All Hallows' Eve is the evening before the Christian festival of All Saints Day, otherwise known as All Hallows. The word hallows is from Old English halig, a holy man. It was originally held on the 1st of May, but in 834 the Christian church moved it to the 1st of November. It is held to celebrate Pope Boniface IV's desecration of the Pantheon at Rome in 610. The Pantheon was originally a Pagan temple dedicated to all the gods of the Romans.
The Celtic New Year
The Celts counted their days from sundown to sundown and hence what we call the 'eve,' i.e. the time before, of this festival was the beginning of it. For the Celtic peoples of Europe this was the time of Summer's End, akin to our modern New Year's Eve. It was a time when the veil between the worlds of the living and the dead was at its thinnest, a time for honouring the departed and seeing into the future.
Old Hallowe'en, or Hallowe'en Old Style (usually abbreviated O.S.), is the day on which the sun reaches 15 degrees Scorpio and is the old Scottish Quarter Day of 11th November, since Christianised as Martinmas Day. It is a significant astrological date, sometimes described as a "power point" and symbolised by the eagle.
Many other cultures celebrate this time as a festival of the dead from ancient Egypt to pre-conquest Mexico.
In an ingenious perversion of the truth Christians have persuaded themselves that witches held their sabbats around the time of the high Christian festivals in evil mockery of their faith. In actual fact the Christian church strategically planted its arbitrary festivals on Pagan holy days to subvert them.
Today Halowe'en enjoys widespread popularity. In the British Isles it has always been commemorated with fun and games, and since large scale Irish emigration to the USA in the 1840's has developed strong roots in modern American culture too. Now one sees its popularity gaining ground in the previously staunch Catholic countries of France and Germany. And yet every year, guaranteed, some misguided Christian, somewhere, will be campaigning to ban it.
Hallowe'en in Modern Witchcraft
Originally celebrated as November Eve by Wicca, Samhain, as it now more commonly known, is widely celebrated as the principle festival of Witchcraft, the Grand Sabbat. In the Alexandrian tradition it is said that "Samhain is the time when doors of the Underworld are open for the Witches, and they can communicate with the dead and those ancestors to whom they look for guidance" (Alex Sanders, The Alex Sanders Lectures. Magickal Childe, 1984).