Following the establishment of All Hallows' Day and its vigil, All Hallows' Eve in the 8th century A.D., Odilo of Cluny popularized the day to pray for All Souls, forming the third day of the triduum of Allhallowtide. It has been thought that the first three days of Allhallowtide may have originated as a ritualistic remembrance of the deluge in which the first night, Hallow's Eve remembers the wickedness of the world before flood. The second night then celebrates the saved who survived the deluge and the last night celebrates those who would repopulate the Earth.