Halloween

Pope Boniface IV established All Saints' Day, originally on May 13, in the 7th century C.E., but in the following century, perhaps in an effort to supplant the pagan holiday with a Christian observance, it was moved to November 1. The evening before All Saints' Day became a holy, or hallowed, eve and thus Halloween.

It begins the observance of Allhallowtide, the time in the liturgical year dedicated to remembering the dead, including saints, martyrs, and all the faithful departed.