Samhain, October 31st, the Celtic Pagan religious festival. End of Summer, end of the harvest, and beginning of the darkest period of the year. For the original and ancient cult, it was the end of the year, and also according to other, more sulfurous pagan cults. The date appears in the Compendium Maleficarum of 1608, written by Francesco Maria Guazzo, marked as the second more influential Witches Sabbath, after The Walpurgis Night at the end of April.
Back in time, they wrote many analyses about the last day of October. From the original pagan festival throughout cultural reinterpretations. Renamed in middle English Alholwmesse, meaning All Saints’ Day, it became eventually Halloween.