigan is thought of as one of many triple goddess personifications.
Beings and souls from the Otherworld were said to come into our world at Samhain. It is still the custom in some areas to set a place at the Samhain feast for the souls of dead kinfolk and to tell tales of one’s forebears.
Fairies were thought to steal humans on Samhain and fairy mounds were to be avoided. People took steps to allay or ward-off these harmful spirits and fairies. They stayed near to home or, if forced to walk in the darkness, turned their clothing inside-out or carried iron or salt to keep the fairies at bay. Offerings of food were left at the door for the fairies to ensure their favor in the coming year.
Turnip lanterns, sometimes with faces carved into them, were common at Samhain in the 19th century in parts of Ireland and the Scottish Highlands. The purpose of these lanterns may have been threefold. They may have been used to light one’s way while outside on Samhain night; to represent the spirits and otherworldly beings; and/or to protect oneself and one’s home from them. They were sometimes set on windowsills to keep the bad spirits out of one’s home.
Wearing costumes and masks may have been another way to befuddle, ward-off the harmful spirits and fairies. Guising or mumming was common at winter festivals in general, but was particularly appropriate to a night upon which supernatural beings were said to be abroad. In Ireland, costumes were sometimes worn by those who went about before nightfall collecting for a Samhain feast. Trick-or-treating may have come from the custom of going door-to-door collecting food for Samhain feasts, fuel for Samhain bonfires and/or offerings for the spirits and fairies.
Wiccans celebrate a variation of Samhain as one of the yearly Sabbats of the Wheel of the Year. It is deemed by most Wiccans to be the most important of the four "greater Sabbats". Samhain is seen by some Wiccans as a time to celebrate the lives of those who have died, and it often involves paying respect to ancestors, family members, elders of the faith, friends, pets and other loved ones who have died. In some rituals the spirits of the dead are invited to attend the festivities. It is seen as a festival of darkness, which is balanced at the opposite point of the wheel by the spring festival of Beltane, which Wiccans celebrate as a festival of light and fertility.