Samhain was a hig holy day of the pre-Christian Celts. It celebrated the completed harvest and the start of a new year. During this time of transition barriers between yhe natural and supernatural world were reduced and spirits could easily return. Even after Christianity became the new religion of the Celts they continued to observe Samhain. When the clergy could not stamp out, what they considered a pagan practice, Rome invented All Saints Day to mask the celebration and to try and give it some legitamacy. Many aspects of other Christian hollidays also reflect Celtic Druidism.